KaWaTech Pre Design

8/20/2019 KaWaTech Pre Design

http://slidepdf.com/reader/full/kawatech-pre-design 1/135

MOST-BMBF

joint project

Vietnamese-German Cooperation for the Developmentof sustainable Karst Water Technologies

Pre-Design

for the pilot implementation of a hydro power driven water

pumping and distribution system(“Concept 1” )

Edited by Karlsruhe Institute for Technology (KIT)

Institute for Water and River Basin Management (IWG), Prof. Dr.-Ing. Dr. h.c. mult. Franz Nestmann

Institute of Concrete Structures and Building Materials (IMB), Prof. Dr.-Ing. Harald S. Müller

With contribution of KSB AG

Division for Hydraulic Services, Dr.-Ing. Jochen Fritz

Karlsruhe, 10.03.2015



Pre-Design

/ 127

Content

1 Introduction ...................................................................................................................................... 4

1.1 Background and objective of the document .......................................................................... 4

1.2 Summary of the planned pilot system for hydro power driven water pumping and

distribution (Concept 1) ......................................................................................................... 5

1.2.1 Motivation and objective ......................................................................................... 5

1.2.2 Hydro power driven water pumping module at Seo Ho HPP for water conveying

to Ma U ................................................................................................................... 6

1.2.3 System to distribute water from Ma U to the supply area Dong Van City ............ 10

1.2.4 Systems to distribute water from Ma U to the supply areas Sang Ma Sao and

North Slope .......................................................................................................... 12

1.3 Overview of the measures described in the Pre-Design ..................................................... 12

2 Specification of measures .............................................................................................................. 14

2.1 Weir and intake structure ..................................................................................................... 14

2.1.1 Location and present state ................................................................................... 14

2.1.2 Description of measures ...................................................................................... 15

2.1.3 Materials and services ......................................................................................... 16

2.2 Sand trap ............................................................................................................................. 16


2.2.2 Description of measures to minimize water losses and to prevent flotsam entry

into the headrace channel .................................................................................... 17

2.2.3 Description of measures to improve the sediment deposition capacity ............... 18


2.3 Headrace channel ............................................................................................................... 25




2.4 Intake pool ........................................................................................................................... 28




2.5 Penstock bypass to PAT-pump-modules ............................................................................ 39





Pre-Design

/ 127


2.6 Extension of power house and tailwater pool ...................................................................... 50

2.6.1 Location of power house extension ..................................................................... 50



2.7 Machinery and equipment ................................................................................................... 56



2.8 Pressure supply pipe ........................................................................................................... 60

2.8.1 Location ................................................................................................................ 60


2.8.3 Material and services ........................................................................................... 77

2.9 Distribution tank Ma U ......................................................................................................... 81

2.9.1 Location ................................................................................................................ 81

2.9.2 Functionality ......................................................................................................... 82



2.10 Distribution from the tank Ma U to the tank Dong Van City ................................................. 91

2.10.1 Location ................................................................................................................ 91


2.10.3 Materials and services ....................................................................................... 100

2.11 Storage tank Dong Van City .............................................................................................. 103

2.11.1 Location .............................................................................................................. 103

2.11.2 Description of measures .................................................................................... 104


2.12 Distribution from the tank Dong Van City to the existing network of Dong Van City ......... 112

2.12.1 Location .............................................................................................................. 112

2.12.2 Description of measures .................................................................................... 112


3 Summary of materials and services ............................................................................................. 119

4 Time schedule .............................................................................................................................. 126

Attachment A Isometric drawings of penstock bypass

Attachment B Isometric drawings of pressure supply pipe



Pre-Design

/ 127

1 Introduction

1.1 Background and objective of the document

September 2013 marks the beginning of the Vietnamese-German Cooperation for the Development of

Sustainable Karst Water Technologies (KaWaTech) funded by the Vietnamese Ministry of Science

and Technology (MOST) and the German Federal Ministry of Education and Research (BMBF). The

joint R&D-project is scheduled until August 2016.

On 19th

of February 2014 the Vietnamese and German partners agreed on implementing a pilot

system for hydropower driven water pumping and distribution based on a novel technical concept –

the so called Concept 1 (see Minutes of Discussion from 19.02.2014 and Reconfirmation Document

from 27.02.2014). The draft of Concept 1 contains the implementation of a hydropower driven water

pumping module at the existing Seo Ho hydropower plant (later referred to as Seo Ho HPP) to partially

pump up the river’s water to the village of Ma U. This water supply system shall be characterized by

high efficiency and robustness as well as by low operation and maintenance costs and effort in order

to enable a sustainable long-term operation. Furthermore, the draft includes the construction of a new

storage and distribution tank at Ma U as well as of new distribution facilities. Hereby, starting from the

tank, water might be distributed to the three supply areas Dong Van City, the villages around Sang Ma

Sao and the villages northeast of Dong Van City (see Fig. 1).

In line with the decision on the pilot implementation the partners also agreed on a task distribution as

well as on a preliminary implementation schedule (see Minutes of Discussion from 19.02.2014 and

Reconfirmation Document from 27.02.2014). In principle, the German partners are responsible fordeveloping the technical concept, the Bill of Quantities and the successive Pre-Design.

Furthermore, they are in charge for the development, testing and provision of the innovative

water pumping modules including their transport to Vietnam. In addition, they support the

implementation through expert monitoring with temporary technical accompaniment on site

and the accomplishment of capacity development measures. The Vietnamese partners are

responsible for preparing the Final Engineering Design as well as for the accomplishment and

financing of the successive construction and implementation works including the provision of

materials and transport to the construction site, custom duties and domestic transport for

materials delivered to Vietnam by the German partners.

The construction start of the system parts Seo Ho HPP – Tank Ma U – Dong Van City (see section

1.2.2 and 1.2.3) is planned for summer 2015. The implementation of the facilities to distribute water to

the villages around Sang Ma Sao and to the villages northeast of Dong Van City (see section 1.2.4)

could commence at the same time or at a later date.

The Bill of Quantities for the pilot implementation of a hydro power driven water pumping and

distribution system (“Concept 1”) (later referred to as Bill of Quantities) was handed over for budget

planning of Concept 1 in June 2014 from the German to the Vietnamese partners. At the end of

October 2014 the German partners received the message via VIGMR that the financing had been

approved. The present document Pre-Design for the pilot implementation of a hydro power driven

water pumping and distribution system (“Concept 1”) (later referred to as Pre-Design) is based on this

document. However some sections of the present Pre-Design include comprehensive updates. For the

preparation of this present document additional field trips to Dong Van in July/August 2014 andNovember 2014 and laboratory investigations were carried out by KIT.



Pre-Design

/ 127

The scope of this present document is to provide a pre-design including specific data which

can be used by the Vietnamese partners for preparing the Final Engineering Design. The

development of this Final Engineering Design by the Vietnamese partners has to consider the

national standards, the actual local boundary conditions, the provision of materials, custom

duties, the domestic transport and the execution of the construction works. Both the Pre-

Design and the Final Engineering Design shall be comprehensively reviewed by the German

and the Vietnamese side in order to develop a collaborative project plan resp. plan of measures

considering all relevant influencing factors.

The basic concepts of the planned pilot implementation are explained in more detail in section 1.2.

The necessary measures are outlined in section 1.3 and specified in section 2. The bill of materials is

stated in section 3 and refers to the measures described within this pre-design. The preliminary time

schedule is shown in section 4.

1.2 Summary of the planned pilot system for hydro power driven water

pumping and distribution (Concept 1)

1.2.1 Motivation and objective

In the area of Dong Van Karst Plateau water supply is insufficient due to the regional topographic,

climatic, hydrological and geological conditions. Because of the karst underground in the mountainous

region and its high infiltration rate, most water bodies of the region are found only in complex cave

systems or deep valleys, making its usage difficult for the region’s inhabitants. In combination with thetypical concentration of rain over three to four months in summer, this leads to a glaring lack of water

in the region, especially in the dry months. The Dong Van Karst Plateau was declared Global Geopark

assisted by UNESCO in 2010. While the expected resulting increase in tourism in the region offers

opportunities for economic development, it will also increase the water demand and, thus, worsen the

already existing problem of water scarcity.

Especially in such climates with a distinctive dry season, small and micro hydropower plants without

seasonal reservoir often can only be operated in low partial load ranges with greatly reduced efficiency

grades due to low available discharges. As a consequence, power plants with low economic or

mechanical efficiency are temporarily shut down during dry periods. During these shutdown periods,

precious water for both power generation as well as for water supply remains unused. The scope of

the KaWaTech project is to develop a hydro power driven water pumping module to exploit the

remaining unused water quantities for pumping and supply (Concept 1).

It is planned to realize a pilot implementation of Concept 1 at the existing Seo Ho HPP, which is

situated at 705 meters above sea level (masl). By mechanically coupling reverse driven pumps, which

then function as turbines (Pump as Turbine, PAT), to high pressure water pumps, water can be

delivered from Seo Ho HPP via a high pressure supply pipe to a distribution tank in the village of Ma

U, situated on a mountain ridge at 1,250 masl. From there, the water will be distributed by an

innovative system of pipelines and storage tanks to the main town of the area, Dong Van City, the

villages surrounding Sang Ma Sao (supply area Sang Ma Sao) and the villages northeast of Dong Van

City (supply area North Slope). Due to the extreme topography and the associated high delivery heads

of up to approx. 550 m, requirements regarding machinery and supply pipes are high. Fig. 1 outlinesthe situation. The hydro power driven water pumping module at Seo Ho HPP including the supply pipe



Pre-Design

/ 127

to Ma U is described in more detail in the next section 1.2.2. The planned system to distribute water

from Ma U to the supply areas Dong Van City, Sang Ma Sao and North Slope is described in the

subsequent sections 1.2.3 and 1.2.4.

Fig. 1: Map of Seo Ho HPP area – Layout of the measures in the project area

1.2.2 Hydro power driven water pumping module at Seo Ho HPP for water conveying to Ma U

Fig. 2 illustrates schematically the infrastructure of the existing Seo Ho HPP as well as the main

components of the planned hydro power driven water pumping system. Fig. 3 shows the vertical

profiles of the existing penstock and the supply pipe to the distribution tank Ma U.

Fig. 2: Major components of the planned hydro power driven water pumping system (additional components to beconstructed are printed in blue; existing components to be restored/modified in red)



Pre-Design

/ 127

Fig. 3: Vertical profiles of the existing penstock and the supply pipe

The intake structure, which is situated on the weir crest, diverts water from Seo Ho River into the sand

trap. After passing the two sand trap basins, the water runs mostly underground through the headrace

channel into the intake pool. The lateral overflow of the intake pool is used to purge water in case the

available amount exceeds the amount required for machinery operation. From the intake pool, the

water runs into the penstock, where it is conducted to the existing turbines (see section 2.1 - 2.4).

As described in this present document, the penstock could be connected to new PAT-pump-modules

by a branch-off pipe (penstock bypass), which can be implemented according to the draft shown in

section 2.5. In order to secure these pumping modules, the existing powerhouse of Seo Ho HPP might

be extended (see section 2.6). Here, a pipe system feeds the two modules, each consisting of a PAT

and a pump.

The machines will be mechanically coupled, meaning that the energy generated by the PAT is

transmitted directly to the pump without the need of intermediate conversion to electrical energy (see

section 2.7). From the PATs, the water will be discharged into a tailwater pool and then flow back into

Seo Ho River through an open channel (see section 2.6). According to this concept, the water from the

pumps will run through a new high pressure supply pipe with approximate length of approx. 2,460 m to

a new distribution tank situated in the village Ma U, overcoming a total height difference of approx.

550 m referring to Seo Ho HPP (see section 2.8). Fig. 4 shows the flow system in the existing

powerhouse and the new extension building.

According to preliminary design approaches, the water supply machinery to be installed next to Seo

Ho HPP will consist of two identical modules, each using a KSB Multitec (multistage centrifugal pump)

with 5 stages as PAT (efficiency approx. ηmax = 71 %) and a KSB Multitec with 16 stages as pump

(efficiency approx. ηmax = 69 %). Each module has a total design flow (discharge PAT and pump) ofapprox. Qtotal = 54 l/s including a design delivery rate of approx. Qpump = 11 l/s.



Pre-Design

/ 127

Compared to the PAT-driven modules Seo Ho HPP shows a lower maximum total efficiency of

ηmax = 63 % (efficiency of turbines and generator). In low partial load operation (discharge below

100 l/s) the plant’s efficiency even decreases to 49 – 57 % (calculation by KIT based on on-site

measurements). To supply water with the electricity generated by Seo Ho HPP, an electric motor is

required which is also afflicted with energetic losses (maximum efficiency of a new electric motor

suitable for this application at 93 – 95 %) and further decreases the total efficiency. Thus, at

discharges below 100 l/s the PAT-driven modules can be operated more efficiently instead. Here,

besides the above mentioned efficiencies for PAT and feed pump no more energetic losses will occur

due to the direct coupling of both machines.

Fig. 4: Current draft of the flow schematics inside the power house and the extension building



Pre-Design

/ 127

In this regard the parallel setup of 2 modules is particularly advantageous since they can be operated

in single or in dual mode to cover a wide range of lowest discharges (see Fig. 5). Hereto, a throttling

device for both modules is included in the design to cover these low flow rates. Thus different

operational strategies are possible depending on the available water yield.

Fig. 5: PAT-pump-module and pump discharge diagram

Single module operation: The operation of 1 module requires a total minimum flow of approx. 42 l/s

(fully throttled down) to approx. 54 l/s (not throttled) delivering approx. 6 l/s (fully throttled down) to 11

l/s (not throttled). With the use of the throttling device, water pumping operation is ensured even in

times of extreme drought (which coincides with very high water demand of the local people).

Dual module operation: The operation of 2 modules requires a total minimum flow of approx. 83 l/s

(fully throttled down) to approx. 105 l/s (not throttled) and will net a delivery rate of approx. 11 l/s (fully

throttled down) to 20 l/s (not throttled). This operation mode is depending on a sufficient water yield

but shall be used in times of high water demand in the supply areas. According to data analyses and

measurements carried out by KIT in the last three years, the minimum runoff of Seo Ho River during

dry season amounted approx. to 100 - 120 l/s. This would be sufficient to operate both modules.

Parallel operation to Pelton turbine: Due to the low total flow required to operate a single module,

parallel operation of a module and a turbine (if requested) should be feasible throughout the whole

year. The minimum flow to operate one Pelton turbine is approx. 65 l/s. In addition to the necessary

discharge of 54 l/s for a PAT-pump-module (not throttled), the total required discharge of approx.

119 l/s corresponds to the average dry season runoff of 100 - 120 l/s (average value in the period the

last three years).



Pre-Design

/ 127

Within the stated discharge ranges the PAT-driven water supply plant can be operated highly flexible

regarding the prioritization of water supply and/or generation of electricity. Depending on the

respective demand the operating personnel can decide at any time if the works water shall be used for

water supply and/or generation of electricity.

In summary, the planned system has the following advantages:

High level of operating reliability even during extreme dry periods with minimal discharge

Redundancy concerning damage or malfunction of single machines and/or components

Interchangeability of (spare) parts

Low maintenance and training requirements

Low complexity of the control system

Parallel operation of PAT-pump-module and turbine possible throughout the whole yearFlexibility of control and regulation as well as towards future water demand increases

PAT efficiency exceeding the Pelton turbines’ efficiency

1.2.3 System to distribute water from Ma U to the supply area Dong Van City

Fig. 6: Overview project area with the supply system

To distribute the pumped water from the tank at Ma U to the supply areas technically robust solutions

were developed which basically do not require any daily operation effort (“self -running system”).

Furthermore the solutions allow a planned limitation of the water quantities distributed. Thus, the

consumers are able to only realize withdrawals not higher than the water quantity allocated to the

consumers. This enables an equitable distribution of the available water resources. The distribution to

Dong Van City is described in the following.



Pre-Design

/ 127

The tank at Ma U has two functions. It has a certain storage capacity to buffer the variations between

inflow and outflow. In order to distribute certain proportions of the inflow to the supply areas, the tank

furthermore serves as a facility to divide the inflow proportionally into three defined outflows to the

supply areas Dong Van City, Sang Ma Sao and North Slope.

The tank’s construction sees a pre-chamber which collects the total inflow (water pumped from Seo

Ho HPP). The pre-chamber has three weirs. The weir overflows are collected in three chambers from

which the water is distributed through pipes to the supply areas. The allocation of the inflow to the

three chambers and, thus, the definition of the proportion of the inflow, each supply area is supplied

with, can be flexibly defined by choosing the width of the weirs (weir overflow/total inflow = weir

width/total weir width). The advantage of that solution is the fact that the varying inflow is proportionally

allocated to the supply areas without any daily operation.

Fig. 7: Unscaled scheme of the storage tank at Ma U

It is planned to distribute the water to the supply areas according to the prevailing water demand within

the supply areas. The main share will be distributed to Dong Van City via a supply pipe to a storage

tank above Dong Van City. The tank is connected to the distribution network of Dong Van City (close

to the existing pumping station). The elevation of the tank of 1,123 masl above Dong Van City allows a

supply of Dong Van City by gravity. The system input and pressure is controlled by a plunger located

at the connection point. The outflow pipe to the distribution network may be constantly open. The

installed house tanks with floating valves within the distribution network prevent wastage of water at

the consumer level. To limit the pipe pressure due to the elevation difference between the tank at Ma

U and the tank above Dong Van City a pressure breaker facility has to be installed. This facility

basically is a small tank.



Pre-Design

/ 127

Fig. 8: Unscaled scheme of a pressure breaker with floating valve

The pressure breaker and the tank Dong Van are equipped with floating valves to control the inflow

into the tanks. Whenever the water level within the tank Dong Van reaches its maximum the floating

valve stops the inflow and prevents tank overflow. The water level of the pressure breaker rises until

the according floating valve stops the inflow. Finally the water level within the according chamber of

the tank Ma U rises. Possibly it reaches the weir height and water level within the pre-chamber

respectively. In this case the water not used in Dong Van City is distributed to the other supply areas.

In case the existing elevation difference between the tank Ma U and Dong Van City shall be exploited

for hydro power generation someday in future the planned pipe infrastructure may be used. The

pressure breaker then simply has to be by-passed.

1.2.4 Systems to distribute water from Ma U to the supply areas Sang Ma Sao and North Slope

To supply the villages around Sang Ma Sao a new distribution tank is connected via a pipe to the

according chamber of the tank in Ma U (see section 1.2.3). The distribution tank consists of a pre-

chamber and two chambers. The functioning of the proportional allocation of the water works like the

tank in Ma U by weirs which is described in section 1.2.3. One chamber serves as storage for the

population and the school of Sang Ma Sao. The second chamber supplies the already existing three

village tanks.

To supply the 12 villages northeast of Dong Van City within the so called supply area North Slope a

pipe connects four distribution tanks to the according chamber of the Ma U tank. The design and the

operation of the distribution tanks are equal to the one in Sang Ma Sao. One chamber of each

distribution tank supplies village tanks and the second chamber the next distribution tank. In mostvillages already existing village tanks and pipes can be integrated into the distribution system. The

village tanks have to be equipped with floating valves. These would close the inlet if the tank is full.

Thus, the water which is not needed in one village is available for other villages.

1.3 Overview of the measures described in the Pre-Design

In the following Fig. 9 an overview of the measures and its location is given. The specification of each

measure can be found in section 2.



Pre-Design

/ 127

Fig. 9: Overview of the measures and its location

Tab. 1: Overview of the measures in the project area (see Fig. 9)

Number Section of the measure

1 2.1 Weir and intake structure

2 2.2 Sand trap

3 2.3 Headrace channel

4 2.4 Intake pool

5 2.5 Penstock bypass to PAT-pump-modules

6 2.6 Extension of power house and tailwater pool

7 2.7 Machinery and equipment

8 2.8 Pressure supply pipe

9 2.9 Distribution Tank Ma U

10 2.10 Distribution from the tank Ma U to the tank Dong Van City

11 2.11 Storage tank Dong Van City

12 2.12 Distribution from the tank Dong Van City to the existing network of Dong Van City

13 2.13 Distribution to the supply area Sang Ma Sao, see annotation

14 2.14 Distribution to the supply area North Slope, see annotation

Annotation: The specification of the measures 13 and 14 are not part of this Pre-Design

document. These will be handed in later.



Pre-Design

/ 127

2 Specification of measures

Important note:

In this chapter the measures for the implementation of concept 1 are specified. For sections 2.2 and

2.4 it has to be noted that some measures are optional and have to be implemented only on

demand. The chronological dependencies between the construction measures, which are described in

detail in sections 2.5 to 0, have to be respected during the planning and implementation process. In

section 4 a time schedule is shown which summarizes all single implementation steps.

2.1 Weir and intake structure

2.1.1 Location and present state

The weir is the part of the hydro power plant which shows the most severe damages. It is located in a

steep part of the valley, shortly before the river overcomes a height difference of 200 m through

various cascades. The weir is a conventional overflow weir with a height of 5.8 m and a width of 17 m.

On the right side of the weir crest (in flow direction), there is an intake structure consisting of an inlet

channel, which directs water to the sand trap (see Fig. 10). The channel is covered by a metal grid

with a width of 0.5 m and a length of 5 m. This rack’s rods have a clearing of approx. 3 cm and prevent

larger bed loads and other solid materials to enter the sand trap and the headrace channel,

respectively. According to the construction plans, the channel has a declination of 13.2 % and a depth

between 0.30 and 0.86 m.

Fig. 10: Weir and intake structure (5.12.2014, KIT)

The weir is subdivided in the middle in two parts with different geometry. The right part with the intake

channel has a length of 8.5 m and an inclination of 45°. The other side also has a length of 8.5 m but

an inclination of 55° with a step at its end. The weir crest and the weir backs do not show a hydro-



Pre-Design

/ 127

dynamically optimized form. The structure does not consist completely of concrete, but shows a core

of raw and crude limestone stuck together, similar to prepacked concrete which is covered with a top

layer of concrete. A crosswise reinforcement of flat steel bars with a diameter of 8 mm in a distance of

100 mm was detected.

In the steeper part of the weir, an additional layer of concrete was apparently applied on the weir crest

at a later point of time, probably to restore the original crest height after strong erosion processes.

However, that layer is separated with an aquiferous crack over the whole length from the concrete

underground (see Fig. 11).

Fig. 11: Undermined weir part on theright side of the weir (5.12.2014, KIT)

Fig. 12: Hydro abrasion on weir back (5.12.2014, KIT)

The whole weir shows severe damages due to hydro-abrasion and water undermining. Further, the

wall on the right side was recently damaged by a rock fall. The weir crest is heavily eroded, the

reinforcement partly not covered by concrete anymore.

The same can be stated for the weir back, where the concrete cover and even partly the reinforcement

are ground down on the whole width by hydro-abrasion. This is particularly apparent in the middle of

the weir where the concrete cover is completely gone and the rock core opened (see Fig. 12).

2.1.2 Description of measures

The intake structure is an integral part of the hydro power plant and is part of the weir. Therefore, as a

first step it is reasonable to secure the weir structure against any further damages which could result in

an impairment of the intake structure. This includes particularly the stabilization or reconstruction,

respectively, of the weir base on the right side to prevent a future slipping of the weir.

This measure could be realized similar to the construction of the present structure (compare Fig. 9)

with the usage of prepacked concrete. The omnipresent raw limestone aggregates are assembled at

the beginning without mortar to form the raw shape of the intended weir structure.



Pre-Design

/ 127

The aggregates generally should have a medium diameter between 80 and 150 mm. They can

originate from karst limestone quarries near to the site or can be even collected directly from the

surrounding of the site. These raw aggregates should be slightly fractionized and stuck together with

cement mortar to form the chosen structure, which should be subsequently covered with a layer of

crosswise reinforced concrete.

2.1.3 Materials and services

Tab. 2: List of materials and services for measures at the weir and intake structure

Position Materials / services and description Amount Unit

2.1 Transportation of materials to construction site 1 ls

2.2 Excavation of the weir base area on the right side (limestone can be partlyused for reconstruction of the weir base)

10 m³

2.3 Stabilization of the weir basis with prepacked concrete and reinforcedconcrete, respectively

20 m³

2.2 Sand trap


From the intake structure on the weir crest, the water flows into the sand trap. The sand trap consists

of two long and narrow basins, measuring 17 and 14 m in length with a minimum width of 1.4 m. The

construction is separated in the middle with a cross-section constriction, which once kept a sluice gate,but now is constantly open. The sand trap is bordered by a high and steep wall against the mountain

slope on the right side, on the left side by masonry with a width of 50 cm starting from the ground. This

results in a depth of the sand trap between 2.1 and 3.5 m. The masonry built out of raw limestone is

plastered with a cement mortar.

The first basin of the sand trap has a length of 14 m and a width of 1.4 m. Originally several

crossbeams made out of reinforced concrete were arranged 1 m below the wall crest to support the

right wall and probably to act as bearings for a channel ceiling. However, most of the beams were

destroyed by rock fall. The second basin has a length of 17 m and a starting width of 1.8 m, but

passes over at its end in a square basin with an edge length of 4 m. On the right side at the end of the

second basin, there is the intake opening to the headrace channel with a size of 60 × 70 cm (W x H).

Steel sluice gates are installed in both basins on the left side to allow emptying and sediment flushing.

The pools are overall seen in a sufficiently good structural condition and show, besides some

vegetation covering, no essential damages. An exception can be seen in the first basin, where both

the left and the right wall were damaged by a serious rock fall. Parts of the masonry were torn down

and a rock remained situated on the masonry (see Fig. 13). The mentioned cross-beams were

probably also destroyed due to this event. However the resulting debris in the sand trap was removed,

so that no further loss of its functionality currently exists. Other damages can be observed at the sluice

gate in the second basin, where the anchorage is broken out (see Fig. 15). The other sluice gate

shows no such damage, probably due to the larger width of the wall resulting in a bigger load

distribution area. Significant water losses (20 to 30 l/s measured during a field trip in February 2014)

can be observed at the sluice gates as the gates are not closing correctly, with remaining gaps on thechannel bed and on the lateral guidance of the gates.



Pre-Design

/ 127

Fig. 13: Sand trap, view from upstream (5.12.2013, KIT) Fig. 14: Sluice gate of second pool (25.02.2014, KIT)

2.2.2 Description of measures to minimize water losses and to prevent flotsam entry into the

headrace channel

To minimize water losses and to improve the yield of the plant, especially during dry seasons,

leakages at the sluice gates have to be avoided. Therefore, the gate structures have to be examined

and restored to a proper functionality, sealing any gaps in the gate channel bed and the lateral

guidance. Additionally, concrete rehabilitation works are necessary at the gate anchorage structures.

Fig. 15: Broken sluice gate anchorage (13.12.2014, KIT) Fig. 16: Water losses from gate (13.12.2014, KIT)

To prevent flotsam entering the headrace channel respectively the intake pool and penstock a trash

rack has to be installed between the outlet of the sand trap and the intake of the headrace channel.

Fig. 17 shows the current state of the headrace channel’s intake, Fig. 18 a sketch with themodification. The trash rack rods should have a round profile with a diameter of approx. 2 cm. The



Pre-Design

/ 127

spacing of the rods to each other should be approx. 6 to 8 cm. The trash rack itself should have a

leaning slope of 70° to 80° relative to the horizontal, should be side-mounted with hinges and lockable

e.g. with padlock. Thereby it can be opened for cleaning purpose and to access the headrace channel.

The trash rack should be embedded on a box of concrete or stonework and a metal plate (see Fig.

18). All metal parts of the trash rack should be rust-proof.

The trash rack should be installed on a concrete foundation made out of prepacked concrete. The

ground structure of limestone should be covered by a layer of reinforced concrete. The principal

construction method is explained in section 2.1.2.

Fig. 17: Current state of headrace channel intake(25.02.2014, KIT)

Fig. 18: Intake of headrace channel intake aftermodification with trash rack

2.2.3 Description of measures to improve the sediment deposition capacity

2.2.3.1 Background information sediment deposition capacity

Suspended loads are mineral or organic particles that are carried by water. Concentration and grain

size of suspended loads in works water of hydropower plants are significant parameters for the

durability of turbines and pumps. Medium to long-term exceedance of limiting values of those

parameters can cause hydro-abrasional damage to the machinery. To protect the intended PAT-

pump-modules (developed and delivered by KSB AG), it is necessary to comply with the following limit

values, which match with the common requirements for high-pressure hydro power plant applications:

- Maximum suspended load concentration: 20 mg/l

- Maximum grain size of suspended load: 0.25 mm

0.7 m

0.85 m



Pre-Design

/ 127

2.2.3.2 Evaluation of critical grain size

Sand trap and intake pool are located upstream to the intended PAT-pump-modules and have a

sediment deposition capacity which is depending on their geometric dimensions. Thereby those

structures can help to comply with the above stated limiting values. Hereto the critical grain size of

existing sand trap and intake pool was evaluated by KIT applying theoretical analysis approaches of

Vischer & Huber 1 and Ortmanns

2. Generally, suspended grains, which are smaller than a certain

critical grain size, cannot be fully withheld inside a hydraulic structure; in the present case they would

partially enter the penstock. The mentioned approaches consider the settling path of a suspended

grain and the necessary sedimentation basin length (see schematic diagram in Fig. 19). Thereby the

approach of Vischer & Huber takes into account the reduction of the settling velocity caused by basic

turbulence which generally characterizes open channel flows. Ortmanns considers in addition the

turbulence impact in the inlet zone of a sedimentation basin.

Fig. 19: Simplified settling path of a suspended grain

With a discharge of Q = 400 l/s (max. hydraulic capacity of the headrace channel, calculated by KIT

based on on-site measurements including safety margins), an effective sand trap dimension of 15 x

1.4 x 0.8 m (L x W x H) and an effective intake pool dimension of 6.5 x 2.1 x 2.7 m (L x W x H), the

critical grain size can be determined with both approaches as shown in Tab. 3.The effective dimension

of the basin neglects the basin’s edge areas due to their reduced sediment deposition capacity.

Tab. 3: Critical grain size of sand trap and intake pool (the inlet area is hereby not considered)

Approach Sand trap Intake Pool

Vischer & Huber ~ 0.5 mm ~ 0.3 mm

Ortmanns ~ 0.4 mm ~ 0.7 mm

1 Vischer und Huber, Wasserbau: Hydrologische Grundlagen, Elemente des Wasserbaus, Nutz- und

Schutzbauten an Binnengewässern. Publishing house Springer 20022 Ortmanns, Entsander von Wasserkraftanlagen. Publishing house Versuchsanstalt für Wasserbau,

Hydrologie und Glaziologie ETH-Zentrum 2006



Pre-Design

/ 127

For these results it has to be considered that both approaches have been empirically developed and

entail uncertainties. However they lead to the conclusion that the limiting values for the maximum grain

size cannot be complied with the existing sand trap and intake pool of the Seo Ho HPP.

For further evaluations of the sediment deposition the KIT carried out in situ investigations of the

suspended loads and their concentration during field trips to Dong Van in July/August and November

2014. These investigations by the KIT-Institute for Water and River Basin Management (IWG,

KaWaTech-sub-project 1) were comprehensively supported by departments of KIT’s Institute for

Applied Geosciences, namely the Department of Hydrogeology (AGW, KaWaTech-sub-project 2) and

the Department of Aquatic Geochemistry (IMG, KaWaTech-sub-project 3). Fig. 20 exemplarily shows

a microscopic enlargement of suspended loads of works water from the Seo Ho HPP which was

extracted directly before the penstock’s entrance. These investigations reassure that the limiting

values for the maximum grain size cannot be complied with the existing hydraulic infrastructure.

Fig. 20: Microscopic enlargement of suspended sediments of the works water of Seo HPP (16.01.2015, KIT)

2.2.3.3 Evaluation on suspension concentration

Additional in situ investigations of the suspended load concentration were carried out during field trips

to Dong Van in July/August and November 2014. In the November field trip an advanced method was

additionally applied to measure the suspended load concentration. Fig. 21 and Fig. 22 show the

results of these investigations complemented by discharge measurements. These results show that

the suspended load concentration complies with the limit value of 20 mg/l at most measurements.

Only in the period from 20th to 22

nd of July the limit was exceeded significantly (see Fig. 23). Further

investigations lead to the conclusion that in this period serious rainfall events in the Dong Van region

took place causing the exceedance of the limiting values. This context will be evaluated by further data

acquisition and analysis in the 1st term of 2015. Based on current insights it can be assumed that the

limiting value for the suspension load concentration is exceeded temporarily during the main rainseason triggered by serious rainfall events.



Pre-Design

/ 127

Fig. 21: Suspended load concentration and discharge July/August 2014

Fig. 22: Precipitation data of measurement stations in Lung Phin and Ta Phin



Pre-Design

/ 127

Fig. 23: Suspended load concentration and discharge November 2014

2.2.3.4 Summary of evaluation results and measures to improve sediment deposition capacity

The evaluation of the sediment deposition capacity of Seo Ho HPP’s existing hydraulic flow system

has shown that it cannot fully comply with the given limiting values for the tolerable suspended load

concentration and grain size.

To ensure high life expectancy of the machinery the sediment deposition capacity has to be improved.

The related technical and financial effort could be minimized by a successive approach. After

implementation of a first measure (test stage) at the intake pool (see section 2.4.2.2) and the

successive evaluation of the achieved improvements a decision is to be made if further improvements

are required.

If a further improvement is necessary the implementation of additional measures at the intake pool

(see section 2.4.2.3) has to be accomplished. If (against current expectations) even these measures

are not fully sufficient the implementation of optional measures at the sand trap (see section 2.2.3.5)

has to be considered. The successive approach is shown schematically in Fig. 24.

The suspended load concentration of the works water can be reduced significantly due to the in

sections 2.2.3.5, 2.4.2.1 and 2.4.2.2 described measures. However, with an appropriate effort it cannot

be supposed to achieve a sufficient retention of very high loads of suspended sediment caused by

extreme rainfall events. Therefore, the installation of a warning system is planned to temporarily shut

down the water supply system in case of extreme discharge events (see section 2.7). This warning

system will be included in the water supply facility’s controlling system, which will be developed and

implemented by KIT.



Pre-Design

/ 127

Fig. 24: Successive approach to improve the sediment deposition capacity of Seo Ho HPP’s hydraulic system

2.2.3.5 Optional measures to improve the sediment deposition capacity of the sand trap

The measures described below are optional in case the settling efficiency of the intake pool

cannot be increased sufficiently (see sections 2.4.2.2 and 2.4.2.3). The implementation is hence

only on demand and could take place in the 1st

term of 2016. Therefore they have to be taken

into account in the budget, but not yet into the Final Engineering Design. These measures

contain the removal of the restriction between basin 1 and 2 and the enlargement of basin 2.

Fig. 25: Sketch of the sand trap with top view after optional modification to improve sediment deposition capacity (implementation only on demand)

Enlargement

of basin 2

Removal of

restriction

DRAFT



Pre-Design

/ 127

The restriction between basin 1 and 2 is a control cross section, which can be used to determine the

discharge at this point. However, the restriction decreases the sediment deposition capacity due to a

local increase of the flow velocity, which interrupts the process of deposition. A removal of the

restriction eliminates this local acceleration and thereby increases the sediment deposition capacity of

the sand trap. An enlargement of basin 2 elongates the possible sedimentation path and by that also

increases the sediment deposition capacity.

Fig. 25 shows a sketch of the sand trap after the described optional modification. In case of necessity

to carry out these optional measures a further Pre-design will be delivered from German side.


The list of materials below (Tab. 3) is mandatory to implement the required measures described

in section 2.2.2 and is within the responsibility of the Vietnamese partners.

Tab. 4: List of materials and services for measures to improve the sediment deposition capacity of the sand trap



4.2 Sealing of gaps in gate channel bed and lateral guidance of thesluice gatesDetailed localization and excavation of the existing gapsRoughening of the concrete surfacesFitting and installation of steel parts

Application of new concrete layer

2 ls

4.3 Steel parts for gate channel bed and lateral guidance of the sluice gates 2 ls

4.4 Rehabilitation of the anchorage of the sluice gate in basin 2Excavation of the existing breaks-offsRoughening of the concrete surfaces

Application of new reinforced concrete to restore the areaRe-installation of sluice gate

1 ls

4.5 Trash rack 1 ls

4.6 Concrete foundation for the new trash rack 1 m³

The list of materials below (Tab. 5) is within the responsibility of the Vietnamese partners and

is optional in case the sediment deposition capacity of the intake pool cannot be increased

sufficiently (see sections 2.4.2.2 and 2.4.2.3). Therefore they have to be taken into account in

the budget, but not yet into the Final Engineering Design.

Tab. 5: List of materials and services for optional measures at the sand trap


5.1 Removal of the restrictionConcrete excavation worksConcreting works to restore proper functionality

31

m³m³

5.2 Enlargement of the sand trap basin 2Soil excavation worksConcrete excavation worksConcreting of basin bed with reinforced concreteConcreting of basin walls with reinforced concrete

16 - 324512

m³m³m³m³



Pre-Design

/ 127

2.3 Headrace channel


Fig. 26: Map of Seo Ho HPP area - Headrace channel

The headrace channel connects the sand trap with the intake pool and is constructed as a U-shaped

concrete channel with dimensions of 0.6 x 0.7 m (W x H). The continuously concreted channel is

covered by concrete slabs. It runs mostly underground and is only visible at 2 spots (see Fig. 27),

which both are within the first third of the total length (starting from the sand trap). According to the

construction plans, it has an inclination of 2 ‰. With a levelling using the intake at the sand trap and

the above mentioned 2 visible spots as sampling points, the channel ’s incline was validated by KIT. At

the beginning, the concrete slabs form the narrow path along the right side of the valley leading to the

intake pool (see Fig. 28). In the rear part however, the channel seems to be far deeper and is covered

completely with soil and rock to an unknown extent, so that the accessibility is not given anymore.

Although the construction materials stated in the construction plan, which are masonry plastered withcement mortar and some concrete sections, could not be verified for the channel’s entire length, they

seem plausible taking into consideration the design of the sand trap. The distance between sand trap

and intake pool is 790 m, although the channel itself does not run directly into the intake pool. Instead,

a steel pipe of unknown length connects the intake pool with the headrace channel. The construction

plans of the hydropower plant state a channel length of 638 m. Due to the before mentioned facts, this

data could not be verified yet. The channel’s theoretical maximum hydraulic capacity was determined

with the Darcy-Weisbach equation. Therefore an inclination of 2 ‰, a sand roughness of 3 mm and U -

shaped channel dimensions with 0.6 x 0.7 m (W x H) with a clearance of 0.1 m to the slab was

applied. Based on these boundaries a maximum discharge of approx. Qmax = 400 l/s was calculated

(this value is afflicted with uncertainties due to lacking data about the channel’s geometry and

inclination). However, due to the unknown condition of some sections of the headrace channel thisvalue is afflicted with uncertainties.



Pre-Design

/ 127

Fig. 27: Open course of the headrace channel withaccessible concrete slab cover (5.12.2013, KIT)

Fig. 28: Underground, inaccessible (covered) course(5.12.2013, KIT)

A partly channel inspection has revealed that the channel surfaces are in a quite good condition (see

Fig. 29). However, the concrete ceiling slabs show cavities due to edge fractures and unplastered

joints which give way to intruding roots (see Fig. 30). The incoming roots cause critical obstructions of

the channel at several spots, which result in a drastically reduced hydraulic capacity. Additionally, the

root obstructions can lead to flotsam jam, reducing the hydraulic capacity even further (see Fig. 31).

Fig. 29: Clean headrace channel section (25.02.2014, SPEKUL)



Pre-Design

/ 127

Fig. 30: Root obstruction (25.02.2014, SPEKUL) Fig. 31: Root obstruction and flotsam (25.02.2014,SPEKUL)


The described damages are to treat straightforward by removing the root obstructions and

subsequently renewing the joints of the affected concrete slabs. To being able to carry out these

measures, the channel has to be opened over its whole length in regular intervals of approx. 70 m.

Therefore it is necessary to get an access to the channel even in the areas with a high covering on top

which concerns especially the second half of the headrace channel. For example, it would be

conceivable to build vertical manholes by installing stacked concrete rings to a height depending on

the respective covering on top of the channel (see Fig. 32).

Fig. 32: Illustration of the vertical manhole



Pre-Design

/ 127

The quantities stated in Tab. 6 refer to the number of revision openings, not the amount of concrete

rings. The intruding roots and accumulated waste or flotsam jam have to be removed entirely.

Subsequently the corresponding concrete slabs have to be lifted and put back in place with a new

filling of their joints. However, the most important point in this regard is the establishment of a regular

inspection and maintenance management system to avoid such damages in the future. Through

removal of the root obstructions and the accomplishment of regular maintenance ensure a proper

discharge efficiency of the head race channel and therefore an output of the PAT-pump-modules and

existing Seo Ho HPP corresponding to the respective design.


Tab. 6: List of materials and services for measures at the headrace channel



6.2 Construction of inspection openings every 70 mSoil and rock excavation for approximately 10 openings (e.g.manholes)Precast concrete rings (height 10 cm)

Unknowndue tocoveringof thechannel

6.3 Inspection & maintenance of the whole channelRemoval of root obstructions and flotsam jamsLifting of concrete slabs and renewal of joints wherenecessary (amount unknown)

700 m

2.4 Intake pool


The intake pool is a transitional structure from the headrace channel to the penstock. It serves multiple

purposes: For provision of sufficient water in case of sudden changes in turbine operation (surge tank

function), to purge surplus water over a lateral overflow and last but not least for the detention of

sediments.

The intake pool has a length of 10.5 m, a width of 2.1 m and a maximum depth of 3 m. It is built of

reinforced concrete with a wall thickness of 0.3 m. The area above the connection to the penstockpipeline is overbuilt with a concrete pavilion. The area between the 4 columns of the pavilion amounts

to 2.5 × 4.5 m and has a height of 2.5 m. The columns have a square cross-section with an edge

length of 0.22 m. On the left side (flow direction) of the intake pool, there is a 4 m long weir acting as

lateral overflow. Its crest shows some slight damages (break-offs), through which further water is lost.

This overflowing water is used by the operating personnel at Seo Ho HPP to monitor the water level

visually. The more narrow part in front of the intake to the penstock pipeline is closed over the whole

height with a trash rack to withhold flotsam. However, the rack is heavily damaged for unknown

reasons. The irregular openings are closed with a mesh network (see Fig. 37). On the left side of the

trash rack, there is a sluice gate which is used for flushing sediments out of the pool. Currently, the

installed gate causes water losses due to leakages (see Fig. 39). During the field trip in February

2014, a total water loss of 10 l/s caused by leakages at the gate was observed. Behind the trash rackthere is another sluice gate, by which the penstock pipeline can be closed.



Pre-Design

/ 127

Fig. 33: Map of Seo Ho HPP area - Intake pool

Fig. 34 - Fig. 42 show the current dimensions and state of the intake pool.

Fig. 34: Intake pool (22.07.2011, KIT)



Pre-Design

/ 127

Fig. 35: Intake pool (empty, upstream view)(22.02.2014, KIT)

Fig. 36: Intake pool (empty, downstream view)(22.02.2014, KIT)

Fig. 37: Intake pool damaged trash rack (22.02.2014,

KIT)

Fig. 38: Intake pool flushing sluice gate (22.02.2014,

KIT)



Pre-Design

/ 127

Fig. 39: Water losses from sluice gate at intake pool(9.12.2013, KIT)

Fig. 40: Lateral overflow with break-offs at intake pool(9.12.2013, KIT)

Fig. 41: 3D model of the intake pool (before modification, present state)



Pre-Design

/ 127

Fig. 42: Lateral overflow at intake pool (see Fig. 40), break-off dimensions [mm]

Damages can be particularly seen at the roof of the intake pavilion. Two holes in the roof and one in

the bottom result most probably from rock fall. Also the columns and the girders are seriously

damaged. The holes in the roof are smaller than the bottom hole with a diameter of approx. 0.45 m. It

displays the remaining reinforcement, while the concrete in this spot completely vanished (see Fig.

43). Also the concrete of the columns’ feet is partly broken out up to the middle due to reinforcement

corrosion which results in a total demolition of the cross-section (see Fig. 44).

Fig. 43: Hole in the bottom (5.12.2013, KIT) Fig. 44: Destroyed column foot (5.12.2013, KIT)

The roof in this part of the pavilion is partly broken. Particularly the corner girders are in poor condition

so their connection to the columns and their load bearing capacity is not ensured anymore (see Fig.

45 and Fig. 46). Besides the pavilion, the pool’s structure seems to be in quite good conditionalthough some sintered cracks can be observed and the lateral overflow shows two small break-offs.



Pre-Design

/ 127

Investigations with a reinforcement detector at the walls of the intake pool revealed a crosswise

arrangement of the reinforcement in a distance of 0.2 m with a strong fluctuating concrete cover

between 25 and 65 mm (see Fig. 47). The determination of the compressive strength with a rebound

hammer gave a mean value of 46 MPa.

Fig. 45: Pavilion roof (1) (5.12.2013, KIT) Fig. 46: Pavilion roof (2) (5.12.2013,KIT)

Fig. 47: Wall of the intake pool with reinforcement arrangement (5.12.2013, KIT)



Pre-Design

/ 127


The measures at the intake pool focus on two objectives: Restore the functionality and increase the

sediment deposition capacity.

2.4.2.1 Measure to restore the intake pool’s functionality

To achieve this objective sustainably, the following measures are required: Restoring the lateral

overflow at the weir crest to ensure an even overflow height of the weir, examination and sealing of

gaps in the sluice gate channel bed and the lateral guidance, repairing or replacing of the trash rack to

prevent flotsam input into the penstock and complete demolition as well as reconstruction of the

pavilion as a protective construction against rock fall.

After the restoration of an even weir crest height of the lateral overflow, water discharge should be

avoided, since the full width will be overflowed. This concept interdicts the current method of visual

water level checking. It is therefore planned to install a water level monitoring device with radio

transmission to Seo Ho power house, where the water level will be shown on a digital display. This

system can also be used to display a warning signal in cases of impermissible low / high water level.

The necessary equipment for this system will be provided by the German project partners (see section

2.7). This monitoring method will be of great value both for water supply by the new facility as well as

for generating electricity applying the already existing Seo Ho HPP.

The new trash rack rods must have a rectangular profile with a thickness of 0.5 cm and a depth of at

least 3 cm. The spacing between the rods has to be 2 to 3 cm. The trash rack has to be bordered by ametal frame and subdivided with horizontal metal beams in order to stabilize the construction. The

trash rack itself is to be mounted in the two vertical slots, which are embedded in the intake pool side

walls. The width of the trash rack has to be designed according to the distance between these two

slots. All used materials have to be rust-proof. Fig. 49 is showing a sketch of the new trash rack.

2.4.2.2 Measure to improve the intake pool’s sediment deposition capacity

In section 2.2.3.4 a successive approach is described to enhance the sediment deposition capacity of

Seo Ho HPP’s entire hydraulic structure. The first measure of this approach focuses on the intake

pool. Suspended grains deposited underneath the height of the intake edge cannot enter the penstock

anymore (see Fig. 48 and Fig. 49). Therefore the height of this edge must be increased to improve the

pool’s sediment deposition capacity. A rounding of the intake zone as shown in Fig. 49 reduces locally

the vortex formation, homogenizes therefore the flow and by that improves the sediment deposition

capacity as well. While operating the Pelton turbines and PAT-pump-modules a water overlap of the

intake edge has to be at least 1.65 m (value according to state-of-the-art literature, including a safety

margin) to prevent the inclusion of air in the works water. This minimum water overlap was determined

with the approaches of Gordon3.

The adaption of the intake zone in front of the penstock could be realized also with a kind of

prepacked concrete as its only function (from a structural point of view) is to bear the vertical forces

3 Heinemann und Feldhaus, Wasserbau: Hydraulik für Bauingenieure. Publishing house Teubner 2003



Pre-Design

/ 127

resulting of the hydrostatic pressure load. The proportions can be seen in Fig. 49. However, minor

adjustments of these geometric values to the conditions on site might be required. As construction

material also the omnipresent karst limestone may be used. The core of the intake zone can be

composed of thoroughly cleaned limestone and a cement mortar. To reduce the mortar consumption,

the limestone should have minimal porosity and a regular shape to avoid cavities when building the

intake zone. The outer appearance of the ground structure must show an equal but rough surface with

5 to 10 mm deep grooves to enable a strong bond with the top mortar layer to be applied in the next

work step.

Fig. 48: Cross-sectional downstream view of intake zone before modification

This mortar layer is applied on all surfaces of the intake zone with a layer thickness of 15 mm.

Subsequently, an appropriate reinforcement mesh is installed (e.g. with a layer of chicken wire) on

which a second mortar layer with a thickness of 10 mm is applied wet-on-wet before the hardening of

the first layer. This exterior plaster is intended to protect the core of the structure.

The measure described below regarding the installation of a baffle and 2 racks inside the

intake pool is financed and implemented by the German side. The measure will also be

optimized based on field investigations by the German side during the first term of 2015.

Therefore the baffle and 2 racks do not need to be included in the Final Engineering Design.

Due to the high flow velocity at the pool’s inlet in combination with the high incline of the pool ’s inflow

area, the water entrance through a pipe, which is connected to the headrace channel, has a large

turbulence impact into the intake pool. This turbulence impact causes a very high heterogeneous flow

situation and thus also a low sediment deposition capacity. To improve this state the German side will

install a vertical hanging baffle and 2 racks in the first term of 2015 (see Fig. 50). The baffle in

combination with the 2 racks will enable spatial concentrated energy dissipation, which will lead to a

more homogenous flow situation and therefore to a higher sediment deposition capacity.

Before modification



Pre-Design

/ 127

Fig. 49: Cross-sectional downstream view of intake zone after modification

Fig. 50: Cross section upstream view of the intake pool with installed baffle and 2 racks for reduction of theturbulence impact

Water overlap ofintake edge

Intakeedge

Baffle

Racks

After modification



Pre-Design

/ 127

To prevent anthropogenic sediment and rubbish entry in the intake pool (e.g. due to playing children)

the entire inlet pool shall be surrounded by a fence including a gate (see Fig. 51). This measure is

within the responsibilities of the Vietnamese side.

Fig. 51: View on the intake pool after modification surrounded by an exemplary fence

The monitoring system mentioned in section 2.4.2.1 to keep the operating water level within a certainrange will be combined with a turbidity sensor. This sensor will be used to display an alert in case of

exceedance the limit for the suspension concentration caused e.g. by serious rainfall events. The

required measuring devices will be provided by the German project partners (see also section 2.7).

2.4.2.3 Optional measures to improve the sediment deposition capacity of the intake pool

The measures described in this section are optional in case the tasks explained in section

2.4.2.2 do not increase the sediment deposition capacity of the intake pool sufficiently.

Therefore they have to be taken into account in the budget, but not yet into the Final

Engineering Design. The implementation is only on demand and could be carried out in the 2nd

term of 2015.

Fig. 52 is showing a sketch of the optional measures to improve the sediment deposition capacity of

the intake pool. The measures contain the enlargement of the intake pool including an upstream

shifting of the baffle and racks, reducing the incline of the inlet zone, modification of the headrace

channel inlet pipe into an open channel structure and displacement (to upstream side) of the lateral

weir crest (overflow). All of these measures will lead to a more homogenous flow situation in the intake

pool and thereby to a higher sediment deposition capacity. In case of necessity to carry out these

optional measures further construction details will be additionally delivered from the German side to

the Vietnamese partners.

Gate



Pre-Design

/ 127

Fig. 52: View on the intake pool after implementation of optional measures (implementation only on demand)


The list of materials in Tab. 7 and Tab. 8 are within the responsibility of the Vietnamese

partners and are mandatory to implement the required measures of section 2.4.2.1 and 2.4.2.2.

The materials for the baffle and racks as well as the measuring devices (water level & turbidity

sensors) are within the responsibility of the German partners.

Tab. 7: List of materials and services for measures at the intake pool


7.1 Reinforced concrete 20 m³

7.2 Various steel partsFor gate channel bed and lateral guidance rehabilitationPossibly also rehabilitation of gate necessary

1 ls

7.3 Various steel parts for trash rack repairing / replacement 1 ls


7.5 Restoration of lateral overflow weir crestExcavation of the existing breaks-offsRoughening of the surfaces

Application of new concrete layer and/or steel guidance parts

1 ls

7.6 Sealing of gaps in gate channel bed and lateral guidanceExcavation of the existing gapsRoughening of the surfaces

Application of new concrete layerFitting and installation of steel parts

1 ls

7.7 Repairing or replacing of the trash rack 1 ls

7.8 Fence including gate 1 ls

7.9 Installation of the fence 1 ls

The list of materials below is within the responsibility of the Vietnamese partners and is

optional in case the sediment deposition capacity of the intake pool cannot be increased

sufficiently by implementing the tasks stated in section 2.4.2.2. Therefore they have to be takeninto account in the budget, but not yet into the Final Engineering Design.

Displacement ofweir crest

Enlargement ofintake pool Modification of the

headrace channelinlet

Upstream

shifting of baffleand racks



Pre-Design

/ 127

Tab. 8: List of materials and services for optional tasks to improve the intake pool’s sediment deposition capacity


8.1 Earth and rock excavation 100 m³


8.3 Steel or cast iron pipe, DN 500, PN 6 5 m

8.4 Breaking up of old concrete (existing pool) 15 m³

8.5 Services for enlargement of the intake poolEarth and rock excavation of the enlargement areaConcreting of the pool enlargementEarthworks for the restoration of the pathway

1 ls

8.6 Channel and pipe connection to headrace channelExcavation of the steel pipe at the beginning of the intake pool

Cutting & welding of the pipeline according to conditions on siteInstallation of the new pipe according to the conditions on siteConcreting of inlet channelEarthworks for the restoration of the pathway

1 ls

The list of materials below is within the responsibility of the German partners.

Tab. 9: List of materials and services for implementation of baffle and racks inside the intake pool


9.1 Various steel parts for installation of baffle and racksConstruction of baffle and racks including guidanceInstallation of baffle and racks

1 ls

2.5 Penstock bypass to PAT-pump-modules


Fig. 53: Map of Seo Ho HPP area



Pre-Design

/ 127

The existing penstock is a 720 m long DN 500 steel pipe which is mainly installed above ground

connecting the intake pool with the turbines in the power house of Seo Ho HPP. The first and the last

section of the penstock run underground (see Fig. 53).


Fig. 54: Satellite view of Seo Ho HPP and a possiblerouting of the bypass (Bing Maps 2014)

Fig. 55: Existing penstock of Seo Ho HPP and apossible routing of the bypass (5.12.2013, KIT)

To supply the PAT-pump-modules with water, a bypass from the existing penstock to the modules has

to be built. The bypass must be implemented as a DN 300 steel pipe, whereby its total length depends

on the final routing. Responsible for the implementation is the Vietnamese side, whereby the works

have to be accomplished in two construction stages.

2.5.2.1 Construction stages of the penstock bypass

1 st

construct ion stage: Implementation of branch pipe and bypass layingIn a 1

st construction stage the bypass connection to the existing penstock and the main part of the

bypass laying has to be done. Fig. 56 shows schematically where the bypass (red pipe) might end in

the 1st construction stage. The figure also shows the pressure supply pipe (blue), which is described in

more detail in section 0. Depending on the design of the power house of the water supply system it

would also be possible to end the 1st stage at the area behind the existing power house. As soon as

the decision about the power house design is made, the final routing of the bypass shall be clarified by

German and Vietnamese side. Based on this decision the Vietnamese side can then work out the

Final Engineering Design for this part of the plant. Independent from the final routing of the bypass its

final segment to the power house extension area (future location of the water supply facility)

has to build in a 2nd

construction stage. Thereby an easier and more precise connection of the

bypass to the PAT-pump-modules will be possible.

Penstockundergroundsection

Extensionarea ofpowerhouse

Bypass

Revisionvalve



Pre-Design

/ 127

Fig. 56: Schematic unscaled sketch of a potential routing of the bypass after 1st construction stage

2 nd construct ion stage: Implementation of final bypass segment

In a 2nd

construction stage the final bypass segment to the power house extension area has to be

built. The last bypass abutment must be decoupled from the floor slab of the power house extension

(see section 2.6) to avoid an impact from any settling processes. The 2nd

construction stage must

be done in parallel to the implementation of the PAT-pump-modules. It has to be carried out bythe Vietnamese side in consultation with the German partners. The pipe laying in the 2

nd

construction stage can be realized above or at the foot of the retaining wall. Fig. 57 shows

schematically where the bypass should end in the 2nd

construction stage. The final pipe segment

(black part in Fig. 57), which connects the bypass with the PAT-pump-modules, will be

provided and installed by the German side.

Fig. 57: Schematic unscaled sketch of a potential routing of the bypass after 2nd

construction stage

Final pipesegment

Retainingwall

Retainingwall

1st construction stage

2nd

construction stage



Pre-Design

/ 127

2.5.2.2 Piping of the penstock bypass

The branch pipe shall be connected to the penstock with an angle of 90° before the penstock vanishes

underground (see Fig. 55). This angle will distinctly simplify the installation on site while causing only

minor hydraulic losses. As close as possible to the branch, a revision valve (PN 25, DN 300) is to be

installed in the bypass, which enables the decoupling of the entire water supply system from the

penstock e.g. for revision tasks. Fig. 54 and Fig. 55 show a possible bypass routing. However it would

also be possible to connect the branch with the target area on the powerhouse forecourt resp. the

extension area directly. In this case a partial removal of the mound would be required.

Independent from the final routing the components used for construction of the bypass have to be

defined as follows.

Straight pipe segments need to have a minimum wall thickness of 5.6 mm. The calculation is based

on a steel P235 (minimum strength 235 N/mm²). Longitudinally welded or seamless pipes can be

used. For the welds a weld value of 0.8 was applied.

Pipe elbows have a lower pressure capability than straight pipe segments. Thus, greater wall

thicknesses are required. The strength test for the pipe elbows should be based on the standard DIN

EN 10253-2 type A (reduced utilization factor). For the pipe elbows a radius of 3 times diameter shall

be applied. Greater pipe elbow radii are permitted. If closer pipe elbow radii will be used, an increase

of the wall thickness is required.

Tab. 10 contains information about the recommended welding procedure as well as the specification

of the required materials.

Tab. 10: Specification of the welding procedure

Group of materials / no. according to CR ISO 15608Base materialMaterial no.

1 / 1.1P235TR11.0254

Pipe dimensions 323.9 x 5.6

Welder ’s qualification test corresponding to DIN ENISO 9606-1

111 T BW FM1 B s5,6 D323,9 PH ss nb

Welding processRoot run, filler bead, final run

Manual arc welding (111)

Welding filler corresponding to EN 12070 Böhler FOX EV 50 7018-1 E 42 5 B

Joint preparation DIN EN ISO 9692-1

Key figure

Preparation of the welding edgeTo produce by grinding or sawing

Weld heat treatment during welding Not required

Weld inspection According to DIN EN ISO 5817, assessmentgroup C

Testing Visual inspection = 100 %Radiographic test scope of testing = 50 %Tightness vacuum = 100 %



Pre-Design

/ 127

To avoid any damages of the bypass caused by occurring loads during regular operation or in case of

water hammer (e.g. caused by pressure surge) and to ensure an economic construction process,

foundations combined with bearings have to be dimensioned with a systematic approach according to

the respective loading situation. In total 2 types of foundations and 3 types of bearings have to be

differentiated as follows. All components were dimensioned based on the loads given in Tab. 11,

which are calculated without safety margins.

Tab. 11: Forces occurring at the bypass both during regular operation and in case of water hammer do notinclude safety factors (see coordinate system Fig. 108 and Fig. 109)

Foundation type Fx Fy Fz Fx Water hammer *

Fixed point ± 61.5 kN ± 6 kN - 21 kN ± 23.1 kN

Slide and guide

bearings

± 11.5 kN ± 6 kN - 17 kN -

* Additional axial load to the forces occurring during regular operation

All figures in the next sections which do show foundations and bearings shall be considered as

exemplary and schematic. Thus, the foundations and bearings have to be adjusted to the on-site

conditions (e.g. to the mountain slope).

2.5.2.3 Foundation types for the penstock bypass

To avoid future damages in the water distribution system and to ensure an economic construction

process, concrete foundations as support for the pipeline were pre-dimensioned with a systematic and

comprehensive approach according to the load situation of the separate bearing types (see Tab. 11).

According to the loads stated in Tab. 11 the permissible distance between bearing points was set to

10 m. In close proximity to kinks of the pipeline this distance has to be reduced (see attachment).

Fixed po int fou nd ation s (15/201-ST-01-108-c):

The fixed points have to be dimensioned according to the respective forces which result from the

change of pipeline direction, from the pipes dead load as well as from wind load.

Fig. 58: Side view of the foundation for fixed points

WITH reinforcement

Fig. 59: Front view of the foundation for fixed points

WITH reinforcement



Pre-Design

/ 127

Under regular operating conditions the recommended dimensions of the concrete foundations can be

seen in Fig. 58 and Fig. 59. For fixed points the dimensions are length x width x height (L x W x H) =

2.0 x 1.5 x 0.75 m³. They should be realized by a concrete of a characteristic strength of f ck = C25/30.

The size of the foundations was calculated without partial safety factors. However, the concrete

properties were lowered by a factor of 0.85 and in addition a global safety factor for all concrete

foundations of 2.0 was assumed in this pre-design.

The installation of a minimum reinforcement to account for a ductile member failure is optional. The

permitted contact pressure was assumed to be 150 kN/m². However, it is recommended to verify this

assumption when checking the in-situ ground conditions before the beginning of the construction

works. Further, all proofs against sliding, tilting and ground failure must be verified according to the

respective national Vietnamese standards (especially in slope areas).

If it is decided to design the foundations to account also for the additional loads which may occur due

to a water hammer (see Tab. 11, right column), the foundations shall be fixed to the rock ground e.g.

with embedded reinforcement bars as illustrated in Fig. 60.

Fig. 60: Exemplary illustration of a concrete foundation fixed to the ground with embedded reinforcement bars

Slide and guid e bearing fou ndation s (15/201-ST-01-107):


seen in Fig. 64 and Fig. 65. For the slide and guide bearings the dimensions are L x W x H = 0.5 x 1.0

x 0.5 m³. They should be realized with a concrete with a characteristic strength of f ck = C25/30. The

installation of a minimum reinforcement to account for a ductile member failure is optional.

The permitted contact pressure was assumed to be 150 kN/m². However, it is recommended to verify

this assumption when checking the in-situ ground conditions before the beginning of the construction




to a water hammer (see Tab. 11, right column), the foundations shall be fixed to the rock ground e.g.

with embedded reinforcement bars as illustrated in Fig. 60.



Pre-Design

/ 127

Fig. 61: Side view of the foundation for slide/guidebearings WITH reinforcement

Fig. 62: Front view of the foundation for slide/guidebearings WITH reinforcement

2.5.2.4 Bearing types for the penstock bypass

On top of each foundation a bearing has to be installed to guide the bypass and to transfer the

occurring forces to the respective foundation. In total 3 bearing types have to be differentiated as

follows. Note that the dimensions of the bearings’ components are independent from the construction

of the foundation (i.e. with or without reinforcement).

Fixed p oin t bearin gs (15/201-ST-01-108-c):

For the dimensioning of the fixed points the maximum design pressure is decisive. Fixed points have

to be arranged between all expansion bends, whereby a piping without fixed points is not permitted.

The bearings and their fixation on the foundations might be constructed as shown in Fig. 63 to Fig. 66.

Fig. 63: Side view fixed point bearing Fig. 64: Front view fixed point



Pre-Design

/ 127

Fig. 65: Cross sectional views of the fixation Fig. 66: Isometric view of the fixed point bearing

Slidin g and gu ide bearin gs (15/201-ST-01-107):

Slide bearings in the area of expansion bends have to be constructed without guide rails (see

description for guide bearings below). All guide bearings should be equipped with guide rails (securing

the position of the pipe and absorption of wind loads). In Fig. 67 to Fig. 70 the recommended

construction of a slide bearing and of a guide bearing as well as of the fixations on the foundation are

shown. Guide bearings shall be applied in straight sections as shown in the routing attached to thisPre-Design. In close proximity to the elbows slide bearings without the guide rail shall be applied. The

minimum distance between elbow and first bearing as stated in the attached routing has to be

respected. The bearings shall be constructed with steel/steel sliding surfaces (low-friction bearings

made of PTFE are not recommended.

Fig. 67: Side view slide and guide bearing Fig. 68: Front view slide and guide bearing



Pre-Design

/ 127

Fig. 69: Cross section view of the fixation Fig. 70: Isometric view on the slide and guide bearing

The reinforced guide bearing is to be constructed before and after each kink in the pipe with an angle

bigger than 10°. The difference between slide and guide bearings is the guide rail which should only

adapted at guide bearings as shown in Fig. 67. For the dimensioning of the guide bearing themaximum design pressure is decisive.

Expansion concept for sing le sect ions:

Since the expansion of the penstock is not known a U-arch with a dimension of 3 m is required close

to the branch-off location (see attachment). Thus possible expansions of the penstock can be

compensated. The following section of approx. 50 m contains one fixed point to absorb the pipe forces

due to thermal expansion, due to the dead load of the pipe and due to pressure forces in case of water

hammer (see Tab. 11).


All pipe segments shall be welded, whereby the weld seam must be of high quality to withstand the

operating pressures (locally more than 20 bar). Therefore a certified welder is required. Only the

revision valve shall be installed with flanges, which must be produced for a nominal pressure of PN25.

All material required for the installation of the bypass from the branch to the extension area is

summarized in the following table. The given amounts (e.g. pipe length, number of bolts, nuts,

washers, etc.) include safety margins in order to be able to adapt the pipe system on-site to the local

conditions. Only rust proof or zinc-coated steel parts shall be used. The dimensioning process

for all pipe segments includes a safety factor of 1.5 referring to the required strength.



Pre-Design

/ 127

Tab. 12: List of materials and services for the penstock bypass to PAT-pump-modules


10.1 Steel pipe (penstock bypass straight section)Nominal diameter: 300 mmOutside diameter: 323.9 mmWall thickness: 5.6 mmPressure level: PN 25Material: Steel P235

80 m

10.2 Steel elbow pipe (penstock bypass curved section)Nominal diameter: 300 mmOutside diameter: 323.9 mmWall thickness: 7.1 mm

Pressure level: PN 25 Angle: Depending on routingRadius: 2x DN = 600 mmMaterial: Steel P235

7 pcs

10.3 Steel flange1)

Nominal diameter: 300 mmPressure level: PN 25Type: Welding neck flange

3 pcs

10.4 Hexagon shaft bolt,

Type: M 2748 pcs

10.5 Hexagon nutType: M 27

48 pcs

10.6 Washer

Type: M 27

96 pcs

10.7 Elastomeric sealDN 300

3 pcs

10.8 Materials for welding (number of joints) 23 pcs

10.9 Revision valve

Nominal diameter: 300 mmPressure level: PN 25

1 pcs

10.10 Fixed points (2, referring to drawing 15/201-ST-01-108-c):Concrete with a characteristic strength of f ck = C25/30dimensions according to the static requirements l x w x h = 2.0x 1.5 x 0.75 m³, approximately 2.25 m³ per fixed point eachBolts Hilti HIT-HY 200-A + HIT-V-R M16 (or comparable)Steel plate 150 x 250 x 20 mm (min. tensile strength 235

N/mm²)Steel plate 160 x 140 x 10 mm (min. tensile strength 235N/mm²)U-profile U140 (min. tensile strength 235 N/mm²)U-profile U200 (min. tensile strength 235 N/mm²)Pipe bearing thickness 7.1 mm (min. tensile strength 235N/mm²)

4.5

168

16

112

m³

pcspcs

pcs

lslspcs

10.11 Slid bearings (4, referring to drawing 15/201-ST-01-107):Concrete with a characteristic strength of f ck = C25/30dimensions according to the static requirements l x w x h = 0.5x 1.0 x 0.5 m³, approximately 0.25 m³ per bearing eachBolts Hilti HST M16 (or comparable)Steel plate 200 x 200 x 20 mm (min. tensile strength 235

N/mm²)Steel plate 110 x 100 x 10 mm (min. tensile strength 235

1.0

328

8

m³

pcspcs

pcs



Pre-Design

/ 127

N/mm²)Profiled steel HEA100 (min. tensile strength 235 N/mm²)Pipe bearing type LSL 23.0300.150-37.2 by Witzenmann (orcomparable) (min. tensile strength 235 N/mm²)

18

lspcs

10.12 Guide bearings (4, referring to drawing 15/201-ST-01-107):Concrete with a characteristic strength of f ck = C25/30dimensions according to the static requirements l x w x h = 0.5x 1.0 x 0.5 m³, approximately 0.25 m³ per bearing eachBolts Hilti HST M16 (or comparable)Steel plate 200 x 200 x 20 mm (min. tensile strength 235N/mm²)Steel plate 110 x 100 x 10 mm (min. tensile strength 235N/mm²)

Profiled steel HEA100 (min. tensile strength 235 N/mm²)Guide rail L 50 X 5 (min. tensile strength 235 N/mm²)Pipe bearing type LSL 23.0300.150-37.2 by Witzenmann (orcomparable) (min. tensile strength 235 N/mm²)

1.0

328

8

148

m³

pcspcs

pcs

lspcspcs

10.13 Adaptation of pipe routing to local terrain conditionsEarthworks (excavation, possibly partial break-up of retainingwall)Possibly cutting and re-welding of pipe pieces to adapt toterrain

1 ls

10.14 Welding of bypass (DN 300) to penstock (DN 500) 1 ls

10.15 Piping 80 m

10.16 Pipe-to-flange welding 3 ls

10.17 Flange-to-flange screwing 2 ls

10.18 Pipe-to-pipe welding 23 ls10.19 Installation of revision valve 1 ls

10.20 Concreting of abutments 10 ls

10.21 Corrosion protection application (including fittings, flanges, etc.) 80 m²

Annotations:

1) Flange thickness differs from manufacturer to manufacturer. Bolt lengths and shaft lengths

thus have to be (re)defined after a manufacturer for steel flanges has been selected.2)

Flange thickness depends on the type of revision valve/compensator. Bolt lengths and shaft

lengths thus have to be (re)defined after a specific valve/compensator has been selected.

The pipe material and equipment has to be in accordance with the standards listed below orequivalent to them. These are, but are not limited by, the following:

EN 10220 – Seamless and welded steel tubes – Dimensions and masses per unit length

EN 10224 – Non- alloy steel tubes and fittings for the conveyance of water and other aqueous

liquids – technical delivery conditions

EN 1092-1 – Flanges and their joints – Circular flanges for pipes, valves, fittings and

accessories, PN designated – Part 1: Steel flanges

EN 10311 – Joints for the connection of steel tubes and fittings for the conveyance of water

and other aqueous liquids

EN ISO 4014 – Hexagon head bolts – Product grades A and B

EN ISO 4032 – Hexagon head nuts – Product grades A and B

EN 1515 – Parts 1 – 4 Flanges and their joints – Bolting

EN ISO 7089 – Plain washers – Normal series, Product grade A



Pre-Design

/ 127

EN 681 – 1 – Elastomeric Seals – material requirements for pipe joints seals

EN 1074 Valves for water supply – Fitness for purpose requirements and appropriate

verification tests – Part 1: General requirements

EN 1074 Valves for water supply – Fitness for purpose requirements and appropriate

verification tests – Part 2: Isolating valves

EN 287-1 Qualification test of welders

EN 1011 – Welding – Recommendations for welding of metallic materials

EN ISO 23277 – Non-destructive testing of welds – Penetrant testing of welds – Acceptance

levels

EN 805 – Water supply – Requirements for systems and components outside buildings

ISO 15348 – Pipe work – Metal bellows expansion joints – General

prEN 14917 – Metal bellows expansion joints for pressure applications

2.6 Extension of power house and tailwater pool

2.6.1 Location of power house extension

In front of the entrance of the existing power house is a vacant, partially paved area with dimensions of

approximately 8.5 x 14.6 m (see Fig. 71 and Fig. 72). The extension of the power house to

accommodate the PAT-pump-modules and a tailwater pool shall be built there.

Fig. 71: Vacant area next to Seo Ho HPP powerhouse (5.12.2014, KIT)



Pre-Design

/ 127

Fig. 72: Top view of unscaled sketch on the vacant area next to Seo Ho HPP powerhouse


There are two options to accommodate the 2 PAT-pump-modules with the related piping, valves and

measurement system. The decision which option will be realized mainly depends on the dimension of

the construction road, which is within the responsibility on the Vietnamese side. Both options A and B

and the associated measures are described in the following sections 2.6.2.1 and 2.6.2.2. Both options

will require the implementation of a tailwater pool, which is described in section 2.6.2.3.

Important note: Both options have different time schedules and differ in design details. After

choosing one option by Vietnamese side, missing details (i.e. exact position of the tailwater

pool) will be delivered from German side.

2.6.2.1 Option A: On-site installation of the water supply system

Option A provides the idea to transport the single components of the PAT-pump-modules to the

construction site next to the Seo Ho HPP powerhouse. Afterwards the PAT-pump-modules aremounted on site. Due to smaller and lighter packing boxes of the single components the construction

road from Khe Lia along the headrace channel to the Seo Ho HPP can be built smaller compared to

option B. The biggest packing boxes have a dimension of approx. 1,200 kg and a maximum weight of

approx. 3.2 x 1.1 x 1 m (L x W x H). The construction road must be capable to transport these packing

boxes. The disadvantage of option A in comparison of option B is a higher technical effort associated

with a longer mounting time of the PAT-pump-modules on site. Furthermore, a new building must be

built to accommodate the PAT-pump-modules properly.

Prior to mounting the PAT-pump-modules the new building must be erected. It has to cover a square

of at least 7.5 x 7.5 m (see Fig. 73) showing a minimum clear height of 3 m. The height should be

adequate to place a tripod crane for proper maintenance of the modules. To the upper retaining wall

(see Fig. 73) a distance of approx. 2 m must be kept, to the left retaining wall a distance of 0.5 m.



Pre-Design

/ 127

Fig. 73: Top view of unscaled sketch on the shape of the new building

The building itself could be built with a standard masonry and e.g. a corrugated metal roof on a timber

framing referring to the existing power house. However, it must be placed on a reinforced foundation

(floor slab) which can absorb the occurring loads from the piping system and from the machinery. This

foundation must cover the entire area of the new building. The shafts of the tailwater pool (see section2.6.2.3) can be embedded in the foundation as well. The foundation is designed to have a height of

0.3 m over the total square of at least 11.5 m x 7.5 m. It should be made out of reinforced concrete

with a minimum characteristic strength of f ck = C25/30. At the upper side of the foundation and at the

bottom, a reinforcement with a bar diameter of 12 mm each 150 mm should be installed crosswise in

longitudinal and transverse direction.

Fig. 74: Example for the new power house construction for Option A of the water supply system



Pre-Design

/ 127

Tab. 13: Time schedule of construction stages of option A

Construction stage Implementation part Responsibility

1st

Foundation (floor slab)Tailwater pool (see section 2.6.2.3) New building

VN

2n

PAT-pump-modules GER

2.6.2.2 Option B: Pre-installation of the water supply system in a shipping container

Option B provides the pre-installation of all components of the PAT-pump-modules (including piping,

valves etc.) in Germany inside a shipping container. Afterwards the container is transported to Seo Ho

HPP, mounted to a new built floor slab and connected to bypass and supply pipe. In this case the

construction road must be capable to transport a 20 feet shipping container showing dimensions of

approx. 6 x 2.5 x 2.6 m (L x W x H) with a weight of approx. 8,000 kg. The advantage of option B in

comparison to option A is a distinctly reduced mounting time of the PAT-pump-modules on site.

Furthermore, a roofing above the container would be sufficient instead of an entirely new building.

Fig. 75: Top view of unscaled sketch on the shape of the new roof

The roofing must be erected after the PAT-pump-modules are mounted. It has to cover a square of at

least 7.5 x 7.5 m (see Fig. 75) showing a minimum clear height of 3 m. Here also a distance to the

upper retaining wall of approx. 2 m must be kept, to the left retaining wall a distance of 0.5 m. The new

roofing must be placed on a reinforced foundation which can absorb the occurring loads transferred

from the piping system via the container including the dead weight of the piping system and the

machinery. The shafts of the tailwater pool (see section 2.6.2.3) can be embedded in the foundation

as well. The foundation is designed to have a height of 0.3 m over a total square of at least 11.5 m x

7.5 m. It should be made out of reinforced concrete with a minimum characteristic strength of f ck =

C25/30. At the upper side of the foundation and at the bottom, a reinforcement with a bar diameter of

12 mm each 150 mm should be installed crosswise in longitudinal and transverse direction.



Pre-Design

/ 127

Fig. 76: Example for the new power house construction for Option B of the water supply system

Tab. 14: Time schedule of construction stages of option B

Construction stage Implementation part Responsibility

1st

Foundation (floor slab)Tailwater pool (see section 2.6.2.3)

VN

2n

PAT-pump-modules GER3

r Roof VN

2.6.2.3 Tailwater pool

For both possibilities a tailwater pool including 2 pipe shafts is required as well as an open channel

which shall guide the water back into Seo Ho River.

Fig. 77: Top view unscaled sketch on tailwater pool including shafts, open channel to Seo Ho River



Pre-Design

/ 127

The tailwater pool’s position depends on the choice of option A or B (see 2.6.2.1 and 2.6.2.2). After

the selection of a proper option missing details will be delivered from German side. The pool’s

dimensions, however, will be equal for option A and B. The PAT suction pipes and the drainage pipes

will purge into the tailwater pool. These pipes have to be laid into the two shafts. The pool itself shows

dimensions of 4.5 x 2.0 x 1.5 m (L x W x H) and a connection to an open channel with dimensions of

approx. 0.5 x 0.5 m (W x H) containing a slope of at least 2 ‰. This channel can be covered with a

grid or concrete slabs. This pool is designed to have an equal wall thickness of 0.2 m. It should be

made out of reinforced concrete with a minimum characteristic strength of f ck = C25/30. On both wall

sides, a reinforcement mesh with an amount of 4.24 cm²/m should be installed.

Fig. 78: Downstream view on an unscaled sketch of the tailwater pool


Tab. 15: List of materials and services for the power house extension and the tailwater pool

Position Materials / services and description Amount Unit13.1 Earth excavation 60 m³


13.3 A Masonry walls (option A) 100 m²

13.3 B Pillars (option B) 8 ls

13.4 Corrugated metal roof on a timber framing 80 m²


13.6 Construction of the power house extensionConcreting of a floor slab with reinforced concreteConstruction of masonry wallsConstruction of a corrugated metal roof on a timber framing

1 ls

13.7 Concreting of machinery foundations for the modules 2 ls

13.8 Construction of a tailwater pool and channel to Seo Ho River

Excavation worksConcreting of pool and channel bed and walls

1 ls

Shafts

Open channel to

Seo Ho River



Pre-Design

/ 127

2.7 Machinery and equipment


2.7.1.1 Machinery

The machinery and the related piping system will be installed on the vacant area in front of the existing

powerhouse. This applies for option A (transport of single components and installation on-site) as well

as for option B (pre-installation in a shipping container). Either way, the powerhouse piping system will

then be connected to the penstock bypass, to the tailwater pool and to the pressure supply pipe. In

order to enable a controllable, efficient and safe operation of the water supply facility, the pipe system

will be equipped with different hydraulic valves. All components installed inside the new powerhousewill be provided by the German project partners. All components are chosen to be highly suitable for

this application by means of high robustness, low maintenance and easy to handle characteristics.

The hydraulic dimensioning both of the machinery and of the piping system is carried out by

KIT and KSB AG. However, until the finalization of the test rig runs at KSB AG, the layout may

be subject to minor changes. In this case the boundary conditions for the construction works

of the Vietnamese partners will not be modified.

Fig. 79: Schematic layout of PAT-pump-modules of Option A

Referring to the drafts for options A and B, the water for both modules runs through the penstock

bypass (DN 300) to the extension area. The DN 300 valve (1) represents the transition from the

penstock bypass and power house pipe system and is used as a revision valve. The flow is then

divided into the PAT (main routing) and the pump feeder (branch routing). The main routing is then

divided symmetrically by a T-branch pipe, whereby each PAT feeder is equipped with a valve (5)

(start/stop of the respective module, revision tasks) and a compensator (6) (decoupling of vibrations).The branch pipe to the feed pumps is likewise divided symmetrically by a T-branch pipe, whereby



Pre-Design

/ 127

each pump feeder is also equipped with a valve (2) and a compensator (6). The water running through

the PAT is transferred into the tailwater pool (see section 2.6). The water fed into both high-pressure

pumps first runs through single pressure pipes before they are joined by a T-branch pipe. Each of

these single pipes is equipped with a non-return valve (7) and a revision valve (8). The unified

pressure supply pipe further contains a revision valve whereby the entire powerhouse can be

decoupled from the pressure supply pipe for revision tasks. The construction contains drainage pipes

both for the bypass and for the pressure supply pipe equipped with valves (9) (10).

Tab. 16: Components installed inside the new powerhouse (Option A)

No. Component Amount Nominal diameter Nominal pressure

1 Revision valve 1 pc. DN 300 PN 25

2 Pump valve suction side 2 pc. DN 125 PN 253 Dismantling joint 6 pc. DN 300 (1 pc.)DN 200 (3 pc.)DN 150 (2 pc.)

PN 25PN 25PN 63

3a Dismantling elbow 5 pc. DN 125 (2 pc.)DN 100 (1 pc.)DN 150 (2 pc.)

PN 25PN 25PN 63

4 Control valve DN 200 1 pc. DN 200 PN 25

5 PAT valve pressure side 2 pc. DN 200 PN 25

6 Compensator 6 pc. DN 125 (2 pc.)DN 100 (2 pc.)DN 65 (2 pc.)

PN 25PN 25PN 63

7 Non-return valve 2 pc. DN 150 PN 63

8 Pump valve pressure side 2 pc. DN 150 PN 639 Drainage valve 1 pc. DN 100 PN 25

10 Drainage valve 1 pc. DN 100 PN 63

Fig. 80: Schematic layout of PAT-pump-modules of Option B



Pre-Design

/ 127

Tab. 17: Components installed inside the new powerhouse (Option B)

No. Component Amount Nominal diameter Nominal pressure

1 Revision valve 1 pc. DN 300 PN 25

2 Pump valve suction side 2 pc. DN 125 PN 25

3 Dismantling joint 3 pc. DN 300 (1 pc.)DN 200 (1 pc.)DN 150 (1 pc.)

PN 25PN 25PN 63

3a Dismantling elbow 8 pc. DN 125 (2 pc.)DN 200 (2 pc.)DN 100 (1 pc.)DN 150 (2 pc.)DN 100 (1 pc.)

PN 25PN 25PN 25PN 63PN 63

4 Control valve DN 200 1 pc. DN 200 PN 255 PAT valve pressure side 2 pc. DN 200 PN 25

6 Compensator 6 pc. DN 125 (2 pc.)DN 100 (2 pc.)DN 65 (2 pc.)

PN 25PN 25PN 63

7 Non-return valve 2 pc. DN 150 PN 63

8 Pump valve pressure side 2 pc. DN 150 PN 63



2.7.1.2 Monitoring system

The German project partners will develop an adapted control system for the water supply facility,

which will consist of various measuring devices. This includes a pressure sensor to continuously

monitor the water level inside the intake pool, whereby the current method of visual water level

monitoring at the weir crest will be replaced. The data will be radio transmitted to Seo Ho power house

in order to keep the operating personnel informed if the operation is within the permitted range.

Furthermore, a turbidity probe will be installed in order to continuously evaluate the sediment

concentration and to be able to shut down the water supply facility in case of impermissible high

sediment loads. The amount of water transferred to the reservoir in Ma U will be measured by an

inductive flow meter, which will be installed in the pressure supply pipe. The condition of the

machinery will be monitored by measuring the rotation speed of all machines since this is an indicator

of a proper operation mode.

Furthermore, the control system will contain alert settings since impermissible operating conditionsshall be avoided at any time. Therefore limiting values for all relevant operating parameters will be

decided by German and Vietnamese partners and successively set to guarantee a sustainable and

efficient operation of the water supply facility.


The selection of machines and components based on the currently known local conditions is to be

accomplished by KIT and KSB AG. Furthermore, the piping system will be dimensioned (including e.g.

pipe diameters, position of valves, etc.) and a proper load bearing system (i.e. position and

dimensions of the abutments) will be designed by these project partners. This applies both for option A

and B. The planned test rig runs with the machinery will be accomplished by KSB AG in August 2015after final assembly of the water supply modules. As agreed the German project partners will be in



Pre-Design

/ 127

charge for the provision of the machinery, the related control system for operation, the valves and the

pipe system from the penstock bypass to the suction pipe leading to the tailwater pool. This includes…

…the machinery and all required components (e.g. couplings, etc.), …

…all kinds of straight pipes, elbows, reducers, etc. for this section, …

…various valves in different sizes such as butterfly, plunger and non-return valves, …

…compensators resp. flexible joints as well as…

…the electrical control system comprising besides others an inductive flow meter.

The connection to the parts provided by the Vietnamese partners shall be the end of the bypass as

described in section 2.5, the connection of the PAT suction pipes to the tailwater pool as described in

section 2.6 as well as the connection to the pressure supply pipe as described in section 2.8. Since a

greater part of the items mentioned above has to be imported to Vietnam, the German side will be incharge for the shipment to the Vietnamese harbor resp. airport. As stated in Tab. 18 the Vietnamese

partners, however, are responsible for the customs duties including all administrative processes and

the provision of the related handling costs as well as for the final transportation to the construction site.

The list of services in Tab. 18 is within the responsibility of the Vietnamese partners:

Tab. 18: List of materials and services for the installation of machinery and equipment in the power house


16.1 Customs duties in Vietnam (incl. handling cost and administrationprocesses). All administrative processes have to be settled and timedin accordance to the project’s time schedule (see section 4)

1 ls

16.2 A Dom. transport of machinery/equipment to Seo Ho HPP (Option A) 1 ls

16.2 B Dom. transport of machinery in 20’ shipping container (Option B) 1 ls

The list of materials and services Tab. 19 are within the responsibility of the German partners:

Tab. 19: List of materials and services for the installation of machinery and equipment in the power house


17.1 A Installation of machinery and measuring equipment (Option A) 1 ls

17.1 B Installation of pre-installed container (Option B) 1 ls

17.2 Connection to bypass and pressure supply pipe on-site 1 ls

17.3 Installation of monitoring equipment 1 ls



Pre-Design

/ 127

2.8 Pressure supply pipe

2.8.1 Location

To pump the drinking water from the hydropower plant Seo Ho to the distribution tank in Ma U a

pressure supply pipe is necessary (see Fig. 81 red box). With a length of 2,455 m the pressure supply

pipe must overcome about 547 meters of altitude. The route is shown in Fig. 81 and Fig. 83.

Fig. 81: Location of Seo Ho HPP, pressure supply pipe and tank in Ma U


2.8.2.1 Routing of the pressure supply pipe

To overcome the high pressures rapidly, a steep route of the pressure supply pipe is preselected (see

Fig. 82). Thus, lower pressure levels can be used for larger parts of the pipes (see Fig. 82). To

simplify the construction in the field, the beginning of the pipe is parallel to the existing pressure pipe

and in the upper part the route follows the path to Ma U. In the following Fig. 82 - Fig. 91 and Tab. 20the data of the route of the pipe can be found. Detailed isometric drawings are shown in appendix B.

However, the routing needs to be checked and revised if necessary in the course of the

developing of the Final Engineering Design. Changes in the routing of the pipe might lead to

the need for revision of the design, particularly of the dimensioning and allocation of

foundations, compensations, water hammer protection and air valves.



Pre-Design

/ 127

Fig. 82: Profile of the pressure supply pipe

Fig. 83: Routing of the pressure supply pipe; pressure supply pipe (orange line), numbered points are themeasured points in Tab.

4

4 www.bing.com



Pre-Design

/ 127

Fig. 84: Detail 1, point 1 -35 Fig. 85: Detail 2, point 3 – 6

7

Fig. 86: Detail 3, point 6 – 117

Fig. 87: Detail 4, points 11 – 207

5 www.bing.com



Pre-Design

/ 127

Fig. 88: Detail 5, points 20 – 246 Fig. 89: Detail 6, points 24 – 28

8

Fig. 90: Detail 7, points 28 – 318 Fig. 91: Detail 8, points 31 – 35

8

Tab. 20: Data of the routing of the pressure supply pipe

Point

Length of

the pipe

section [m]

Length of

the pipe

ongoing [m]

Horizontal

distance [m]

Difference in

height[m]

Height

[masl]

x-

coordinate

y-

coordinate

1 0 0 0 0 706,9 533533 25765862 82,9 82,9 77,0 30,6 737,5 533575 2576522

3 251,8 334,7 220,4 121,8 859,3 533634 2576313

4 165,7 500,4 164,1 23,2 912,2 533777 2576276

5 369,7 870,1 276,5 245,4 1127,9 533835 2575983

6 23,0 893,1 23,0 -0,6 1127,3 533858 2575980

7 82,3 975,4 82,3 0,7 1128 533936 2575955

8 43,0 1018,4 42,4 7,0 1135 533971 2575931

9 48,2 1066,6 48,2 1,6 1136,6 534017 2575917

10 58,1 1124,7 56,7 12,6 1149,2 534051 2575872

11 37,0 1161,7 36,2 7,7 1156,9 534063 2575838

6 www.bing.com



Pre-Design

/ 127

12 23,8 1185,5 23,8 -0,3 1156,6 534081 257582213 10,5 1196,0 10,5 0,6 1157,2 534083 2575811

14 13,1 1209,1 12,9 2,2 1159,4 534079 2575799

15 41,0 1250,1 40,2 8,3 1167,7 534060 2575763

16 27,2 1277,3 26,6 5,6 1173,3 534070 2575738

17 32,0 1309,3 31,7 4,2 1177,5 534087 2575711

18 23,9 1333,2 20,6 12,1 1189,6 534107 2575703

19 59,8 1310,1 59,5 -5,6 1184 534155 2575737

20 125,7 1518,7 125,6 5,8 1189,8 534274 2575777

21 99,1 1617,8 99,0 4,4 1194,2 534330 2575859

22 42,1 1659,9 42,1 1,3 1195,5 534372 2575868

23 46,2 1706,1 46,2 1,8 1197,3 534412 2575844

24 75,3 1781,4 75,1 5,1 1202,4 534471 2575798

25 131,3 1912,7 130,2 16,7 1219,1 534599 257577426 62,8 1975,5 62,5 6,0 1225,1 534657 2575797

27 31,0 2006,5 31,0 0,8 1225,9 534684 2575780

28 28,7 2035,2 28,6 2,1 1228 534712 2575774

29 80,6 2115,8 80,4 6,1 1234,1 534791 2575764

30 24,2 2140,0 23,3 6,5 1240,6 534793 2575741

31 104,2 2244,2 104,2 1,8 1242,4 534851 2575654

32 61,0 2305,2 60,8 4,4 1246,8 534904 2575683

33 56,2 2361,4 56,1 -2,8 1244 534918 2575628

34 43,4 2404,8 43,2 4,0 1248 534924 2575585

35 51,0 2455,8 51,0 2,0 1250 534975 2575585

Annotations: The measurements in the field were performed with a TruPulse Laser Rangefinder. TheTruPulse consists of a distance measuring sensor and an integrated slope sensor. By emitting infrared

pulses and measuring the time required for each pulse to move from the rangefinder to the target and

back, the distance is determined. The GPS waypoints were measured with a GPS-handheld. The

reference system of the GPS points is in VN_2000_UTM_Zone_48N.

2.8.2.2 Boundary conditions, operating parameters and load assumptions

2.8.2.2.1 Delivery rate

The delivery rat is between 11 and 20 l/s.

2.8.2.2.2 Design pressure

The maximum design pressure (MDP) is 73 bar at the lowest point of the pipe (Point 01) at an altitude

of about 700 masl according to the calculation of the company KSB AG, see section 2.8.2.8. This

pressure contains the geodetic water pressure of 547 m (H = 543 m + 4 m (filling the tank from the

top)), the dynamic head of 7 – 31 m (depending on the delivery rate and the roughness of the pipe)

and the increase of pressure due to the water hammer. The water hammer was determined for a worst

case scenario (see section 2.8.2.8). With increasing height the geodetic pressure decreases and, thus,

the MDP decreases until a MDP of 18 bar at the highest point of the pipe, in case no water hammer

protection is implemented (Tank Ma U, 1250 masl). The design parameters have been adjusted

accordingly, e.g., grading of the required pipe wall thickness.



Pre-Design

/ 127

Negative pressures could only occur due to a water hammer. In the worst case scenario described in

section 2.8.2.8, the pressure would drop to vapor pressure from pipe length 870 m until pipe length

2,455 m (tank in Ma U). Even though this case is hypothetical and would most likely not occur, it is

provided for a water hammer protection device to prevent the pressure drop (see 2.8.2.8.3).

2.8.2.2.3 Design temperature

For the calculation of the pipe static following temperature was selected:

Minimum temperature: -10 °C

Maximum temperature: 50 °C

Starting from a mounting temperature of 10 °C, the temperature difference is - 20K to 40K.

Displacements due to the temperature differences are absorbed by appropriate compensation

elements (so-called natural compensation by U-bend and L / Z bend).

2.8.2.2.4 Other loads

Wind loads of 0.162 kN/m for the pipe DN 150 are selected. This corresponds to a dynamic pressure

of 0.8 kN/m².

2.8.2.3 Piping (diameter, material and wall thickness)

2.8.2.3.1 Diameter and material

As material a steel P235 is selected. Due to the expectable maximum delivery rate of approximately20 l/s a diameter of DN 150 is necessary (by calculating with a roughness of 0.1 mm and the

maximum delivery rate as mentioned before, the losses are 31 m).

2.8.2.3.2 Wall thickness

The maximum design pressure (MDP) decreases with increasing geodetic height and, thus,

decreasing geodetic pressure. According to the MDP a certain wall thickness is required. Four pipe

sections with a specific MDP were defined as can be seen in the isometric drawings summarized in

appendix B.

Tab. 21: Division of the pipe in four pipe sections

SectionMin. and max. geodetic

height [masl]

Maximum

design pressure

[bar]

Wall thickness

Straight pipe

[mm]

Wall thickness

Pipe elbow

[mm]

I

(Point 01 – TP01)705 – 830 73 6.3 11

II

(TP01 – TP02)830 – 980 60 5.6 7.1

III

(TP02 – TP03)980 – 1080 45 4.5 5.6

IV

(TP03 – Point 35)1080 - 1250 35 4.0 4.5



Pre-Design

/ 127

Straight pipe segments need to have a minimum wall thickness as shown in Tab. 21. The values

given in Tab. 21 are minimum wall thicknesses. The calculation is based on a steel P235 (minimum

strength 235 N/mm²). Longitudinally welded or seamless pipes can be used. For the welds a weld

efficiency rating of 0.8 was applied.

Pipe elbows have a lower pressure capability than straight pipe segments. Thus, greater wall

thicknesses are required. The strength test for the pipe elbows bases on the standard DIN EN 10253-

2 type A (reduced utilization factor). For the pipe elbow radius a design of 3D was applied. The pipe

elbow radius 3D corresponds to 1.5 of the pipe diameter. Greater pipe elbow radii are statically safe. If

closer pipe elbow radii will be used, an increase of the wall thickness is necessary.

T-branches have not been evaluated statically in the pipeline statics. If T-branches will be used, these

must be reinforced (a strength calculation has to be done before). Alternatively fittings according to thestandard DIN-EN 10253-2 type B (full utilization factor) with a minimum wall thickness of the straight

pipe can be used.

2.8.2.4 Pipe connection

The pipe segments have to be welded. The welded joints have to comply the criteria listed in Tab. 22

which correspond to the named standards.

Tab. 22: Requirements for the pipe connection

Group of materials/number corresponding to

CR ISO 15608Base materialMaterial number

1/1.1

P 235TR11.0254

Pipe and elbow dimensions168.3 x 4.0 mm; 168.3 x 4.5 mm; 168.3 x 5.6 mm;168.3 x 6.3 mm; 168.3 x 7.1 mm; 168.3 x 11.0 mm

Welder’s qualification test corresponding toDIN EN ISO 9606-1

111 T BW FM1 B s4.0 D168.3 PH ss nb111 T BW FM1 B s5.6 D168.3 PH ss nb

Welding process Manual arc welding (111)

Welding filler corresponding to EN 12070 Böhler FOX EV 50 7018-1 E 42 5 B

Weld preparation corresponding to DIN ENISO 9692-1

Preparation of the welding edge By mechanical sanding or sawing

Weld heat treatment during welding Not necessary

Weld inspection Corresponding to DIN EN ISO 5817, class C

TestsVisual inspection = 100 %Radiographic inspection, scope of testing = 50 %Tightness vacuum = 100 %



Pre-Design

/ 127

2.8.2.5 Bearing and foundation concept

2.8.2.5.1 Permissible bearing distances

The span of the pipe is limited to 6.5 m in order to limit the deflections resp. the bearing loads. On pipe

elbows (bending angle > 25°) bearings with a maximum distance of 1.6 m have to be provided.

2.8.2.5.2 Required alignment of Fixed points

In the pipe segments between two expansion bends (U-bend, L-and Z-bend), a fixed point has to be

constructed. The fixed point is used to control the displacement and to absorb the forces during

operation and in the case of a water hammer. The bearing type fixed point is defined in section

2.8.2.5.4. The locations of the fixed points of the planned pressure supply pipe are shown in the

isometric drawings (see appendix B).

2.8.2.5.3 Required alignment of Slide bearing and Guide bearing

It is recommended to equip pipe bearings in straight segments with lateral guidance. In the areas of

expansion bends, slide bearings without lateral support are to be used. The minimum distance from

the expansion bend (pipe elbow) to the first guide bearing have to be complied. The respective first

guide bearing before and after a bend is to reinforce. The bearings with steel/steel sliding surfaces

have to be used. The bearing types slide and guide bearing are defined in section 2.8.2.5.4. The

locations of the fixed points of the planned pressure supply pipe are shown in the isometric drawings(see appendix B).

2.8.2.5.4 Bearing types

Bearing type Fixed point (15/201-ST-01-105 and 15/201-ST-01-106)

Fig. 92: Side view Fixed point horizontal

(15/201-ST-01-105)

Fig. 93: Front view Fixed point horizontal (15/201-

ST-01-105)



Pre-Design

/ 127

For the dimensioning of the fixed points the maximum design pressure is decisive (see sections

2.8.2.2.1 and 2.8.2.8). Fixed points are arranged between all expansion bends. A piping without fixed

points is not recommended. In the Fig. 92 - Fig. 95 the recommended construction of a fixed point for

horizontal and angled piping and its fixation on the foundation is shown.

Fig. 94: Side view Fixed point angled (15/201-ST-

01-106)

Fig. 95: Front view Fixed point angled (15/201-

ST-01-106)

Bearing type Reinforced guide bearing (15/201-ST-01-103 and 15/201-ST-01-104)

Fig. 96: Side view reinforced guide bearinghorizontal (15/201-ST-01-103)

Fig. 97: Front view reinforced guide bearinghorizontal (15/201-ST-01-103)

The reinforced guide bearing is to construct before and after a kink in the pipe, which is bigger than10°. For the dimensioning of the guide bearing the maximum design pressure is decisive. In the Fig.



Pre-Design

/ 127

96 - Fig. 101 the recommended construction of a reinforced guide bearing for horizontal and angled

piping, its fixation on the foundation and the pipe bearings are shown.

Fig. 98: Side view reinforced guide bearing

angled (15/201-ST-01-104)

Fig. 99: Front view reinforced guide bearing

angled (15/201-ST-01-104)

Fig. 100: Pipe bearing, LSF 43.0150.107.37.2 by

Witzenmann

Fig. 101: Pipe bearing, LSF

43.0150.107.37.2 by Witzenmann

Bearing type Slide bearing and guide bearing (15/201-ST-01-101 and 15/201-ST-01-102)

Slide bearings in the area of expansion bends have to be constructed without guide rails. All other

guide bearings should be equipped with guide rails (securing the position of the pipe and absorption of

wind loads). In the Fig. 102 - Fig. 107 the recommended construction of a sliding and guide bearing

for horizontal and angled piping, its fixations on the foundation and the pipe bearings are shown.



Pre-Design

/ 127

Fig. 102: Side view slide bearing and guide

bearing horizontal (15/201-ST-01-

101)

Fig. 103: Front view slide bearing and guide bearinghorizontal (15/201-ST-01-101)

Fig. 104: Side view slide bearing and guide bearingangled (15/201-ST-01-102)

Fig. 105: Front view slide and guide bearing angled (15/201-ST-01-102)



Pre-Design

/ 127

Fig. 106: Pipe bearing, LSL 23.0150.107-37.2 byWitzenmann

Fig. 107: Pipe bearing, LSL 23.0150.107-37.2 byWitzenmann

2.8.2.5.5 Foundations

Concrete foundations as support for the pipeline were pre-dimensioned with a systematic and

comprehensive approach according to the loading situation of the separate bearing types which vary

depending on the course of the pipeline (see Tab. 23 - Tab. 25 and sections 2.8.2.2 and 2.8.2.3). The

loads are calculated without any safety margins.

Fig. 108: Side view of a pipe with coordinatesystem

Fig. 109: Plan view on a pipe with coordinatesystem

Tab. 23: Loads without safety margins for the fixed points (coordinate system see Fig. 108 and Fig. 109)

Direction Loads

Fx +/- 26 kNFy +/- 11 kN

Fz - 9 kN

Additional load of water hammer

Fx, water hammer +/- 68 kN

Fy, water hammer +/- 17 kN

Fz, water hammer -25 kN until +21 kN


seen in Fig. 92 - Fig. 105. For the guide and slide bearings the dimensions are length x width x height

l x w x h = 0.5 x 1.0 x 0.5 m³, for the reinforced guide bearings l x w x h = 1.0 x 1.0 x 0.75 m³ and for

the fixed points the dimensions are l x w x h = 2.0 x 1.5 x 0.75 m³. They should be realized with a

concrete with a characteristic strength of f ck = C25/30. The installation of a minimum reinforcement toaccount for a ductile member failure is optional.



Pre-Design

/ 127

The size of the foundations was calculated without partial safety factors. However, the concrete

properties were lowered by a factor of 0.85 and in addition a global safety factor for all concrete

foundations of 2.0 was assumed in this pre-design.

Tab. 24: Loads without safety margins for the reinforced guide bearings

Direction Loads

Fx +/- 7 kN

Fy +/- 7 kN

Fz - 9 kN

Additional load of water hammer

Fy, water hammer +/- 14 kN

Fz, water hammer 4 kN

Tab. 25: Loads without safety margins for the slide bearing and guide bearing

Direction Loads

Fx 7 kN

Fy 5 kN

Fz - 9 kN

The permitted contact pressure was assumed to be 150 kN/m². However, it is recommended to verify

this assumption when checking the in-situ ground conditions before the beginning of the construction




to a water hammer (see Tab. 6 - Tab. 8), which seems to be quite unlikely (see section 2.8.2.8), there

are basically two options. It would be possible in this case either to enlarge the dimensions of the

foundations according to the additional static requirements or to fix them to the rock ground e.g. with

embedded reinforcement bars which is illustrated in Fig. 110.

Fig. 110: Exemplary illustration of a concrete foundation fixed to the ground with embedded reinforcement bars



Pre-Design

/ 127

2.8.2.6 Expansion compensation concept

In this section the needed compensations for pipe expansions are described for each pipe segment in

reference to the isometric drawings, which can be found in the appendix B.

The segment from Point 01 until Point 03 has a distance of approximately 332 m. To compensate the

displacement, two U-bends are used. A U elbow can be placed directly at Point 02 (kink in the peak of

the U-bend, outreach 2.5 m). The use of U-bends in the area of kinks prevents the occurrence of

higher forces at the kinks. The second U-bend has an outreach of 3 m and compensates the

displacement of a 150 m pipe segment.

The segment from the Point 03 until the Point 04 has a distance of approximately of 166 m. The

displacement of a 110 m pipe segment is compensated by U-bend with an outreach of 2 m. The otherdisplacements can be compensated by the L-bends (app. 60° elbows) in the Points 03 and Points 04.

The greatest slope of the pipe is between the Point 04 and Point 05. It is approximately 42°. The fixed

points in this segment are used to anchor the downward forces (sliding down of the pipeline). The

thermal expansions of the pipe in this segment can be compensated by two U-bends (outreach app.

2.5 m).

The following segment from Point 05 until Point 13 consists of sub-segments with several small and

medium kink angles (15° to 30°). The displacement is compensated by two U-bends at the Point 07

and Point 10. Fixed points are positioned in the area of the Point 06, Point 09 and Point 12.

In the segment Point 13 until Point 18 with a pipe length of 136 m, the displacements arecompensated by a Z-bend at the Point 17 with an outreach of approximately 1.8 m.

The thermal expansions in the segment Point 18 until Point 25 is compensated by two U-bends (Point

20, Point 24) and an expansion bend at Point 25. The U-bends have an outreach of 2 – 2.5 m

(asymmetric) and absorb the displacement of 150 m of the pipe.

In the following of the pipe routing (Point 25 – Point 35) the pipe segments are shorter (maximum 105

m), thus, the displacement is compensated by the expansion bends at the existing kinks. In the middle

of straight segments, fixed points have to be constructed. The fixed points are mainly used to anchor

the forces resulting from the water hammer event.

For a detailed presentation of the expansion concept, it is referred to the isometric drawings shown inappendix 0.

The use of the permissible tensions for the operating parameters (fatigue analyses for the temperature

range of -10°C – 50°C) is about 85 %. Thus, a sufficient buffer for the length adjustment due to

adaptation to the local boundary conditions exists.

2.8.2.7 Corrosion protection

In order to ensure the durability of the pipe, it should be protected against corrosion. The pipe has to

be painted by coat paint.



Pre-Design

/ 127

2.8.2.8 Water hammer protection

2.8.2.8.1 General explanation

The extension of the hydro power plan Seo Ho consists of two pump modules. Each pump is driven by

a turbine. Both machines are directly connected by a coupling. No rational reason is seen, which leads

to a total failure of the system. The only reason can be a destruction of the coupling or a shaft

breaking. For reasons of a 100% secure a water hammer calculation and analysis of the hypothetical

total failure was done and is described in the following.

2.8.2.8.2 Water hammer analysis without a water hammer protection

The worst case regarding water hammer would be the sudden total failure or breakdown of the PaT-

pump modules. A reason for that case could be, e.g., a destruction or break of the coupling or the

shaft of the PaT-pump modules. However this case is hypothetical and would most likely not occur.

In the worst case scenario, the maximum positive pressure is 70 bar at the lowest point of the pipe

(Point 01) at an altitude of about 700 masl and 18 bar at the highest point of the pipe at an altitude of

1250 masl according to the calculation of the company KSB AG (see Fig. 111). This pressure contains

the geodetic water pressure of 547 m (H = 543 m + 4 m (filling the tank from the top)), the dynamic

head of 31 m (due to the maximum delivery rate of 20 l/s and a pipe roughness of 0.1 mm) and the

increase of pressure due to the water hammer.

In the worst case scenario, the pressure drops to vapor pressure from pipe length 700 m until pipelength 2,455 m (tank in Ma U) according to the calculation of the company KSB AG (see Fig. 111).

After collapsing of the vapor bubble the according section of the pipe would be exposed to dangerous

pressures. Hence, water hammer protection devices, as specified in the next section 2.8.2.8.3, should

be installed to prevent the pressure drop.

Fig. 111: Results of the water hammer analysis for worst case scenario without water hammer protection



Pre-Design

/ 127

2.8.2.8.3 Specification of the water hammer protection

Air vessel

To be on the safe side an air vessel should be installed at pipe length 870 m at an altitude of 1,127.3

masl to avoid a drop to vapor pressure (see point 6 in Tab. 20 and Fig. 82). The air vessel should be

in PN25 and has to have a total volume of 500 l with a gas volume of approx. 350 l (70%) at an

operating pressure of 12,5 bar (rel.) to realize an outlet operating pressure of 13,5 bar (abs.). E.g., an

air vessel of the company Olaer, type DDH 500-25/90 with a connection DN100 would be appropriate

(see. Fig. 112 and http://www.olaer.ch/Downloads/Wasser/en/old_0470-e.pdf). The air vessel might

be installed directly on the pressure supply pipe. However, it is recommended to install a gate valve in-

between pipe and air vessel. Furthermore, it is recommended to install a LED water level display in

order to be able to monitor the functionality of the air vessel. To protect the air vessel a chamber hasto be build. The chambers are to construct with reinforced concrete and lids with a handle, which is

lockable.

Fig. 112: Exemplary specification of an appropriate air vessel (Olaer, type DDH 500-25/90)



Pre-Design

/ 127

Air valves

Furthermore, air valves have to be installed at the local high points 18, 30 and 32 of the pipe in order

to avoid vapor pressures and to enable a smooth operation (see. Tab. 20 and Fig. 113). The air valves

are specified in the next section 2.8.2.9. (In Fig. 113 the water hammer analysis with the installed air

vessel and air valves is shown. The pressure does not drop to vapor pressure.)

Pipe wall thickness

In Fig. 113 (bottom) is seen that pressure peaks up to 73 bar at the lowest point of the pipe at an

altitude of about 700 masl occur in short-term (Point 01 = PS outlet). Hence, the maximum pressure of

73 bar due to water hammer has been considered as maximum design pressure (MDP) for the design

of the pipe (material, wall thickness), see section 2.8.2.2.2.

Fig. 113: Results of water hammer analysis for worst case scenario with water hammer protection



Pre-Design

/ 127

Changes in the routing of the pipe, described in section 2.8.2.1, might lead to the need for

revision of the location and specification of the water hammer protection devices. This must be

considered in the course of the developing of the Final Engineering Design.

2.8.2.9 Air valves

At each local high point an air valve must be mounted. For the suggested route of the supply pipe (see

section 2.8.2.1) at three locations air valves have to be installed with the specifications summarized in

Tab. 26 (exemplary specification of an appropriate air valve: VAG Duojet, type KAT-A 1919).

Tab. 26: Location (see. Tab. 20) and specification of the air valves

Point (seeTab. 20) Length of thepipe [m] Height [m] PN [bar] DN Min. inletaperture [mm]

18 1333.2 1189.6 35 50 10

30 2140.0 1240.6 35 50 10

32 2305.2 1246.8 35 50 10

Changes in the routing of the pipe, described in section 2.8.2.1, might lead to a revision of the

location and specification of the air valves, (to be considered in the Final Engineering Design.

2.8.2.10 Construction stages of the pressure supply pipe

The pressure supply has to be constructed in two construction stages as described in section 2.5.2.1

to ensure a precise connection of the pressure supply pipe with the pumping modules.

2.8.3 Material and services

2.8.3.1 Piping

The dimensioning process for all pipe segments includes a safety factor of 1.5 referring to the

required strength of the material.

Tab. 27: List of materials for piping

Position Materials Amount Unit

27.1 Piping Material P235DN 150OD 168.3Wall thickness: 6.3 mm

~ 280 m

27.2 PipingMaterial P235DN 150OD 168.3Wall thickness: 5.6 mm

~ 330 m

27.3 PipingMaterial P235DN 150

OD 168.3Wall thickness: 4.5 mm

~ 150 m



Pre-Design

/ 127

27.4 Piping Material P235DN 150OD 168.3Wall thickness: 4 mm

~ 1700 m

27.5 Pipe elbowMaterial P235DN 150OD 168.3BA3DWall thickness: 11 mm

9 pcs

27.6 Pipe elbowMaterial P235

DN 150OD 168.3BA3DWall thickness: 7.1 mm

10 pcs

27.7 Pipe elbowMaterial P235DN 150OD 168.3BA3DWall thickness: 5.6 mm

4 pcs

27.8 Pipe elbowMaterial P235DN 150

OD 168.3BA3DWall thickness: 4.5 mm

43 pcs

The pipe material has to be in accordance with the standards listed below or equivalent to them.

These are, but are not limited by, the following:




EN 1333 – Flanges and their joints – pipework components – Definition and selection of PN


Tab. 28: List of materials for welding; calculation with 6 m pipe segments


28.1 Materials for welding: Number of joints 410 pcs




DIN EN ISO 9606-1 – Qualification test of welders



Pre-Design

/ 127

DIN EN ISO 9692-1 – Welding and allied processes – Types of joint preparation, Part 1

Manual metal-arc welding, gas-shielded metal-arc welding, gas welding, TIG welding and

beam welding of steels

2.8.3.3 Bearing and foundations

Tab. 29: List of materials for bearings


29.1 Fixed points (21, referring to drawing 15/201-ST-01-105 respectively -106):

Concrete with a characteristic strength of f ck = C25/30dimensions according to the static requirements l x w x h = 2.0 x1.5 x 0.75 m³, approximately 2.25 m³ per fixed point each

Steel plate 250 x 150 x 20 mm (min. tensile strength 235 N/mm²)Steel plate steel 160 x 140 x 1 mm (min. tensile strength 235N/mm²)U-profile (min. tensile strength 235 N/mm²)Pipe shell, min. thickness same as the pipe (min. tensile strength235 N/mm²)Profiled steel HEA 140 (min. tensile strength 235 N/mm²)L-profile steel 50 x 5 mm (min. tensile strength 235 N/mm²)Bolts Hilti HIT-HV200-A + HIT-V-D M16 (or comparable)

47.25

21168

4221

1264242

m³

pcspcs

pcspcs

pcspcspcs

29.2 Reinforced guide bearings (70, referring to drawing 15/201-ST-01-103respectively -104):

Concrete with a characteristic strength of f ck

= C25/30dimensions according to the static requirements l x w x h = 1.0 x1.0 x 0.75 m³, approximately 0.75 m³ per reinforced guidebearing each

Steel plate 300 x 300 x 25 mm (min. tensile strength 235 N/mm²)Profiled steel HEA140 (min. tensile strength 235 N/mm²)Bolts Hilti HIT-HV200-A+HIT-V-D M16 (or comparable)Pipe bearing type LSF 43.0150.107-37.2 by Witzenmann (orcomparable) (min. tensile strength 235 N/mm²)

52.5

7028028070

m³

pcspcspcspcs

29.3 Slid and guide bearings(329, referring to drawing 15/201-ST-01-101respectively -102):

Concrete with a characteristic strength of f ck = C25/30dimensions according to the static requirements l x w x h = 0.5 x

1.0 x 0.5 m³, approximately 0.25 m³ per bearing eachSteel plate 150 x 150 x 15 mm (min. tensile strength 235 N/mm²)Steel plate 110 x 100 x 10 mm (min. tensile strength 235 N/mm²)Profiled steel HEA100 (min. tensile strength 235 N/mm²)Guide rail L 50 X 5 (min. tensile strength 235 N/mm²)Bolts Hilti HST M16 (or comparable)Pipe bearing type LSL 23.0300.150-37.2 by Witzenmann (orcomparable) (min. tensile strength 235 N/mm²), onle for guidebearing

82.25

329658987591316329

m³

pcspcspcspcspcspcs



Pre-Design

/ 127


Tab. 30: List of materials for corrosion protection


30.1 Coating for protection against corrosion ~ 1,300 m²

The corrosion protection has to be in accordance with the standards listed below or equivalent to

them. These are, but are not limited by, the following:

EN ISO 12944 part 1 – 8

2.8.3.5 Water hammer protection

Tab. 31: List of materials for the water hammer protection


31.1 Air vesselVolume: 500 l (350 l gas, 70%), operating pressure: 12.5 bar,operating pressure outlet: 1.5 barPN 25DN100

Gate valveDN100

Chamber

Reinforced concrete

1

1

3

pcs

2.8.3.6 Air valves

Tab. 32: List of materials for air valves


32.1 Air valveDN 50PN 35

3 pcs

2.8.3.7 Services

Tab. 33: List of services for the pressure supply pipe

Position Service Amount Unit

33.1 Land purchase for the pressure supply pipe 2,455 m

33.2 Transport of materials to construction site 1 ls

33.3 Piping 2,455 m

33.4 Pipe-to-pipe welding 410 pcs

33.5 Construction of foundations 420 pcs

33.6 Installation of the bearings 420 pcs

33.7 Installation of the air valves

33.8 Installation of the air vessel

33.9 Painting of corrosion protection ~ 1,300 m²



Pre-Design

/ 127

The services have to be in accordance with the standards listed below or equivalent to them. These

are, but are not limited by, the following:




levels

2.9 Distribution tank Ma U

2.9.1 Location

To distribute the pumped water to the consumers within the supply areas Dong Van City, Sang Ma

Sao and North Slope a distribution tank will be constructed in the village Ma U. It represents a

geodetic highpoint which allows supplying the supply areas by gravity. The exact location of the tank

was determined together with the Ha Giang and Dong Van People’s Committees on 13th of November

2014. The tank will be constructed next to the school in Ma U at an altitude of 1,250 masl (see Fig.

114).

Fig. 114: Location of the distribution tank in Ma U7

7 www.bing.com



Pre-Design

/ 127

2.9.2 Functionality

The tank in Ma U has two functions. It has a certain storage capacity to buffer the variations between

inflow and outflow. In order to distribute certain proportions of the inflow to the supply areas, the tank

furthermore serves as a facility to divide the inflow proportionally into three defined outflows which

supply Dong Van City, the supply are Sang Ma Sao and the supply area North Slope.

The tank’s construction sees a pre-chamber which collects the total inflow (water pumped from Seo

Ho HPP). The pre-chamber has three weirs. The weir overflows are collected in three chambers from

which the water is distributed through pipes to the supply areas. The allocation of the inflow to the

three chambers and, thus, the definition of the proportion of the inflow, each supply area is supplied

with, can be flexibly defined by choosing the width of the weirs (weir overflow/total inflow = weir

width/total weir width). The advantage of that solution is the fact that the varying inflow is proportionallyallocated to the supply areas without any daily operation.


2.9.3.1 Basic structure of the distribution tank

The distribution tank will have a total storage volume of 110 m³. The tank consists of a pre-chamber

and three chambers, which each supply a supply area (see Fig. 115). Note that Sang Ma Sao and Ma

U will be supplied by one chamber. Each chamber is equipped with a supply pipe including a gate

valve (see Fig. 115). In order to ensure a flow of water towards the supply pipe, the bottoms of the

three chambers as well as the pre-chamber have to be built with a slope of 2% towards the respectiveemptying pipe. A water sump in the area of the supply pipe is necessary to avoid sucking air by the

pipe (see Fig. 116). The exact dimensions can be found in the following figures. The weir, the inflow,

outflow and the run of the pipes outside of the tank are in the Fig. 117 - Fig. 122 in more detail. The

array of the openings in the ceiling can be found in the Fig. 123.

The walls and the ceiling of the tank are designed to have a thickness of 20 cm each, the slab of 30

cm. It should be made out of reinforced concrete with a minimum characteristic strength f ck = C30/37.

At both sides of the walls, ceiling and slab, a reinforcement with a bar diameter of 12 mm each 150

mm should be installed crosswise in longitudinal and transverse direction.



Pre-Design

/ 127

Fig. 115: Section 1-1: Ground plan of the distribution tank; Dimensions in meter

C HA MB E R

: V I L L A GE S N ORT H S L OP E

C HA MB E R

: D ON GV A N

C HA MB E R

: S A N GMA S A OA NDMA U

P RE C HA MB E R

DN1 0 0

DN1 0 0

DN1 0 0

DN

1 0 0

D N 1 0 0

DN7 5

DN 5 0 D

N1 0 0

1 . 0 0

4 . 3 0

0 .7 0

0 .2 0

0.20

0 .2 0

0.200.20

DN1 5 0

I NF L OW

SLOPE: 2%

S L OP E : 2 %

S L OP E : 2 %

S L OP E : 2 %

OV E RF L OW

C R O S

S B A R

C R O S

S B A R

C R O S S

B A R

2

2

3 3

GA T E V

A L V E

E MP T Y I N GA ND OV E RF L OW P I P E ,MA T E RI A L : S T E E L

S UP P L Y P I P E

MA T E RI A L

: S T E E L

N ORT H

1.004.001.00

DN2 0 0

0.440.441.941.940.440.44

0 . 5 0

0 . 5 0

D N 1 5 0

0.40 0.40 0.40

SLOPE: 2%



Pre-Design

/ 127

Fig. 116: Section 2-2: Side view of the distribution tank; Dimensions in meter

2.9.3.2 Supply and emptying pipe

Each chamber is equipped with a supply pipe and a gate valve. In order to ensure security of supply in

a possible failure of one chamber, the supply pipes of the respective chambers are connected to each

other and separated by gate valves (see Fig. 115). For maintenance measures each chamber must be

able to be emptied. Therefore an emptying pipe with a gate valve branches of each supply pipe. For

the pre-chamber an emptying pipe is provided as well. It is located directly under the overflow at the

SLOPE:2%

SLOPE:2%

DN100

1.00

0.70

DN150

I N F L O W P I P E , M A T E R I A L S T E E L

4.30

0.20

0.20

OVERFLOW

EMPTYINGPIPE,DN100

SUPPLYPIPE

EMPTYINGPIPE

1

1

DETAIL1AND2

DETAIL3

2.20 1.800.20

0.30

4

4

0.30

0.30



Pre-Design

/ 127

bottom (see Fig. 116). All emptying pipes and the overflow run together to one pipe (see Fig. 115).

This pipe should be end in a field next to Ma U to provide the water to the local agriculture.

SUPPLY PIPE

SANG MA SAO

SUPPLY PIPE

DONG VAN CITY NORTH SLOPEEMPTYING PIPE

OVERFLOW

DN100

SUPPLY PIPE

GATE VALVE

EMPTYING PIPE

PRE-CHAMBER

2 . 7

0

1 . 2

2

0 . 5

0

DN

150

0.40

0.20

0.402.100.402.100.64 0.40

0 . 4

0

Fig. 117: Section 3-3: Routing of the emptying and overflow pipes; Dimensions in meter

2.9.3.3 Inflow and overflow

The tank will be filled above the water level. A submerged inlet should be avoided. The nozzle of the

inlet shows a 90° arc pointing down. Thus, the energy of the jet dissipates in the water of the pre-

chamber (see Fig. 118). For safety reasons the tank has to be equipped with an overflow, which is

mounted at the top of the pre-chamber (see Fig. 119). Outside of the tank the overflow pipe isconnected with the emptying pipe to remove the water (see Fig. 117).



Pre-Design

/ 127

DN150

0.10

0 . 1

0

0.10

0 . 1

5

0 . 4

0

0.30

0 . 1

0

Fig. 118: Detail 1: Detailed side view of the inflow(Note: Overflow is eliminated for this figure);Dimensions in meter

OVERFLOW

0.41 0.41

0 . 2 0

0 . 1 0

0 . 1 8

Fig. 119: Detail 2: Detailed side view of the overflow(Note: Inflow is eliminated for this figure); Dimensionsin meter

2.9.3.4 Weirs

Weirs between the pre-chamber and the three chambers allow that water flows from the pre-chamber

to the chambers. The widths of the weirs define the distribution of the inflow to the chambers and,

thus, to the supply areas. 0.4 m above the weir three crossbars are installed (see Fig. 120). The

material of the crossbars can be wood or reinforced concrete. The crossbars should be fixed in thepartition wall. Barrier plates are mounted at the crossbar to reduce the width of the weir to finally

regulate the discharge to the chamber (see Fig. 121 and Fig. 122). The width of the weir can be set

fine due to the possibility of overlapping of the barrier plates.

Fig. 120: Front view of the weir with the installed crossbar andbarrier plates (Chamber: Villages north slope and chamber:Sang Ma Sao and Ma U); the construction for the chamberDong Van is the same but differs in the width (4 m)

Fig. 121: Scheme of the installation of thebarrier plates



Pre-Design

/ 127

Fig. 122: Detail 3: Side view of the weir and the barrier plate

2.9.3.5 Openings in the ceiling of the tank

In the ceiling of the tank openings are necessary to have access to the chambers for reasons of repair

and to set the widths of the weirs. Four openings are provided to enable access to each chamber of

the tank (see Fig. 123). The four accesses are equipped with hinged lids. The material of the lids

should be any kind of metal. At the openings a handle must be provided and the lids must be lockable

to avoid unauthorized entrance by persons. Inside of each chamber ladders of stainless steel have to

be installed to climb down into the chamber. For the three chambers ladders with a length of 4 m and

a width between 0.4 – 0.5 m are necessary. For the pre-chamber a ladder with a length of 1.8 m and

the same width as the others is required. The ladders should be fixed at the walls for safety reasons.

The exact dimensions take out of the figures.



Pre-Design

/ 127

Fig. 123: Section 4-4: Ground plan of the distribution tank with the openings in the ceiling (hatchedcross/diagonal); Dimensions in meter

2.9.3.6 Chamber for the valves

To protect the valves against unauthorized use, valve chambers have to be provided. The chambers

are to construct with reinforced concrete and lids with a handle, which is lockable.

INFLOW

OVERFLOW

GATEVALVE

EMPTYINGANDOVERFLOW

PIPE,MATERIAL:ST

EEL

SUPPLYPIPE

MATERIAL:STEEL

N

ORTH

0.75

0.75

0.75

0.750.750.75

0.200.20

0.75

0.75

0.20



Pre-Design

/ 127


2.9.4.1 Construction of the tank

Tab. 34: List of materials for the construction of the tank in Ma U

Position Material Amount Unit

34.1 Reinforcement steel with a yield strength of f y = 500 N/mm² 5,500 kg

34.2 Concrete with a characteristic strength of f ck = C30/37 50 m³34.3 Application of a waterproof plaster on the inner tank walls 264 m²

The materials for the tank have to be in accordance with the standards listed below or equivalent to


EN 1508 – Water supply – Requirements for systems and components for the storage of water

2.9.4.2 Valves and tank facilities

Tab. 35: List of materials for the valves and tank facilities

Position Material Amount Unit35.1 Gate Valve

Material: SteelDN 100PN 6

9 pcs

35.2 Inflow pipe

Material: Steel P235DN 150OD 168.3 mmWall thickness 3.6 mm

4 m

35.3 Inflow fitting


1 pcs

35.4 Supply pipe


10 m

35.5 Emptying and overflow pipe

Material: Steel P235DN 200, OD 219.1, wall thickness 3.6 mmDN 150, OD 168.3, wall thickness 3.6 mmDN 100, OD 114.3, wall thickness 3.2 mm

25

4.5

15.5

m

m

m

35.6 Flanges

Material steelDN 100

18 pcs



Pre-Design

/ 127

PN 635.7 Bolts

Hexagon shank M16

36 pcs

35.8 Nuts

Hexagon nut M16

36 pcs

35.9 Washers

Plain washer M16

72 pcs

35.10 Overflow hopper

Material: SteelPN 6

1 pcs

The valves and the tank facilities have to be in accordance with the standards listed below or

equivalent to them. These are, but are not limited by, the following:

EN 1074 – Valves for water supply – Fitness for purpose requirements and appropriate

verification tests – Part 1 – 3

EN 1092 – 1 – Flanges and their joints – Circular flanges for pipes, valves, fittings andaccessories, PN designated – Part 1: Steel flanges

EN 10311 – Joints for the connection of steel tubes and fittings for the conveyance of waterand other aqueous liquids

EN ISO 4014 – Hexagon head bolts – Product grades A and B

EN 1515 – Parts 1 – 4 Flanges and their joints – Bolting

EN ISO 7089 – Plain washers – Normal series, Product grade A

Tab. 36: List of materials for the weirs


36.1 Crossbar

Material: wood or reinforced concreteLength: 1 mLength: 4 m

2

1

pcs

36.2 Bolts 3 ls

36.3 Barrier plates

Material: Metal sheet60 x 10 x 0.3 cm³

30 pcs

Tab. 37: List of materials for the openings of the tank


37.1 Lids with a handle

Material: Metal0.75 x 0.75 m²

4 pcs

37.2 Ladder

Material: Stainless steelLength 4 m, width 0.4 – 0.5Length 1.8 m; width 0.4 – 0.5

3

1

pcs



Pre-Design

/ 127

2.9.4.3 Services

Tab. 38: List of services for the storage tank in Ma U

Position Service Amount Unit

38.1 Land purchase for the tank 45 m²


38.3 Construction of the distribution tank 133 m³

38.4 Installation of the valves and tank facilities 11 ls

38.5 Installation of the weirs 3 ls

38.6 Installation of the inflow, supply, emptying and overflow pipe 6 ls




2.10 Distribution from the tank Ma U to the tank Dong Van City

2.10.1 Location

In this chapter the measures for implementing a supply pipe from the distribution tank Ma U (1,250

masl) through a pressure breaker (1,182 masl) to the storage tank above Dong Van City (1,123 masl)

will be described. The pipe with its routing, piping, pipe connection, foundations and the corrosion

protection are described in the sections 2.10.2. The functionality and the structure of the pressure

breaker are described in section 2.10.2 as well. For descriptions of the storage tank above Dong Van

City and the connection of the tank to the distribution network of Dong Van City see the next section

2.11 and the subsequent section 2.12.

Fig. 124: Location of the distribution tank Ma U, supply pipe and the storage tank Dong Van City



Pre-Design

/ 127


2.10.2.1 Routing

The routing of the pipe is along the existing path/road from Ma U to Dong Van City (see Fig. 126). The

profile and the data of the supply pipe can be found in Fig. 125 respectively in Tab. 39.


developing of the Final Engineering Design.

Fig. 125: Profile of the supply pipe from the distribution tank Ma U to the storage tank Dong Van City



Pre-Design

/ 127

Fig. 126: Routing of the supply pipe from the distribution tank in Ma U over a pressure breaker to the storage tankabove Dong Van; supply pipe (orange line), numbered points are the measured points in Tab. 39

8

Tab. 39: Data of the planned route

PointLength of the

pipe section [m]Length of the

pipe ongoing [m]Horizontal distance

[m]

Differencein height

[m]Height [masl]

1 0 0 0 0 1247,2

2 21,6 21,6 21,2 1,2 1246

3 9,8 31,5 8,7 4,6 1241,4

4 61,1 92,6 60,3 10 1231,4

5 35,4 127,9 35,3 2,2 1229,2

8 www.bing.com



Pre-Design

/ 127

6 34,7 162,7 34,7 1,1 1228,17 37,3 199,9 37,1 3,4 1224,7

8 30,8 230,7 30,7 2,7 1222

9 22,3 253,0 22,2 1,8 1220,2

10 93,3 346,3 93,1 6,5 1213,7

11 36,9 383,2 35,9 8,5 1205,2

12 45,9 429,2 45,7 4,7 1200,5

13 51,3 480,5 51,3 1,5 1199

14 47,0 527,5 46,8 4,7 1194,3

15 102,3 629,8 101,6 11,7 1182,6

16 45,2 675,0 45,2 0,3 1182,3

17 46,9 721,9 46,5 5,8 1176,5

18 74,7 796,6 74,5 5,4 1171,1

19 62,2 858,8 62,1 4,2 1166,9

20 45,0 903,8 44,7 5,4 1161,5

21 84,9 988,7 84,6 7 1154,5

22 27,2 1015,9 27,0 3,4 1151,1

23 67,8 1083,7 67,4 7,3 1143,8

24 77,2 1160,9 76,3 11,7 1132,1

25 74,1 1235,0 73,9 5,2 1126,926 32,7 1267,7 32,7 1,8 1125,1

27 59,8 1327,6 59,7 -4,2 1129,3

28 50,4 1378,0 50,2 -4,9 1134,2

29 23,4 1401,5 23,4 1,3 1132,9

30 68,7 1470,1 68,6 2,9 1130

31 45,3 1515,5 45,3 2,1 1127,9

32 56,8 1572,3 56,7 4 1123,9

2.10.2.2 Piping

For the supply of Dong Van City by gravity, a supply pipe from the distribution tank in Ma U to the

storage tank above Dong Van City will be constructed. The length of the pipe is approx. 1,573 m.

Because the pipe is constructed above ground and, thus, exposed to sunlight and mechanical forces,

a steel P235 is selected as material. Due to the expectable maximum delivery rate of approximately

13.5 l/s a diameter of DN 100 is necessary to ensure a supply of Dong Van City by gravity (by

calculating with a roughness of 0.1 mm and the maximum delivery rate as mentioned before, the

losses are 42 m). Taking into account bypassing the pressure breaker in the future for using hydro

power, the design pressure (DP) is 12.7 bar due to the difference in height between the tank Ma U and

the storage tank Dong Van (). The maximum design pressure (MDP), thus, is 14.7 bar considering a

water hammer protection of 2 bar. This results in a required wall thickness of 3.2 mm according to the

standard EN-DIN 2460 Steel water pipes and fittings.



Pre-Design

/ 127

Summary of the pipe characteristics:

Tab. 40: Boundary conditions for the distribution pipe

Material Steel P235

Diameter DN 100

Maximum design pressure (MDP) 14.7 bar

Wall thickness 3.2 mm

Routing Above ground


The pipe segments will be welded. The weld must be of high quality to withstand the operatingpressure (see description of the operating pressure in section 0). The welding of joints shall be in

accordance with EN 1011 and DIN 2559. Therefore a certified welder is necessary according to the

standard EN 287-1.

2.10.2.4 Foundation

As support for the supply pipe, foundations shall be constructed at regular intervals. The distance

between the slide bearings is 7.8 m, thus, for this pipe length of almost 1,600 m, 200 slide bearings

are necessary. To absorb the operating pressure and the forces due to temperature expansion, 30

fixed points are necessary, which will be constructed at the kinks of the pipe. To avoid future damages

in the water distribution system and to ensure an economic construction process, the foundations have

to be dimensioned with a systematic and comprehensive approach according to each foundations

loading situation which may vary depending on the course of the pipeline.

2.10.2.5 Corrosion Protection

In order to ensure the durability of the pipe, it must be protected against corrosion. The pipe has to be

painted by coat paint.

2.10.2.6 Pressure breaker

2.10.2.6.1 Functionality

To avoid high pressures a pressure breaker has to be built. The pressure breaker basically is a tank

which splits the pipe in two parts and provides for atmospheric pressure at the location of the tank.

The pressure breaker has to be located at an elevation of 1,182 masl. The location can be found in

Fig. 126 Thus, a maximum pressure of 6.8 bar in the upper part and of 5.9 bar in the lower part of the

pipe is achieved. To dissipate the energy the inflow will be above the water level and to avoid an

overflow, a floating valve will be installed.

Annotation: In case the existing elevation difference between the tank Ma U and Dong Van City shall

be exploited for hydro power generation someday in future the planned pipe infrastructure may be

used. The pressure breaker then simply has to be by-passed.



Pre-Design

/ 127

2.10.2.6.2 Basic structure

The pressure breaker will have a total storage volume of 3 m³ and an operating volume between 1.5

and 2.3 m³ according to the setting of the floating valve. The operating volume prevents an oscillation

of the floating valve (ongoing opening and closing). In order to ensure a flow of water towards the

supply pipe, the bottom of the pressure breaker has to be built with a slope of 2% towards the

emptying pipe. A water sump in the area of the supply pipe is necessary to avoid sucking air by the

pipe (see Fig. 128). The exact dimensions can be found in the following figures. The inflow, outflow

and the run of the pipes outside of the pressure breaker are in the Fig. 127 - Fig. 129 in more detail.

The detailed views of the overflow, inflow and an example of a floating valve can be seen in Fig. 130 -

Fig. 132. The array of the opening in the ceiling can be found in the Fig. 133.

OVERFLOW

DN 100

DN 100

INFLOW

DN 100

SLOPE 2%

SUPPLY PIPE

MATERIAL: STEEL

EMPTYING

ANDOV

ERFLOW

PIPE

M A T E R I A L : S T E E L

11

1.40

1 . 2

0

0.30

0 . 1

0

DN150

NORTH

GATE VALVE

3

3

SLOPE 2%

0 . 8

7

FLOATING VALVE

FLOAT 0 . 2

0

Fig. 127: Section 2-2 Ground plan of the pressure breaker; Dimensions in meter

The walls and the ceiling of the pressure breaker are designed to have a thickness of 20 cm each, the

slab of 30 cm. It should be made out of reinforced concrete with a minimum characteristic strengthf ck = C30/37. At both sides of the walls, the ceiling and slab, a reinforcement with a bar diameter of 12

mm each 150 mm should be installed crosswise in longitudinal and transverse direction.



Pre-Design

/ 127

SLOPE 2%

SLOPE 2%DN 100

SUPPLY PIPE

EMPTYING PIPE

OVERFLOW

INFLOW

DN 100

DN 100

1 1

4 4

GATE VALVE

DETAIL 1 DETAIL 2

1 . 8

0

0.401.000.30

0 . 2

0

FLOATING VALVEFLOAT

Fig. 128: Section 1-1 Side view of the pressure breaker; Dimensions in meter

2.10.2.6.3 Supply and emptying pipe, overflow

The pressure breaker is equipped with a supply pipe and a gate valve. For maintenance measures the

pressure breaker must be able to be emptied. Therefore an emptying pipe with a gate valve branches

of the supply pipe (see Fig. 129). For safety reasons the pressure breaker has to be equipped with an

overflow (see Fig. 130). Outside of the tank the overflow pipe is connected with the emptying pipe to

remove the water (see Fig. 129). This pipe should be end in a field next to the path to Dong Van to

provide the water to the local agriculture.



Pre-Design

/ 127

OVERFLOW

DN 150

D N 1

0 0

D

N 1

0 0

GATE VALVE

0 . 4 0

0.20 0.16

0 . 4 0

0.60

Fig. 129: Section 3-3 Routing of the emptying and overflow pipes; Dimensions in meter

OVERFLOW

DN 100

0.15

0 . 2

0

0 . 1

0

0.30

Fig. 130: Detail 2 Detailed side view of the overflow; Dimensions in meter



Pre-Design

/ 127

2.10.2.6.4 Inflow and floating valve

The pressure breaker will be filled above the water, to dissipate the energy of the jet. The nozzle of the

inlet has a 90° arc pointing down.

As mentioned before a floating vale will be installed. As a possible example a floating valve and its

specification is described in the following and shown in Fig. 132 which includes the mentioned

numbers in the text. The floating valve is composed of a main valve (1), a handle (2), a float bar (3)

and a float (4). The float and the float bar increase with the increasing water level. This is transferred

mechanically over the handle to the main valve which closes tightly. The main valve remains close

until the float reaches the lower stop. The difference between the top and bottom water level isadjustable from 50 mm to 600 mm (source: www.erhard.de).

DN 100

0.40

0 . 1

0

0 . 0

5

FLOAT

Fig. 131: Detail 1 Detailed side view of the inflow andthe installed floating valve; Dimensions in meter

Fig. 132: Scheme of the floating valve; see descriptionof the figure in section 0

9

2.10.2.6.5 Openings in the ceiling of the tank

In the ceiling of the pressure breaker an opening is necessary to have access to the chamber forreasons of repair and to set the floating valve. One opening is provided to enable access to the tank

(see Fig. 133). The access is equipped with a hinged lid. The material of the lid should be any kind of

metal. At the opening a handle must be provided and the lid must be lockable to avoid unauthorized

entrance by persons. Inside of the pressure breaker a ladder of stainless steel has to be installed to

climb down. The ladder needs a length of 1.8 m and a width between 0.4 – 0.5 m. The ladders should

be fixed at the walls for safety reasons.

9 www.erhard.de



Pre-Design

/ 127

NORTH

GATE VALVE

0.75

0 . 7

5

Fig. 133: Section 4-4 Ground plan of the pressure breaker with the opening in the ceiling (hatchedcross/diagonal); Dimensions in meter


To protect the valves against unauthorized use, a valve chamber has to be provided. The chamber is

to construct with reinforced concrete and a lid with a handle, which is lockable.


2.10.3.1 Piping

Tab. 41: List of materials for piping; Ma U - storage tank Dong Van City


41.1 Piping:

Material: Steel P235DN 100OD 114.3Wall thickness 3.2 mm

1,573 m






EN-DIN 2460 Steel water pipes and fittings.



Pre-Design

/ 127


Tab. 42: List of materials for pipe connection: Ma U - storage tank Dong Van City; Calculation for 6 m pipesegments



The pipe connection by welding has to be in accordance with the standards listed below or equivalent

to them. These are, but are not limited by, the following:


2.10.3.3 Foundation

Tab. 43: List of materials for the foundations


43.1 Fixed points with assumed dimensions of 40 x 40 x 40 cm (30):

Reinforcement steel with a yield strength of f y = 500 N/mm²approximately 4.5 kg per fixed point each

Concrete with a characteristic strength of f ck = C20/25approximately 0.064 m³ per fixed point each

135

2

kg

m³

43.2 Sliding supports (200):

Reinforcement steel with a yield strength of f y = 500 N/mm²approximately 1.3 kg per sliding support each

Concrete with a characteristic strength of f ck = C20/25approximately 0.036 m³ per sliding support each

260

7.2

kg

m³


Tab. 44: List of materials for corrosion protection


44.1 Coating for protection against corrosion 565 m²

The corrosion protection has to be in accordance with the standards listed below or equivalent tothem. These are, but are not limited by, the following:

EN ISO 12944 part 1 – 8

2.10.3.5 Pressure breaker

Tab. 45: List of materials for pressure breaker


45.1 Reinforcement steel with a yield strength of f y = 500 N/mm² 300 kg

45.2 Concrete with a characteristic strength of f ck = C30/37 3 m³

45.3 Application of a waterproof plaster on the inner tank walls 13 m²



Pre-Design

/ 127

Tab. 46: List of materials for the valves and facilities of the pressure breaker


46.1 Gate valve

Material: steelDN 100PN 6

3 pcs

46.2 Floating valve

Material steelDN 100PN 6

1 pcs

46.3 Inflow pipe

Material: Steel P235

DN 100OD 114.3 mmWall thickness 3.2 mm

2 m

46.4 Inflow inlet

Material: steelDN 100OD 114.3 mmWall thickness 3.2 mm

1 m

46.5 Overflow pipe

Material: steelDN 100OD 114.3 mm

Wall thickness X.X mm

2 m


Material: Steel P235PN 6

1 pcs

46.7 Supply pipe


1 m

46.8 Emptying pipe

Material: Steel P235DN 100, OD 114.3 mm, wall thickness 3.2 mmDN 150, OD XXX.X mm, wall thickness X.X mm

1

5

m

m46.9 Flanges


10 pcs

46.10 Bolts

Hexagon shank M16

20 pcs

46.11 Nuts

Hexagon nut M16

20 pcs

46.12 Washers

Plain washers M16

40 pcs

The valves and facilities for the pressure breaker have to be in accordance with the standards listedbelow or equivalent to them. These are, but are not limited by, the following:



Pre-Design

/ 127



2.10.3.6 Services

Tab. 47: List of services


47.1 Land purchase for supply pipe and pressure breaker 1,573 m


47.3 Piping 1,573 m

47.4 Pipe-to-pipe welding 263 ls

47.5 Construction of foundationsFixed pointsSliding supportsRestricted guidance

30

200

30

pcs

pcs

pcs

47.6 Painting of corrosion protection 565 m²

47.7 Construction of pressure breaker 1 ls

47.8 Installation of the valves and tank facilities 6 pcs


Note: Position 10.25 is a calculation for 6 m pipe segments






levels

EN 805 – Water supply – Requirements for systems and components outside building

2.11 Storage tank Dong Van City

2.11.1 Location

To buffer differences between the amount of water Dong Van City is supplied with and the

consumption within Dong Van City a storage tank above Dong Van City will be constructed (see Fig.

134). The storage tank will be located at 1,123 masl in the west of Dong Van City. The coordinates of

the location of the tank are 535719, 2574486 (x-coordinate, y-coordinate; reference system:

VN_2000_UTM_Zone_48N). From there the water distribution system of Dong Van City is supplied by

gravity. In the following sections the functionality, basic structure and the run of the pipes of the tank is

described.



Pre-Design

/ 127

Fig. 134: Location of the storage tank Dong Van City10


2.11.2.1 Basic structure of the storage tank

The storage tank above Dong Van City will have two chambers with a total storage volume of 450 m³

(225 m³ per chamber). This volume gives the possibility of storing more than a third of the maximum

delivery rate of approx. 13.5 l/s in the time period of no demand in Dong Van City. Furthermore, the

storage volume is equal to the daily consumption of 5,000 people with a specific demand of 90 l/cap/d.

(Annotation: the tank construction enables an extension of the tank by additional chambers on twosides of the tank.) The planned tank consists of two chambers for reasons of maintenance and repair

(see Fig. 135). In order to ensure a flow of water towards the supply pipe, the bottoms of the two

chambers have to be built with a slope of 2 % towards the supply pipes. A water sump in the area of

the supply pipe is necessary to avoid sucking air by the pipe (see Fig. 136). The exact dimensions can

be found in the following figures. The inflow, outflow and the run of the pipes outside of the tank are in

the Fig. 135 - Fig. 137 in more detail. In the Fig. 138 and Fig. 139 the inflow and the overflow can be

seen in more detail. The array of the openings in the ceiling can be found in the Fig. 140.

10 www.bing.com



Pre-Design

/ 127

The walls and the ceiling of the storage tank are designed to have a thickness of 20 cm each, the slab

of 30 cm. They should be made out of reinforced concrete with a minimum characteristic strength

f ck = C30/37. At both sides of the walls, ceiling and slab, a reinforcement with a bar diameter of 12 mm

each 100 mm should be installed crosswise in longitudinal and transverse direction.

S L O P E 2 %

S L O P E 2 %

C H A M B E R I

C H A M B E R I I

D N 1 0 0

D N 1 0 0

D N 1 5 0

D N 1 0 0

O V E R F L O W

E M P T Y I N G A N D O V E R F L O W P I P E


S U P P L Y P I P E


O V E R F L O W

2

2

3 3

D N 1 0 0

1 . 3 9

0 . 4 4

1 . 9 4 1 . 3 9

G A T E V A L V E

I N F L O W

I N F L O W

F L O A T I N G V A L V E

1 . 9 4 1 . 9 4

S L O P E 2 %

S L O P E 2 %

5 . 0 0 5 . 0 0

2 . 9 4 2 . 9 4

9

. 3 0

0 . 7 0

0 . 5 0

0 . 5 0

2 . 9 4 1 . 4 4

N O R T H

1 . 0 0

0 . 3 0

Fig. 135: Section 1-1 Ground plan of the storage tank Dong Van; Dimensions in meter



Pre-Design

/ 127

Fig. 136: Section 2-2 Side view of the storage tank Dong Van; Dimensions in meter



Pre-Design

/ 127

2.11.2.2 Supply and emptying pipe

Each chamber is equipped with a supply pipe and a gate valve. The supply pipes leaving the

chambers join to one single supply pipe (see Fig. 135). For maintenance measures each chamber

must be able to be emptied. Therefore an emptying pipe with a gate valve branches of each supply

pipe (see Fig. 135 - Fig. 137). The overflow pipes of both chambers run together with the emptying

pipe to one pipe.

SUPPLY CHAMBER I SUPPLY CHAMBER IIEMPTYING AND OVERFLOW PIPE DN 150

DN

100

DN

100

D

N

100

DN

100

GATE VALVE

1.85 2.11 1.85

OVERFLOW OVERFLOW

1.642.68

5 .

1 7

0 .

8 1

0 .

4 0

Fig. 137: Section 3-3 Routing of the emptying and overflow pipes; Dimensions in meter

2.11.2.3 Inflow, floating valve and overflow

The tank will be filled above the water level. A submerged inlet should be avoided. The nozzle of the

inlet has a 90° arc pointing down, thus, the energy of the jet dissipates in the water of the tank (see

Fig. 138).

As mentioned before a floating valve will be installed to prevent a filling up of the storage tank. The

functionality of the floating valve is described in section 2.10.2.6.4.

For safety reasons the tank has to be equipped with an overflow (see Fig. 139). Outside of the tank

the overflow pipe is connected with the emptying pipe to remove the water (see Fig. 137).



Pre-Design

/ 127

FLOATING VALVE

DN 100

0 . 4

0

0 . 1

0

0.65

FLOAT

Fig. 138: Detail 1 Detailed side view of the inflow andthe installed floating valve; Dimensions in meter

OVERFLOW

0.50 0.50

0 .

1 0

0 .

5 0

DN 100

Fig. 139: Detail 2 Detailed side view of the overflow;Dimensions in meter

2.11.2.4 Openings in the ceiling of the tank

In the ceiling of the tank openings are necessary to have access to the chambers for reasons of repair

and to set the floating valve. Two openings are provided to enable access to each chamber of the tank

(see Fig. 140). The two accesses are equipped with hinged lids. The material of the lids should be anykind of metal. At the openings a handle must be provided and the lids must be lockable to avoid

unauthorized entrance by persons. Inside of each chamber ladders of stainless steel have to be

installed to climb down into the chamber. The ladders need a length of 5 m and a width between 0.4 –

0.5 m. The ladders should be fixed at the walls for safety reasons.



Pre-Design

/ 127

N O R T H

0.75

0 . 7

5

0 . 8

0

0 . 7

5

0.75

2 . 4

5

2 . 0

0

3 . 6

6

Fig. 140: Section 4-4 Ground plan of the storage tank with the opennings in the ceiling (hatched cross/diagonal);Dimensions in meter


To protect the valves against unauthorized use, valve chambers have to be provided. The chambers

are to construct with reinforced concrete and lids with a handle, which is lockable.


2.11.3.1 Construction of the tank

Tab. 48: List of materials for the construction of the storage tank Dong Van City


48.1 Reinforcement steel with a yield strength of f y = 500 N/mm² 16,000 kg

48.2 Concrete with a characteristic strength of f ck = C30/37 135 m³

48.3 Application of a waterproof plaster on the inner tank walls 450 m²



Pre-Design

/ 127

2.11.3.2 Valves and tank facilities

Tab. 49: List of materials for the valves and tank facilities


49.1 Gate Valve


6 pcs

49.2 Floating valve


2 pcs

49.3 Inflow pipeMaterial: Steel P235DN 100OD 114.3 mmWall thickness 3.2 mm

15 m

49.4 Inflow fitting

Material: SteelDN 100

2 pcs

49.5 Supply pipe

Material: Steel P235DN 100OD 114.3 mm


11 m

49.6 Emptying and overflow pipe

Material steelDN 150, OD 168.3 mm, wall thickness 3.6 mmDN 100, OD 114.3 mm, wall thickness 3.2 mm

20

14

m

49.7 Flanges


16 pcs

49.8 Bolts

Hexagon shank M16

32 pcs

49.9 Nuts

Hexagon nut M16

32 pcs

49.10 Washers

Plain washer M16

64 pcs


Material: SteelPN 6

2 pcs

The storage tank, valves and the tank facilities have to be in accordance with the standards listed

below or equivalent to them. These are, but are not limited by, the following:






Pre-Design

/ 127

Tab. 50: List of materials for the openings of the tank


50.1 Lids

Material: Metal0.75 x 0.75 m²

2 pcs

50.2 Ladder

Material: Stainless steelLength 5 m, width 0.4 – 0.5

2 pcs

2.11.3.3 Services

Tab. 51: List of the services for the storage tank of Dong Van


51.1 Land purchase for the tank 100 m²

51.2 Transport of materials to construction side 1 ls

51.3 Construction of the storage tank 500 m³

51.4 Installation of the valves and tank facilities 10 pcs


The storage tank, valves and the tank facilities have to be in accordance with the standards listed

below or equivalent to them. These are, but are not limited by, the following:

EN 1074 – Valves for water supply – Fitness for purpose requirements and appropriateverification tests – Part 1 – 3




Pre-Design

/ 127

2.12 Distribution from the tank Dong Van City to the existing network of Dong

Van City

2.12.1 Location

Fig. 141: Location of the storage tank above Dong Van City, the supply pipe and the connection to the distributionsystem of Dong Van City at the pumping station

The storage tank Dong Van City (see section 2.11) is connected to the distribution system of Dong

Van City via a supply pipe. The pipe with its routing, piping etc. is described in the sections 2.12.2.1 -

2.12.2.5. The connection to the existing distribution system is described in section 2.12.2.6.


2.12.2.1 Routing

The routing of the pipe is along a path from the storage tank Dong Van City to the pumping station in

Dong Van City where the pipe will be connected to the existing distribution system. The profile, the

routing and the according data of the supply pipe can be found in Fig. 142 and Fig. 143 respectively in

Tab. 52.


developing of the Final Engineering Design.



Pre-Design

/ 127

Fig. 142: Profile of the supply pipe from the storage tank above Dong Van to the to the existing network of DongVan City

Fig. 143: Routing of the supply pipe from the storage tank above Dong Van City to the existing distribution systemof Dong Van City; supply pipe (orange line)

11

11 www.bing.com



Pre-Design

/ 127

Tab. 52: Data of the planned route

PointLength of the

pipe section [m]Length of the

pipe ongoing [m]Horizontal distance

[m]

Differencein height

[m]Height [masl]

1 0,0 0,0 0,0 0 1123,9

2 49,5 49,5 49,3 4,9 1119

3 64,3 113,8 64,1 4,8 1114,2

4 29,6 143,5 29,6 1,3 1112,9

5 17,8 161,3 17,7 1,9 1111

6 21,6 182,9 21,4 3,1 1107,9

7 86,3 269,1 85,7 9,9 1098

8 10,0 279,2 10,0 0,7 1097,3

9 24,2 303,4 24,2 0,4 1096,9

10 37,1 340,5 37,0 3 1093,9

11 47,6 388,1 47,5 3,3 1090,6

12 50,3 438,4 50,3 1,9 1088,7

13 35,2 473,6 35,1 2,6 1086,1

14 36,8 510,5 36,8 1,2 1084,9

15 36,3 546,8 36,1 3,8 1081,1

16 50,8 597,6 50,8 1,1 108017 27,1 624,7 27,1 0,6 1079,4

18 35,5 660,2 35,5 0,9 1078,5

19 33,7 693,9 33,7 1,6 1076,9

20 45,2 739,2 45,2 2,1 1074,8

21 93,2 832,4 93,1 3,9 1070,9

22 38,7 871,0 38,6 2,2 1068,7

23 28,3 899,3 28,2 1,7 1067

24 43,9 943,2 43,7 4,6 1062,4

25 32,9 976,1 32,9 1 1061,4

26 73,8 1050,0 73,8 2,2 1059,2

27 53,7 1103,7 53,7 2,2 1057

28 86,5 1190,2 86,5 1,3 1055,7

2.12.2.2 Piping

For the supply of Dong Van City by gravity, a supply pipe from the storage tank Dong Van City to the

existing distribution system at the pumping station will be constructed. The length of the pipe is

approx. 1,190 m. Because the pipe is constructed above ground and, thus, exposed to sunlight and

mechanical forces, a steel P235 is selected as material Due to the expectable maximum delivery rate

of approximately 13.5 l/s a diameter of DN 100 is necessary to ensure a supply of Dong Van City by

gravity (by calculating with a roughness of 0.1 mm and the maximum delivery rate as mentioned

before, the losses are 31 m). The design pressure (DP) is 6.9 bar due to the difference in height



Pre-Design

/ 127

between the tank dong Van City and connection to the distribution system. The maximum design

pressure (MDP), thus, is 8.9 bar considering a water hammer protection of 2 bar. This results in a

required wall thickness of 3.2 mm according to the standard EN-DIN 2460 Steel water pipes and

fittings.

Tab. 53: Summary of the pipe characteristics

Material Steel P235

Diameter DN 100

Maximum design pressure (MDP) 8.9 bar


Routing Above ground

2.12.2.3 Pipe Connection

The pipe segments will be welded. The weld must be of high quality to withstand the operating

pressure (see description of the operating pressure in section 2.12.2.2). The welding of joints shall be

in accordance with EN 1011 and DIN 2559. Therefore a certified welder is necessary according to the

standard EN 287-1.


In order to ensure the durability of the pipe, it must be protected against corrosion. The pipe has to be

painted by coat paint.

2.12.2.5 Foundations

As support for the supply pipe, foundations shall be constructed at regular intervals. The distance

between the slide bearings is 7.8 m, thus, for this pipe length of almost 1,200 m, 155 slide bearings

are necessary. To absorb the operating pressure and the forces due to temperature expansion, 26

fixed points are necessary, which will be constructed at the kinks of the pipe. To avoid future damages

in the water distribution system and to ensure an economic construction process, the foundations have

to be dimensioned with a systematic and comprehensive approach according to each foundations

loading situation which may vary depending on the course of the pipeline. There should be a regular

scheme regarding the design of the pipeline, which is already explained in section 2.10.2.4 and which

can be used in analogy here.

2.12.2.6 Connection with the existing distribution system of Dong Van City

The situation of the connection of the supply pipe from the storage tank Dong Van city to the existing

distribution system at the pumping station is shown in Fig. 144. To control the system input is

necessary (see Fig. 145). A plunger valve is a valve which generates pressure losses in the pipe by

throttling. The plunger valve in this installation has the function to reduce the pressure to an

appropriate pressure for supplying the households and to control the flow into the system. The plunger

valve will be installed with a diameter of DN 100. A non-return valve will be installed after the existing

pump to prevent a flow from the storage tank into the pumping station. The non-return valve needs a

diameter of DN 100 to be installed in the existing pipe at the pumping station.



Pre-Design

/ 127

The distribution system should be either feed by the pumping station or the storage tank. When

operating both at the same time the pumping station might not be able to produce any discharge due

to the pressure at the outlet pipe controlled by the plunger valve.

Fig. 144: Connection of the supply pipe (dashed blue line) to the existing network (black line)

Fig. 145: Scheme of the connection of the supply pipe (dashed blue line) to the existing network (black line) withthe necessary valves (red)


2.12.3.1 Piping

Tab. 54: List of materials for piping from the storage tank Dong Van City - Connection to existing network of DongVan City (next to pumping station)


54.1 Piping:

Material: Steel P235DN 100OD 114.3 mmWall thickness: 3.2 mm

1,190 m



Pre-Design

/ 127







Tab. 55: List of materials for the pipe connection; Calculation for 6 m pipe segments



The pipe connection by welding has to be in accordance with the standards listed below or equivalent

to them. These are, but are not limited by, the following:



Tab. 56: Materials for corrosion protection for the supply pipe


56.1 Coating for protection against corrosion 428 m²

The corrosion protection has to be in accordance with the standards listed below or equivalent to


EN ISO 12944 part 1 – 8

2.12.3.4 Foundations

Tab. 57: List of materials for foundations


57.1 Fixed points with assumed dimensions of 40 x 40 x 40 cm (26):

Reinforcement steel with a yield strength of f y = 500 N/mm²

approximately 4.5 kg per fixed point each

Concrete with a characteristic strength of f ck = C20/25approximately 0.064 m³ per fixed point each

120

1.7

kg

m³

57.2 Sliding supports (155):

Reinforcement steel with a yield strength of f y = 500 N/mm²approximately 1.3 kg per sliding support each

Concrete with a characteristic strength of f ck = C20/25approximately 0.036 m³ per sliding support each

200

5.6

kg

m³



Pre-Design

/ 127

2.12.3.5 Connection with the existing distribution system

Tab. 58: List of materials for the connection of the supply system with the existing distribution system of Dong Van


58.1 Plunger valve


1 pcs

58.2 Non-return valve


1 pcs

The valves have to be in accordance with the standards listed below or equivalent to them. These are,

but are not limited by, the following:


2.12.3.6 Services

Tab. 59: List of services


59.1 Land purchase for supply pipe 1,190 m


59.3 Piping 1,190 m

59.4 Pipe-to-pipe welding 199 ls

59.5 Painting of corrosion protection 428 m²

59.6 Construction of foundations

Fixed pointsSliding supportsRestricted guidance

26

155

26

pcs

pcs

pcs

59.7 Installation of the plunger valve 1 pcs

59.8 Installation of the non-return valve 1 pcs

Note: Position 12.12 is a calculation for 6 m pipe segments. The services have to be in accordance

with the standards listed below or equivalent to them. These are, but are not limited by, the following:




levels




Pre-Design

/ 127

3 Summary of materials and services

The following Tab. 60 and Tab. 61 are a summary of all necessary materials and services within

responsibility of the Vietnamese partners which are related to measures proposed in this present

document. Each item listed in the tables (No.) is shortly described and specified in more detail in

section 2 (see according positions).

Tab. 60: List of materials within the responsibility of the Vietnamese partners

No. Position Materials Amount Unit

Pipe (steel)

Pipe material (steel)

1. 8.3 Optional: DN 500, PN 6 5 m

2. 10.1 DN 300, OD 329.9 mm, wall thickness 5.6 mm, P235 80 m

3. 10.2DN 300, elbow pipe, OD 329.9 mm, wall thickness 7.1 mm,various angles, P235

7 pcs

4. 27.1 DN 150, OD 168.3, wall thickness 6.3 mm, P235 280 m




8. 27.5DN 150, elbow pipe, OD 168.3, BA3D, wall thickness 11.0mm, P235

9 pcs


10 pcs

10. 27.8DN 150, elbow pipe, OD 168.3, BA3D, wall thickness 5.6

mm, P2354 pcs


43 pcs

12. 35.5 DN 200, OD 219.1 mm, wall thickness 3.6 mm, P235 25 m

13.

35.235.546.849.6

DN 150, OD 168.3 mm, wall thickness 3.6 mm, P235

44.5520

mmmm

14.

35.435.541.146.346.4

46.546.746.849.349.549.654.1

DN 100, OD 114.3 mm, wall thickness 3.2 mm, P235

1015.51,57321

2111511141,190

mmmmm

mmmmmmm

Pipe connection (steel)Flanges (steel, welding neck flange)

15. 10.3 DN 300, PN 25 3 pcs

16.35.646.949.7

DN 100, PN 6181016

pcspcspcs

Bolts (Hexagon shank)

17. 10.4 M 27 48 pcs



Pre-Design

/ 127

18. 35.746.1049.8

M 16 362032

pcspcspcs

19. 10.10 Hilti HIT-HY 200-A + HIT-V-R M16 (or comparable) 16 pcs

20.10.1110.12

Hilti HST M16 (or comparable)3232

pcspcs

21. 36.2 To be adjusted to the on-site conditions 3 ls

Nuts (Hexagon nut)

22. 10.5 M 27 48 pcs

23.35.846.1149.9

M 16362032

pcspcspcs

Washers (Plain washer)

24. 10.6 M 27 96 pcs

25.35.946.1249.10

M 16724064

pcspcspcs

Elastomeric seals

26. 10.7 DN 300 3 pcs

Materials for welding (number of joints)

27. 10.8 DN 300 23 pcs

28. 28.1 DN 150 410 pcs

29.42.155.1

DN 100263199

pcspcs

Corrosion protection

30.

10.2130.144.156.1

Coating for protection against corrosion

801,300565428

m²m²m²m²

Valves, fittings and other steel parts

Revision valve

31. 10.9 DN 300, PN 25 1 pcs

Inflow fitting

32.35.349.4

DN 150, PN 612

pcspcs

Air valve (steel)

33. 32.1 DN 50, PN 35 3 pcs

Gate valve (steel)

34.35.146.149.1

DN 100, PN6936

pcspcspcs

Floating valve (steel)

35.46.249.2

DN 100, PN 612

pcspcs

Overflow hopper (steel)

36.35.1046.649.11

PN 6112

pcspcspcs

Other steel parts

37. 4.3 Steel parts for gate channel bed and lateral guidance 2 ls

38. 4.5 Trash rack 1 ls

39. 7.2Various steel parts for gate channel bed and lateralguidance rehabilitation, possibly also rehabilitation of gate

1 ls



Pre-Design

/ 127

necessary40. 7.3 Various steel parts for trash rack repairing/replacement 1 ls

41. 7.8 Fence including gate 1 ls

42. 10.10

Steel plate 150x250x20 mm (min. tens. str. 235 N/mm²)Steel plate 160x140x10 mm (min. tens. str. 235 N/mm²)U-profile U140 (min. tens. str. 235 N/mm²)U-profile U200 (min. tens. str. 235 N/mm²)Pipe bearing thickness 7.1 mm (min. tens. str. 235 N/mm²)

816112

pcspcslslspcs

43. 10.11

Steel plate 200x200x20 mm (min. tens. str. 235 N/mm²)Steel plate 110x100x10 mm (min. tens. str. 235 N/mm²)Profiled steel HEA100 (min. tens. str. 235 N/mm²)Pipe bearing type LSL 23.0300.150-37.2 by Witzenmann(or comparable) (min. tens. str. 235 N/mm²)

8818

pcspcslspcs

44. 10.12

Steel plate 200x200x20 mm (min. tens. str. 235 N/mm²)Steel plate 110x100x10 mm (min. tens. str. 235 N/mm²)Profiled steel HEA100 (min. tens. str. 235 N/mm²)Guide rail L 50 x 5 (min. tens. str. 235 N/mm²)Pipe bearing type LSL 23.0300.150-37.2 by Witzenmann(or comparable) (min. tens. str. 235 N/mm²)

88148

pcspcslspcspcs

45. 29.1

Steel plate 250 x 150 x 20 mm (min. tensile strength 235N/mm²)Steel plate steel 160 x 140 x 1 mm (min. tensile strength235 N/mm²)U-profile (min. tensile strength 235 N/mm²)Pipe shell, min. thickness same as the pipe (min. tensilestrength 235 N/mm²)

Profiled steel HEA 140 (min. tensile strength 235 N/mm²)L-profile steel 50 x 5 mm (min. tensile strength 235 N/mm²)Bolts Hilti HIT-HV200-A + HIT-V-D M16 (or comparable)

21168

4221

1264242

pcspcs

pcspcs

pcspcspcs

46. 29.2

Steel plate 300 x 300 x 25 mm (min. tensile strength 235N/mm²)Profiled steel HEA140 (min. tensile strength 235 N/mm²)Bolts Hilti HIT-HV200-A+HIT-V-D M16 (or comparable)Pipe bearing type LSF 43.0150.107-37.2 by Witzenmann(or comparable) (min. tensile strength 235 N/mm²)

7028028070

pcspcspcspcs

47. 29.3

Steel plate 150 x 150 x 15 mm (min. tensile strength 235N/mm²)Steel plate 110 x 100 x 10 mm (min. tensile strength 235N/mm²)

Profiled steel HEA100 (min. tensile strength 235 N/mm²)Guide rail L 50 X 5 (min. tensile strength 235 N/mm²)Bolts Hilti HST M16 (or comparable)Pipe bearing type LSL 23.0300.150-37.2 by Witzenmann(or comparable) (min. tensile strength 235 N/mm²), onle forguide bearing

329

658987591316329

pcs

pcspcspcspcspcs

48.

34.143.143.245.148.157.157.2

Reinforcement steel with a yield strength of f y = 500 n/mm²

5,50013526030016,000120200

kgkgkgkgkgkgkg

49. 36.3 Barrier plates 60 cm x 10 cm x 0.3 cm 30 pcs50. 37.1 Lids with a handle 0.75 m x 0.75 m 4 pcs



Pre-Design

/ 127

50.1 2 pcs

51. 37.2LadderLength 4 m, width 0.4 - 0.5 mLength 1.8 m, width 0.4 - 0.5 m

31

pcspcs

52. 50.2LadderLength 5 m, width 0.4 - 0.5 m

2 pcs

Plunger valve

53. 58.1 DN 100, PN 6 1 pcs

Non-return valve

54. 58.2 DN 100, PN 6 1 pcs

Concrete, masonry and plaster

55.7.113.2

Reinforced concrete2030

m³m³

56. 8.2 Optional: Reinforced concrete 20 m³57. 4.6 Concrete foundation for the new trash rack 1 m³

58.

43.143.257.157.2

Concrete with a characteristic strength of f ck = C20/25

27.21.75.6

m³m³m³m³

59.

10.1010.1110.1229.129.229.3


4.51147.2552.582.25

m³m³m³m³m³m³

60.

34.2

45.248.2


50

3135

m³

m³m³

61.34.345.348.3

Application of waterproof plaster on the inner tank walls26413450

m²m²m²

62. 13.3 A Masonry walls (option A) 100 m²

63. 13.3 B Pillars (option B) 8 ls

64. 13.7 Concreting of machinery foundations for the modules 2 ls

65. 36.1Crossbar made of concrete (alternative: wood)Length 1 mLength 4 m

21

pcspcs

Roofing

66. 13.4 Corrugated metal roof on a timber framing 80 m²

Tab. 61: List of services within the responsibility of the Vietnamese partners

No. Position Service Amount Unit

67.

2.14.16.17.413.516.2 A

16.2 B33.2

Transport of materials to construction site 1 ls



Pre-Design

/ 127

38.247.251.259.2

68.2.213.1

Soil, rock and concrete excavation works1060

m³m³

69.8.18.4

Optional: Soil, rock and concrete excavation works10015

m³m³

70.

10.1533.347.359.3

Piping

802,4551,5731,190

mmm

71. 10.16 Pipe-to-flange welding 3 ls

72. 10.17 Flange-to-flange screwing 2 ls

73.

10.1410.1833.447.459.4

Pipe-to-pipe welding

123410263199

lslslsls

74.

10.2133.947.659.5

Corrosion protection application (including fittings, flanges,etc.)

801,300565428

m²m²m²m²

75.

10.1933.759.7

59.8

Installation of valves 1 ls

76.38.447.851.4

Installation of valves and tank facilities11610

pcspcspcs

77. 38.5 Installation of the weirs 3 ls

78.38.647.951.5

Installation of the inflow, supply, emptying and overflowpipe

648

lslsls

79. 51.3 Construction of the storage tank 500 m³

80. 47.7 Construction of pressure breaker 1 ls

81. 38.3 Construction of the distribution tank 133 m³

82. 2.3Stabilization of the weir basis with prepacked concrete andreinforced concrete, respectively

20 m³

83.4.27.6

Reconditioning of the sluice gates21

lsls

84. 4.4 Rehabilitation of the anchorage of the sluice gate in basin 2 1 ls

85. 10.20 Concreting of abutments 10 ls

86. 6.3 Inspection & maintenance of the whole channel 700 m

87. 6.2 Installation of revision openings every 70 m 1 ls

88. 7.5 Restoration of lateral overflow weir crest 1 ls

89. 8.5 Optional: Enlargement of the intake pool 1 ls

90. 7.7 Repairing or replacing of the trash rack 1 ls

91. 7.9 Installation of the fence 1 ls

92. 8.6Optional: Reconstruction of inlet channel and pipeconnection to headrace channel

1 ls

93. 10.13 Adaptation of pipe routing to local terrain conditions 1 ls94. 13.6 Construction of the power house extension including the 1 ls



Pre-Design

/ 127

floor slab95. 13.7 Concreting of machinery foundations for the modules 2 ls

96. 13.8Construction of the tailwater pool and the channel to SeoHo River

1 ls

97. 16.1

Customs duties in Vietnam (incl. handling cost andadministration processes). All administrative processeshave to be settled and timed in accordance to the project’stime schedule (see section 4)

1 ls

98. 5.1 Optional: Removal of the restriction 1 ls

99. 5.2 Optional: Enlargement of the sand trap basin 2 1 ls

100.38.151.1

Land purchase for the tank45100

m²m²

101. 47.1 Land purchase for supply pipe and pressure breaker 1,573 m

102. 59.1 Land purchase for the supply pipe 1,190 m103. 33.6 Installation of the bearings 420 pcs

104. 33.5 Construction of foundations 420 pcs

105. 47.5

Construction of foundationsFixed pointsSliding supportsRestricted guidance

3020030

pcspcspcs

106. 59.6

Construction of foundationsFixed pointsSliding supportsRestricted guidance

2615526

pcspcspcs

Tab. 62: List of materials within the responsibility of the German partners


1. 9.1 Various steel parts for installation of baffle and racks 1 ls

2. 14.1 Revision valve, DN 300, PN 25 1 pcs

3. 14.2 Pump valve suction side, DN 125, PN 25 2 pcs

4. 14.3

Dismantling jointDN 300, PN 25DN 200, PN 25DN 150, PN 63

132

pcspcspcs

5. 14.3a

Dismantling elbow

DN 125, PN 25DN 100, PN 25DN 150, PN 63

212

pcspcspcs

6. 14.4 Control valve, DN 200, PN 25 1 pcs

7. 14.5 PAT valve pressure side, DN 200, PN 25 2 pcs

8. 14.6

Flexible jointDN 125, PN 25DN 100, PN 25DN 65, PN 63

222

pcspcspcs

9. 14.7 Non-return valve, DN 150, PN 63 2 pcs

10. 14.8 Pump valve pressure side, DN 150, PN 63 2 pcs

11. 14.9 Drainage valve, DN 100, PN 25 1 pcs

12. 14.10 Drainage valve, DN 100, PN 63 1 pcs

13. - Water supply modules 2 pcs14. - Monitoring system consisting of various measurement 1 ls



Pre-Design

/ 127

devices

Tab. 63: List of services within the responsibility of the German partners


15. 9.1 Construction of baffle an racks including guidance 1 ls

16. 9.1 Installation of baffle and racks 1 ls

17. 17.1 AInstallation of machinery and measuring equipment (Option

A)1 ls

18. 17.1 B Installation of pre-installed container (Option B) 1 ls

19. 17.2 Connection to bypass and pressure supply pipe on-site 1 ls

20. 17.3 Installation of monitoring equipment 1 ls



Pre-Design

/ 127

4 Time schedule

In a preliminary time schedule is proposed (see Tab. 64).

Tab. 64: Preliminary time schedule for the pilot implementation of a hydro power driven water pumping anddistribution system (“Concept 1”) and their responsibilities.

Activity 2014 2015 2016

07-09 10-12 01-03 04-06 07-09 10-12 01-03 04-06 07-09 10-12

Final Pre-Design

Final Engineering Design for construction and

installation works

Matching of Final Engineering DesignChoice of Option A or B of power house

extension

Road construction/maintenance to Seo Ho

HPP & rehabilitation of infrastructure

Provision of pressure supply pipe materials

from Seo Ho HPP to tank in Ma U

(with financial contribution from German side)

Customs duties of pressure supply pipe

materials (if needed) in Vietnam and domestic

transport of all materials to construction side

Construction of the pressure supply pipe incl.

foundations from Seo Ho HPP to tank Ma U

Construction of the distribution tank Ma U and

storage tank Dong Van

Supply pipes from tank Ma U to supply areas

(Dong Van City, Sang Ma Sao, North Slope)

Extension of power house, construction of

foundation for machinery including shafts for

PAT-suction pipes and tailwater pool

Restoration & rearrangement of Seo Ho HPP

weir, sand trap, headrace channel and intake

pool

Temporary accompaniment of construction

measures

Installation of baffle and racks at intake pool to

improve sedimentation capacity

Determination respective the implementation

of optional measures at the intake pool to

improve the sediment deposition capacity

Implementation of optional measures at the

intake pool to improve the sediment deposition

capacity (only on demand)

Determination respective the implementation

of optional measures at the sand trap to

improve the sediment deposition capacity

Implementation of optional measures at the

sand trap to improve the sediment deposition

capacity (only on demand)

German responsibility Vietnamese responsibilityGerman and Vietnamese

responsibility



Pre-Design

/ 127

Activity 2014 2015 2016

07-09 10-12 01-03 04-06 07-09 10-12 01-03 04-06 07-09 10-12

Final design of PAT-pump-modules including

pipe system for machinery, valves and

electrical controlling devices

Production of PAT-pump-modules including

pipe system for machinery, valves and

electrical controlling devices

Test rig runs of PAT-pump-modules

Shipping of PAT-pump-modules to Vietnam

Customs duties of PAT-pump-modulesmachinery parts in Vietnam and domestic

transport of all devices to the construction site

Construction of branch pipe bypass for PAT-

pump-module incl. foundations (1. stage)

Installation of PAT-pump-modules, pipe

system for machinery, valves, electrical

controlling devices including connection to

bypass and pressure supply pipe

Construction of branch pipe bypass for PAT-

pump-module incl. foundations (2. stage) and

connection to machinery

Development of O&M-manuals, training of

operating personnelCommissioning and inauguration

Operation and maintenance (O&M)

German responsibility Vietnamese responsibilityGerman and Vietnamese

responsibility



Pre-Design

Attachment A: Isometric drawings of penstock bypass (see section 2.5)

Attachment A 1: Overview of the penstock bypass’s routing with respect to the bearing concept



Pre-Design

Attachment B: Isometric drawings of pressure supply pipe (see section 2.8)

Attachment B 1: Overview of the pressure supply pipe’s routing with respect to the bearing concept



Pre-Design

Attachment B 2: Section 1 of the pressure supply pipe’s routing with respect to the bearing concept



Pre-Design


KaWaTech Pre Design

Documents

Transcript of KaWaTech Pre Design