2. Project Overview
2.4 Project Components
2.5.1 Waste Water Collection Pipe Network (1) Works and the Layout(1) Works and the Layout
Waste water collection pipe network will cover areas of Xichuan River, Beichuan River and Beichuan Zone(Area).
1) Layout of Waste Water Collection Pipeline on South Bank of Xichuan River It is planned in the Project to arrange a main waste water collection pipe on the south bank of the Xichuan River from Yangjiawan Village to Duoba, which will collect all the waste water on the south bank of the Xichuan River from Duoba to Yangjiawan Village, which will flow into the existing downstream waste water collection pipes and finally flow into the No.4 WWTP for treatment.
Figure 2.5-3 Layout of Waste Water Collection Pipeline on South Bank of Xichuan River
Gravel Road Irrigated Land Woodland
Figure 2.5-4 Waste Water Collection System on the South Bank
of Xichuan River Figure 2.5-5 Current Status of Areas across/along Which the Pipeline on South Bank of Xichuan River Is Planned 1: Main combined waste water collection pipe; 2: Main interception
pipe; 3: Overflow well; 4: The fourth WWTP; 5: Outlet; 6: Overflow outlet; 7: Sedimentation well
No.4 WWTP under construction
Planned Waste Water Pipe Existiing Waste Water Pipe
Combined system will be adopted for short term for waste water collection pipeline along Xichuan and Beichuan rivers. Along with completion of road construction along both banks of the rivers in the long run and rainwater collection system and preliminary rainwater treatment system put into place gradually, the combined system will be changed to separate system consecutively. Such arrangement for waste water collection pipe system also couples with construction and development of waste water treatment plants in the short and long terms.
(1) Waste water collection pipes are designed based on needs of 2030, since sewage amount in the short term will be relatively small, combined system can make better use of the available pipe space. Along with increase of sewage from the service areas, the combined system can be gradually changed to separate system, and the current pipe diameter can still meet sewage collection requirement then.
(2) Sewage from both banks of Xichuan River and Beichuan River will flow into No.4 and No.5 WWTPs after being collected. At present, construction of both WWTPs are based on a treatment capacity of 30 thousand m3/d for the short term, while it is predicted that the flowing-in sewage will be only around 23 thousand m3/d in the near future. Therefore, use of combined system can meet the treatment requirement of combined waste water, and ensure better use of capacity of the WWTPs.
Since the road along Xichuan River is not yet constructed, the waste water collection pipeline will be installed along the existing gravel road or in the irrigated land or woodland.
2) Layout of Waste Water Pipeline on Both Banks of Beichuan River
It is planned in the Project to arrange main waste water collection pipe along the Beichuan River on both banks from Ningda Road toll-gate to Datong Waste Water Treatment Plant, with diameters ranging from DN800 to DN1000.
Combined waste water collection system will be adopted in the short term and it will be changed gradually to separate system when the road system and rainwater discharge system are completed in the area.
Since the roads along Beichuan River are not yet constructed, the waste water collection pipeline will be installed along the existing gravel road or in the irrigated land or woodland.
3) Layout of Waste Water Pipeline in Beichuan Zone
As the land relief in the Beichuan Zone is high in the north and the west and low in the south and the east, the layout is made in accordance with the road directions:
the master main sewer (waste water pipe) is arranged along the Tiedong Road which is a south-north road, the main sewers are arranged along Binghe Road which is a south-north road, and branch sewers (branch waste water pipes) are arranged along other east-west roads. In this zone, the waste water will be collected into the main interception pipe of the Beichuan River, flowing into the main interception pipe on the north bank of the Huangshui River and then entering into the No.3 WWTP for treatment.
Figure 2.5-6 Layout of Pipeline along Both Banks of Beichuan River
Gravel Road Irrigated Land wood Land
Figure 2.5-7 Waste Water Collection System along Both Banks of Beichuan River Figure 2.5-8 Current Status of Areas across/along Which the Pipeline on Both Banks of Xichuan River Is Planned 1: Main combined waste water collection pipe; 2: Main
interception pipe; 3: Overflow well; 4: No.5 WWTP; 5: Outlet;
6: Overflow outlet; 7 : Sedimentation well
Planned Waste Water Pipe Existingd Waste Water Pipe
No.5 WWTP under construction Waste Water Pipe under construction
Figure 2.5-9 Layout of Wastewater Pipes in Beichuan Area
Figure 2.5-10 Illustration of Altitudes of Beichuan Area Figure 2.5-11 Current Status of Site
(2) Prediction of Waste Water Amount and the Transfer Scheme
Results of predicted waste water collection amounts in 2030 are included in the following table.
Table 2.5-2 Summary of Predicted Waste Water Collections in 2030
No. Areas
Population Served
（104 persons）
Service Area
（ha）
Waste Water Collected
（104 m3/d） Discharged to 1 South Bank of
Xichuan River 17.2 1442 4.36 The Fourth WWTP
2 East Bank of
Beichuan River 2.45 940 0.80 The Fifth WWTP
3 West Bank of
Beichuan River 5.90 3800 1.64 The Fifth WWTP
4 Beichuan Zone 4.00 290 1.10 The Third WWTP
(3) Type of Foundation for the Pipeline
For the reinforced concrete sewer pipe, 120º plain concrete foundation will be used, and C35 concrete is the casting standard. The foundation is illustrated as follows.
Figure 2.5-12 Illustration of Foundation of Pipeline Table 2.5-3 Dimensions of Plain Concrete Foundation
DN Thickness of
Pipe Wall a Dimensions of the FoundationB C1 C2 Slope
300 40 80 540 80 95 1:0.75
400 47 100 694 100 123 1:0.75
600 60 100 920 100 180 1:0.75
800 80 120 1200 120 240 1:0.75
1000 100 150 1500 150 300 1:0.75
(4) Main Quantities
The main quantities of the urban waste water collection pipe network are shown in Tables 2.5-4 through to 10.
1) Xichuan River Waste Water Collection Pipeline(Yangjiawan village-Duoba)
Backfilling and compaction by layer, 100-200 mm per layer
C35 Concrete Ground Elevation
Table 2.5-4 Pipe Material and Quantities of Well Chambers for Xichuan River
No. Description Specification material Unit Quantity Remarks
1 Reinforced concrete
pipe DN800 Reinforced
concrete m 2600 Main pipe
2 Reinforced concrete
pipe DN1000 Reinforced
concrete m 10920 Main pipe
3 Reinforced concrete
pipe DN400 Reinforced
concrete m 2480 Branch pipe
4 Rectangular waste
water pipe manhole 1100X1100 Reinforced
concrete No. 65
5 Rectangular waste
water pipe manhole 1100X1300 Reinforced
concrete No. 218 In branch pipe
6 Circular waste water
pipe Manhole Φ1000 Brick No. 82 In branch pipe
7 Sedimentation Well Φ1250 Reinforced
Concrete No. 7 In branch pipe
8 Overflow Well 1650x1650 Reinforced
Concrete No. 7 In branch pipe
Table 2.5-5 Activities Needed to Be Accomplished before Construction of the Pipeline
No. Activities Unit Quantity Remark
1 Construction of
Temporary Roads m2 18830 For pipeline located in flood land, irrigated land areas, 5380m 2 Compensation to
Green Crops m2 40140 For pipeline located in irrigated land, 4460m
3 Restoration of
gravel road surface m2 13360 For pipeline located along gravel road, 3340m
4 Land Acquisition
for Manholes mu 0.7 For manholes located in irrigation land areas
(90 such manholes) 5 Compensation for
tree seedlings No. 9600 For pipeline located in the woodland, 4800m
6 Stone Masonry m3 3750 River channel slope protection
2) Waste Water Collection Pipeline along Both Banks of Beichuan River (Ningda Road toll-gate-Datong WWTP)
Table 2.5-6 Pipe Material and Quantities of Well Chambers for East Bank of Beichuan River
No. Description Specification material Unit Quantity Remarks Remarks
1 Reinforced concrete
pipe DN800 Reinforced
concrete m 2665 Main pipe
Main pipe 2 Reinforced concrete
pipe DN1000 Reinforced
concrete m 12500 Main pipe
Main pipe 3 Reinforced concrete
pipe DN400 Reinforced
concrete m 1835 Branch pipe Main pipe
4 Rectangular waste
water pipe manhole 1100X1100 Reinforced
concrete No. 66 Branch pipe
5 Rectangular waste
water pipe manhole 1100X1300 Reinforced
concrete No. 278 In branch
pipe 6 Circular waste water
pipe Manhole Φ1000 Brick No. 52 In branch
pipe
7 Sedimentation Well Φ1250 Reinforced
Concrete No. 9 In branch
pipe
8 Overflow Well 1650x1650 Reinforced No. 9 In branch To be provided
Concrete pipe in branch pipes
Table 2.5-7 Activities Needed to Be Accomplished before Construction of the Pipeline on East Bank of Beichuan River
No. Activities Unit Quantity Remark
1 Construction of
Temporary Roads m2 20090 For pipeline located in flood land, irrigated land areas, 5740m 2 Compensation to
Green Crops m2 30600x1.5 For pipeline located in irrigated land, 5100m
3 Restoration of
gravel road surface m2 13360 For pipeline located along gravel road, 3340m
4 Land Acquisition
for Manholes mu 540 For manholes located in irrigation land areas
(104 such manholes) 5 Compensation for
tree seedlings No. 8480 For pipeline located in the woodland, 4240m
Table 2.5-8 Pipe Material and Quantities of Well Chambers for West Bank of Beichuan River
No. Description Specification Material Unit Quantity Remarks
1 Reinforced concrete
pipe DN800 Reinforced
concrete m 2665 Main pipe
2 Reinforced concrete
pipe DN1000 Reinforced
concrete m 12500 Main pipe
3 Reinforced concrete
pipe DN400 HDPE m 1835 Main pipe
4 Manhole 1100X1100 Reinforced
concrete No. 35
5 Manhole 1100X1300 Reinforced
concrete No.
275
6 Circular Manhole Φ1000 Brick No. 52 In branch pipe
7 Sedimentation Well Φ1250 Reinforced
concrete No.
12 In branch pipe
8 Overflow Well 1650x1650 Reinforced
concrete No.
12 In branch pipe
Table 2.5-9 Activities Needed to Be Accomplished before Construction of the Pipeline on West Bank of Beichuan River
No. Activities Unit Quantity Remark
1 Construction of
Temporary Roads m2 23905 For pipeline located in flood land, irrigated land areas, 6830m 2 Compensation to
Green Crops m2 35820x1.5 For pipeline located in irrigated land, 5970m
3 Restoration of
gravel road surface m2 18860 For pipeline located along gravel road, 4715m
4 Land Acquisition
for Manholes mu 624 For manholes located in irrigation land areas
(120 such manholes) 5 Compensation for
tree seedlings No. 4040 For pipeline located in the woodland, 2020m