1. “Design of Water Supply and Sewer Systems” IV. Water Tank (Service Reservoir). Dimensioning and Constructing (Drawing 4) Main Procedures 1. Determination of the water tank volume and dimensions 2. Dimensioning of the pipe systems 3. Constructioning of the water tank

2. Determination of the water tank volume The volume of the water tank is designed to serve two purposes:  To insure the balance between the even water flow, entering the system and the uneven consumption in the settlement (regulation volume).  To store water for the requirements of the fire service (fire volume) IV. Water Tank. Dimensioning and Construction Topic IV.1 Determination of the water tank volume and dimensions -Total volume of the tank, m 3 - Regulation volume of the tank, m 3 tank, m 3 - Fire volume, m 3

3. IV. Water Tank. Dimensioning and Construction Topic IV.1 Determination of the water tank volume and dimensions Regulation volume The regulation volume of the tank can be precisely calculated if the water inflow/outflow regimes are known. Otherwise it is accepted to be a percentage of the maximum daily demand of the settlement. Type of the settlement Regulation volume of the tank, as a percentage of the Q max,d I category (I and II functional type) 30 - 50 II category (III and IV functional type) 50 - 60 III category (V,VI and VII functional type) 60 - 70

4. IV. Water Tank. Dimensioning and Construction Topic IV.1 Determination of the water tank volume and dimensions Fire volume The fire volume of the tank must insure, in case of fire burst out, delivery of water to the settlement for a period of three hours. Fire water flowrate, l/s for the project Expected fire duration, h

5. IV. Water Tank. Dimensioning and Construction Topic IV.1 Determination of the water tank volume and dimensions Tank Dimensions The dimensions of the tank are determined under the condition: minimal volume of the walls.

6. IV. Water Tank. Dimensioning and Construction Topic IV.1 3. Construction of the water tank Plan of the tank

7. IV. Water Tank. Dimensioning and Construction Topic IV.2. Dimensioning of the pipe systems Longitudinal section of the tank

8. Cross section of the tank IV. Water Tank. Dimensioning and Construction Topic IV.2. Dimensioning of the pipe systems

9. IV. Water Tank. Dimensioning and Construction Topic IV.2. Dimensioning of the pipe systems

10. IV. Water Tank. Dimensioning and Construction Topic IV.2. Dimensioning of the pipe systems Inflow pipe system (steel) It is fixed at 10 – 15 cm over the maximal water level in the water chambers of the tank. Feeding pipe system It starts from the bottom of the tank with two strainers and has a bending, which is aimed at keeping the fire volume inviolable. The axis of the bending is fixed at the fire volume level - h f The stop valve under the bending is normally closed. It has to be opened, in case of fire, if at that moment the tank level has reached its minimum. A pipe with diameter 20mm connects the top of the bending with the atmosphere (10 cm over maximal tank water level) to prevent the bending becoming a siphon.

11. IV. Water Tank. Dimensioning and Construction Topic IV.2. Dimensioning of the pipe systems Overflow and emptying pipe system  Overflow pipe: D 1  Overflow funnel: D 2 = (1.5 – 2) D 1 length of the overflow funnel edge, m overflow height, m ≤ 0.10 m h = ?  Check-up for the head loss in the overflow pipe: available geometrical height, m head loss (friction and minor) along the pipe, m = 0.033, friction factor = 5- 6, sum of the minor loss factors along the pipe = 12-15 m,length of the pipe = 12-15 m, length of the pipe H loss ≤ H g  Emptying pipe: D 3 The design quantity is calculated under the condition to provide emptying of one of the tank chambers for a period of 8-12 hours. The velocity in the pipe must not be higher than 2.5 – 3.0 m/s. The common pipe section accepts the bigger diameter from D 1 and D 3.

12. Topic IV.3. Construction of the water tank IV. Water Tank. Dimensioning and Construction Walls: external walls - reinforced concrete, thickness – 20 cm; external walls - reinforced concrete, thickness – 20 cm; internal (circulation) walls – concrete, 30 cm; internal (circulation) walls – concrete, 30 cm;Bottom: main layer – reinforced concrete, thickness – 15 cm; main layer – reinforced concrete, thickness – 15 cm; underling layer – concrete, 10 cm; underling layer – concrete, 10 cm; bottom slope: longitudinal (to the feeder strainer) - 1%; bottom slope: longitudinal (to the feeder strainer) - 1%; cross, bilateral – to the bottom axis – 5%; cross, bilateral – to the bottom axis – 5%; Ceiling: reinforced concrete, thickness 10 – 12 cm, plate slope 2 – 3 % from the dry chamber to the rear and side walls of the tank; Coatings: internal wet walls – layer 1 (inner) – cement:sand (C:S)=1:2, thic. 1.5cm internal wet walls – layer 1 (inner) – cement:sand (C:S)=1:2, thic. 1.5cm layer 2 (outer) – C:S=1:1, thickness 0.5 cm; layer 2 (outer) – C:S=1:1, thickness 0.5 cm; internal dry walls, lower surface of the ceiling - layer 1; internal dry walls, lower surface of the ceiling - layer 1; external walls, upper surface of the ceiling – layer 1, layer 2 and fused asphalt ; external walls, upper surface of the ceiling – layer 1, layer 2 and fused asphalt ;

13. IV. Water Tank. Dimensioning and Construction Topic IV.3. Construction of the water tank Thermal insulation: ground embankment over the water chambers, thickness 0.80 – 1.00m Ventilation: ventilation chimneys, one for the dry chamber and for the water chambers – one to every 50 m 2 of the water surface. They allow the air to enter and leave the space over the water level during its movement. Ventilation is also necessary to avoid condense over the walls of the tank. Dry chamber: Plan dimensions – depend of the size of the pipes and appurtenances; Plan dimensions – depend of the size of the pipes and appurtenances; minimal distance from a flange of a pipe or fitting to a wall – 0.30m. Height – h T +3.00m. Height – h T +3.00m. Doors (sheet iron): external 1.80/0.90m (locked); internal 1.60/0.70m Doors (sheet iron): external 1.80/0.90m (locked); internal 1.60/0.70m Pits: 0.50/0.50/0.20m in the dry chamber, 0.80/0.80/0.30m in the water ch. Pits: 0.50/0.50/0.20m in the dry chamber, 0.80/0.80/0.30m in the water ch. Ladders: sailor ladder, or reinforcement iron (N18) Ladders: sailor ladder, or reinforcement iron (N18)

14. IV. Water Tank. Dimensioning and Construction Vocabulary of the Terms

15. IV. Water Tank. Dimensioning and Construction