(a) General. The following Design Criteria are summarized herein to establish practical, uniform design of water distribution systems for the Village of Ada. These criteria cover design factors and provides guidelines for evaluation of plans and specifications by the political subdivision having jurisdiction over the review of plans and specifications. These Design Criteria are also intended to conform to the standard drawings for water systems.
(b) Definitions. Regardless of capitalization, definitions are standard.
(1) NSF means National Sanitation Foundation.
(2) ANSI means American National Standards Institute.
(3) ASTM means American Society for Testing and Materials.
(4) AWWA means American Water Works Association.
(5) BEDDING means the earth or other materials on which a pipe or conduit is supported.
(6) CROSS-CONNECTION means:
(1) A physical connection through which a supply of potable water could be contaminated or polluted.
(2) A connection between a supervised potable water supply and an unsupervised supply of unknown portability.
(7) FIRE HYDRANT means a fixture installed throughout urban water distribution systems to provide water for the fire fighting needs.
(8) MAIN means the large water-carrying pipe to which individual user services are connected. Mains are normally connected to each other in a grid type system.
(9) METER means the flow measuring device installed at each service on a distribution system to measure the amount of water consumed by users at that service.
(10) SERVICE means the pipe carrying water to individual houses or other users on a distribution system.
(11) CORPORATION STOP means the fixture tapped into a water main to connect a service to the main.
(c) Basis of Design. The basis of design for water distribution systems shall be the Hazen-Williams Equation, an empirical formula for estimating pipe flow:
V = 1.318CR 0.63 S 0.54
V = Velocity in feet per second
C = Roughness Coefficient
R = Hydraulic Radius (pipe diameter in feet for pipes flowing full) in feet
S = Head loss per unit length of pipe
Distribution systems shall be designed for the estimated maximum day rate of flow, or the fire flow plus the estimated average day rate of flow, whichever is more demanding.
(d) Minimum Pressure. The minimum allowable pressure in the water distribution system, at times of no fires, shall be 50 pounds per square inch in all mains, and 8 pounds per square inch at the most remote house fixture in the system. The minimum fire flow for design purposes shall be 600 gallons per minute at a residual pressure of 20 pounds per square inch.
(e) Maximum Velocity. The maximum velocity of the water in the system shall be 10’ per second.
(f) Water Mains. The value of C to be used in the Hazen-Williams Equation shall be C=140. The minimum size of water mains shall be 6” diameter. Dead-ending mains shall be minimized by looping of all mains. Where dead-ends occur, they should be provided with a fire hydrant for flushing purposes.
The minimum depth of water mains shall be 4’ 6” from the top of the pipe to the finished grade elevation. The maximum depth of water mains shall be 5’ and 6” from the top of the main to the finished grade elevation, except where utilities must be underpassed or as directed by the Village.
(g) Water Service Lines. The value of C to be used in the Hazen-Williams Equation shall be C = 130. The minimum diameter of service lines shall be ¾”, unless the distance from the main to the meter exceeds 120’, where the minimum service line diameter shall be 1 inch. Table 1 lists required minimum service sizes as determined by residential population. Fire hydrant services shall have a minimum diameter of 6”, but shall be no larger than the water main. For all ¾” services, a corporation stop shall be installed on the main at a 45° angle above horizontal. For services larger than 2”, a tapping sleeve and valve must be installed. Table 2 shows the maximum size of service taps allowed for various sizes of water mains.
TABLE 1
MINIMUM SIZE -- WATER SERVICES AND METERS
RESIDENTIAL AREAS
No. of Families | Service Size (inches) | Meter Size (inches) |
1 | 3/4 | 5/8 x 3/4 |
2-5 | 1 | 1 |
6-8 | 1-1/2 | 1-1/2 |
9-12 | 2 | 1-1/2 |
13-20 | 2 | 2 |
21-50 | 4 | 3 |
51-115 | 4 | 4 |
TABLE 2
MAXIMUM SIZE - WATER SERVICE TAPS
Pipe Diameter (inches) | 6 | 8 | 10 | 12 |
Tap Sizes (inches) | 1 | 1-1/4 | 1-1/2 | 2 |
The minimum depth of service lines shall be 3’ 6” from the top of the line to the finished grade elevation. The maximum depth of service lines shall be 5’ from the top of the line to the finished grade elevation, except where utilities must be underpassed.
A curb stop and curb box shall be installed between the curb and sidewalk for each house and apartment unit unless otherwise approved the Village. The curb stop box shall be plumbed and centered over the curb stop and shall be free of debris. House service installations shall conform to the standard drawings.
(h) Restraining and Concrete Blocking for Water Mains. All water main bends of more than 5° shall be securely blocked against movement by using concrete blocking placed against undisturbed earth. Dimensions and quantities of blocking shall be as shown on the standard drawings. All mechanical bends, tees, etc. shall be restrained using mechanical restraining joints.
(i) Fire Hydrants. Fire hydrants shall be placed at all intersections and never more than 500’ apart.
Fire hydrants shall be installed with a break flange located approximately 2” above the ground level to protect-against flooding in case of impact to hydrant. Fire hydrants shall be consistent with the standard drawings.
A valve must be installed on all fire hydrant service lines. All connections between the main and the hydrant shall be restrained by anchoring pipe, tie bolts or retainer glands.
(j) Meter Installation. Meter installation for individual services shall be consistent with the standard drawings. Table 8.1 lists required meter sizes as determined by Maximum Flow Demand for Commercial-Industrial applications. Meters must be installed prior to connecting the service to the main and before service starts. No common meters will be approved. All meters must have remote readers.
TABLE 8.1
METER SIZE FOR COMMERCIAL-INDUSTRIAL APPLICATIONS
Maximum Flow Demand (GPM) | Meter Size (inches) |
20 | 5/8 x 3/4 |
30 | 3/4 |
50 | 1 |
100 | 1-1/2 |
160 | 2 |
320 | 3 |
500 | 4 |
1000 | 6 |
(k) Valves. Valves shall be located at all branches of a cross and tee- intersections, and at intervals not to exceed 500’ in residential districts and 500’ in commercial and industrial districts.
(l) Backflow Prevention. All commercial, industrial and other OEPA required users shall provide adequate backflow prevention between the public water system and the customer’s system. These devices shall be approved by OEPA and the Village of Ada prior to installation. These devices shall be tested and inspected annually. These devices shall be repaired or replaced if they do not meet the testing requirements. An annual report shall be submitted to the Village detailing the testing procedures and results.