The design of a water supply system or treatment process encompasses a broad area. Application of this part is dependent upon the type of system or process involved.
The system including the water source and treatment facilities shall be designed for maximum day demand at the design year.
Design shall consider
a. functional aspects of the plant layout,
b. provisions for future plant expansion,
c. provisions for expansion of the plant waste treatment and disposal facilities,
d. access roads,
e. site grading,
f. site drainage,
i. chemical delivery.
Design shall provide for:
a. adequate ventilation,
b. adequate lighting,
c. adequate heating,
d. adequate drainage,
e. dehumidification equipment, if necessary,
f. accessibility of equipment for operation, servicing, and removal,
g. flexibility of operation,
h. operator safety,
i. convenience of operation,
j. chemical storage and feed equipment in a separate room to reduce hazards and dust problems.
The appropriate regulating authority must be consulted regarding any structure which is so located that normal or flood stream flows may be impeded.
Main switch gear electrical controls shall be located above grade, in areas not subject to flooding.
Dedicated standby power shall be required by the reviewing authority so that water may be treated and/or pumped to the distribution system during power outages to meet the average day demand. Alternatives to dedicated standby poewer may be considered by the reviewing authority with proper justification.
Adequate facilities should be included for shop space and storage consistent with the designed facilities.
Each public water supply shall have its own equipment and facilities for routine laboratory testing necessary to ensure proper operation. Laboratory equipment selection shall be based on the characteristics of the raw water source and the complexity of the treatment process involved. Laboratory test kits which simplify procedures for making one or more tests may be acceptable. An operator or chemist qualified to perform the necessary laboratory tests is essential. Analyses conducted to determine compliance with drinking water regulations must be performed in an appropriately certified laboratory in accordance with Standard Methods for the Examination of Water and Wastewater or approved alternative methods. Persons designing and equipping laboratory facilities shall confer with the reviewing authority before beginning the preparation of plans or the purchase of equipment. Methods for verifying adequate quality assurances and for routine calibration of equipment should be provided.
As a minimum, the following laboratory equipment shall be provided:
a. Surface water supplies shall provide the necessary facilities for microbiological testing of water from both the treatment plant and the distribution system. The reviewing authority may allow deviations from this requirement.
b. Surface water supplies shall have a nephelometric turbidimeter meeting the requirements of Standard Methods for the Examination of Water and Wastewater.
c. Each surface water treatment plant utilizing flocculation and sedimentation, including those which lime soften, shall have a pH meter, jar test equipment, and titration equipment for both hardness and alkalinity.
d. Each ion-exchange softening plant, and lime softening plant treating only groundwater shall have a pH meter and titration equipment for both hardness and alkalinity.
e. Each iron and/or manganese removal plant shall have test equipment capable of accurately measuring iron to a minimum of 0.1 milligrams per liter, and/or test equipment capable of accurately measuring manganese to a minimum of 0.05 milligrams per liter.
f. Public water supplies which chlorinate shall have test equipment for determining both free and total chlorine residual by methods in Standard Methods for the Examination of Water and Wastewater.
g. Public water supplies which fluoridate shall have test equipment for determining fluoride by methods in Standard Methods for the Examination of Water and Wastewater.
h. Public water supplies which feed polyphosphates shall have test equipment capable of accurately measuring phosphates from 0.1 to 20 milligrams per liter.
Sufficient bench space, adequate ventilation, adequate lighting, storage room, laboratory sink, and auxiliary facilities shall be provided. Air conditioning may be necessary.
Water treatment plants with a capacity of 0.5 mgd or more should be provided with continuous monitoring equipment (including recorders) to monitor water being discharged to the distribution system as follows:
a. Plants treating surface water and plants using lime for softening should have the capability to monitor and record turbidity and free chlorine residual and pH. In addition, continuous monitoring of entry point disinfection residuals shall be provided for systems with a service population greater than 3,300 people. Monitoring of the parameters to evaluate adequate CT disinfection, such as residuals, pH and water temperature, should be provided.
b. Plants treating ground water using iron removal and/or ion exchange softening should have the capability to monitor and record free chlorine residual.
Sample taps shall be provided so that water samples can be obtained from each water source and from appropriate locations in each unit operation of treatment. Taps shall be consistent with sampling needs and shall not be of the petcock type. Taps used for obtaining samples for bacteriological analysis shall be of the smooth-nosed type without interior or exterior threads, shall not be of the mixing type, and shall not have a screen, aerator, or other such appurtenance.
The facility water supply service line and the plant finished water sample tap shall be supplied from a source of finished water at a point where all chemicals have been thoroughly mixed, and the required disinfectant contact time has been achieved (see Section 4.3.2). There shall be no cross-connections between the facility water supply service line and any piping, troughs, tanks, or other treatment units containing wastewater, treatment chemicals, raw or partially treated water.
Consideration shall be given to providing extra wall castings built into the structure to facilitate future uses whenever pipes pass through walls of concrete structures.
All water supplies shall have an acceptable means of metering the finished water.
To facilitate identification of piping in plants and pumping stations it is recommended that the following color scheme be utilized:
|Settled or Clarified||Aqua|
|Finished or Potable||Dark Blue|
|Alum or Primary Coagulant||Orange|
|Caustic||Yellow with Green Band|
|Chlorine (Gas and Solution)||Yellow|
|Fluoride||Light Blue with Red Band|
|Lime Slurry||Light Green|
|Ozone||Yellow with Orange Band|
|Phosphate Compounds||Light Green with Red Band|
|Polymers or Coagulant Aids||Orange with Green Band|
|Soda Ash||Light Green with Orange Band|
|Sulfuric Acid||Yellow with Red Band|
|Sulfur Dioxide||Light Green with Yellow Band|
|Backwash Waste||Light Brown|
|Sewer (Sanitary or Other)||Dark Gray|
|Compressed Air||Dark Green|
|Other Lines||Light Gray|
In situations where two colors do not have sufficient contrast to easily differentiate between them, a six-inch band of contrasting color should be on one of the pipes at approximately 30 inch intervals. The name of the liquid or gas should also be on the pipe. In some cases it may be advantageous to provide arrows indicating the direction of flow.
All wells, pipes, tanks, and equipment which can convey or store potable water shall be disinfected in accordance with current AWWA procedures. Plans or specifications shall outline the procedure and include the disinfectant dosage, contact time, and method of testing the results of the procedure.
An operation and maintenance manual including a parts list and parts order form, operator safety procedures and an operational trouble-shooting section shall be supplied to the water works as part of any proprietary unit installed in the facility.
Provisions shall be made for operator instruction at the start-up of a plant or pumping station.
Consideration must be given to the design requirements of other federal, state, and local regulatory agencies for items such as safety requirements, special designs for the handicapped, plumbing and electrical codes, construction in the flood plain, etc.