§ 42-196. Sanitary sewerage facilities.

(a)

General. All subdivisions developed subsequent to this article shall be provided with an approved sewerage disposal system conforming to the current criteria adopted by the city and the requirements of Texas Natural Resources Conservation Commission Design Criteria for Sewerage Systems. Materials and construction shall meet the requirements of standard specifications for public works construction.

(b)

Basic requirements. The following are basic requirements:

(1)

No sewer main shall be less than six inches in nominal diameter. Sewer service lines shall not be less than four inches in diameter. Sewer lines shall utilize PVC, SDR-35 pipe where applicable unless size or special conditions warrant other materials.

(2)

All sewers shall be designed with consideration for serving the full drainage area subject to collection by the sewer in question except as modified with the concurrence of the city engineer because of the projected rate of development or the financial feasibility of the proposed extension.

(3)

Manholes shall be located at all intersections of other sewers and at intermediate spacings along the line. Generally the maximum spacing should not exceed 500 feet. Manholes should be located at all changes in grade and at the ends of all sewers.

(4)

Sewers should be designed with straight alignment whenever possible. When horizontal curvatures must be used, the smallest radius should be determined by the pipe manufacturers data, but in no case less than a 100-foot radius shall be used.

(5)

All sewers shall be designed with hydraulic slopes sufficient to give mean velocities, when flowing full or half full, or not less than two feet per second on Kutter's or Manning's formulas using an n value of 0.011, except that the minimum allowable grades shall be maintained as follows:

Line size	Minimum grade
4-inch service	2.00%
6-inch line	1.00%
8-inch line	0.40%
10-inch line	0.29%
12-inch line	0.22%
15-inch line	0.16%
18-Inch Line	0.12%
24-inch line and larger	0.10%

 

(6)

No connection shall be made to any sanitary sewerage system within the city which will permit the entrance of surface water and waste of other than domestic sewage characteristics.

(7)

All materials and workmanship incorporated in the sewage system extensions shall be in accordance with the currently adopted standard specifications for public works construction.

(8)

All lateral and sewer mains installed within a subdivision must extend to the borders of the subdivision as required for future extensions of the collecting system regardless of whether or not such extensions are required for service within the subdivision.

(9)

Service laterals shall be constructed at an elevation designed to gravity flow the lot or tract of land to which it will serve as computed at a grade of two percent from the service riser pipe to the proposed building site. However, the minimum cover for a service riser pipe at the property line or easement line shall be a minimum of four feet. All service laterals below proposed areas to be paved shall be installed and properly backfilled prior to compaction of the subgrade and placement of the paving.

(10)

Any service lateral used for the discharge of industrial waste into the city's sanitary sewers shall have a control manhole constructed and maintained by the discharger of the industrial waste. The control manhole shall be constructed downstream from any storage tanks or pretreatment works and shall be used by the city for sampling and monitoring the industrial waste.

(11)

Sewage lift stations (pumping stations) will not be allowed unless physical conditions will not permit a conventional gravity flow sewer system. All lift stations will utilize two pump or duplex systems, with each pump having the capacity to meet maximum flow demands. The pumping system shall utilize automatic mercury float control switches for start-stop and automatic pumping cycles. The facilities may be designed for specific locations, employing wet-well/dry-well, surface mounted pumps or submergible pumps. The city engineer will review and direct the type of lift station to be installed.

(12)

Connection with the sanitary sewer system shall be required except where the city determines that such connection will require unreasonable expenditure when compared with other methods of sewage disposal and that alternate methods will protect public health and water quality. Where septic systems are installed, the subdivider shall conduct percolation tests under the supervision of the county health department to determine the adequacy of proposed lot sizes. If a waste water treatment plant system is to be installed, the discharge permits for such system must be obtained from the state natural resources conservation commission and U.S. Environmental Protection Agency prior to approval of the final plat by the planning and zoning commission.

(Code 1994, ch. 9, art. 54; Ord. No. 248, exh. A(art. 54), 3-24-1997)