Detailed plans shall be submitted for the district’s review, which provide the location, size, type and direction of flow of the proposed sewers and the connection with existing sewers. These plans shall be separate from water plans and shall conform to the current district plan preparation requirements.
Construction of new sewer systems or extensions of existing systems will be allowed only if the existing receiving system is capable of supporting the added hydraulic load.
Collector and interceptor sewers shall be designed for the ultimate development of the tributary areas.
Sewer systems shall be designed and constructed to achieve total containment of sanitary wastes and maximum exclusion of infiltration and inflow.
Computations and other data used for design of the sewer system shall be submitted to the district for approval as appropriate and required by the district.
The sewage facilities shall be designed and constructed in conformance with the current State Department of Ecology Criteria for Sewage Works Design and WSDOT Standard Specifications for Road, Bridge, and Municipal Construction, and current amendments thereto, revised as to form to make reference to local governments, and as modified by the district’s requirements and standards.
Material and installation specifications shall contain appropriate requirements that have been established by the industry in its technical publications, such as ASTM and APWA standards. Requirements shall be set forth in the specifications for the pipe and methods of bedding and backfilling so as not to damage the pipe or its joints, impede cleaning operations and future tapping, nor create excessive side fill pressure or deformation of the pipe, nor seriously impair flow capacity.
All sewers shall be designed to prevent damage from superimposed loads. Proper allowance for loads on the sewer because of the width and depth of trench should be made. When standard-strength sewer pipe is not sufficient, extra-strength pipe shall be used.
Before final acceptance of the sewer system by the district, all pipes, manholes, and other appurtenances shall be cleaned of all debris and foreign material, and tested to district standards. The impacted public right-of-way area shall be constructed or restored to the satisfaction of the land use agency.
The district shall own, operate and maintain the public sewer system within the public right-of-way and/or dedicated district utility easement including the main line and lateral pipes. The private side sewer system from the end of the sewer lateral to the structure shall be the responsibility of the property owner. [Res. 835 § 2 (Exh. 2), 2022; Res. 735 § 1, 2017.]