6.20.410 Private side sewers.
Private side sewers are located outside of the public right-of-way or district easements and are the extension from the end of the district sewer lateral to the building connection point.
A permit application and payment of applicable general facility charges and fees are required for all new side sewer connections, as well as repairs or revisions to existing side sewers, in accordance with SLWSDC 6.20.220 and 9.05.070. Construction on private property may be performed by owner if approved by the district.
(1) All sewer service connections to district facilities shall be gravity service unless otherwise approved by the district. If gravity service is not feasible, interior sewage pumps may be authorized by the district and connection shall be made to the sewer system in accordance with the district standard details. A pumping agreement shall be executed between the district and the property owner and recorded on the property title. No exterior sewage pumps are allowed in the district.
(2) Private side sewer pipe for residential property shall be four inches or larger. Side sewer pipe for duplexes, multifamily, industrial, commercial, etc., shall be six inches or larger.
(3) Pipe material shall be PVC ASTM D3034, and shall be installed at two percent minimum grade. If minimum depths cannot be achieved, the pipe material shall be ductile iron or C900.
(4) Pipe shall be bedded with pea gravel or clean free draining sand.
(5) Side sewers shall be inspected by the district prior to backfilling. Side sewers shall be plugged and tested in the presence of the district inspector by a low-pressure air test or filling with water. Water leakage rate shall not exceed 0.31 gal./hr. for four-inch pipe and 0.47 gal./hr. for six-inch pipe, per 100 feet of pipe.
(6) At the connection point to the building, minimum cover shall be 18 inches over top of pipe from a point located 30 inches out from the structure.
(7) Parallel water and sewer lines shall be 10 feet apart horizontally wherever possible and have a vertical separation of 18 inches if a vertical crossing is necessary.
(8) No more than 100 feet is allowed between cleanouts. If multiple cleanouts are required on a straight section of pipe, they should be evenly spaced, or one cleanout placed near the middle of the run. Cleanouts are required for each combined bend equal to or greater than 90 degrees. Cleanouts shall be installed per district standard details.
(9) All pipe joints shall be rubber gasket type. Approved couplings shall be used when transitioning from one pipe type to another, such as from ductile iron or concrete to PVC.
(10) A cleanout shall be installed at the right-of-way or easement line with the installation of the private side sewer pipe in accordance with district standard details.
(11) Backwater valves shall be installed on all side sewers where required by the current Uniform Plumbing Code. If required, backwater valves shall be installed inside the structure for all new construction, but may be exterior for retrofit situations in accordance with district standard details. A backwater valve agreement shall be executed between the district and the property owner and recorded on the property title.
(12) Prior to final connection to the structure, all side sewer and lateral pipes shall be flushed and cleaned, and all debris removed.
(13) Existing homes served by septic systems converting to district sewer service are to demonstrate proper abandonment of the septic tank to Snohomish Health District standards and WAC 246-272A-0300. The contractor shall provide a copy of documentation regarding sewage pumping to the district. [Res. 835 § 2 (Exh. 2), 2022; Res. 735 § 1, 2017. Formerly 6.20.440.]