(1) Prior to construction, the sewer plans shall be reviewed and approved by the Department of Ecology with an affidavit stating such on file at the district’s office, unless the review and approval is waived by Ecology.
(2) Work shall be performed only by contractors experienced in laying public sewer mains.
(3) Prior to any work being performed, the developer shall contact the district’s engineer to set forth his proposed schedule.
(4) All materials shall be new and undamaged.
(5) Developer shall obtain approval of materials to be used from the district prior to ordering of materials.
(6) Sewer mains shall be laid only in dedicated streets or in easements that have been granted to the district. A street is normally not considered until the plat, which created it, has been filed with the county auditor.
(7) All service connections to the district sewer system shall be a gravity connection. If service lines to structures or lots to be served are over 200 feet (not including panhandle), the developer shall install an eight-inch sewer main within 100 feet of the farthest lot with a manhole at the end in an easement granted to the district. Parallel side sewers shall be separated by a minimum of five feet horizontally from each sewer service and 10 feet from parallel water services.
(8) The sewer mains shall run parallel to and five feet southerly or westerly of street centerline where possible. The sewer main shall maintain a minimum 10-foot horizontal separation from proposed or existing water mains.
(9) The minimum slope for eight-inch gravity mains shall be one-half percent (except the minimum slope for dead-end runs shall be one percent for eight-inch gravity mains). The minimum slope for six-inch side sewer laterals shall be two percent and the maximum shall be 100 percent (45 degrees).
(10) The maximum distance between manholes shall be 400 feet unless approved by the district.
(11) Manholes shall be a minimum of eight feet deep unless approved by the district.
(12) Manholes greater than 20 feet deep shall be a minimum of 54 inches inside diameter.
(13) Manholes greater than 25 feet deep should not be submitted for review without prior approval of deep design concept by the district. Deep designs will not be approved if alternative service can be provided with shallower gravity service, even if the property developing will have to delay development.
(14) Manholes shall be provided with a one-tenth-foot drop across the channel.
(15) Terminating manholes, where sewer extension may occur, shall be channeled accordingly.
(16) Locking lids shall be provided for all manholes and all manhole lids shall have the word “sewer” cast integrally onto its surface.
(17) All manholes shall be accessible to maintenance vehicles.
(18) Manholes in easements shall be provided with a green fiberglass locator marker post with the footage to the manhole stenciled on with two-inch letters.
(19) All side sewer laterals shall be of the same material as the main line unless approved by the district.
(20) Front lot corners and a property line stake shall be staked prior to construction for side sewer tee location.
(21) Side sewers are normally extended to the lowest property corner and located a minimum of 10 feet from the side lot line and are extended past dry utilities unless prior approval from district for alternate location.
(22) Side sewer connections allowed directly into manholes shall be constructed to match the sewer main crown and the manhole channeled accordingly.
(23) All commercial, industrial or school food establishments shall be equipped with an approved grease interceptor located outside the building, as required by the district, prior to discharging to the sewer main. Sizing to be confirmed by a professional engineer licensed in the state of Washington.
(24) Provide the district a copy of the cut sheets prior to construction.
(25) Pipe trenches shall not be backfilled until pipe and bedding installation has been inspected by the district.
(26) Final air testing shall not be accepted until all underground utilities have been installed, compaction is completed, and the lines have been flushed, cleaned, deflection tested and television inspected.
(27) Road restoration shall be per Snohomish County, city and/or state design and construction standards. The developer shall become familiar with all county, city and state conditions of required permits, and shall adhere to all conditions and requirements.
(28) Manhole rim, sewer location, and invert elevations shall be field verified after construction by the developer’s engineer(s) and the “as constructed” drawings individually stamped by a professional engineer licensed in the state of Washington which shall attest to the fact that the information is correct. [Res. 735 § 1, 2017.]