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Home My WebLink AboutPRE2022-00031 WRITTEN NARRATIVESeptic System Components Septic Tank: ≥1,500 gal two-compartment State-approved septic tank; with two 24"-diameter access risers above inlet and outlet, extending up to-grade, equipped with lids, bonded to rings integral to tank. Tank to be equipped with influent baffle/drop tube and outlet drop tube and rigid effluent filter with 1/16" orifice size. Suggested effluent filter: Clarus Environmental WW1 (Zoeller Pumps) Effluent Filter Part No. 170-0078. Gravity-Flow Transport Pipelines: 4-inch PVC ASTM D-3034 sloped 2% (¼ inch per ft) from proposed source(s) to septic tank. 4-inch PVC ASTM D-3034 from septic tank to distribution box, sloped as needed. Pipe runs equipped with long-sweep clean-outs, positioned as needed, secured at surface for expected >30-year lifetime. Distribution Box: Plastic or Concrete D-Box with at least seven effluent connections at the same elevation. Unit bedded with pea gravel. Effluent connections equipped with speed-levelers. D-Box equipped with riser, equipped with secured lid. Gravity Drainfield: Seven 3-ft wide x 41-ft long gravel trenches, installed horizontally, with infiltrative surface approximately 19 to 27-inches below ground surface. One 4"-diameter perforated PVC distribution lateral per trench, fitted with long-sweep sanitary tee at the distal end, with slip cap, not glued, to serve both as lateral end clean-out and infiltrative surface inspection port. 4-inch PVC upswept lateral ends shall be end-sawed to loosen connection with end caps, to prevent caps from sticking. Distal ends installed within ≥6"-diameter cylindrical utility vaults (or equivalent) extending 1-2" above grade, capped, secured and marked. Construction Notes Septic System Layout: The septic system designer must supervise layout of the system prior to excavating. Laser leveling or similarly precise systems must be used for leveling, to ensure precisely horizontal infiltrative surfaces. Septic Tank Placement: The tank excavation must have a horizontal bottom prior to adding bedding material. Six inches (6") of pea gravel bedding must be provided to properly support tank in order for tank warranty to remain effective. If shallow groundwater is encountered during tank installation, a newly-installed tank should be filled with water to prevent floating, in case groundwater rises around it. Tank must be covered with a 1-ft minimum thickness compacted soil, or structural fill, to a maximum cover of 3-ft, unless a heavy load-rated tank is used. Risers: Access risers should be installed above septic tank openings. Risers and lids should extend 2 to 3 inches above grade to help prevent debris from falling into risers upon opening. Tank access risers shall be bonded to integral rings built into tank openings, using 3M™ Marine 5200 Adhesive Sealant, or equal, or better. Monitoring Ports: Future septic system inspections will be simplified with properly-installed monitoring ports at key points in the drainfield, at least two per lateral. Monitoring ports should extend down to the bottom of the drain rock layer, no deeper than 27 inches below the pre-disturbance ground surface. Monitoring ports must be installed during drainfield construction and prior to covering. They must be anchored by any of several means, in order to maintain their stability for several decades. Using wood or other biodegradable materials is not recommended for anchoring/stabilizing systems. Sheet 1 of 4. Residential Septic System Description and Construction Notes Property Owners: Richard D. & Renee F. Rathvon 660 Twana Way; Quilcene, WA 98376 Jefferson County Parcel Number 701164005 Parcel Area: 5.47 acres (238,000 ft2) Conventional Gravity-Discharge to Gravel Trenches Drinking Water Source: Proposed Water Well; Location TBD Proposed Septic System Capacity: 5-BR, 600 gal/day peak flow (average ≤450 gpd) Soil Types 3 & 4; Application Rate: 0.7 gal/ft2/day Minimum Infiltrative Surface Area: 600 gpd/0.7 gpd/ft2 = 860 ft2 No indicators of seasonally-shallow ground water down to ≥63" below ground surface Designed By: Everett A. Sorensen, P.E. Evergreen Engineering Services 715 Grant Street Port Townsend, WA 98368-2405 ev_sorensen@hotmail.com 360-821-9960 July 18, 2022 Sheet Index: 1. Description and Construction Notes 2. Site Plan 3. Septic Tank Details 4. Drainfield Distribution Trench Details Potential Building Site Drawn By: Everett A. Sorensen, P.E.Evergreen Engineering Services 715 Grant Street Port Townsend, WA 98368-2405 ev_sorensen@hotmail.com 360-821-9960 July 18, 2022; Revised September 15, 2022 Proposed Drainfield: Seven 48-ft x 3-ft Trenches Provide 1,000 ft2 of Infiltrative SurfaceNote: Trenches may curve to follow elevation contours Sheet 2 of 4 Overall Site Plan with Proposed Septic System Layout Rathvon Property 660 Twana Way; Quilcene, WA 98376 County Parcel 701164005 5.47 Acres (238,000 SF) S3S1 S2S4 S6 S7 S8 S9 Note: Pending water well must be located greater than 100 ft from drainfield. All other water system components must be at least 10 ft from all septic system components Proposed 1,500-gal septic tank Proposed >4,500 SF Reserve Area Proposed 7-Outlet D-Box Original Scale: 1 inch = 80 ft 0 160 240 Ft80 Proposed 4-inch Sewer Background LIDAR & Contours from Jefferson County on-line GIS 230'Parcel BoundaryS5 ≥1,500 gal Two-Compartment Septic Tank Approved Concrete or Polyethylene Tank Secure Lids 4-inch diameter gravity-drain from wastewater source, sloped 2% (Typically ASTM 3034 standard PVC sewer piping with integral bell and gasket) Optional Clean-out finished above grade with threaded plug set in 4"x18"x18" concrete pad (or equivalent stabilized installation) Sanitary Tee Typical accumulated solids Typical accumulated floating mat 3" Min. Sep. Effluent Outlet 12" Min. Sep. Sheet 3 of 4 Proposed Septic Tank Cross-Section Proposed Septic System Rathvon Property 660 Twana Way Quilcene, WA 98376 County Parcel 701164005 5.47 Acres (238,000 SF) 6"-8" thick pea gravel bedding Horizontal Excavation Septic Tank Installation Requirements: 6 inches of pea gravel shall be spread on horizontal compacted excavation bottom before placing tank, level, on pea gravel Tank risers shall be bonded to ring integral to tank with 3M™ Marine 5200 Adhesive Sealant, or equal, or better, and grouted on the outside of the joint, Excavation Extent Maximum solids accumulation prior to pump-out Drawn By: Everett A. Sorensen, P.E.Evergreen Engineering Services715 Grant StreetPort Townsend, WA 98368-2405ev_sorensen@hotmail.com360-821-9960July 18, 2022 Tank Inlet ≥16"below grade Inlet Drop-Tube (or baffle) Effluent Drop-Tube To D-Box Ground Surface Access risers extending 1 to 2 inches above-grade bonded to integral tank ring Ring Integral to Tank Sewage Entry Optional 4" Thin wall-to-thick wall adapter (needed to adapt typical tank drop tube assembly to schedule 40 PVC) Compartment 1Comp. 2 Dividing Baffle Removable effluent filter screen with 1/16" max. mesh size installed within effluent drop tube. Recommended model: Clarus (Zoeller) 170-0078 Septic Tank Effluent Filter Grout around inlet pipe Grout around outlet pipe PVC cap, not glued 4" slotted PVC Horizontal Trench Bottom, less than 1 inch elevation variation over length Trench Cross-Section, Side View Not-To-Scale Coarse drain rock Backfilled Soil Cover Undisturbed Soil Not-To-Scale 2" to 3" Stub-Up Filter fabric above drain rock ½-inch orifices spaced 12" apart, off-center Secure Lid10" min. cylindrical utility vault Trench Depth ≤27" Sanitary Tee Doubles as Lateral Clean-Out and Infiltrative Surface Inspection Port Drawn By: Everett A. Sorensen, P.E.Evergreen Engineering Services715 Grant StreetPort Townsend, WA 98368-2405ev_sorensen@hotmail.com360-821-9960July 18, 2022 Sheet 4 of 4 Drainfield Distribution Trench Cross-Section Proposed Septic System Rathvon Property 660 Twana Way; Quilcene, WA 98376 County Parcel 701164005 5.47 Acres (238,000 SF) 3 ft minimum Trench Cross-Section End View Not-To-Scale 4" slotted PVC 6" minimum cover Drain Rock Filter fabric above gravel Finished grade directs drainage away from trench Backfilled Soil Cover Finished Surface; Vegetation Restored Undisturbed Soil Undisturbed Soil Undisturbed Soil2" minimum 6" minimum Pre-Disturbance Ground Surface Minimum 6" sidewall into native material 27-inch Trench Depth at High Side