310 C.M.R. 15.211
(1) All systems must conform to the minimum setback distance for septic tanks, holding tanks, pump chambers, treatment units and soil absorption systems, including reserve area, measured in feet and as set forth below. Where more than one setback applies, all setback requirements shall be satisfied.
Septic Tank Soil Absorption System Holding Tank Pump Chamber Treatment Unit Grease Traps
Property Line 10[5] 10[5] Cellar or Crawl Space Wall, Swimming Pool (inground), foundation drain 10 20 Slab Foundation 10 10 Water Supply Line (pressure) 10[1] 10[1] Surface Waters (except wetlands) 25 50 Bordering Vegetated Wetland (BVW), Salt Marshes, Inland and Coastal Banks 25 50 Surface Water Supply - Reservoirs and Impoundments 400 400 Tributaries to Surface Water Supplies 200 200 Wetlands bordering Surface Water Supply or Tributary thereto 100 100 Certified Vernal Pools 50 100[2] Private Water Supply Well or Suction Line 50 100 Public Water Supply Well (2) (2) Irrigation Well 10 25 Open, Surface or Subsurface Drains which discharge to Surface Water Supplies or tributaries thereto 50 100 Other Open, Surface or Subsurface Drains (excluding foundation drains) which intercept seasonal high groundwater table [3] 25 50 Other Open, Surface or Subsurface Drains (excluding foundation drains) 5 10 Leaching Catch Basins & Dry Wells 10 25 Downhill Slope not applicable 15[4]
[1] Disposal facilities shall be at least 18 inches below water supply lines. Wherever sewer lines must cross water supply lines, both pipes shall be constructed of class 150 pressure pipe and shall be pressure tested to assure watertightness. [2] The required setback shall be 50 feet where the applicant has provided hydrogeologic data acceptable to the Approving Authority demonstrating that the location of the soil absorption system is hydraulically downgradient of the vernal pool. Surface topography alone is not determinative.
[3] Surface or subsurface drains which will regularly or periodically intercept the seasonal high groundwater table and carry that groundwater away from an area must meet the specified setbacks. [4] The setback distance shall be measured from a naturally-occurring downhill slope which is not steeper than 3:1 (horizontal:vertical). A minimum 15 foot horizontal separation distance shall be provided between the top of the two inch layer of c to ½ inch washed stone above the pipe, or the geotextile material above the pipe or the top of the chamber and the adjacent downhill slope. For a system located in an area with any adjacent naturally occurring downhill slope steeper than 3:1, slope stabilization shall be provided in accordance with best engineering practice which may include construction of a retaining wall designed by a Massachusetts Registered Professional Engineer. [5] Locating a system component or any part thereof beyond a property line of the facility, whether pursuant to an easement or otherwise, requires a variance issued in accordance with 310 CMR 15.410, except that the placement of fill or grading material beyond the property line of the facility, pursuant to an easement or otherwise, shall not require a variance under 310 CMR 15.410.