Code of Massachusetts Regulations › 310 CMR - DEPARTMENT OF ENVIRONMENTAL PROTECTION › Title 310 CMR 15.000 - The State Environmental Code, Title 5: Standard Requirements for the Siting, Construction, Inspection, Upgrade and Expansion of On-site Sewage Treatment and Disposal Systems and for the Transport and Disposal of Septage › Subpart C - DESIGN, CONSTRUCTION, REPAIR, AND REPLACEMENT OF ON-SITE SEWAGE DISPOSAL SYSTEMS › Section 15.211 - Minimum Setback Distances

Current through Register 1525, July 5, 2024
(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 Holding Tank Pump Chamber Treatment
								Unit Grease Traps
Soil Absorption System
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 1/8 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.