Rhode Island Code of Regulations › Title 250 - Department of Environmental Management › Chapter 150 - Water Resources › Subchapter 10 - Wastewater And Storm Water › Part 6 - Rules Establishing Minimum Standards Relating to Location, Design, Construction and Maintenance of Onsite Wastewater Treatment Systems › Section 250-RICR-150-10-6.23 - Minimum Setback Distances

Current through June 14, 2024
A. The horizontal
				  distances between the parts of an OWTS and the items listed in §§
										6.23(B) through
				  (E) of this Part shall not be less than those
				  shown. Where a proposed OWTS cannot meet the horizontal distances in
				  §§
										6.23(B) through
				  (E) of this Part, a variance request shall be
				  required pursuant to §
										6.51 of this Part unless
				  the setback reduction is specifically allowed in Notes accompanying each
				  Table.
B. Minimum Setback Distances
				  - General
Building Sewer, Grease Tank, Distribution Box,
								  Pump Tank, Septic Tank, Septic Tank Effluent Pipe (ft) (Note 12)
Leachfield (ft)
(Note 12)
Well Serving Non-potable Uses (Note
								  13)
25
50
Water Supply Line
10 (Note 1)
25
Property Line
10 (Note 2)
Design Flow (gpd)
(ft)
0 - 2000
10
>2000 - 5000 (Note 3)
50
> 5000 (Note 4)
min. 50 (Note 5)
Foundation
5 (Not applicable to building
								  sewer)
25 (Note 6)
Subsurface drains, foundation drains, or storm
								  drains (see also §§
																6.23(C) and
								  (D) of this Part):
- Upgradient and side gradient of the
								  OWTS:
- Downgradient of the OWTS:
15 (Note 7)
25 (Note 7)
25 (Note 8)
50 (Note 9)
Edge of any land at a level lower than the invert
								  of the distribution line
10
10
Stormwater Infiltration System
25 (Note 10)
25 (Note 10)
Swimming Pools:
In-ground:
10
25
Above ground:
10
10
Design Flow < 5000 gpd
Design Flow [GREATER THAN EQUAL TO] 5000 gpd
								  (Note 4)
Design Flow < 5000 gpd
Design Flow [GREATER THAN EQUAL TO] 5000 gpd
								  (Note 4)
Coastal Shoreline Feature (Note 11) not in a
								  Critical Resource Area, Flowing Water (Rivers and Streams), Open Bodies of
								  Water (Lakes and Ponds), Other Watercourses Not Mentioned Above, and Any
								  Stormwater Management Structure That Potentially Intercepts
								  Groundwater
25
50
50
100
Notes: The reductions in setback distances
								  allowed below in Notes (1) through (13) will not be granted if the setback
								  distances in §
																6.23(B) of
								  this Part can be met. A variance request pursuant to §
																6.51 of this Part shall not
								  be required for the reductions indicated below.
(1) The distance between the building sewer or
								  septic tank effluent pipe and a water supply line may be reduced and the lines
								  may cross provided that either the building sewer or septic tank effluent pipe
								  or water supply line is sleeved whenever the lines are within ten feet (10') of
								  each other. The sleeve shall be seamless or schedule 40 PVC or equivalent with
								  watertight joints and it shall have a watertight seal that is fastened to the
								  pipes with a stainless steel retractable clamp. Whenever possible, the building
								  sewer and septic tank effluent pipe should be laid below water supply lines at
								  crossings.
Pressurized building sewers or pressurized septic
								  tank effluent pipes shall be laid below water supply lines at crossings. If the
								  setbacks to a water supply line for a public water system cannot be met, the
								  applicant must obtain, and submit to the Department, written permission from
								  the water supplier.
(2) Not applicable to building sewer and septic
								  tank effluent pipe. Setback distance of ten feet (10') applies for all OWTS
								  components not specifically listed.
(3) Any single leachfield designed to treat more
								  than two thousand (2,000) but less than five thousand (5,000) gallons per
								  day.
(4) As defined in §
																6.39(A)(1)
								  of this Part.
(5) Distance shown is the minimum for upgradient
								  and side gradient directions. Downgradient separation distance will be based on
								  nitrate modeling undertaken pursuant to §
																6.39 of this Part and shall
								  be a minimum of fifty feet (50').
(6) Distance may be reduced to fifteen feet (15')
								  with no foundation drain. Full foundation details must be shown on the plan.
								  Distance may be reduced to eight feet (8') where a foundation slab elevation,
								  pile foundation, or the basement floor elevation is higher than the invert of
								  the distribution lines in the leachfield.
(7) The distance between the building sewer or
								  septic tank effluent pipe and a drain may be reduced and the building sewer or
								  effluent pipe may cross the drain provided that the building sewer or septic
								  tank effluent pipe is sleeved whenever they are within twenty-five feet (25')
								  of the drain. The sleeve shall be seamless or schedule 40 PVC or equivalent
								  with watertight joints, and it shall have a watertight seal that is fastened to
								  the pipes with a stainless steel retractable clamp.
(10) On a residential property with both an OWTS
								  and a stormwater infiltration system, the distance between any OWTS component
								  and the stormwater infiltration system may be reduced to fifteen feet (15') if
								  the stormwater infiltration system has been designed in accordance with the
								  Rhode Island Stormwater Design and Installation Standards Manual.
(11) The minimum setback distance from the inland
								  edge of the coastal shoreline feature of the ocean or Narragansett Bay is
								  either fifty feet (50') or twenty-five feet (25') plus the CRMC calculated
								  shoreline change setback pursuant to §
																1.9 of 650-RICR-20- 00-1,
								  Red Book, whichever is greater. Shoreline change rates and maps are available
								  on CRMC's web site. This setback distance is doubled for OWTSs with design flow
								  greater than five thousand (5,000) gallons per day.
C.
				  Minimum Setback Distances from Drinking Water Supply Watershed Critical
				  Resource Area Features (distances in feet from all OWTS components). See also
				  §
										6.60
				  of this Part, Figure 2. If it is shown to the Department's satisfaction by
				  clear and convincing evidence that the feature of concern in this table is
				  upgradient (for both groundwater and surface water flow) of the OWTS, the
				  minimum setback distance will be determined from §
										6.23(B) of
				  this Part. Subsurface drains to lower the seasonal high groundwater table are
				  not permitted in accordance with §
										6.44(B) of
				  this Part.
Feature
OWTS Design Flow
OWTS Design Flow [GREATER THAN EQUAL TO] 5000 gpd
								  (Note 1)
Impoundment with Intake for Drinking Water Supply
								  and Adjacent Freshwater Wetlands (Note 2)
200
400
Subsurface Drains and Foundation Drains that
								  Discharge Directly to the Impoundment
200
400
Subsurface Drains and Foundation Drains that
								  Discharge to a Drainage Swale that Subsequently Discharges to the
								  Impoundment:
200
400
Paved Swale
200
400
Unpaved Swale < 200 feet long
200
Unpaved Swale [GREATER THAN EQUAL TO]200 feet
								  long
100
Tributaries, Tributary Freshwater Wetlands,
								  Swales, and Storm Drains that Discharge Directly to the
								  Impoundment
100 (Note 3)
200 (Note 3)
Subsurface Drains, Foundation Drains, and Storm
								  Drains that Discharge to Tributaries and Tributary Freshwater
								  Wetlands
100 (Note 3)
200 (Note 3)
Any other Watercourse in the Drinking Water
								  Supply Watershed (Not Connected to the Impoundment) or Areas Subject to Storm
								  Flowage
50
100
Notes: The reductions in setback distances
								  allowed below in Note (3) will not be granted if the setback distances in
								  §
																6.23(C) of
								  this Part can be met. A variance request pursuant to §
																6.51 of this Part shall not
								  be required for the reductions indicated below.
(1) As defined in §
																6.39(A)(1)
								  of this Part.
(2) Distances measured from the yearly high water
								  mark.
(3) The distance between the building sewer or
								  septic tank effluent pipe and a drain may be reduced and the building sewer or
								  effluent pipe may cross the drain provided that the building sewer or septic
								  tank effluent pipe is sleeved whenever they are within twenty-five feet (25')
								  of the drain. The sleeve shall be seamless or schedule 40 PVC or equivalent
								  with watertight joints, and it shall have a watertight seal that is fastened to
								  the pipes with a stainless steel retractable clamp.
D.
				  Minimum Setback Distances from Features in the Salt Pond and Narrow River
				  Critical Resource Area (distances in feet from all OWTS components). See also
				  §
										6.61
				  of this Part, Figure 3. If it is shown to the Department's satisfaction by
				  clear and convincing evidence that the feature of concern in this table is
				  upgradient (for both groundwater and surface water flow) of the OWTS, the
				  minimum setback distance will be determined from §
										6.23(B) of
				  this Part. Applications for an OWTS permit that are approved by DEM are subject
				  to the requirements of CRMC.
Feature
OWTS Design Flow <5000 gpd
OWTS Design Flow [GREATER THAN EQUAL TO] 5000
								  gpd(Note 1)
Salt Pond/Narrow River Coastal Shoreline
								  Features, excluding the ocean
200
400
Subsurface Drains and Foundation Drains that
								  Discharge Directly to the Salt Pond/Narrow River
200
400
Subsurface Drains and Foundation Drains that
								  Discharge to an open Drainage Swale that Subsequently Discharges to the Salt
								  Pond/Narrow River:
Paved Swale
200
400
Unpaved Swale < 200 feet long
200
400
Unpaved Swale [GREATER THAN EQUAL TO] 200 feet
								  long
150
300
Tributaries, Tributary Freshwater Wetlands,
								  Swales, and Storm Drains that Discharge Directly to the Salt Pond/Narrow
								  River
150 (Note 2)
300 (Note 2)
Subsurface Drains, Foundation Drains, and Storm
								  Drains that Discharge to Tributaries and Tributary Freshwater
								  Wetlands
150
300
Any Other Watercourse in Salt Pond/Narrow River
								  Critical Resource Area (Not Connected to Salt Pond/Narrow River), Areas Subject
								  to Storm Flowage, or the inland edge of the coastal shoreline feature of the
								  ocean. (Note 3)
50
100
Notes: The reductions in setback distances
								  allowed below in Note (2) will not be granted if the setback distances in
								  §
																6.23(D) of
								  this Part can be met. A variance request pursuant to §
																6.51 of this Part shall not
								  be required for the reductions indicated below.
(1) As defined in §
																6.39(A)(1)
								  of this Part.
(2) The distance between the building sewer or
								  septic tank effluent pipe and a drain may be reduced and the building sewer or
								  effluent pipe may cross the drain provided that the building sewer or septic
								  tank effluent pipe is sleeved whenever they are within twenty-five feet (25')
								  of the drain. The sleeve shall be seamless or schedule 40 PVC or equivalent
								  with watertight joints, and it shall have a watertight seal that is fastened to
								  the pipes with a stainless steel retractable clamp.
(3) The minimum setback distance from the inland
								  edge of the coastal shoreline feature of the ocean is either fifty feet (50')
								  or twenty-five feet (25') plus the CRMC calculated shoreline change setback
								  pursuant to §
																1.9 of 650-RICR-20- 00-1,
								  Red Book, whichever is greater. Shoreline change rates and maps are available
								  on CRMC's web site. This minimum setback distance is doubled for OWTSs with
								  design flow greater than five thousand (5,000) gallons per day.
E.
				  Minimum Setback Distances from Drinking Water Wells
OWTS Design Flow (gpd)
Distance in Feet from Leachfield/Septic Tank
								  Effluent Pipe, Tanks/Building Sewer (Notes 1 and 5)
Distance in Feet from All OWTS Components (Notes
								  1 and 5)
Private Drinking Water Well (Note
								  2)
Public Well - Drilled (rock), Driven, or
								  Dug
Public Well - Gravel Packed, Gravel
								  Developed
< 1,000
100/75/50 (Notes 3 and 4)
200
400
1,000 - <2,000
150/75/50
200
400
2,000 - <5,000
200/75/50
200
400
5,000 - <10,000
300/75/50
300
400
[GREATER THAN EQUAL TO]10,000
400/75/50
400
400
Notes: The reductions in setback distances
								  allowed below in Notes (2) and (3) will not be granted if the setback distances
								  in §
																6.23(E) of
								  this Part can be met. A variance request pursuant to §
																6.51 of this Part shall not
								  be required for the reductions indicated below.
(1) Large Systems - These distances are minimum
								  distances for large systems as defined in §
																6.39(A)(1)
								  of this Part. Greater distances may be required based on the Impact Analysis in
								  §
																6.39(C) of
								  this Part.
(2) Distance from the building sewer may be
								  reduced when the building sewer is constructed of Schedule 40 PVC or
								  equivalent.
(3) The minimum setback distances to wells on the
								  subject property may be reduced to 80/60/40 (leachfield/tank/building sewer)
								  feet for residential OWTSs on lots ten-thousand (10,000) square feet and larger
								  under the following conditions:
(A) The design flow is less than five hundred
								  (500) gallons per day;
(B) The OWTS utilizes a Department-approved
								  nitrogen reducing technology;
(C) The OWTS discharges to a pressurized shallow
								  narrow drainfield designed in accordance with §
																6.37(D) of
								  this Part ; and
(D) The OWTS separation distance between the
								  infiltration surface and groundwater is three feet (3') or greater.
(4) The minimum setback distances shall be
								  increased to 150/75/50 (leachfield/tank/building sewer) for OWTSs with a design
								  flow of less than one thousand (1,000) gallons per day if the OWTS is designed
								  for Category 1 soils per §
																6.33 of this Part. For such
								  OWTSs utilizing a Department approved nitrogen reducing technology discharging
								  to a bottomless sand filter or pressurized shallow narrow drainfield
								  constructed in accordance with §
																6.37(D) of
								  this Part, the minimum setback distances may be 100/75/50
								  (leachfield/tank/building sewer).
(5) In addition to the required setbacks between
								  wells and the proposed OWTS, well setbacks shall also apply between any
								  existing well serving the building for which the OWTS is proposed and any other
								  existing OWTS. Such existing OWTS may require upgrade to meet these
								  Rules.