Statutes, codes, and regulations
Rhode Island Administrative Code
Title 250 - Department of Environmental ManagementChapter 150 - Water ResourcesSubchapter 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

250 R.I. Code R. 250-RICR-150-10-6.23

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Current through December 26, 2024
Section 250-RICR-150-10-6.23 - Minimum Setback Distances
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.

250 R.I. Code R. 250-RICR-150-10-6.23

Amended effective 11/25/2018
Amended effective 12/28/2021
Amended effective 7/1/2022