Regulatory Setbacks and Buffers RIDEM OWTS

Transcription

1 Regulatory Setbacks and Buffers RIDEM OWTS Brian Moore Supervising Sanitary Engineer RIDEM Onsite Program Definitions - Watercourse Any of the following: pond brook river marsh stream lake wet meadow swamp other standing body of water bog fen Including any affected by tidal waters Definitions Subsurface Drain Any system of below surface piping or highly permeable material intended to lower the groundwater table of an area, and which has an outlet to the surface for the collected groundwater. e.g.: Foundation drain, french drains. Definitions Storm Drain Any pipe or structure design to collect, carry and/or divert surface runoff. Definitions Tributary Flowing body of water or watercourse that provides intermittent or perennial flow to downgradient watercourses that eventually discharge to the waters of concern (e.g., reservoir impoundment or salt pond). Definitions Tributary Wetland Freshwater wetlands within a watershed that are connected via a watercourse to the waters of concern (e.g., drinking water supply impoundment or coastal wetland or tidal waters). 1

2 Definitions Wellhead Protection Area Area as designated by the Director in the DEM Rules and Regulations for Groundwater Quality surrounding a public well or wellfield through which water will move toward and reach such well or wellfield. Definitions Bedrock and Rotten Rock Bedrock: Rock, commonly called ledge, that forms the earth s crust. Bedrock includes rotten rock. Rotten Rock: Any decomposed but still coherent rock. Rotten Rock is greater than 50% coherent rock and lies above equal or more coherent rock. Definitions Restrictive Layer A soil horizon that is assigned to a soil category 10 as defined in Rule Note 1: Distance may be reduced when seamless sleeves are used. 2

3 Note 2: Not applicable to building sewer and septic tank effluent pipe. Note 3: Any single leachfield designed to treat more than two thousand (2000) but less than five thousand (5000) gallons per day. Note 5: Distance shown is the minimum for upgradient and side gradient directions. Downgradient separation distance will be based on nitrate modeling and shall be a minimum of 50 feet. Note 4: As defined in Rule Note 7: Distance may be reduced when seamless sleeves are used. Note 6: 15 feet if no foundation drain. 8 feet with slab or when basement floor elevation is higher than building sewer. Note 8: If the slope is <3% over leachfield and 50 perimeter, then setback is 50 in all directions unless GW flow study shows drain is upgradient. Note 9: If drain is watertight, bedded in sand or bank run gravel; above the SHGWT; then setback may be 25. 3

4 Note 10: On 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 15 feet if the stormwater infiltration system has been designed in accordance with RI Stormwater Design and Installation Standards Manual or RI Stormwater Management Guidance for Individual Single-Family Residential Lot Development. All setbacks are doubled for OWTS 5000 gpd. Note 11: The minimum setback distance from the ocean or Narragansett Bay is either fifty (50) feet or twenty five (25) feet plus the CRMC calculated shoreline change setback pursuant to the CRMP Section 140, whichever is greater. This setback distance is doubled for OWTSs with design flow greater than five thousand (5000) gallons per day. Swales: Paved = 200 Setback Unpaved, < 200 long = 200 Setback Unpaved, 200 long = 100 Setback Table Page 49 Note 2: Distances measured from the yearly high water mark. Table Page 49 Note 3: Distance may be reduced when seamless sleeves are used. 4

5 Swales: Paved = 200 Setback Unpaved < 200 = 200 Setback Unpaved 200 = 150 Setback Table 22.3 Page 50 All setbacks are doubled for OWTS 5000 gpd. Table 22.3 Page 50 Table Page 50 CRMC Shoreline Change Maps Note 3: The minimum setback distance from the ocean or Narragansett Bay is either fifty (50) feet or twenty-five (25) feet plus the CRMC calculated shoreline change setback, whichever is greater. This minimum setback distance is doubled for OWTSs with design flow greater than five thousand (5000) gallons per day. Table 22.3 Page 50 Table Minimum Setback Distances from Drinking Water Wells Note 2: Distance may be reduced when seamless sleeves are used. Note 1: Large Systems- These distances are minimum distances for large systems as defined in Rule Greater distances may be required based on the Impact Analysis in Rule

6 Table 22.4 Minimum Setback Distances from Drinking Water Wells Note 2: Distance from the building sewer may be reduced when the building sewer is constructed of Schedule 40 PVC or equivalent. Table 22.4 Minimum Setback Distances from Drinking Water Wells Note 3: Distances may be reduced to 80/60/40 feet for residential OWTSs on lots 10,000 sq. ft. and larger if: (A) The design flow is less than five hundred (500) gallons per day; (B) The OWTS utilizes a Department approved Category 1 nitrogen reducing technology; (C) The OWTS discharges to a PSND designed in accordance with DEM guidelines; and (D) The OWTS separation distance to groundwater is three (3) feet or greater. Table 22.4 Minimum Setback Distances from Drinking Water Wells Note 4: The minimum setback distances shall be increased to 150/100/75 for OWTSs with a design flow of less than 1000 gallons per day if the OWTS is designed for Category 1 soils. For such OWTSs utilizing a BSF or PSND constructed in accordance with DEM guidelines, the minimum setback distances may be 100/75/50. Rule 32.4: Depth to Groundwater The leachfield shall be located in an area where the SHGT is a minimum of two (2) feet below the original ground surface. On lots 20,000 sq. ft or larger, the leachfield may be located in an area where the SHGT is less than twenty-four (24) inches but greater than or equal to eighteen (18) inches from the original ground surface if the OWTS utilizes a bottomless sand filter and the applicant has no variance requests. Rule 32.5: Depth to Restrictive Layer or Bedrock The leachfield shall be located in an area where a restrictive layer or bedrock is a minimum of four (4) feet below the original ground surface. The minimum depth to a restrictive layer or bedrock shall be met within twenty-five (25) feet of all sides of the leachfield. Vertical Separation Distance: Groundwater Rule 32.7: The bottom of the stone underlying the leachfield shall be at least three (3) feet above the seasonal high groundwater table. 6

7 Vertical Separation Distance: Groundwater In the Salt Pond and narrow River Critical Resource Areas and In Drinking Water Supply Watersheds Rule 39.5 and 40.3: The bottom of the stone underlying the leachfield shall be at least four (4) feet above the seasonal high groundwater table when either soil category 1, 2, 3, 4, or 6 are encountered in determining the maximum leachfield loading rate Vertical Separation Distance: Restrictive Layer or Bedrock Rule 32.8: The bottom of the stone underlying the leachfield shall be at least 5 feet above a restrictive layer or bedrock. This 5 foot vertical separation shall be maintained to a distance of 25 feet from the side wall of the leachfield. In the upgradient direction, the 5 foot vertical separation may be waived as long as the restrictive layer or bedrock is no higher than the bottom of the stone within 25 feet of the leachfield. Excavating into a restrictive layer or bedrock is not permitted. What if a Design Can t Meet Setback Requirements? You can: Change the design, or Request a Variance. DEM may grant a variance to setbacks but WILL NOT APPROVE requests for the following Rule 48.2 Variance Review Standards - Denials (E)- Denial (ii) The variance request is from the requirements of Rule 14.2 on a site located in the Salt Pond or Narrow River Critical Resource Areas unless the applicant demonstrates that a net reduction in overall, long-term nitrogen loading to the watershed will result. (Rule lists all scenarios where request for variance will not be approved.) (Rule Any dwelling or other building having plumbing fixtures from which wastewater is produced, where no public wastewater system is available or accessible, shall be provided with an OWTS. All of the components of such OWTS shall be located within the property boundary upon which the building or dwelling is located.) Rule 48.2 Variance Review Standards - Denials (E) (vii) The variance request is for less than the eighty (80) foot minimum setback distance from a private drinking water well; (ix) The variance request is for a depth to groundwater from original ground surface of less than twelve (12) inches or for a depth to a restrictive layer or bedrock of less than thirty six (36) inches; Examples! 7

8 Distances Distances potable well non-potable well potable well 25 to BS, grease trap pump tank, septic tank, ST effluent pipe 50 to leachfield non-potable well 10 to BS, grease trap pump tank, septic tank, ST effluent pipe 25 to leachfield potable well Distances private well Distances foundation (25 ); no drain (15 ); slab (8 ) fill perimeter (10 ) 5 to grease trap pump tank, septic tank, ST-EP property lines (10 ) (all components but BS and ST-EP) fill perimeter (10 ) Distances- Foundation Drain 25 to BS, grease trap pump tank, septic tank, ST effluent pipe Distances- Foundation Drain 50 downgradient 50 in all directions if slope < 3% 8

9 Lake (not a drinking water supply) Distances- Foundation Drain 25 Upgradient 50 in all directions if < 3% Distances- Storm Drain 25 if the drain is watertight, bedded in sand or bank run gravel, or laid at an elevation above the seasonal high groundwater table Distances- Above Ground Pool Distances- In-Ground Pool DRINKING WATER SUPPLY Minimum Distances: Wells and Water private well Supplies Gravel packed well Lake all components (25 ) cesspool water line (10 ) water pressure line (25 ) Distances- Watercourses Not in a CRA 9

10 Distances Not in DW/CRA Distances Not in DW/CRA flagged edge of wetland Table 22.2: Minimum Distances in DW Watershed flagged edge of wetland Definitions Salt Pond and Narrow River Critical Resource Areas Areas designated as CRA s include: Trustom Pond Quonochontaug Pond Maschaug Pond Green Hill Pond Point Judith Pond Potter Pond Winnapaug Pond Cards Pond Ninigret Pond Narrow River and its watershed 10

11 SALT POND cesspool well all components (150 ) Definitions Drinking Water Supply Watershed Critical Resource Areas Drinking water reservoirs and their watersheds for the following water suppliers: Woonsocket Providence Eleanor Slater Hospital Newport Table 22.3: Minimum Distances- Salt Pond/Narrow River CRA Bristol County Pawtucket New Shoreham Cumberland Jamestown Stone Bridge FD Yawgoog Scout Reservation 11

12 DRINKING WATER SUPPLY all components (100 ) cesspool Any Questions?? Table 22.2: Minimum Distances- Drinking Water Supply Watershed CRA 12