Wetland Setbacks for Onsite Waste Water Treatment Systems, OWTS, Buildings

Sec. 6.12. Wetland Setbacks for Onsite Waste Water Treatment Systems, OWTS, Buildings.

and Impervious Surfaces. Section 6.12.1 Purpose and Authority (1) Purpose. The standards and provisions in this section are intended to protect the health, safety and general welfare of the Town’s residents, property owners and businesses, to prevent nuisance, to prevent degradation of North Smithfield’s surface or ground waters, and to maintain and enhance the water quality function of wetlands and associated wetland buffers, in accordance with goals of the North Smithfield Comprehensive Plan. It establishes standards and procedures for the use of wetland buffers, including the location and design of OWTS, buildings, impervious cover and other land development, and use of best management practices to minimize pollution sources, ensure proper management of storm water runoff, and adequate treatment of pathogen and nutrient inputs to wells, groundwater and surface waters from onsite wastewater treatment systems.

As per RIGL 45-24-30 the methods of protection recognize: 1) The natural characteristics of the land, including its suitability for use based on soil characteristics, topography and susceptibly to surface and groundwater pollution; 2) The values of unique or valuable natural resources and features; 3) The availability and capacity of existing and planned public and/or private services and facilities; 4) The goals and patterns of land use contained in the North Smithfield Comprehensive Plan.

• (2) Authority. The Town of North Smithfield recognizes its authority to adopt requirements that are more restrictive than State minimum standards to address the combined impacts of land use, storm water runoff and wastewater effluent to locally important water resources. These State standards include: the Rules Establishing Minimum Standards Relating to Location, Design, Construction and Maintenance of Onsite Wastewater Treatment Systems (OWTS Regulations); the Rules and Regulations Governing the Administration and Enforcement of the Freshwater Wetlands Act (Rules); and the Rhode Island Storm water Design and Installation Standards Manual, as promulgated by the Rhode Island Department of Environmental Management (RIDEM). The following requirements are hereby established in accordance with The RI Zoning Enabling Act RIGL 45-24. These requirements shall be considered an addition to, and not a replacement for, the referenced regulations and any subsequent amendments thereto.

• (3) Wetlands and water bodies covered under this ordinance include: Wetland, freshwater are defined as in G.L. 1956, 2-1-20 as follows: Marshes; swamps; bogs; ponds; rivers; river and stream floodplains and 6-4 banks; areas subject to flooding or storm flowage; emergent and sub emergent plant communities in any body of fresh water including rivers and streams and that area of land within 50 feet of the edge of any bog, marsh, swamp, or pond.

• (4) Scientific findings. There is ample and defensible scientific justification for increased buffer width benefiting water quality (EPA 2006; Wenger, 1999; Vermont Agency of Natural Resources, 2005). The EPA (2006) notes that nitrogen removal efficiencies of 80-90% are obtained for wetland buffers overall that are 30m or approximately 100ft wide. In contrast, only 65-75% of nitrogen is removed for buffers 15m, or approximately 45 ft. wide. Grass buffers alone are only 75% effective at 28m; and only 50% effective at 16m. Water bodies with little or no riparian buffer zones are found to have two to three times the annual nitrate concentration of streams with buffers. Wenger (1999) reviewed 140 scientific studies and notes, “Reduction of various forms of nitrogen in surface runoff is reasonably well correlated with buffer width.” Studies of sediment in surface runoff show that the most efficient width for sediment removal is 82 feet. The Vermont Agency of Natural Resources summarized 22 scientific studies recommending buffer widths for riparian ecosystem function. Eighty percent of the studies recommended a mean width of 100 feet. Wenger (1999) writes that a 100 ft option, including adjacent wetlands “provides the greatest level of protection for stream corridors, including good control of sediment and other contaminants, maintenance of quality aquatic habitat, and some minimal terrestrial wildlife habitat.”

• 6.12.2. Onsite Wastewater Treatment (OWTS) setback.

• • (1) This section applies only to properties located within any surface water supply basins in town, including the surface water supply basins for Woonsocket’s Reservoirs 1, 2 and 3, and to school well-head protection areas, as delineated in the North Smithfield, RI Zoning Ordinance Map:

• • Water Supply Protection Overlay District. Except as provided in subsections (2), (3), (4) and (5) of this section, no component of an onsite wastewater treatment system (OWTS) facility designed to leach liquid wastes into the soil shall be located within 150 feet of the defined edge or channel of any Freshwater Wetland as defined in the Rules. This section shall not be interpreted to require a 150-foot setback from a riverbank wetland, areas of land within fifty feet 50’ of wetlands (perimeter wetlands) or area(s) subject to storm flowage as defined in the Rules.

• • (2) No part of an OWTS or other facility designed to leach liquid wastes into the soil shall be located within 200 feet of any drinking water supply impoundment or tributary that directly discharges to a drinking water supply, including storm and subsurface drains that directly discharge to a tributary stream surface water body.

• • (3) Subsection (1) of this section shall not apply to any replacement, major repair, alteration or modification of a system or facility which exists 20 days after the Date of Passage of this Section provided that the replacement, repair, alteration or modification meets the Minimum Requirements for Advanced OWTS Treatment as defined herein. 6-5

    (4) Subsection (1) of this section shall not apply to the location of such a system on a residential lot located in a subdivision which received final approval from the Planning Board or from RIDEM prior to the adoption of this section provided that the replacement, major repair, alteration or modification meets the Minimum Requirements for Advanced OWTS Treatment as defined herein.

• • (5) Administrative review: Development within the areas required to have an OWTS system shall comply with the development standards listed below. Development proposals that meet these standards will be reviewed administratively by the zoning enforcement officer and/or his her designee after review with the town planner. The town may engage professional assistance to assist with the professional review of applications and advise with the applicant responsible for such cost. Applications failing to meet one or more of the development standards listed below shall require a special use permit per section 6.12.2.(5).

• • The administrative review shall apply the following criteria:

• a. The design of the OWTS and layout of the building site in general shall minimize or mitigate the potential for ground and surface water contamination to the greatest extent possible.

• b. The system, once in use, will not pose a threat to public health and safety or cause any degradation of ground or and surface water quality, including adverse effects due to cumulative impact.

• c. The foundation not including pilings/footings of a dwelling shall have a 12-inch separation between the bottom elevation of the structure and the seasonal high groundwater table. All foundation elements below the seasonal high-groundwater table shall be engineered to allow for free passage of water.

• d. All new OWTSs and OWTSs requiring major repair shall have been approved by RIDEM and provide for either denitrification or enhanced pathogen removal.

• e. If the setback does not meet the standard in Section 6.12.2(1), the applicant shall demonstrate that the OWTS and associated building have been sited as far as possible from the wetland edge.

• • (6) Special Use Permit Criteria. The Zoning Board of Review may grant a Special Use Permit for construction of an OWTS not less than 100’ from Freshwater Wetlands as defined in the Rules provided that the applicant submits a site plan meeting the requirements of Section 7(I) 6-6 demonstrating that the buffer provided is sufficient to substantially attenuate pollutants from the OWTS and associated land disturbance, and:

• 1. Advanced OWTS Treatment meeting the performance standards of section (7) and approved by RIDEM are used.

• 2. Will not degrade the quality of groundwater or any wetland or surface water body, either directly or indirectly, on site or off site; 3. Will result in the least site disturbance and removal of vegetation as possible, every attempt shall be made to site the wastewater treatment system and the associated dwelling as far as possible from the wetland edge;

• 4. Will not obstruct floodways or reduce the net capacity of the site to retain floodwaters;

• 5. Will not cause any sedimentation of wetlands, and will include all necessary erosion and sediment control measures; plans for erosion and sediment control and storm water management shall be completed which meets standard requirements for such plans and also includes:

• • a. The limits of disturbance during construction including areas to be cleared and/or graded, construction easements, temporary stockpiles and material/equipment storage areas, and protection of individual trees and groups of trees to avoid construction injury by fencing off trees at the drip line. In critical areas the limits of disturbance will be fenced off in the field.

• • b. A plan for re-vegetation, stamped by a landscape architect of wetland buffers, slopes and erodible areas.

• 6. Will not reduce the capacity of any wetland to absorb pollutants;

• 7. Will not degrade the recreational or educational value of any wetland or water body;

• 8. Will not reduce the capacity of any wetland to recharge groundwater; and

  9. The potential for wetland impact based on the type of development, soil type, potential for future disturbance of the buffer and size of the wooded swamp or pond to be buffered is determined to be minimal.

• • (7) Performance Standards: Applications for a Special Permit under provisions of this Section shall meet the following minimum performance standards:

• • A. Minimum Requirements for Advanced OWTS Treatment. All new, replacement and alterations for OWTS that do not meet the dimensional requirements set forth in Section 6-7 6.12.2. (1) and (2) above shall be approved by RIDEM and provide advanced treatment to achieve the following levels, as measured at the outlet of the treatment unit prior to discharge to a drain field, and to achieve the following performance based on siting.

• 1. System Type - Category 1 Alternative and innovative system as defined by RIDEM Use of a Category 1 Alternative and Innovative system shall be required in the watersheds of drinking water supplies, other phosphorus-sensitive surface waters, and areas where maximum pathogen and nutrient removal is required for either protection of surface or ground waters.

• 2. System Type - Category 2 Alternative and innovative system as defined by RIDEM Use of a Category 2 Alternative and innovative system may be permitted in watersheds of non-critical water resources.

• 3. Permitted OWTS Technologies. Installation of Advanced OWTS treatment technologies permitted shall be those technologies certified by RIDEM pursuant to their procedures and regulations. Innovative or alternative OWTS technologies shall have documented the ability to achieve the minimum treatment requirements set forth in this Ordinance.

• 4. Seasonal High Water Table Determinations. For the purpose of determining the seasonal high water table, detailed soil morphological data to a depth of four feet shall be prepared and submitted by a professional soil scientist recognized by the Soil Science Society, Southern New England Chapter, or ARCPAC certified, professional soil scientist or licensed Class IV Soil Evaluator.

• 5. Operation and Maintenance. All installations of Advanced OWTS Treatment technologies, or any other OWTS with mechanical components, shall include a continuous Operation and Maintenance (O & M) agreement with the property owner that shall be duly recorded in Land Evidence Records.

• • B. Minimum Requirements for Storm Water Management. 1) Total impervious cover shall be reduced to the maximum extent practicable using Low Impact Development (LID) methods as specified in the RI Storm water Design and Installation Standards Manual and supporting guidance documents (as amended), and shall not exceed the maximum allowed within a given district. Elevated structures with roofs allowing for groundwater infiltration that are less than 120 square feet in size are exempt when calculating this percentage. Impervious cover shall be calculated based on the area of the parcel suitable for development, excluding wetlands, hydric soils, high flood zone, and other lands identified as unsuitable for development. The use of permeable pavements is encouraged where the risk of groundwater contamination is low. 6-8 2) Storm water control measures shall be designed to ensure that no net increase between pre and post development site conditions in volume or rate of storm water runoff for a 25 year frequency rainfall occurs onto adjacent properties or roadways from the proposed individual residential lot.

• • C. Storm water Management Plan. A detailed storm water management plan shall be submitted to the Town that includes a drainage plan and drainage calculations prepared by a Rhode Island Registered Professional Engineer. Proposed grading shall maintain existing natural drainage patterns to the degree feasible. Use of small scale “low impact development” storm water controls designed to disperse, store, filter and infiltrate storm water runoff at points close to where runoff is generated, with minimal site alteration and filing shall be required.

• • D. Storm Water Controls and OWTS Location. Storm water runoff shall be diverted from any OWTS. Also, there shall be a minimum fifteen foot horizontal separation distance between any OWTS drain field and the edge of any storm water infiltration system, or as otherwise required by the RI Stormwater Design and Installation Standards Manual and supporting guidance documents as amended.

• • E. Required Information. A development plan shall be filed with the Building Official’s Office and the Planning Department to show the following information:

• 1. Property boundary lines with area and dimensions of property to be developed;

• 2. Vicinity plan showing adjacent or nearby properties, uses, OWTS, wells, wetlands, streams, or surface water reservoirs within a 500 foot radius;

• 3. Topographic map of property showing existing and proposed two foot contours;

• 4. Site specific soils map of property prepared by a professional soil scientist recognized by the Soil Science Society, Southern New England Chapter, or ARCPAC certified.

• 5. Storm water management plan;

• 6. Soil erosion and sediment control plan, and;

• 7. Wetlands delineation map as field verified by DEM for new OWTS construction or alteration.

• 8. A plan for re-vegetation of the buffer following constructing using native shrubs and trees for maximum water quality protection benefit and habitat value.

• 6.12.3. Structure and Impervious Surface setback. 6-9 (1) Except as provided in subsections (2)-(7) of this section, no part of a residential, commercial or industrial structure (including accessory structures such as garages or sheds) or impervious surface shall be located within 100 feet of Freshwater Wetlands as defined in the “The Rules” and in “Definitions”, Section 20 of this Zoning Ordinance. This section shall not be interpreted to require a 100-foot set back from a riverbank wetland or land within fifty feet 50’ of wetlands (perimeter wetlands) or area(s) subject to storm flowage as defined in the Freshwater Wetlands Act.

• • (2) Subsection (1) of this section shall not apply to the location of such a structure which received final approval from the Planning Board prior to the adoption of this section.

• • (3) Subsection (1) of this section shall not apply to: 1) areas where the wetland buffer area is already substantially developed and retains none of the natural features necessary to support native flora or fauna and where the volume of storm water runoff has been maintained at predevelopment levels, or restored to the extent possible.

• • (4) Subsection (1) of this section shall not apply to the location of elevated structures with roofs allowing for groundwater infiltration that are less than 120 square feet in size.

• • (5) Subsection (1) of this section shall not apply to the following accessory structures to existing households: Decks, porches, gazebos, patios, above-ground swimming pools, in-ground swimming pools, fences, signs, and permitted accessory residential and/or non-residential structures under two hundred (200) square feet

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6.12.4. Substandard Systems: Cesspools According to RIDEM’s OWTS Regulations, cesspools are not an approved method of sewage disposal and all existing cesspools are considered to be substandard. As such, all cesspools should be brought into conformance with current and local standard within 12 months after the sale or transfer of a property, or by January 1, 2020, whichever date comes first.

This subsection shall take effect as of (Jan. 1, 2014) unless: either a listing agreement contract with a licensed real estate broker shall have been signed by the owner(s) of the property and the broker prior to (June 1, 2013), in which case any buyer(s) of said property from that owner(s) while the listing agreement contract is in effect shall be exempt from this requirement; or a purchase and sales agreement for the property shall have been signed by the owner(s) of the property and the prospective buyer(s) prior to (June 1, 2013), in which case, the buyer(s) named in such purchase and sales agreement shall be exempt from this requirement.

• • 6.12.4.1. Hardship extension. Property owners of a Substandard system may qualify for a hardship extension of up to five years if the Substandard OWTS is not failed, and their household income is less than 80% of the appropriate household size area median income determined by federal Housing and Urban Development standards for the community in which the Substandard system is located. The Public Works Department shall develop an application for hardship extension.

• 6.12.5. Definitions. Wetland, freshwater are defined as in G.L. 1956, 2-1-20 as follows: Marshes; swamps; bogs; ponds; rivers; river and stream floodplains and banks; areas subject to flooding or storm flowage; emergent and sub emergent plant communities in any body of fresh water including rivers and streams and that area of land within 50 feet of the edge of any bog, marsh, swamp, or pond. Category 1 System: Advanced treatment units that are time dosed and have been classified by the RI Department of Environmental Management as meeting effluent standards less than or equal to 20 mg/l for both BOD5 and TSS; and FOG (fats, oil and grease) of less than or equal to 5 mg/l. Example Category 1 systems: textile filter, peat filter, recirculating sand filter, single pass sand filter, trickling filter). Category 2 Systems: Advanced treatment units that are not time dosed and have been classified by the RI Department of Environmental Management to at least meet effluent standards of 30 mg/l for both 6-11 BOD and TSS; and FOG (fats, oil and grease) of less than or equal to 5 mg/l. (Examples: FAST, 5 Singulair, Bioclere, RUCK) Major Repair (of an OWTS): Any work performed on an OWTS, excluding minor repairs, in order to repair or replace a failed system. Minor Repair (of an OWTS): Any work performed on an OWTS involving the repair, replacement or upgrade of the building sewer, septic tank or distribution box and/or the installation of inspection ports and/or effluent filters on septic tanks. Nitrogen Reducing System: An alternative system classified by the Rhode Island Department of Environmental Management as a nitrogen reducing system under RIDEM Innovative or Alternative ISDS Technologies List as amended and which achieves a minimum total nitrogen removal of fifty percent and a reduction to less than or equal to 19mg/l total nitrogen.