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HomeMy WebLinkAboutNarrative 2.5.2026Project Narrative i Yarmouth Stormwater Retrofit Design and Implementation Project Grove Street Site (HIH-3), Yarmouth, MA Table of Contents SUMMARY ............................................................................................................ 1 1.0 INTRODUCTION ............................................................................................ 2 1.1 Background ................................................................................................................................ 2 1.2 Project Goals ............................................................................................................................. 2 2.0 GENERAL SITE DESCRIPTION .......................................................................... 3 2.1 FEMA Designation ..................................................................................................................... 3 2.2 State-listed Rare Species Habitat .............................................................................................. 3 2.3 Wetland Resource Areas ........................................................................................................... 4 2.4 Receiving Water and Watershed ............................................................................................... 5 2.5 Environmental Justice Communities ......................................................................................... 5 3.0 PROPOSED PROJECT ...................................................................................... 6 4.0 PROTECTION OF RESOURCE AREA INTERESTS .................................................. 7 4.1 Coastal Dune ............................................................................................................................. 8 4.2 Riverfront Area Redevelopment ............................................................................................... 8 4.3 Coastal Flood Zone (LSCSF)...................................................................................................... 10 4.4 Coastal Watershed .................................................................................................................. 13 4.5 Erosion and Sedimentation Control ........................................................................................ 14 5.0 REFERENCES ................................................................................................ 15 ATTACHMENTS Attachment A – Locus Maps Figure 1 – USGS Topographic Map Figure 2 – Aerial Photograph Figure 3 – FEMA Flood Zones & National Flood Insurance Program Figure 3A – FIRMette Map Figure 4 – Environmental Constraints Figure 5 – Soils Figure 6 – Environmental Justice Communities Figure 7 – Impaired Waters Attachment B – Wetlands Memorandum Attachment C – Project Plans Attachment D – Stormwater Report [electronic copy only] Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 1 of 15 Yarmouth Stormwater Retrofit Design and Implementation Project Grove Street , Yarmouth, MA February 2026 SUMMARY The Applicant (the Town of Yarmouth), in partnership with the Association to Preserve Cape Cod (APCC), is proposing a stormwater retrofit project at Grove Street in Yarmouth, MA. This initiative is part of a broader effort, the Yarmouth Stormwater Design and Implementation Project, aimed at enhancing water quality within the town. The project builds upon the comprehensive assessment and stormwater management plan funded by Massachusetts Office of Coastal Zone Management (CZM) in FY23. Its primary objectives are to advance the design, permitting, and installation of high-priority Stormwater Control Measures (SCMs). Specifically, the proposed retrofit involves the development of a new green stormwater infrastructure (GSI) system at the end of Grove Street to treat nearly the full 1 inch of runoff (93%) of the area draining to Hyannis Inner Harbor. Designed to enhance water quality and manage runoff from larger storms, the project aligns with the Massachusetts Stormwater Standards to the maximum extent practicable for this retrofit project. These efforts will significantly enhance water quality by maximizing stormwater pollutant removal (% bacteria, nitrogen, and phosphorus) and water quality volume treated. The entirety of the proposed project will occur in LSCSF, coastal dune and its 100-foot buffer zone, and within the 0-100-foot Riverfront Area, jurisdiction resources under the Massachusetts Wetlands Protection Act and/or the Town of Yarmouth Wetlands Protection Bylaw. Work within the coastal dune is limited to enhancement plantings with beachgrass and maintaining the existing low-impact access path to the beach. The proposed stormwater improvements at Grove Street are expected to significantly reduce on-going impacts to the surrounding resource areas. The net result of this project will be improved water quality, reduced runoff, improved infiltration, as well as improved wildlife habitat and coastal resiliency of the surrounding resource areas. Downgradient resource areas will be protected during and immediately following construction through implementation of an erosion and sedimentation control program. Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 2 of 15 1.0 INTRODUCTION Coastal embayments across Cape Cod are significantly degraded by nutrient and bacteria impairment. Land uses including stormwater runoff and fertilizer use contribute , on average, 20% of the controllable nitrogen load within our coastal watersheds (Cape Cod Commission 208 Plan, 2015) and bacterial contamination, including cyanobacteria, regularly causes closures of beaches. In the report by the Association to Preserve Cape Cod (APCC) (APCC’s 2022 State of the Waters), 90% of the coastal embayments and 39% of the freshwater ponds assessed received unacceptable water quality scores. These high nutrient loads are of concern for the environment, our coastal economy, and public health as they negatively impact habitat for fish and shellfish, and can result in unsafe conditions for swimming, fishing , and boating. 1.1 Background As part of a Coastal Zone Management (CZM) Coastal Habitat and Water Quality Grant, the Town of Yarmouth Department of Public Works (DPW), together with APCC, and Horsley Witten Group, Inc. (HW) conducted a comprehensive assessment and developed a town-wide stormwater management plan. This plan identified and prioritized stormwater retrofit sites along the south shore of Yarmouth. Concept designs were evaluated and ranked based on several criteria: potential pollutant removal (including load and drainage are a), the water quality status of the associated waterbody, construction cost and feasibility, and additional benefits such as restored shellfish and anadromous fish habitats, improved climate resilience, and opportunities for public education. With additional support from a second Coastal Habitat and Water Quality Grant, 25% designs were developed for five high-ranking priority sites, and two of those sites were chosen to advance through 100% design and construction, and a third site (this site) was advanced through 75% design. With additional funding from a recent third Coastal Habitat and Water Quality Grant, this site will be advanced through 100% design. 1.2 Project Goals The purpose of this project is to improve water quality in Hyannis Inner Harbor and Lewis Bay and to improve the Town Way to Water (in conjunction with the separate Yarmouth Ways to Water project) by reducing or eliminating pollutant loads from stormwater runoff at the end of Grove Street using green stormwater infrastructure (GSI) and stormwater control measures (SCMs). Specifically, the project aims to maximize pollutant removal (% bacteria, nitrogen and phosphorus) and water quality volume treated, while also improving public access. Over time, it is anticipated that SCMs will lead to a reduction in nutrient levels within downgradient waters and a reduction in the frequency and/or length of beach closures and shellfish bed closures related to bacteria contamination. As required for retrofit projects, the stormwater system for Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 3 of 15 the project has been designed to conform to the requirements of the Massachusetts Stormwater Standards (MASMS) to the maximum extent practicable. 2.0 GENERAL SITE DESCRIPTION The Grove Street site (HIH-3) is located at the southern end of Grove Street, on the northwest side of Lewis Bay, where there is public access to Grove Street Beach (Photo 1). The project is proposed within the Right-of- Way (ROW) on Grove Street at the beach access point (Attachment A, Figures 1 and 2). The site is bordered by residential properties to the east and west. Resource areas located at or adjacent to this site include Salt Marsh, Coastal Beach, Coastal Dune, Riverfront Area, and Land Subject to Coastal Storm Flowage (LSCSF). Stormwater infrastructure in this area is very limited, with no catch basins, manholes, or pipes present. The site contains an existing SCM – a clogged leaching basin. Grove Street stormwater runoff ultimately discharges into Hyannis Inner Harbor, which flows into Lewis Bay and then opens into Nantucket Sound. Hyannis Inner Harbor provides habitats for shellfish growing areas but is listed as impaired for total nitrogen and fecal coliform. 2.1 FEMA Designation The current FEMA Flood Insurance Rate Map (Community Panel No. 25001C0569J, effective July 16, 2014) indicates that the Grove Street site (HIH-3) is located within Special Flood Hazard Area Zone VE (1% annual chance of flooding, base flood elevation 13 feet) and Special Flood Hazard Area Zone AE (1% annual chance of flooding, base flood elevation 11 feet ) (Attachment A, Figures 3 and 3A). 2.2 State-listed Rare Species Habitat According to the most recent version of the Massachusetts Natural Heritage Atlas (15th Edition, August 1, 2021), the project site does not occur within areas of Estimated Habitat of Rare Photo 1. View of project site looking north from Grove Street Beach (November 2023). Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 4 of 15 Wildlife and/or Priority Habitat of Rare Species, as designated by the Massachusetts Natural Heritage and Endangered Species Program (NHESP) (Attachment A, Figure 4). 2.3 Wetland Resource Areas Resource areas located at or adjacent to the Grove Street site (HIH-3) site include Salt Marsh, Coastal Beach, Coastal Dune, Riverfront Area, and LSCSF, as defined under the Massachusetts Wetlands Protection Act (M.G.L. Ch. 131 § 40) and the Town of Yarmouth Wetlands Protection Bylaw (Chapter 143). HW wetland biologists identified and delineated these wetland resource areas (Photo 2) in November 2023. The HW Wetlands Report, which encompasses several sites, including the Grove Street site (HIH-3), is included as Attachment B. A brief description of the resource areas at this site is provided below. Salt Marsh is present to the south of the proposed project site, extending further east and northwest, following both sides of an unnamed perennial tidal stream that flows north to south into Lewis Bay through the 8 Grove Street and 2 Highland Street properties west of Grove Street. A small section of Coastal Beach is present just north of the Salt Marsh at the Grove Street site, where the salt marsh vegetation transitions to coarse, unconsolidated sand with some scattered pebbles and shells. A Coastal Dune is present between the proposed project site and the Coastal Beach area, where the slope rises 1-2 feet from the beach to meet the end of the Grove Street pavement. The dune extends to the west onto the 8 Grove Street property, where it is confined by Salt Marsh and a retaining wall located northwest on that property. The dune also extends further to the east onto the 9 Vernon Street property where it is confined by lawn and landscaped areas. Photo 2. Coastal Resource Areas at the Grove Street site, looking southwest from the end of Grove Street (November 2023). Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 5 of 15 Riverfront Area, associated with the unnamed, tidally influenced perennial stream that flows into Lewis Bay to the west of Grove Street encompasses the entire site, extending 200 feet landward from the Mean High Water Line (MAHW). LSCSF encompasses the entire site. The boundary of LSCSF coincides with the FEMA Floodzone AE (el. 11) and VE (el. 13) boundaries (Attachment A, Figures 3 and 3A depict the limits of these resource areas as identified by MassGIS). 2.4 Receiving Water and Watershed Grove Street runoff ultimately discharges into Hyannis Inner Harbor, which flows into Lewis Bay, a bay that opens into Nantucket Sound. Hyannis Inner Harbor provides habitat for shellfish growing areas. However, it is listed as impaired for total nitrogen and fecal coliform by the most recent Massachusetts DEP 303(d) – 2022 Integrated list of Waters. Hyannis Inner Harbor is located in the Lewis Bay Watershed, for which total maximum daily load documents (TMDLs) have been developed for nitrogen. Lewis Bay itself requires a TMDL, as it falls under Category 5. The full list of impairments for this portion of the watershed is listed below, and a map showing these resources is included in Attachment A, Figure 7: • Hyannis Inner Harbor (MA96-82) Yarmouth, Lewis Bay Watershed – Impaired for total nitrogen and fecal coliform; Category 4a (TMDL completed) of the 2022 Integrated List of Waters. • Lewis Bay (MA96-36) Yarmouth, Lewis Bay Watershed – Impaired for total nitrogen, estuarine bioassessments, fecal coliform, and nutrient/eutrophication biological indicators; Category 5 (TMDL required) of the 2022 Integrated List of Waters. Since the site discharges near a public beach, shellfish growing area, and within soils with a high infiltration rate, it is considered a critical area and subject to Massachusetts Stormwater Management Standards (MASMS) Standard 6. 2.5 Environmental Justice Communities The project site is located within one mile of several mapped Environmental Justice (EJ) communities (Attachment A, Figure 6). In Massachusetts, a neighborhood is defined as an EJ population if one or more of the following four criteria are true: the annual median household income is not more than 65 percent of the statewide annual median household income; minorities comprise 40 percent or more of the population; 25 percent or more of households lack English language proficiency, or minorities comprise 25 percent or more of the population and the annual median household income of the municipality in which the neighborhood is located does not exceed 150 percent of the statewide annual median household income. Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 6 of 15 The Commonwealth of Massachusetts states that EJ is based on the principle that all people have a right to be protected from environmental hazards and to live in and enjoy a clean and healthy environment. The principle of EJ is the equal protection and meaningful involvement of all people with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies and the equitable distribution of environmental benefits. The Town held a public meeting at the 25% design phase to engage with the community and obtain feedback on the proposed site elements and overall design. Overall, the proposed project is anticipated to benefit these communities as well as the greater Town population in Yarmouth, the adjacent municipality sharing common water resources along Hyannis Inner Harbor and Lewis Bay, and the visiting public by improving water quality within the watershed and the recreational amenities provided by these waters. 3.0 PROPOSED PROJECT The proposed stormwater management includes a GSI approach to capture, detain, treat, and infiltrate runoff. The stormwater management system was designed to meet MASMS Standard 1, so that no new untreated stormwater runoff will be directed to any off -site areas or resource areas. The GSI practice proposed at this site is a bioretention area. Pretreatment will be provided with a sediment forebay. Flow from large storm events will flow through the bioretention system and discharge towards the beach, as it does in existing conditions. As sea levels and groundwater levels rise over the next 50 years, this resilient GSI practice will be able to adapt to the wetter conditions; it is anticipated that the bioretention area will start to transition to more of a stormwater wetland as groundwater rises. The design incorporates management of invasive species and revegetation with native plantings within the bioretention area. The plantings proposed within the bioretention area consist of a mix of wetland and facultative plants, and it is anticipated that the plant community will naturally adapt as conditions change. The non-structural SCMs proposed at the site include pavement reduction, formalizing a public path, and public education. Pulling the road back away from the resources reduces total volume of stormwater from the site. Formalizing the public access to the water will reduce foot traffic impacts in this sensitive area. The proposed signage at the site will help educate the public on watershed issues, green stormwater infrastructure, and what they can do at their own homes to reduce stormwater pollutants from their lawns and driveways. Details of the proposed project are provided on the attached project plans, entitled “Site HIH-3: Grove Street Stormwater Retrofit Design and Implementation Project – 75% Design Yarmouth, Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 7 of 15 Massachusetts,” dated February 2026 and prepared by HW (Attachment C), and within the Stormwater Management Report, dated February 2026, provided in Attachment D. The project limit of work encompasses 1,916 SF, and will redevelop the lower portion of Grove Street, resulting in the removal of approximately 786 SF of impervious surface (bituminous concrete), and management of approximately 600 SF of invasive plants. Portions of the project will occur within overlapping jurisdictional areas, including the locally regulated resource areas and buffer zones as summarized in Table 1. Table 1. Summary of Resource Area Impacts Jurisdictional Area Impact (SF) Nature of Impact Coastal Dune 216 Invasive species removal, small portion of the relocated low-impact access path, and dune plantings 0-100-foot Riverfront Area 1,916 Redevelopment (bioretention area, access pathway, revegetation) Coastal Flood Zone (LSCSF) 1,916 Bituminous pavement replaced by bioretention area and access pathway; invasives management and revegetation 0-35 foot Buffer Zone to Coastal Dune 1,325 35-50-foot Buffer Zone to Coastal Dune 376 Coastal Watershed 1,916 4.0 PROTECTION OF RESOURCE AREA INTERESTS This proposed stormwater retrofit project aims to enhance water quality in Hyannis Inner Harbor and Lewis Bay and improve the Town Way to Water by reducing or eliminating pollutant loads from stormwater runoff at the end of Grove Street using GSI SCMs. Specifically, the project aims to maximize pollutant removal (% bacteria, nitrogen and phosphorus) and water quality volume treated, benefiting the overall health of the downgradient wetlands and within the watershed. Affected jurisdictional areas located at or adjacent to the Grove Street (HIH-3) site include Riverfront Area, Coastal Dune, LSCSF, and Coastal Watershed. A discussion on how the proposed project is designed to meet the performance standards is provided below. Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 8 of 15 4.1 Coastal Dune Under the regulations at 310 CMR 10.28(3): Any alteration of, or structure on, a coastal dune or within 100 feet of a coastal dune shall not have an adverse effect on the coastal dune by: (a) affecting the ability of waves to remove sand from the dune; (b) disturbing the vegetative cover so as to destabilize the dune; (c) causing any modification of the dune form that would increase the potential for storm or flood damage; (d) interfering with the landward or lateral movement of the dune; (e) causing removal of sand from the dune artificially; or (f) interfering with mapped or otherwise identified bird nesting habitat. While the majority of the proposed project occurs within the 100-foot buffer zone of a coastal dune, a small portion of the proposed project will occur within coastal dune through the supplemental planting of American beachgrass (Ammophila breviligulata). Overall, the project is designed to enhance the quality of the dune and prevent disruption of the dune’s functionality, vegetation, and stability, and will continue to allow for the natural shifting of the dune. Further, the proposed project will not in terfere with bird nesting habitat. Additionally, the project includes reducing paved areas adjacent to the coastal dune to allow natural landward migration of the dune, increasing flood protection benefits. Section 4.03(3) of the Yarmouth Wetland Protection Regulations applies the same Performance Standards for coastal dunes as the Massachusetts Wetlands Protection Act. 4.2 Riverfront Area Redevelopment According to 310 CMR 10.58(5): (a) At a minimum, proposed work shall result in an improvement over existing conditions of the capacity of the riverfront area to protect the interests identified in M.G.L. c. 131 § 40. As noted, the proposed project aims to restore the existing degraded Riverfront Area by implementing green stormwater infrastructure (GSI) and reducing paved areas. These efforts are expected to improve the condition of the Riverfront Area, enhance water quality within the Riverfront Area and the downgradient resources, and potentially provide improved shellfish habitat value. This would further protect the interests under the Massachusetts Wetlands Protection Act. Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 9 of 15 (b) Stormwater management is provided according to standards established by the Department. The proposed stormwater BMPs are designed to meet the Massachusetts Stormwater Management Standards to the maximum extent practicable for a redevelopment project (see Attachment D – Stormwater Management Report). (c) Within 200 foot riverfront areas, proposed work shall not be located closer to the river than existing conditions or 100 feet, whichever is less, or not closer than existing conditions within 25 foot riverfront areas, except in accordance with 310 CMR 10.58(5)(f) or (g). The proposed project will occur no closer to the river than under existing conditions , and the project will result in the removal of pavement closer to the river. (d) Proposed work, including expansion of existing structures, shall be located outside the riverfront area or toward the riverfront area boundary and away from the river, except in accordance with 310 CMR 10.58(5)(f) or (g). Due to the nature of the project and its intended purpose, t he entire limit of work will occur within the inner 0-100 foot Riverfront Area, where portions of the existing pavement at the end of Grove Street will be replaced with a bioretention area. Additional proposed mitigation measures, including management of invasive species and revegetation with native plantings within the Riverfront Area are in keeping with 310 CMR 10.58(5)(f). (e) The area of proposed work shall not exceed the amount of degraded area, provided that the proposed work may alter up to 10% if the degraded area is less than 10% of the riverfront area, except in accordance with 310 CMR 10.58(5)(f) or (g). Approximately 41 % of the Riverfront Area is considered degraded (impervious surface). The proposed project will not exceed the amount of degraded area and will result in a slight reduction of impervious surface within the resource area. (f) When an applicant proposes restoration on-site of degraded riverfront area, alteration may be allowed notwithstanding the criteria of 310 CMR 10.58(5)(c), (d), and (e) at a ratio in square feet of at least 1:1 of restored area to area of alteration not conforming to the criteria. Areas immediately along the river shall be selected for restoration. (…) Not applicable. The proposed project is designed to meet the redevelopment standards for work within Riverfront Area. (g) When an applicant proposes mitigation either on-site or in the riverfront area within the same general area of the river basin, alteration may be allowed notwithstanding the criteria of 310 CMR 10.58(5)(c), (d), or (e) at a ratio in square feet of at least 2:1 of mitigation area Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 10 of 15 to area of alteration not conforming to the criteria or an equivalent level of environmental protection where square footage is not a relevant measure. (…) Not applicable. The proposed project is designed to meet the redevelopment standards for work within Riverfront Area. 4.3 Coastal Flood Zone (LSCSF) While there are currently no performance standards for work within LSCSF under the Massachusetts Wetlands Protection Act, the Yarmouth Wetland By-Law and associated Wetland Protection Regulations carry performance standards for this resource area. According to Section 4.10(3)(a) of the Yarmouth Wetland Protection Regulations: Any activity within land subject to coastal storm flowage which will result in the building upon, removing, filling or altering of land shall not have an adverse effect on the interests protected by the bylaw by: i. reducing the ability of the land to absorb and contain flood waters; The proposed bioretention area is expected to improve flood control measures by slightly reducing the amount of impervious surface, lending to greater resilience of the surrounding resource areas. i. reducing the ability of the land to buffer more inland areas from flooding and wave damage; The proposed project is not expected to have an adverse impact on flooding and/or wave damage to inland areas. The proposed bioretention area is designed to also allow for future flooding and accommodate future sea level rise at this location. ii. increasing the elevation or velocity of flood waters, or by redirecting or increasing flows or causing channelization, in each case at the project site, adjacent or nearby properties, or any public or private way. The proposed project is not a structure and is not expected to increase velocity or flow of flood water, nor cause channelization but instead further the resiliency of the resource areas by removing impervious area and providing for greater absorption of flood waters . iii. displacing or diverting flood waters to other properties or resource areas. Fences and privacy walls, including walls separating one property from another, may obstruct or divert flood flow and waves toward buildings and protected areas. Solid fences (stockade and similar) must be constructed with 6 inches of clearance below to allow the passage of floodwaters and wildlife; Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 11 of 15 This project is not a structure and therefore would not displace or divert flood waters to other properties or resource areas. iv. causing, or creating the likelihood of, damage to other structures on land within the flood plain as debris (collateral damage); Not applicable as the proposed project includes a bioretention area that is not expected to produce debris. The small amount of fencing used to maintain the existing access to the beach from Grove Street is in keeping with existing conditions, where the existing wooden guardrail will be removed and a small length of sand fencing will be installed to protect the coastal dune and maintain the existing access. The area will be further reinforced with beachgrass plantings. Photo 3. View of existing fencing and guardrail at the end of Grove Street, view facing south toward Lewis Bay. v. causing ground, surface or saltate pollution triggered by coastal storm flowage; The proposed project is designed to reduce pollution and improve water quality. vi. reducing the ability of the resource to serve as a wildlife habitat and migration corridor through activities such as, but not limited to the removal of substantial vegetative cover and/or installation of fencing and other structures which prevent wildlife migration across property. Wildlife habitats and migration will not be affected by the proposed work. In fact, the proposed project will result in improved habitat by removing impervious surface and replacing it with a vegetated stormwater practice. Additionally, the proposed beachgrass plantings within the Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 12 of 15 coastal dune will enhance the stability of the coastal dune and further the ability of these resource areas to provide habitat for local wildlife. vii. prevention of the migration of resource areas such as salt marshes due to sea level rise. The proposed project includes pavement reduction to pull the end of Grove Street back from resource areas, which will allow natural migration of resources. Further, the design of the bioretention area will allow this stormwater practice to adapt to future sea level rise (see Attachment D). viii. If flood control and storm damage protection functions have already been impaired, redevelopment must improve existing conditions by reducing impervious surfaces, restoring flood control and storm damage protection functions, installing native plantings, or by restoring or creating other wetland resource areas. Where a previously developed coastal Resource Area has not been regulated under the applicable performance standards to protect the interests of flood control and storm damage prevention, the proposed work shall restore those interests. The proposed project is a redevelopment project that will reduce impervious surface cover and improve flood and stormwater control through the implementation of a bioretention area. And shall meet the following requirements; ix. Existing septic system and cesspool repairs will be allowed provided they meet all Title 5 and local Board of Health thresholds. x. All groundwater elevations shall incorporate seasonable adjustments if test holes and or leaching components are 100 feet or closer from major estuaries. xi. Any proposed deck, shed, or other similar structure must be securely anchored to a footing or foundation. xii. Any activity shall preserve existing soils, vegetation, and other natural conditions that serve as buffers to coastal flooding and storm surges. Items ix through xi are not applicable to the proposed project. Requirement xii will be met through the implementation of GSI (i.e., the bioretention area), which is designed to enhance natural conditions at the project site. According to Section 4.10(3)(b) of the Yarmouth Wetland Protection Regulations: Within the V Zone, in addition to the general performance standards set forth in Section 4.10, (3)(a), the following additional performance standards shall apply: Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 13 of 15 i. No new construction or footprint expansion of any building or other structure, road, impervious surface, or septic system shall be permitted. ii. No new construction or expansion of any structure that redirects or channelizes floods including retaining walls, fences, and sea walls shall be permitted. iii. With respect to any building or other structure, in the event of any substantial repair of the foundation, any substantial improvement (as defined in the state building code), the entire building or structure shall be elevated at least two (2) feet above t he BFE iv. The use of fill is prohibited except for bank, dune, or beach nourishment/restoration Items i through iv are not applicable to the proposed project. Under existing conditions, there is a wooden guardrail (supporting signage to be repurposed for the project (see Photo 3)) as well as more recently installed split rail fencing. The project will remove the guardrail and install a small amount of sand fencing to maintain existing access to the public beach. The pathway will occur partially within areas that are currently paved, and will be established as a sand path. The areas surrounding the path and sand fencing will be planted with beachgrass to further stabilize the existing coastal dune. Further, the proposed bioretention area will replace a portion of the existing paved roadway which will reduce impervious cover and allow the resource areas to be more resilient to coastal flooding. The stormwater control measure has been designed to incorporate a stable and “softer” stone feature overflow to avoid the installation of “structures” such as a granite level spreader, within the velocity zone. 4.4 Coastal Watershed As defined in Section 4.11(2) of the Yarmouth Wetland Protection Regulations: “Coastal Watershed Areas” are those areas mapped and delineated specifically within the “Water Resources Protection Study” prepared for the Town of Yarmouth by I.E.P. Inc. and Wright Pierce, dated August, 1988. For the purposes of this section 4.11, (2), Conservation Commission jurisdiction will be restricted to within 300 feet from a major estuary defined in section 1.06, and such jurisdiction must occur within the mapped area referenced above. The Lewis Bay Watershed is a receiving watershed for the Grove Street (HIH-3) site, which is listed under the “Water Resources Protection Study” (1988) as a Coastal Watershed. Section 4.11(3) of the Yarmouth Wetland Protection Regulations states: In order to properly protect our Coastal Watershed Areas, no project will be allowed that incorporates any of the practices referenced in section 4.11(1)(b) i through vi. Therefore, the Grove Street project is subject to the following Performance Standards, as covered under Section 4.11(1)(b) of the Yarmouth Wetland Protection Regulations: Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 14 of 15 There are presently several land use practices that present serious threats to the quality of our Coastal Watershed Areas. These include but are not limited to the following: i. Outdated underground storage tanks ii. Landfills iii. Stump dumps iv. Road salt storage v. Septic package treatment plants vi. Automotive and construction equipment repairs. Considering the proposed project does not incorporate any of the above land use practices, Section 4.11 of the Yarmouth Wetland Protection Regulations is not applicable to the Grove Street project. 4.5 Erosion and Sedimentation Control Controlling erosion and sedimentation from the construction site is necessary to meet the overall water quality goals of this retrofit project, and to meet MASMS Standard 8. Given the size of the site (less than one acre of disturbance), an NPDES Construction General Permit Stormwater Pollution Plan (SWPPP) is not required. However, planning for effective erosion and sediment controls (ESCs) was important to this project’s design . Therefore, an ESC Plan is included in the design plans (Attachment C), along with a detailed sequence of construction activities and ESC notes. To manage sedimentation, silt socks are proposed along the downgradient edges of the area of disturbance. Regular street sweeping is to be provided along Grove Street to minimize tracking of sediment. Since there is no construction entrance/exit proposed at this site, extra care should be taken in monitoring sediment tracking and sweeping the road. Areas for other sediment traps/basins should be provided on an as-needed basis. Disturbed areas will be stabilized as soon as possible to minimize erosion and sedimentation with pavement, seeding and/or erosion control blankets, if necessary. Notice of Intent Horsley Witten Group, Inc. Grove Street Stormwater Retrofit Project, Yarmouth, MA February 2026 Page 15 of 15 5.0 REFERENCES Association to Preserve Cape Cod. 2022. State of the Waters: Cape Cod Report. Cape Cod Commission. 2015. 208 Plan – Cape Cod’s Area Wide Water Quality Management Plan Updated. I.E.P. Inc. & Wright-Pierce. 1988. Water Resources Protection Study. Prepared for the Town of Yarmouth. MassDEP. 2023. Final Massachusetts Integrated List of Waters for the Clean Water Act 2022 Reporting Cycle. CN 568.1, Massachusetts Department of Environmental Protection, Bureau of Water Resources, Division of Watershed Management, Watershed Planning Progr am. Worcester, MA (Available at https://www.mass.gov/lists/integrated-lists-of-waters-related- reports ). MassGIS (Massachusetts Office of Geographic and Environmental Information). 2025. See their homepage at: http://www.mass.gov/mgis/.