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HomeMy WebLinkAboutNarrative 1.22.2026 1 PROJECT NARRATIVE 56 Pleasant Street, South Yarmouth Marine Bulkhead Replacement The area subject to this Notice of Intent is land on the immediate west shore of Bass River, several hundred feet north of North Cove Landing. Please see the locus maps for the exact location. The land is a residential yard area consisting of a single-family dwelling, semi formal landscape with open grassed and more natural marsh areas leading down a gentle slope to Bass River, a tidal water body. The land area pertaining to this application is a complex of coastal resource areas including Coastal Beach, Salt Marsh, and Land Subject to Coastal Storm Flow as mapped by the 2014 FEMA flood maps. The land slope is gentle and no significant Coastal Bank exists. Land slope falls below 10 % at approx. elev. = 8 with the flood zone inland of that to el. = 12. Further inland a C. Bank may exist based on flood elevation and land slope but this project is along the immediate waterfront. The waterway bank is armored for a portion of the length by an existing marine bulkhead. The wall is licensed under Chapt. 91 License No. 1661. Only access activity will affect the upland which is a lawn area.. The waterway bank along the water frontage is stabilized by a low cap elevation marine bulkhead. A small wood framed stair provides seasonal access to the near-shore area to the north where an informal stone rip rap adequately stabilizes a segment that shore. The proposal is to replace the existing bulkhead in the existing location maintaining the existing elevation. The old wall shall be removed entirely with the debris controlled and laded off site to a suitable disposal site. Available records indicate the possible presence of fill in this area of the Bass River shoreline. The proposed helical anchors shall be monitored for tortional values as per the design specification. Should there be soil weakness encountered due to unconsolidated fill material for any respective anchor an alternate anchor commonly called “ dead men anchor”, which is a stout piling segment installed at the specified anchor length, may be substituted. The work activity to remove, hoist out the old wall remnants and to deliver and install the new wall components shall be by commonly implemented methods utilizing hand work and small machinery with no in- water work activity with exception of the need for work persons to hand- tighten bolts by wading along the wall face. Once the wall is in place and anchored a planting effort will be done to provide further stabilizing of the narrow backfill area. A 5 ft. plant strip is typically required by the Yarmouth Conservation review process and the wall currently has an approx. 5 to 7 ft. width buffer strip. Performance Standards - The project can be found to meet the performance standards for the resource areas potentially affected as outlined below. (Note: There are no DEP performance standards for Land Subject to Coastal Storm Flow). Although a marine wall CES exists and is appropriately permitted the following summary is for the record. The tide range and current characteristics in The Bass River is occasionally affected by dredging activity. Boat traffic wakes and wind effects during times of highest tides and the long-term human activity along the shore have logically led to the erosion of the waterway bank. This erosion became the initial basis for construction of the existing seawall. The performance standards are discussed in the context that the shore of the river is not a natural unperturbed shoreline. For example, erosion of a Coastal Bank might not be a natural process in the absence of other factors such as tide range fluctuation, loss of bordering salt marshes and other man – caused effects that have affected the conditions at locus. 2 Coastal Banks -Sediment Source Banks (310 CMR 10.30) “WHEN A COASTAL BANK IS DETERMINED TO BE SIGNIFICANT TO STORM DAMAGE PREVENTION AND FLOOD CONTROL BECAUSE IT SUPPLIES SEDIMENT TO COASTAL BEACHES, COASTAL DUNES OR BARRIER BEACHES…..” “No new bulkhead, revetment, seawall, groin or other coastal engineering structure shall be permitted on such a coastal bank except that such a coastal engineering structure shall be permitted when required to prevent storm damage to buildings constructed prior to the effective date…” • A low crested marine bulkhead exists. The long – term existing bulkhead affects the significance of the bank as a sediment source. In common practice with an existing bulkhead and a proposed replacement maintaining the approximate existing cap elevation, the value of the Coastal Bank landform typically becomes predominant as a vertical storm buffer. The vertical storm buffer relationship to storm damage prevention and flood control has value and significance for related standards for the interests of storm damage prevention and flood control. • Building use predates August 1, 1978 as evidenced by available information, deeds, aerial photography, etc. Best Available Measures (310 CMR 10.27 & 10.30) Continuing with the low-crested marine bulkhead by replacing it “in-kind’ has the least impact, occupies the least ground projection allowing for the maximum natural ground cover on the landward and seaward sides. Vertical Storm Buffer (10.30) - The bank is functioning as a vertical storm buffer and not at all as a sediment source because of the bank character and presence of the existing bulkhead. “WHEN A COASTAL BANK IS DETERMINED TO BE SIGNIFICANT TO STORM DAMAGE PREVENTION OR FLOOD CONTROL BECAUSE IT IS A VERTICAL STORM BUFFER TO STORM WATERS…..” With respect to the vertical storm-buffer significance of this bank, the proposed project meets the performance standard because it improves bank stability as a storm buffer. “Bulkheads, revetments seawalls, groins or other coastal engineering structures may be permitted on such a coastal bank except when such bank is significant to storm damage prevention and flood control because it supplies sediment to coastal beaches, coastal dunes and barrier beaches…”. The determination can be made that replacing the wall to be similar in location and height as the existing wall furthers the vertical storm buffer bank function. Coastal Beaches- 310 CMR 10.27 – The predominant resource fronting the proposed bulkhead is Land Under the Ocean; with intertidal Coastal Beach for the remainder, primarily the south end. Regulations contained in 310 CMR 10.27 provide an exception relating to 310 CMR 10.30(3)(a) for erosion-management applications that use best available measures to minimize adverse impacts to coastal beaches. The regulations recognize the fact that erosion measures are at times necessary and should have effects to the beach minimized but cannot be 3 avoided completely. The work area shall be limited and the adjacent ground temporarily affected with anticipated recovery over several tide cycles following completion. Salt marsh - Salt Marsh exists at the north end extending to the north away from the project area. Salt marsh is unaffected by the work. Yarmouth Regulations - 4.10 Land Subject to Coastal Storm Flow 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 project maintains the status quo re: the ability of the land to absorb and contain flood waters with less preferential scour. ii. reducing the ability of the land to buffer more inland areas from flooding and wave damage The project enhances this ability as stated because it contributes to bank stability. 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; The existing feature has existed for many decades. The features have been responding to the flood forces delivered to the area for half a century. The repairs will not cause for a significant change to the localized storm action behavior. iv. causing, or creating the likelihood of, damage to other structures on land within the flood plain as debris (collateral damage); Hydraulic relationship to the surroundings is maintained v. causing ground, surface or saltate pollution triggered by coastal storm flowage; No pollution or hazardous source exists vi. causing, or creating the likelihood of, damage to other structures on land within the flood plain as debris (collateral damage); No portion of the existing terrain can become waterborne. The deck and the dock are common waterfront structures and will be properly secured by bolted connections vii. 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. No significant change is being proposed to the land or the marine wall location or elevation viii. prevention of the migration of resource areas such as salt marshes due to sea level rise. • Salt marsh is not applicable. ix. 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 efficacy of the features slated for repair need expected replacement / maintenance and are not impaired to the extent this applies. The project is not intended to return the bank and beach area to a pre-history condition. The project endeavors to restore the listed storm damage and flood 4 control functions of the existing wall. The concept of “substantial improvement” of the wall system is a topic addressed by Yarmouth Wetland Regulations with reference to the Mass Building Code. The replacement of the marine wall is a substantial improvement but triggers no code upgrades. A brief review of alternatives appears below. In practice, unless a CES type demonstrated adverse impacts and there were no overriding reasons, there would be no practical basis to seek alternatives to the existing CES type. • Replacement with vertical wall (bulkhead), whether made of timber, steel or vinyl, is a viable option and it is the selected option. A bulkhead exists on locus. Except for the decayed condition of the existing wall, there are no obvious adverse impacts. The projection of the bulkhead will occupy approx. 1 ft. wide strip of land for the wall length in the same location as existing. The replacement is of a similar height. It is the selected option. • Replace with gabions – Gabions are useful in areas lacking other forms of materials. Gabions place wire fence into the environment with inherent risk of sharp steel edges, wires, corrosion of the baskets, loss of the interior chips. Appearance detriment is also a consideration. • Coir Products -Other alternates methods such as fiber rolls, coir / sand lifts will occupy greater land area and require re-working at far greater frequency. • Stone revetment with cap elevation below the flood elevation. The given flood level is 12. The land elevation at the shore location is approx. elev. = 5 and any CES could be no higher. A stone array can be made of completely native, durable stone material. The resulting stone array would be angled back to absorb wave run-up. These facts and other attributes lend themselves to a more favorable acceptable outcome. However, the location and presence of marsh deposits in combination with the land area requirement for an angled stone revetment moves this alternate further from practical consideration. An 8 ft. total height revetment at a max face angle of 34 degrees ( 1.5 H to 1 V) from horizontal occupies a minimum of an 12 ft. wide strip of land for the length of the feature. Significant excavation accompanies the toe stone installation effort.