3 Old Merrill St - Notice of Intent

What is proposed

Construction of a detached Accessory Dwelling Unit (ADU) with a 750 sq ft footprint adjacent to the existing single‑family house at 3 Old Merrill Street. The proposal includes connections to municipal water and sewer, a permeable two‑car pea‑stone parking area, and a subsurface StormTech SC‑310 chamber infiltration system to manage roof runoff.

Where and how big

The property is a 0.40‑acre (19,722 sq ft) lot on the Merrimack River (Assessor Map 101, Lot 11). The entire lot lies within Riverfront Area; the submission reports 1,200 sq ft of permanent alteration of Riverfront Area (160 sq ft inside the 100‑ft zone and 1,040 sq ft between 100–200 ft). No native woody or herbaceous vegetation removal is proposed. As mitigation, the applicant proposes to renaturalize 2,500 sq ft of existing lawn nearer the river (a 2:1 restoration to alteration ratio).

Stormwater, soils and resource protections

Soils are mapped as Charlton‑Hollis loamy sand (Hydrologic Soil Group A); test pits reported groundwater about 5–7 feet below grade. The roof of the ADU will discharge to gutters and HDPE roof drains that lead to the SC‑310 chamber system. The stormwater report calculates a required recharge volume of 62.5 cubic feet for the proposed impervious area and shows 136 cubic feet of provided storage; HydroCAD modeling and a drainage checklist are included. Construction best management practices, an erosion‑control plan, and an operations and maintenance plan (inspection schedules, cleaning of the overflow grate, and vegetation maintenance) are included in the submission.

Resource area and regulatory notes

Mean Annual High Water (MAHW) along the Merrimack River was field‑delineated and is shown on the plans; no work is proposed at or below the mapped 100‑year flood elevation and no Bordering Vegetated Wetland was observed on the lot. Portions of the property are within mapped NHESP priority habitat; the applicant states the project is exempt from separate Massachusetts Endangered Species Act (MESA) review under 321 CMR 10.14(5) because the ADU is secondary to the primary residence and located on existing maintained lawn without expansion. The filing to the Conservation Commission includes a Notice of Intent (WPA Form 3), permit site plans, a stormwater report, and abutter notification materials.

Status

The Notice of Intent package was submitted to the Amesbury Conservation Commission on May 11, 2026, requesting an Order of Conditions to permit the described work. The WPA Form 3, stormwater report, site plans, and fee payment ($165) are part of the record.