Commission recommends low‑phosphate, straw erosion control for 3‑unit plan at 44 Daniel Webster Highway

MERRIMACK, N.H. — The Merrimack Conservation Commission reviewed plans to raise an existing single‑family house and construct a three‑unit building at 44 Daniel Webster Highway and asked the applicant to revise landscape and erosion‑control notes before the planning board review.

Jim Donison, the civil engineer representing the applicant, described a 13,000‑square‑foot parcel where the proposed three‑unit building will have six parking spaces, water and sewer service, and a leachfield system to intercept and treat drainage before it reaches the road. The applicant told the commission all on‑site drainage will be directed to leaching chambers.

Why it matters: the parcel sits in an Aquifer Conservation District and planned residential overlay, so the commission recommended conservative landscaping and fertilizer practices to protect groundwater.

Conservation concerns and recommendations: commissioners asked that the project remove references that allow hay mulch and instead require straw or other acceptable erosion control; they also requested a revision to clarify that only slow‑release, low‑phosphate (or no‑phosphate where appropriate) fertilizers be used and that soil tests be performed before applying any fertilizer. “We prefer to have the slow‑release phosphorus… the middle number just needs to be as low as possible and slow release,” the commission advised; later the commission asked to change the note to “no phosphate, slow‑release nitrogen” for parcels close to wetlands.

Other design points discussed included the proposed building footprint, retaining wall details (the proposed retaining wall is expected to be about two feet high), and confirmation that most of the site’s remaining area is currently permeable (grass/trees) aside from the driveway. The applicant confirmed he would present the revised notes and plans to the planning board next week.

Next steps: The commission chair said staff will email the planning board with the commission’s requested edits and otherwise had no outstanding concerns, allowing the applicant to proceed to the next stage of review after the notes are updated.

Speakers: [{"name":"Jim Donison","role_title":"Civil engineer representing applicant","affiliation_type":"business","affiliation_name":"Northeast Engineering"},{"name":"Commissioner","role_title":"Commissioner","affiliation_type":"government","affiliation_name":"Merrimack Conservation Commission"}],

authorities:[{"type":"policy","name":"Aquifer Conservation District (local overlay)","referenced_by":["fertilizer/landscaping recommendations"]}],

actions:[{"kind":"referral","motion":"Commission will email the planning board recommending edits to erosion control and fertilizer notes (straw not hay; soil testing prior to fertilizing; low/no‑phosphate slow‑release nitrogen) and otherwise has no objections","mover":"Commissioner","second":"unspecified","tally":{"yes":0,"no":0,"abstain":0},"outcome":"approved","notes":"Advisory comments to Planning Board"}],

discussion_decision:{"discussion_points":["Proposed conversion of single‑family to three units with leaching chambers for drainage","Erosion control should use straw rather than hay mulch; test soils before fertilizer","Prefer low‑phosphate or no‑phosphate slow‑release nitrogen in aquifer/wetland adjacency"],"directions":["Applicant to change notes: no hay; use straw; soil testing; low/no‑phosphate slow‑release nitrogen"],"decisions":["Commission will forward these comments to the planning board and had no other outstanding concerns."]},

proper_names:[{"name":"44 Daniel Webster Highway","type":"location"},{"name":"Northeast Engineering","type":"business"}],

clarifying_details:[{"category":"drainage","detail":"All on‑site drainage directed to leaching chambers before discharging","value":true,"units":"boolean","approximate":false,"source_speaker":"Jim Donison"},{"category":"erosion control","detail":"Replace 'hay mulch' note with 'straw; no hay' for on‑site erosion control","value":true,"units":"boolean","approximate":false,"source_speaker":"Commissioner"},{"category":"fertilizer","detail":"Change note to specify 'no phosphate, slow‑release nitrogen' where near wetlands/aquifer","value":true,"units":"boolean","approximate":false,"source_speaker":"Commissioner"}],

community_relevance:{"geographies":["Daniel Webster Highway corridor"],"funding_sources":[],"impact_groups":["nearby residents","groundwater users"]},

meeting_context:{"engagement_level":{"speakers_count":2,"duration_minutes":30,"items_count":1},"implementation_risk":"low","history":[{"date":"2025-04-28","note":"Applicant scheduled to appear before Planning Board next week; commission to email edits."}]},

searchable_tags:["fertilizer","straw mulch","leaching chambers","aquifer"],

provenance:{"transcript_segments":[{"block_id":"transcript_block_677.24","local_start":0,"local_end":511,"evidence_excerpt":"Jim Donison, Northeast Engineering representing the applicant... convert tax map 2 e lot 1... drainage will be directed to leaching chambers...","tc_start":"00:677.24","tc_end":"00:727.535","text_sha256":""},{"block_id":"transcript_block_900.31","local_start":0,"local_end":260,"evidence_excerpt":"Use of slow release, low phosphate shall be used... We'll change note b to that...","tc_start":"00:900.31","tc_end":"00:968.925","text_sha256":""}]}