Plymouth reviews state-funded stormwater asset management study; $30,000 pilot identifies 12.5 miles of pipe and 1,700 structures

The Plymouth Select Board on a recent meeting heard a final presentation on a state-funded stormwater asset management pilot that inventoried roughly 12.5 miles of storm drainage pipe and about 1,700 drainage structures, and that included camera inspections of selected lines.

The study, funded with a $30,000 grant from the New Hampshire Department of Environmental Services (DES), produced an asset inventory and condition-assessment pilot and recommends creating a living, GIS-linked database the highway department can update as inspections and repairs occur. Justin, the consultant who presented the study, told the board that "your great staff went after and captured a $30,000 grant for this work." The consultant said the pilot used closed-circuit cameras in July and October to gather condition data and that the final report will be delivered to the town this week.

Why it matters: the asset-management approach is intended to reduce the cost of emergency repairs and to allow Plymouth to prioritize investments for repaving and utility work, officials said. The presentation outlined how an inventory plus routine inspections and a capital-improvement plan can stabilize long-term spending and position the town to compete for state funding.

Details from the presentation and discussion: - Inventory and condition work: The consultant said the town already has a partial inventory in GIS and an Excel-based database; the pilot refined mapping and recorded condition data from camera inspections. The consultant described the database as the backbone for the GIS mapping and said it was produced in nonproprietary formats so the town can continue updating it in-house. - Scale of assets: The consultant reported about 12.5 miles of storm drainage pipe and roughly 1,700 structures (manholes, catch basins, inlets/outlets) across town, concentrated in downtown/Main Street areas. - Pilot inspections: The team performed camera TV inspections and structure imaging during short field campaigns in July and October; the work identified sedimentation and sections needing cleaning or repair. - Integration with road work: The consultant emphasized matching utility work to paving schedules so new pavement is not followed quickly by utility digs, calling it a "whole utilities approach" that combines roads, stormwater, sewer and water planning. - Funding pathways: The consultant and Sarah Riddiard, sustainability engineer at NH DES, said the town is better positioned for Clean Water State Revolving Fund (SRF) principal-forgiveness and planning funds after completing the asset-management study. The consultant said DES planning grants can include principal forgiveness up to $100,000 for planning projects; Sarah Riddiard said ARP-funded grant money used for this project has run out, but that "there's principal forgiveness offered on loans, which effectively operates similarly in that the balance of the loan is forgiven at the end of the project." She added DES will offer webinars and that the SRF pre-application is expected to open the first week in April with a May pre-application deadline. - Next steps and timing: The consultant recommended continued mapping refinement, a condition-evaluation cycle (for example televising 10% of the system per year), prioritized capital-improvement planning and pursuing planning grants and SRF funding. The final report will be delivered to town staff this week, and DES staff said they will continue to provide technical support.

Related infrastructure update: staff also briefly reported that the Loon Lake Road culvert replacement was put to construction bid in February, with nine contractors bidding. Town staff said they obtained temporary easements to allow a full road closure during construction, which the presenter said would save approximately $40,000 and about three weeks of construction time compared with installing a temporary bridge and keeping the road open. The town engineer is reviewing bids and may return to the board with a recommendation at a future meeting.

The presentation included a reminder that ownership of assets varies — some pipes and culverts are town-owned, some are college-owned, and some are state-owned — and that clarifying ownership is part of the next steps for mapping and prioritization.

The board did not take a formal vote on the study at the meeting; presenters said the report will be issued to staff and DES and that the town can pursue funding options based on the completed work.

Ending: With the final report imminent, staff said the study should help the highway department better plan maintenance, prioritize capital dollars and position Plymouth for state funding when SRF pre-applications open in April.