Consultants outline Pickpocket Dam removal design, archaeology findings and schedule

Consultants and town engineers updated the Exeter River Advisory Committee on July 13 about the Pickpocket (Pickpocket Falls) Dam removal project, saying they have reached roughly 60% design and are preparing permitting and a wetlands impacts plan.

Paul Velosicich, the town engineer, said the project is funded under a Great Bay 2030 grant of $300,000 and that about 80% of that budget has been spent getting the design to its current phase. "We're close to the 60% design plans now," he said, and staff aim to complete 60% plans and a wetlands impacts plan this August.

Consultant Stephanie Hudock described field work that shaped the design. "We completed our additional survey and wetland delineation," she said, and added that teams completed pebble counts and reference-reach measurements to match the downstream channel. The consultant reported a median pebble size of about 6 inches below the dam and said the design will use similar bed material and sized boulders so restored channels match existing character.

Hudock said probing and geotechnical work revealed a bedrock outcropping beneath the historic gate structure, which the team will tie into rather than excavate. "There is no impact to bedrock," she said, adding the design intends to expose and work around bedrock features.

The consultant said the project has three construction phases: mobilization and establishment of north and south access points; installation of cofferdams, removal of the lower training weir and dam, and island and channel restoration; then moving cofferdams to complete restoration on the remaining side. For drawdown, the team recommended repairing the gate and lowering the impoundment no more than six inches per day with on-site and groundwater monitoring to avoid adverse impacts.

Archaeology work influenced design choices. Hudock told the committee that Phase I fieldwork returned a "high density" of finds, including both pre-contact and post-contact materials, and that a Phase II determination of eligibility is underway. She said the specific locations and artifacts are being protected to prevent looting and that targeted additional study will determine whether further mitigation or avoidance is needed.

On habitat, the team reported they designed fish-passage features around alewife as a hydraulically sensitive design species — adding pools and low-flow channel elements intended to provide resting areas and appropriate velocities for passage. The consultants also described a passive-restoration approach for much of the impoundment sediment (stabilized in place and seeded) while channel sediments with shallower depths will be removed where necessary. "We'll be monitoring during construction, including turbidity monitoring," Hudock said.

Residents raised questions during public comment. Catherine Edison asked whether additional grants beyond the $300,000 Great Bay 2030 award had been secured; Paul Velosicich said no additional grants are currently in hand and no pending applications exist. Resident Robert Spann asked when the DES dam-removal permit would be submitted; Hudock said the team hopes to submit permitting applications in late fall but cautioned that permitting can take roughly a year, which means construction in 2027 is possible but not guaranteed.

The team proposed a public information meeting for Thursday, Aug. 20 at the Exeter Library (presentation about 6 p.m.; room reserved 5:30–7:30 p.m.) to present the current plans and gather feedback. Next technical steps are finishing 60% design, completing the wetlands impacts plan, and preparing permit applications.

The advisory committee heard the update and will expect further progress reports; the consultants said the next full permitting documents and a quantified wetlands impacts estimate should be available after the late-fall permitting submittal process begins.