The site is located at the Town of Wolfeboro, New Hampshire Rapid Infiltration Basin (RIB) facility. Project work consisted of the installation of three (3) cutoff trenches four (4) new engineered natural solution (ENS) outlets to Nineteen Mile Brook and repairs to one (1) existing ENS (ENS-1). The repairs included restoration of the hillside area above ENS-1 where seeps were observed and a landslide occurred in April 2009. The objective of the project was to lower groundwater levels near the cutoff trenches to reduce seepage emergence on hillside slopes and associated erosion and slope instability. The ENS outlets are designed to convey collected water back into the groundwater table and to Nineteen Mile Brook without discrete surface water channelization or erosion/washout of the bank.
LRT designed and installed the dewatering systems and water treatment systems for the project. Specifically, wellpoints were installed for each of the four (4) ENS areas and the cutoff trenches were completed via sumps. LRT provided a water treatment system rated for 600 gallons per minute (gpm) and designed to remove total suspended solids (TSS). Treated groundwater was discharged under a National Pollution Discharge Elimination System (NPDES) Construction General Permit (CGP) and Stormwater Pollution Prevention Plan (SWPPP).