STORMWATER MANAGEMENT FACILITY PRIORITIZATION AND MAINTENANCE -PROJECT DESCRIPTION

Civica was retained by the Town of Newmarket in April 2018, to provide consulting services relating to the inspection and maintenance of 50 of the stormwater management (SWM) facilities owned and operated by the Town. The goal of this project was to inspect the SWM facilities and identify deficiencies and safety hazards, prioritize maintenance work, and provide design and construction administration/inspection services for major and minor maintenance work in 2019 and make recommendations for future maintenance work. 

Pond inspections were completed by field crews using our mobile application (SWMSoft) and the Town’s GIS based data collection system. Bathymetric surveys were performed to determine the level of sediment in each facility. Using the volume of sediment in the pond and the original design criteria, the current level of service of the facility was determined. Major maintenance prioritization was ranked based on the %full of the permanent pool and if the design %TSS removal of the facility was lowered by 5%.

Once all components of the facility were inspected and a level of service was determined, a prioritization matrix was created to determine the facilities with the most crucial deficiencies. Major maintenance requirement rankings were influenced by three major factors; level of performance, the sensitivity of the receiving waters, and the current and predicted sediment loading in the facility, which determine the priority of the deficiencies. In addition to identifying maintenance requirements, this project also looked at retrofit opportunities which could be made either in upstream drainage areas or in an existing pond block which would improve the water quality treatment level of the SWM facilities. 

Detailed design was then initiated to complete major maintenance for one (1) SWM facility and minor maintenance for ten (10) SWM facilities which was completed in 2019 with only minor construction items to be addressed by the Contractor to complete the project in Spring/Summer 2020.  Additional scope was added for major maintenance of one of the stormwater management ponds; the design and permits are complete with construction to occur in 2021.