PROBLEM | The NH Department of Environmental Services (NHDES) Dam Bureau division is required to ensure that all dams in New Hampshire are constructed, maintained and operated in a safe manner. For cases where removing an unwanted or unneeded dam is warranted, the NHDES has created a dam removal process that combines the dam safety program with the wetlands program to identify, evaluate, and remove these dams. The owner of the Sawyer Mill Apartments, a former woolen mill located on the Bellamy River in Dover, NH, required a dam removal feasibility study to submit as part of the Wetlands Application to the NHDES water division for the dam removal. The study helps to evaluate the impacts and feasibility of removing the dam and describes the overall physical setting of the study area including geology, recent land use changes, geomorphology (landforms), and streamflow characteristics. Expected changes to geomorphology, erosion and re-deposition as a result of the dam removal also need to be described.
SOLUTION| Truslow Resource Consulting LLC worked with Waterfront Engineers LLC on the dam removal feasibility study at the Sawyer Mill Apartments on behalf of the owner. To carry out the study, Truslow RC completed:
- collection of background natural resource, natural heritage, biological, environmental, land use, geologic and hydrologic information on the project site and surroundings,
- development of a sediment sampling and analysis plan,
- collection, physical characterization and laboratory analysis of sediment samples,
- geomorphic data collection and analysis on the Bellamy River and impoundments to define channel and stream bank morphology, and
- stream flow estimates and monitoring using a pressure transducer and flow monitoring, as well as existing LoVoTECs and PSU data.
TruslowRC created a series of GIS maps displaying a wide range of data collected in the Bellamy River watershed illustrating land use, natural resources, and potential contaminant sources evaluated as part of the project. It was important to understand land use to calculate expected peak flows and to determine the impacts on the Bellamy River habitat and hydrology pre and post dam removal.
Using the collected data and hydraulic modeling results, a sediment transport analysis, sediment quality evaluation, and water and natural resource impact evaluation was completed. Results were reported in a draft feasibility study in 2014.
Clients/Collaborators
- Sawyer Mill Apartments
- Waterfront Engineering LLC
- Haight Engineering LLC
- NH DES Dam Bureau
- NH Coastal Program
- NOAA Restoration Team
Services Provided
- Hydrology, Geomorphology, & Restoration
- Hydrogeology and Source Water Protection
- Groundwater and Surface Water Quality Sampling
- Resource Planning and Management
- GIS Mapping and Analysis