Hydrogeology > Project Case Study

Bank Filtration Technology

Wright-Pierce was selected by Manchester Water Works to evaluate the application of bank filtration technology for their proposed 15 MGD supplemental drinking water supply at the Merrimack River Hooksett site.

Onshore and offshore geophysical and test well exploration studies were performed which identified a potential high yield sand and gravel aquifer beneath the Merrimack River. A 21 degree, low-angle gravel well 165 feet in length was drilled beneath the river and pump tested for six days at 620 GPM. A detailed groundwater flow model was completed along with a Rhodamine dye time for travel analysis, and detailed water quality laboratory analyses. 

Riverbank filtration was shown to be an excellent barrier against microorganisms. A log credit removal of at least 2.0 for bacteria, viruses, and aerobic spore forming bacteria was assigned. Induced infiltration from the river was estimated to range between 53 to 64%.

Study Results:
Utilizing bank filtration technology will eliminate the need for filtration thereby reducing construction, operation and maintenance costs.

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