Service: Groundwater Wells and Aquifer Management

Bedrock Wells

August 9, 2017

Chazen conducted fracture trace analysis to recommend well drilling locations for a water district in the Town of Southeast. Chazen then managed well installation and testing, resulting in development of successful wells, each exceeding project requirements and providing over 100 gallons per minute. Chazen conducted a hydrogeologic review including examination of geology and field evidence suggesting the presence of fractures which might convey groundwater to wells. Suggested locations which also met set-back requirements from property lines and wetlands were prioritized. … Continue reading “Bedrock Wells”

Sand and Gravel Wells

Chazen conducted a siting study and then designed and installed municipal sand-and-gravel wells for the Town capable of supplying more than 1,000 gallons per minute. To site the wells, Chazen conducted a detailed soil boring program on a parcel of land near the Wappinger Creek. The parcel was found to contain both clay areas and sand-and-gravel zones. Three most-probable sand-and-gravel horizons were selected for installation of candidate production wells. Chazen specified casing and well screen designs and oversaw installation of … Continue reading “Sand and Gravel Wells”

Wellfield Management

The Town retained Chazen to evaluate declining yields from vertical and angled wells installed near the Hudson River. Chazen’s well design reviews and well redevelopment support have helped extend the operational life of this wellfield. The Town selected physical well redevelopment followed by carbon dioxide treatments to redevelop their sand and gravel wells. Chazen managed yield tests before and after physical redevelopment and has continued these evaluations during repeated injection events to record the effectiveness of each treatment. The analysis … Continue reading “Wellfield Management”

Groundwater Backup Well Source

Chazen led a comprehensive groundwater investigation to develop a 400 gallon per minute, 10-week, back-up source of groundwater supply. The Village of New Paltz typically purchases water from the City of New York but periodically needs an alternate high-capacity water source during NYC system shutdowns. Chazen advanced a comprehensive exploration program seeking gravel sources along the Wallkill River Valley near the Village. Saturated sand and gravel was identified under clay deposits. The project team managed the well installation and a … Continue reading “Groundwater Backup Well Source”

State Seal Spring Corrective Evaluations

The State Seal Spring at the Saratoga Spa State Park ceased discharging water at the Joseph L. Bruno Pavilion. Chazen was retained to assess the spring source and recommend immediate and long-term reliability recommendations for this popular water source. Chazen conducted a soil boring program to characterize and develop a conceptual model of the source water hydrogeology, including a review of the systems used to deliver the water to the public pavilion. Chazen conferred with the system operator implementing immediate … Continue reading “State Seal Spring Corrective Evaluations”

Filtration Avoidance

Chazen helped the Village evaluate whether three existing wells situated near the Croton River required microfiltration. A detailed study designed by Chazen indicated that natural sediments provided ample filtration, resulting in significant cost savings to the community. Chazen first conducted a hydrogeologic review of existing well construction details and available hydrogeologic analysis and well logs. These records suggested that layers of silt and clay lay between the river and the saturated sand and gravel horizon supporting groundwater flow to the … Continue reading “Filtration Avoidance”

Onondaga Creek Contaminant Investigations

Chazen developed a conceptual model describing saline mudboils active along Onondaga Creek in the Tully Valley. Chazen’s contaminant investigation identified source and plume migration mechanisms and included mitigation recommendations. Chazen’s hydrogeologists reviewed the specific mechanisms associated with the unique geologic conditions in Tully Valley. Historic halite solution mining caused structural geologic damage including sinkhole development, collapsed rock over solution cavities, general land subsidence, and hillside fissures. Former overland flow and shallow groundwater appear to continue migrating into formerly-isolated deep rock … Continue reading “Onondaga Creek Contaminant Investigations”

Aquifer Resource Planning and Zoning

Chazen completed aquifer resource analysis of the Town of Philipstown to support Town planning initiatives. The development of aquifer planning recommendations was a recommendation of the Town’s Comprehensive Plan because large numbers of residents and businesses use groundwater as their primary source of water supply. Chazen provided Philipstown with various water resource maps and a supportive text. Maps included a reference figure with aquifer boundaries and watersheds, a map showing recharge rates and existing parcels below recommended minimum sizes for … Continue reading “Aquifer Resource Planning and Zoning”

Aquifer Recharge Rates and Septic System Density

Chazen worked with Dutchess County to identify calibrated aquifer recharge rates, useful for aquifer safe-yield budgets and municipal planning. Chazen also recommended minimum sustainable parcel sizes using individual septic systems and domestic wells. Recharge rate analysis included baseflow separation of stream flows to identify flow coming from watershed aquifers. These groundwater outflows were calibrated to the distribution of soil types and long-term rainfall records across three adjoining watersheds to identify average annual recharge rates by hydrologic soil group and rainfall … Continue reading “Aquifer Recharge Rates and Septic System Density”