Bedrock Wells

Sand and Gravel Wells

Wellfield Management

Groundwater Backup Well Source

State Seal Spring Corrective Evaluations

Filtration Avoidance

Onondaga Creek Contaminant Investigations

Aquifer Resource Planning and Zoning

Aquifer Recharge Rates and Septic System Density

Bedrock Wells

Southeast, NY

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.

Chazen then worked with a well driller to advance two wells. Each encountered water-bearing fractures and were advanced to formal well testing. The flow tests each included monitoring of drawdown and collection of water quality samples.

A written report describing the site hydrogeologic work was reviewed by regulating agencies, yielding approvals leading to current productive use of these wells by this community water system.

Sand and Gravel Wells

LaGrange, NY

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 the wells and subsequent well development leading to production of clear water flows from each test well.

Chazen then planned and oversaw pumping tests to evaluate available well yields and water quality. Test results were summarized in a hydrogeologic report within an engineering design report prepared by Chazen. Site infrastructure including a water treatment plant and associated distribution lines were also designed by Chazen.

 

Wellfield Management

Bethlehem, NY

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 has allowed development of recommended schedules and priorities for future treatments. Analyzing these specific capacity yield tests requires tidal corrections due to local estuary conditions near the wells.

Chazen also conducted detailed analyses of the well designs to help the Town select redevelopment methods and energy levels, and better anticipate eventual well replacement and design schedules.

The various wellfield management methodologies being applied in the Town of Bethlehem can substantively extend the lifespan of production wells.

Groundwater Backup Well Source

New Paltz, NY

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 complex pumping test involving soil borings, geophysical study, significant public outreach and domestic well monitoring, detailed test design with regulatory agencies, and precisely defined recommended permit conditions reflecting the unique aquifer setting.

State Seal Spring Corrective Evaluations

State Seal Spring, NY

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 corrective actions. Chazen also provided a hydrogeologic assessment report summarizing technical findings and recommendations for future improvements to enhance the sustainable and high-quality water yield.

Chazen’s work focused on gathering sufficient data to describe the natural environment, examining the source and its limits, reviewing climatic factors influencing aquifer recharge, and examining the infrastructure used to deliver water to the public. Chazen presented both short- and long-term corrective action options.

Filtration Avoidance

Croton-on-Hudson, NY

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 Village wells.

Chazen then developed a test protocol to examine groundwater temperature and electrical conductivity through many pumping cycles. This approach demonstrated very stable groundwater conditions which were quite different from river quality conditions. Chazen also collected groundwater samples for biological review.

Results of the study were presented to the Department of Health, which determined that water from the Village wells did not qualify as Groundwater Under Direct Influence (GWUDI) of surface water, giving assurance to Village residents that these wells provide high-quality groundwater that does not need micro-filtration beyond that already provided by the aquifer sediments.

Onondaga Creek Contaminant Investigations

Onondaga County, NY

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 salt formations, stimulating ongoing brine generation long after formal halite mining operations have ceased. Aquifer pressures move brine upward toward mudboils, springs, and saline wetlands.

Some remedial work has been completed by the property owner, including grouting of former brine mining boreholes and surfacewater diversion from sinkholes. Chazen developed a suite of additional remedial options for consideration, concentrating on methods to limit freshwater entry into the former solution mining chambers, and opportunities to grout primary plume pathways to the Tully Valley mudboils and related discharge points.

Chazen used existing published reports and site inspections. Other Chazen remedial groundwater investigations also included installation of monitoring wells, and soil and groundwater sampling, all following professional investigation protocols and work plan and reporting requirements under brownfield, inactive hazardous waste, or spill program guidance.

Aquifer Resource Planning and Zoning

Philipstown, NY

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 sustainable well and septic system uses, a map showing historic mines in the Town, and a map showing likely directions of groundwater flow to aid Town review of any groundwater plumes.

The accompanying text clarified the uses and limitations of the various figures, provided a series of water resource planning recommendations, and described methodologies used to identify approximate recharge rates and sustainable septic system densities. The report also describing existing water resource uses and threats and recommended adoption of a model zoning ordinance previously developed by Chazen.

The Town then adopted an aquifer protection ordinance based substantially on Chazen’s aquifer mapping and adopted zoning language using the recommended model regulation.

Aquifer Recharge Rates and Septic System Density

Dutchess County, NY

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 value. The resulting recharge rates, specified by hydrologic soil group and annual rainfall value, allow development of site specific or regional aquifer recharge budgets useful to local or regional groundwater allocation and planning efforts.

Chazen then modified an existing nitrate loading model to recommend minimum sustainable septic densities allowing successful rural area uses of domestic wells and septic systems. These recommendations allow identification of density thresholds where central water or sewer service may be needed, and suggests minimum average parcel sizes suitable for rural zoning where central services are not anticipated.

The study was funded by Dutchess County to provide a technical basis for planning and zoning decisions made by Towns throughout Dutchess County. The results have been used to identify areas where existing settled parcel sizes may be too small to ensure reliable groundwater well quality, and to specify large enough rural zoning in areas where Towns hope not to extend central water or wastewater service in the future. The recharge rates have been used in many water budget evaluations.