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Taylor GeoServices Providing Geological, Environmental, Water Supply, Geotechnical & Mapping Services |
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Hydrogeology Services
Public Water Supply Wells
TGS has assisted clients with water supply wells from community water supplies to individual residential wells. Whether installing a community water system for a new development or adding wells to increase capacity, TGS can complete the various tasks required as part of the project and permitting process.
Suitable water supply well locations are sited based on geology, topography and the proposed land use. An aerial photograph fracture trace analysis is often used to assist in identifying favorable water bearing zones. A site visit and meeting with the regulatory agency’s hydrogeologist is conducted to review the proposed well location. A pre-drilling plan that provides the site conditions and proposed well locations, installation procedures and pumping test details is provided to the regulatory agency for approval.
Upon approval, the well is installed by a qualified driller following the protocol established by the state and/or local regulatory agency and which has been outlined in the pre-drilling plan. A geologist will typically observe the well drilling in order to log the hydrogeologic conditions and document the well installation.
Pumping
tests are performed on the newly installed water supply well to evaluate the
aquifer characteristics and obtain the appropriate well yield and other
information needed to engineer the water supply system. Initially a step test
is conducted to estimate an optimal pumping rate for the well. A
long-term constant rate pumping test is then conducted to evaluate the wells
behavior over time. Recorded water level measurements from the pumping well and
observation wells are plotted and evaluated along with information obtained from
the drilling logs and background geologic conditions. At the completion of the
constant rate pumping test water quality samples are collected for the
applicable laboratory analysis.
The findings from the hydrogeological characterization, pumping tests and water quality sampling are discussed in a concise report which is submitted as part of the permitting process.
Hydrogeologic Site Characterizations at Stations
TGS has completed numerous site characterizations at environmentally contaminated sites. Characterizations center around a detailed hydrogeologic investigation to obtain a thorough understanding of the contaminants in the subsurface environment. A sound understanding and conceptual model of the hydrogeological conditions and contaminant fate and transport mechanisms is critical to limiting liability risks, reducing project costs, selecting effective remedial options, and gaining closure in a timely and successful manner. The scope of a characterization can include soil sampling, monitoring wells, groundwater sampling, pumping tests, water level recordings, contaminant fate & transport modeling, vapor intrusion evaluation, risk assessment, potable well survey, geophysics, geologic interpretation and data evaluation. More involved efforts depend largely on the type of contaminant, the magnitude of the impact, and the complexity of the geology. Findings from the characterization are used to confirm the release had no impact or design and implement a pilot study and remedial action plan.
Complex Hydrogeology in Coal Mine Region
An investigation was implemented to identify hydrogeologic conditions and groundwater quality at a former battery recycling facility. The project site was located within a former coal strip mine and was underlain by 11 previously worked deep bedrock mines. Preliminary work included reviewing geologic publications and mining maps to outline the hydrogeologic conditions present around the study area. An extensive rock coring and soil boring program was conducted to evaluate local subsurface conditions. Field activities included drilling observation and logging, rock core evaluation, down hole camera logging, monitoring well construction design (both bedrock and overburden wells), monitoring well installation observation, and rising head aquifer testing. The field data and previous documentations were used to prepare geologic cross sections and establish stratigraphy, groundwater occurrences (e.g., the water table within mine pools) along with potential vadose zone groundwater flow directions (e.g., vertical flow through fractures or horizontally along bedding planes), and potential mine subsidence.
Surface Water Infiltration Program (SWIP)
State regulations required community water supply systems using groundwater to evaluate the potential impact to their wells from surface water infiltration. Existing documents were reviewed to obtain information on the geology, hydrogeology, soils, groundwater and regional topography. Existing records were used to identify well construction details, aquifer characteristics and groundwater quality. A preliminary hydrogeologic report was prepared that detailed the findings, compliance with state guidance criteria, and conclusions regarding the susceptibility of the well to surface water infiltration. The reports were used by the state regulatory agency to establish the need for further monitoring and microparticulate sampling.
Taylor GeoServices, Inc.
http://www.taylorgeoservices.com
Updated 01/22/09