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Browsing Open File Reports by Author "Andres, A.S."
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Item Basic Data For The Geologic Map Of The Seaford Area, Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 1995) Andres, A.S.; Ramsey, K.W.; Schenck, W.S.The Seaford area geologic mapping project (Andres and Ramsey, 1995) was conducted by Delaware Geological Survey (DGS) staff and focused on the Seaford East (SEE) and Delaware portion of the Seaford West (SEW) quadrangles (Fig. 1). Data evaluated in support of mapping from these quadrangles and surrounding areas are documented in this report.Item Digital Watershed And Bay Boundaries For Rehoboth Bay, Indian River Bay, And Indian River(Newark, DE: Delaware Geological Survey, University of Delaware, 2007) McKenna, T.E.; Andres, A.S.; Lepp, K.P.Digital watershed and bay polygons for use in geographic information systems were created for Rehoboth Bay, Indian River, and Indian River Bay in southeastern Delaware. Polygons were created using a hierarchical classification scheme and a consistent, documented methodology that enables unambiguous calculations of watershed and bay surface areas within a geographic information system. The watershed boundaries were delineated on 1:24,000-scale topographic maps. The resultant polygons represent the entire watersheds for these water bodies, with four hierarchical levels based on surface area. Bay boundaries were delineated by adding attributes to existing polygons representing water and marsh in U.S. Geological Survey Digital Line Graphs of 1:24,000-scale topographic maps and by dissolving the boundaries between polygons with similar attributes. The hierarchy of bays incorporates three different definitions of the coastline: the boundary between open water and land, a simplified version of that boundary, and the upland-lowland boundary. The polygon layers are supplied in a geodatabase format.Item Estimate Of Nitrate Flux To Rehoboth And Indian River Bays, Delaware, Through Direct Discharge Of Ground Water(Newark, DE: Delaware Geological Survey, University of Delaware, 1992-05) Andres, A.S.Agricultural fertilizer application, animal (poultry) waste, and wastewater disposal practices of the past 40 years have resulted in widespread nitrate contamination of ground water in coastal Sussex County, Delaware. Discharge of contaminated ground water to Rehoboth and Indian River bays is suspected of being a significant contributor to elevated nutrient concentrations in these surface water bodies, resulting in excessive phytoplankton growth and other related problems.Item Evaluation Of Remote Sensing And Surface Geophysical Methods For Locating Underground Storage Tanks(Newark, DE: Delaware Geological Survey, University of Delaware, 1986-01) Andres, A.S.Delaware Code, Title 7, Chapter 74, Section 7415 states in part: "The Delaware Geological Survey shall investigate the feasibility of utilizing aerial photographs and other new advanced techniques for locating abandoned tanks." In response to this charge, the Delaware Geological Survey has completed a survey of currently available remote sensing and geophysical tools to determine which methods may be utilized to locate underground storage tanks. Limited preliminary field testing has been performed.Item Ground-Water Level And Chemistry Data From The Coastal Sussex County, Delaware, Ground-Water Quality Survey(Newark, DE: Delaware Geological Survey, University of Delaware, 1991-04) Andres, A.S.This report contains the supporting ground-water level and chemistry data and the data collection methodology for Delaware Geological Survey Report of Investigations No. 49, "Results of the Coastal Sussex County, Delaware, Ground-Water Quality Survey" (Andres, 1991). Because raw data are commonly requested, they are published here in open-file format to accommodate those needing it for further analysis.Item Groundwater Monitoring Procedures Part 1: Equipment and Procedures for Manual and Automated Field Measurement of Groundwater Levels in Dedicated Monitoring Wells(Newark, DE: Delaware Geological Survey, University of Delaware, 2018-08) Andres, A.S.; He, C.; McKenna, T.E.The Delaware Geological Survey (DGS) has measured, managed, and distributed groundwaterlevel data for several decades using widely accepted procedures and practices, many of which were derived from interactions with staff of the USGS, consulting firms, and other state agencies. Many of the individual methods and procedures have been described in DGS reports, however, written documentation for these tasks have not been assembled in a single published document. The need for such a document has become more apparent with the development of standards for participation in the National Ground-Water Monitoring Network (SOGW, 2009). This document describes methods used by the DGS for routine manual and automated measurement of groundwater levels in dedicated monitoring wells. Alternative methods used for manual measurement of water levels in other types of wells are noted in this document to provide reference for historical measurements but not described in detail. These methods are excerpted and modified from procedures described by federal agencies and national standards organizations (e.g., ASTM, D4750-2007; Drost, 2005; USEPA, 2007). In this document, the term water levels will be used interchangeably with groundwater levels. Please refer to these and other appropriate documents for additional guidance or contact DGS staff with specific questions. Practices pertaining to data processing and management, metadata, and quality assurance procedures for electronic data are rapidly evolving. Additional sections on these topics will be added to this document as time and resources permit.Item Hydrologeologic Framework Of Southern New Castle County(Newark, DE: Delaware Geological Survey, University of Delaware, 2008) Dugan, B.L.; Neimeister, M.P.; Andres, A.S.Southern New Castle County is dependent on ground water for nearly all of its water supply. The area has been undergoing development from predominately agricultural land use to urban/suburban land use (Delaware Water Supply Coordinating Council [WSCC], 2006). With this development comes a need to more accurately predict the availability of ground water to reduce the potential of overusing the resource.Item Kent County Groundwater Monitoring Project: Results of Subsurface Exploration(Newark, DE: Delaware Geological Survey, University of Delaware, 2019-09) Andres, A.S.; McQuiggan, R.W.; He, C.This report documents the methods and results derived from subsurface exploration, monitoring well installation, and hydraulic testing conducted during the project "Groundwater and Saline Water Intrusion Monitoring Network Infrastructure Improvements: Kent County, Delaware". This project was focused on the aquifers in Kent County that supply water to wells for domestic, public, irrigation, and commercial uses as well as provide base flow to local streams. From shallowest to deepest, they are the Columbia, Milford, Frederica, Federalsburg, Cheswold, Piney Point, Rancocas, and Mt. Laurel aquifers.Item Methodology For Mapping Ground-Water Recharge Areas In Delaware's Coastal Plain(Newark, DE: Delaware Geological Survey, University of Delaware, 1991-08) Andres, A.S.This report documents the development of a methodology for mapping ground-water recharge areas in Delaware's Coastal Plain. It is anticipated that the methodology presented herein will evolve as it is applied to other areas in the State and as computerized geographic information systems become more widely available. This report deals with methodology; the recharge area maps generated in the course of the research are available for review at the DGS.Item Results of Groundwater Flow Simulations In the East Dover Area, Delaware(Newark, DE: Delaware Geological Survey, University of Delaware, 2018-08) He, C.; Andres, A.S.In 2015, staff of the Water Supply Section of the Delaware Department of Natural Resources and Environmental Control (DNREC) informed the DGS of their concerns about overpumping of the unconfined Columbia aquifer in an area east of Dover (Figure 1). In this area, the City of Dover’s Long Point Road Wellfield (LPRW) and numerous irrigation systems pump water from the shallow Columbia aquifer. Overpumping is a cause for concern because it may 1) increase the risk for saltwater intrusion into the aquifer from saline tidal creeks and marshes and, 2) induce extra drawdown that could reduce the transmissivity of the aquifer and decrease well yields. The potential for overpumping will become more significant when an electric generating station served by the LPRW is expected to increase capacity and requires more water. This report summarizes monitoring and modeling that were conducted to investigate the potential impacts of overpumping. Automated water level and salinity sensors were installed and operated in three monitoring wells, and a digital groundwater flow model was constructed. The model was run in both steady-state and transient modes. As is the case with most models, many assumptions and simplifications had to be made because of data limitations. The model was calibrated to a spatially limited set of data. Consequently, model outputs are meant to inform how the aquifers behave given the assumptions and simplifications and will not represent precise predictions of water pressures in the area represented by the model. Additional data are now being collected in the model domain to refine the accuracy and precision of model results.Item Results Of The Domestic Well Water-Quality Study(Newark, DE: Delaware Geological Survey, University of Delaware, 2008) Pellerito, V.; Neimeister, M.P.; Wolff, E.; Andres, A.S.The Delaware Geological Survey conducted a review of existing ground-water quality data collected from shallow (less than 100 feet deep) domestic water-supply wells and small public water-supply wells (serving fewer than 100 residents) to determine the extent to which toxic and carcinogenic compounds are present in the shallow ground water serving domestic water supply wells. These data were generated by several agencies including the Delaware Geological Survey, U.S. Geological Survey, Delaware Department of Natural Resources and Environmental Control, Delaware Division of Public Health Office of Drinking Water, and the Delaware Department of Agriculture Pesticide Management Program.Item Storm-Water and Base-Flow Sampling and Analysis In the Delaware Inland Bays Preliminary Report of Findings 1998-2000(Newark, DE: Delaware Geological Survey, University of Delaware, 2002) Ullman, W.J.; Andres, A.S.; Scudlark, J.R.; Savidge, K.B.This report provides initial research results of a storm-water and base-flow sampling and analysis project conducted by the University of Delaware College of Marine Studies (CMS) and the Delaware Geological Survey (DGS). Base-flow samples were collected from six tributary watersheds of Delaware’s Inland Bays on 29 occasions from October 1998 to May 2000. Water samples were filtered in the field to separate dissolved nutrients for subsequent analysis, and a separate sample was collected and returned to the laboratory for particulate nutrient determinations. On each sampling date, temperature, conductivity, pH, and dissolved oxygen concentrations were determined at each sampling station. Stream discharge measurements at each of these sites were made by the U.S. Geological Survey (USGS) under a joint-funded agreement with the Delaware Department of Natural Resources and Environmental Control (DNREC) and the DGS. Together, the nutrient and discharge data were used to determine the total and unit (normalized to watershed area) nutrient loading from base flow to the Inland Bays from each of these watersheds on a quarterly and annual basis. At the same six stations, storm water was collected during eight storms from May 1999 to April 2000. Storm-water loadings of nutrients from each watershed were calculated from the concentrations of nutrients in water samples collected at fixed time intervals from the beginning of the storm-water discharge period until recession to base flow. These data provide DNREC with a more complete picture of the seasonal dependence of nutrient loading to the Bays from which to establish goals for total maximum daily loads in the Inland Bays watershed.Item Storm-Water And Baseflow Sampling And Analysis In The Nanticoke River Watershed: Preliminary Report Of Findings 2002-2004(Newark, DE: Delaware Geological Survey, University of Delaware, 2007) Andres, A.S.; Ullman, W.J.; Savidge, K.B.This report provides initial research results of a storm-water and baseflow sampling and analysis project conducted by the University of Delaware, College of Marine and Earth Studies and the Delaware Geological Survey. Baseflow samples were collected from four tributary watersheds of the Nanticoke River and one station on the Nanticoke River on 18 occasions from March 2003 to June 2004. Water samples were filtered in the field to separate dissolved nutrients for subsequent analysis, and separate samples were collected and returned to the laboratory for particulate nutrient determinations. On each sampling date, temperature, conductivity, pH, and dissolved oxygen concentrations were determined at each sampling station. The U.S. Geological Survey made stream discharge measurements at each of these sites under a joint-funded agreement with the Delaware Department of Natural Resources and Environmental Control and the Delaware Geological Survey. Together, the nutrient and discharge data were used to determine the total nutrient loads at five stations and unit loads (normalized to watershed area) at two of those stations on a quarterly and annual basis. Problems with watershed delineation and low quality discharge data limit these calculations for some watersheds. At the same five stations, storm water was collected during six storms from March 2003 to June 2004. Storm-water loadings of nutrients in each watershed were calculated from the concentrations of nutrients in water samples collected at fixed time intervals from the beginning of the storm-water discharge period until recession to baseflow. Measured storm loads were used as the basis for estimating loads from unsampled storms. These data provide the Delaware Department of Natural Resources and Environmental Control with a more complete picture of the seasonal dependence of nutrient loading to streams in the Nanticoke River watershed and to Chesapeake Bay receiving waters. These may also be used to establish total maximum daily load goals.