Delaware Geological Survey
Link to: Delaware Geological Survey
NGWMN Contact:
Changming He
302-831-4917
hchm@udel.edu
The Delaware Geological Survey (DGS) is a water-level and water-quality data provider to the National Groundwater Monitoring Network (NGWMN). DGS operates a network of 123 wells and provides data from 38 sites to the NGWMN Portal. Many of the sites have nested monitoring wells completed in multiple, layered, local aquifers and more than 100 monitoring wells have 10 or more years of water-level records. DGS serves water-quality data from other Delaware State agencies that collect groundwater data that meet the NGWMN requirements. DGS has been a part of the Network since 2016.
DGS provides water-level and water-quality data from the Northern Atlantic Coastal Plain, Piedmont and Blue Ridge Carbonate Rocks, and Piedmont and Blue Ridge Crystalline Rocks Principal aquifers.
NGWMN Projects:
Initial project to become a NGWMN data provider.
2016 Round 1: 7/1/2016 to 8/15/2018
Project is to support persistent data service from DGS databases to the NGWMN data portal and to keep site information up to date in agency databases and the NGWMN Data Portal.
Project for an existing data provider to enhance their wells in the NGWMN. They will be expanding the number of sites in the network by adding up to 26 new wells to the water-level Network and up to 20 wells to the water-quality network. They will be providing persistent data services to keep their data flowing to the NGWMN and will be doing some updates to their web services. They will be doing gap filling by adding lithology data at a deep well and updating horizontal and vertical coordinates at 6 network wells. They will also be performing well maintenance by pumping 10 existing wells. Downhole video camera logs will also be done at five of these wells.
2020: 11/16/2020 to 11/15/2022
Project is to provide persistent data services for two years to ensure that data continues to flow to the NGWMN Data Portal, and that sites and site information are up to date.
NGWMN Presentations:
Site Selection and Classification
Site Selection
DGS selected wells for water-level monitoring from its long-standing groundwater monitoring network. DGS currently measures water levels as part of routine network activities and special projects in 123 wells representing three principal aquifers: North Atlantic Coastal Plain aquifer system (USGS code S100NATLCP), Piedmont and Blue Ridge Carbonate Rocks (USGS code N400PDMBRC), and Piedmont and Blue Ridge Crystalline Rocks (USGS code M400PDMBRX) incorporating 13 major and local aquifers. More than 20 sites have nested monitoring wells completed in multiple, layered aquifers to allow calculation of the potential for vertical flow between aquifers. Construction details are known for all of these wells and nearly all have both lithologic and downhole geophysical logs. More than 100 monitoring wells have 10 or more years of water level record. Sites from this monitoring network were considered for addition to the NGWMN for water levels. Wells with less than five years of data were not considered as candidate sites.
DGS has conducted and participated in numerous ground and surface water quality studies (e.g., Andres, 1991; Baxter and Talley, 1996; Sims et al., 1996; Blaier and Baxter, 2000; Ullman et al., 2002, 2007; Andres and Sims, 2013) but funding limitations have stymied efforts to sustain a continuous monitoring program. Through cooperative work with other state agencies DGS evaluated long-term quality monitoring programs in the state to determine which ones generate data that meet the requirements for inclusion in the NGWMN and may be receptive to a cooperative relationship where DGS acquires data, manages those data within DGS systems, and provides data to the NGWMN portal.
Delaware Solid Waste Authority (DSWA) has operated a water-quality and level monitoring program at several facilities since the 1980s in support of permitting and permit compliance. The permitting process requires adherence to quality assurance and performance plans (QUAPP) for well construction, sampling, sample handling and preservation, laboratory analyses, chain-of-custody, data management, and reporting (Daniel Fluman, personal communication, 2016). Multiple aquifers are monitored with nested or clustered wells. DGS staff conducted geophysical logging and hydraulic testing at these facilities in cooperation with DSWA and have routinely harvested and used water level data from DSWA. DGS operates real-time water level monitoring wells at two DSWA facilities. This previous work provided sufficient experience to be confident in the wells and data from DSWA. In turn, DSWA is confident that their data have value to the NGWMN. Background wells were identified from groundwater elevation contour maps and a well cluster was selected from each of two DSWA facilities.
DGS project members met multiple times to review all water level and water quality data and metadata associated with candidate wells and to select candidate wells. Wells selected have adequate period of record and are distributed with respect to locations, coverage from all three of principal aquifers present in Delaware and partial coverage for 13 local aquifers. The wells selected include both unconfined and confined settings, and where possible span updip to downdip transects within a local aquifer. Several of the sites have nested monitoring wells completed in multiple, layered aquifers to allow calculation of the potential for vertical flow between aquifers and assessment of water quality differences between aquifers at the same site.
Site Classification
Because of Delaware's small size, intensive agricultural and urban development, and reliance on groundwater for water supply, all candidate wells for level monitoring fall into the "Known Change" or "Suspected Change" subnetwork categories. In future years, newer monitoring wells, located within large forested tracts, and constructed to monitor water-table level fluctuations will have a long enough record to be added to the NGWMN and will likely meet "Background" subnetwork requirements. The "Known Change" subnetwork was assigned to wells by DGS project members after reviewing hydrographs for indication of pumping influences such as long-term downward trends, heads less than 0 feet (NAVD 88), or daily/weekly level variations that exceed seasonal and annual fluctuations reported in the past (Johnston, 1973; Talley, 1978, 1988; Andres and Martin, 2005; Martin and Andres, 2008). Wells not placed into the "Known Change" subnetwork are placed in the "Suspected Change" subnetwork.
All wells selected from the Delaware Groundwater Network for the level network of NGWMN fit the "Trend" monitoring category as they have a minimum of monthly measurements for greater than five years. Daily mean water-levels are reported for wells equipped with automated level instruments.
Review of water-quality data from DSWA wells found no long-term trends that would indicate groundwater contamination has occurred. Nonetheless, DSWA wells selected for the quality network were placed into the "Suspected Change" subnetwork because they are located near solid waste management facilities where operations may impact water quality in the future. Sampling frequencies and periods of records for DSWA wells meet the requirements to be included in the "Trend" category for water quality.
Data Collection Techniques
Data management protocols for water-level data were first documented by Talley and Windish (1984). Manual and automated water level measurement methods are described in Andres et al. (2018).
Water quality data added to NGWMN by DGS was acquired from the DSWA. A document summarizing sampling protocols used by DSWA (DSWA, undated) is available here. The DSWA monitoring program is conducted to satisfy regulatory and permitting requirements.
Data Management
Data management protocols for water quality data were first documented by Talley and Windish (1984). Talley and Windish (1984) provided a vocabulary of generic identifiers of chemical testing methods. Since that time, specific citations of standard testing methods have been added to the DGS internal database and are included in the DGS web services. NGWMN required metadata elements (i.e., CASRN, chemical system name) that were not included in Talley and Windish (1984) have been added to the DGS internal database so that all of the metadata elements required by NGWMN are included in DGS web services.
Other Agency Information
Web sites of Interest
DGS Groundwater Monitoring Network
Hydrologic Information for Delaware
Groundwater Conditions Summary Graphs
Summary of Water Conditions in Delaware