Maine Geological Survey
Link to: Maine Geological Survey
NGWMN Contact:
Ryan Gordon
(207) 287-7178
ryan.gordon@maine.gov
The Maine Geological Survey (MGS) is a water-level data provider to the National Groundwater Monitoring Network (NGWMN). Prior to 2016, MGS had a network of only 19 well sites with long-term data. After partnering with the NGWMN, MEGS now maintains 51 wells, and serves 32 sites to the Portal. MGS monitors long-term groundwater wells to collect data on background conditions and to provide information about long-term changes to groundwater due to climate change. MGS has been a part of the Network since 2016.
MGS provides water-level data from the New England Crystalline-Rock, New England Carbonate-Rock, and Sand and Gravel aquifers.
NGWMN Projects:
2016 Round 1: 9/1/2016 to 8/31/2018
Initial project to become a NGWMN data provider. The project took place in two phases. In Year 1, MGS worked to set up a local monitoring network and link it with the NGWMN to become a "new data provider". In Year 2, MGS maintained and improved the network and linkages with the NGWMN in the capacity of an "existing data provider".
Project will maintain current network infrastructure, add new wells to the network, and perform field work to gather and fill gaps in information about current network wells and sites.
2020 Round 1: 9/1/2020 to 8/31/2022
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. They will also be adding 10 new NGWMN sites to replace existing sites where data no longer meet NGWMN criteria.
2020 Round 2: 12/30/2020 to 12/29/2022
Project is to fill any site information gaps in new wells selected for the NGWMN as part of the 2020 Round 1 project.
NGWMN Presentations:
December 2016 presentation to the SOGW
Site Selection and Classification
Site Selection
In years before the establishment of the NGWMN, MGS worked with the Maine Department of Environmental Protection (MEDEP) to identify a subset of wells within Environmental and Geographic Analysis Database (EGAD) that serve as background wells at remediation sites and had records covering 10 years or more. Over 1900 wells at 138 sites were identified, and a selection of these was made based on the quality of the record and the absence of pumping influence in the wells. This initial selection included wells at 44 sites across Maine.
The selection process in 2016 began with the initial list of background wells at 44 sites, and then screened these for quality of the record (few missing measurements or outliers), the absence of pumping or active environmental remediation work, a lack of chemical contamination in the background well, and practical concerns such as ease of access. During this task, the knowledge of individual project managers and geologists at MEDEP was vital to help identify appropriate wells at each site. The subsequent list was further refined by MGS geologists considering the spatial distribution of points across the state and the distribution and number of wells in each principal aquifer and in the various depositional units of unconsolidated aquifers. The proximity to existing USGS monitoring wells was also considered. The refined list of wells was then subjected to an extensive search for documented information about each well. Potential monitoring wells that still lacked vital data elements after the search was complete were discarded from further consideration.
Site Classification
The candidate sites were classified into subnetworks and monitoring categories using guidance from the NGWMN Framework Document and the NGWMN Tip Sheets. All 32 wells selected for the Maine Groundwater Monitoring Network were placed in the NGWMN "Background" subnetwork (little or no documented anthropogenic effect) because anthropogenic effects on the groundwater level could be ruled out at all the selected sites. Any potential sites that had nearby industrial groundwater withdrawals or pump and treat operations were excluded from consideration, and the ten-year records at all the selected wells show no indications of anthropogenic effects. Furthermore, because large-scale groundwater withdrawals are uncommon in Maine and aquifers are generally small and discontinuous, pumping effects are typically highly localized, compared to other states with more extensive and heavily utilized aquifers.
The monitoring category in the NGWMN is based on the frequency of measurement. Water level wells in aquifers with small withdrawals are recommended to be measured once per quarter for the "Trend" monitoring category, while wells in the "Surveillance" monitoring category are recommended to be measured at least once every three years. All the wells in the Maine network were placed into the "Trend" category, even though some are not currently measured quarterly, because most were measured quarterly in past years, and we are hoping to increase the frequency to quarterly in 2019 and beyond.
Data Collection Techniques
MGS imposes strict collection protocols and quality protocols are subject to periodic reviews by MGS staff. Collection requirements are established in Chapter 405, which specifies the following:
(2) Sampling, Handling and Analysis of Ground Water. The ground water monitoring program must include consistent sampling procedures that are designed to ensure monitoring results that provide an accurate representation of ground water quality at all monitoring wells installed at a solid waste facility. The approved sampling protocol must be followed throughout the monitoring period of the facility so that data acquired can be compared over time and accurately represent changes in ground water quality. The following procedures must be followed during purging and sampling of monitoring wells, and the handling and analysis of the collected samples:
(a) Prior to purging. Prior to purging the well, static water level must be measured to the nearest 100th of a foot using standard techniques. If a protocol other than low flow sampling is used, well depth must be measured at least annually or more often if suspended solids in the sample suggest that the well integrity has been impaired....
Additionally, each site has a Quality Assurance Project Plan at the Department of Environmental Protection (DEP) that specifies data collection protocols. Most water-level measurements are made using the electric-tape method.
Data Management
Data is controlled for quality at several levels before being published to the NGWMN. Data that go into the network come both from the DEP's EGAD and MGS information sources, since EGAD doesn't store all the information necessary to populate the NGWMN. Additional tables for elevations, aquifer information, and lithology in the MGS database are populated manually by MGS geologists. Drop-down lists are provided for fields that have domains in the database to ensure accurate data entry.
Quality control of the data is performed on the combined data in the MGS database, using a custom design of the Microsoft Access user interface. New data that is routinely imported from the EGAD database is automatically flagged for review by MGS geologists, who can then flag it for release to the NGWMN. Data that are obviously erroneous or appear anomalous can be excluded or modified, and are typically reported to DEP project managers for review and potential correction within the EGAD database. No data in EGAD is ever deleted or modified directly by MGS staff. Other data not directly available from EGAD can be entered or updated as it becomes available to MGS. Data that have been checked for quality and flagged for release to NGWMN are then uploaded to ArcServer and published via web services.