RISK-BASED CORRECTIVE ACTION - WATER WELL SURVEYS
|Hazardous Waste Program fact sheet||
|Division of Environmental Quality Director: Leanne Tippett Mosby||
Missouri has two Risk-Based Corrective Action, or RBCA, processes. One pertaining solely to releases from petroleum storage tanks referred to as the Tanks RBCA. The other pertaining to non-petroleum storage tank releases, referred to as the departmental RBCA. (Furthermore, there are two versions of the Tanks RBCA guidance that are currently being utilized. One version published in 2004 and a revised version published in 2013. Information explaining which Tanks Guidance should be utilized at a site can be found in a document entitled “Guidance Document Applicability for Tank Closures and Changes in Service and Investigations, Risk Assessment, and Corrective action for Releases from Tanks Systems”, dated October 17, 2013, at http://www.dnr.mo.gov/env/hwp/docs/tanks-transition-explanation-11-20-13.pdf.)
Under either process, if contaminants have or are likely to reach groundwater, a groundwater evaluation must be conducted to determine whether, and to what extent, groundwater is being or is likely to be used for any purpose, particularly as a drinking water source. Because the presence of public or private water wells, is a clear indication the water is being used, as part of an overall groundwater evaluation the risk-based corrective action processes require evaluating parties conduct a water well search at and near the site of contamination.
The list below identifies those sections of the Missouri Department of Natural Resource’s Risk-Based Corrective Action Process rule, 10 CSR 25-18.010, and the departmental and Tanks RBCA guidance documents where the water well identification requirements are found.
- 10 CSR 25-18.010(8)(D)2.A.
- Departmental RBCA Technical Guidance, subsections 6.3.2, 6.3.5 and 6.5.3.
- Tanks RBCA Guidance, 2004 subsections 5.4.1, 5.4.4, and 5.5.4.
- Tanks RBCA Guidance 2013, subsections 5.4.1, 5.5.4, and 5.5.1
The identification of water wells is necessary in order to determine whether site-related contaminants are affecting, or have the potential to affect, a public or private water supply being used as a source of drinking water or for agricultural or industrial purposes. This information is critical to accurately assessing the risk associated with the contamination and collection of the information necessarily precedes the risk assessment.
Specific Water Well Survey Requirements
Under both risk-based corrective action processes, when a release of contaminants affects or has the potential to affect groundwater, a water well survey must be conducted to identify:
- All public water wells within a one mile radius of the site.
- All private water wells within a quarter mile radius of the site.
In general, the department expects the well survey requirement to be met through a review of local, state and federal records pertaining to well installations and operation and water sources.
However, in some cases, a physical door-to-door survey of the site and nearby properties will be necessary (and is advised in every case) to more definitively determine whether water wells are present within the prescribed search distances. Both risk-based corrective action processes recognize and address this potential (see subsection 6.5.3 in the departmental RBCA guidance and 5.5.4 and 5.5.1 in the Tanks RBCA 2004 and 2013 guidance documents, respectively).
Those conducting water well surveys should bear in mind that, prior to July 1987, non-public water well certification was not required in Missouri and occurred solely on a voluntary basis.
Therefore, the department’s well certification records are incomplete. Consequently, physical door-to-door well surveys are necessary when site contaminants have or are likely to significantly affect an aquifer, particularly if the contamination has or is likely to migrate off the property of origin and site information indicates the aquifer is being used locally.
When evaluating actual and potential groundwater use and conducting well surveys, consultants and other environmental professionals should consider not only the potential for domestic use of groundwater (e.g., drinking and bathing), but also industrial, irrigation (both large scale agricultural and small scale watering of gardens), livestock and other potential uses. In some cases, even though a community water distribution system may be in place to provide water for domestic use at and in the vicinity of a site, local individuals might still use groundwater and might access the groundwater via hand dug and other shallow wells in addition to typical drilled and cased wells. Hand dug and other shallow wells are unlikely to appear in certification records and are most likely to be discovered only through door-to-door surveys. When conducting such surveys, questions should be fashioned to get information about both domestic and non-domestic uses of groundwater.
Department of Natural Resources Well Survey Information
The department maintains many records related to public and private water wells.
However, as stated above, these records may not contain information on non-public wells installed prior to July 1987. The department’s well records can be obtained from the following sources.
- For the most current well construction and location data, you can contact the Missouri Geological Survey’s Wellhead Protection Section at 573-368-2165. This section conducts searches based on Global Positioning System coordinates of degrees, minutes and seconds and is capable of providing a radius report in quarter-mile increments up to six miles.
- Well data collected by the department after July 1987 is also available online using the department’s new Geosciences Technical Resource Assessment Tool (GeoSTRAT) available at http://www.dnr.mo.gov/geology/geostrat.htm. This toll enables you to easily visualize and explore geospatial data using an interactive mapping feature and can be used to access information about public and private drinking water wells in a the area of your site.
- Data on the installation of public and non-public wells can also be obtained on line from the department’s Well Information Management System (WIMS) at www.dnr.mo.gov/mowells.
- Data for some wells logged by geologists is maintained by the department’s Water Resources Center and is available online at www.dnr.mo.gov/env/wrc/logmain/index.html. You can click on a county and all public and private wells in the county for which log data is available will appear (some of the well logs were developed as long ago as the 1920's). You can then click on a specific well and obtain specific information related to that well.
- Well location and log data is also available by contacting the department’s Water Resources Center directly at 573-368-2175. The center can produce well log reports on a township-range-section basis.
The United States Geological Survey, or USGS, is also a resource for well information. Well and other groundwater information is available online from the Survey’s National Water Information System at http://waterdata.usgs.gov/nwis.
In addition, local city or county governmental entities, in particular local health departments, might be a source of valuable information regarding water wells and other water systems within their jurisdictional boundaries. In addition to well and water system information, local governmental entities might also have information regarding local ordinances pertaining to water well construction, installation, operation and about public water supply systems.
Finally, residents, particularly long-time residents, can be a valuable source of information regarding water wells (both modern, drilled wells and old, hand dug and other shallow wells) at and near a specific site. Door-to-door surveys, as mentioned previously in this fact sheet, are a good way to find residents who might be a source of such information.
None of the information sources discussed herein should be considered, by themselves, as comprehensive sources of well location and construction information. The department is aware that many wells, both active and inactive, exist for which the department and other entities have no records. Numerous water wells were installed before non-public well certification requirements became effective in July 1987, while others might have been installed in violation of certification requirements. The department recommends that well surveys include more than one source of information and a physical survey of the site and surrounding area. When in doubt regarding the need for or the required extent of a water well survey, contact the department’s Hazardous Waste Program at 573-751-3176.
The water well survey requirements discussed here are the minimum standards under the RBCA processes. The department may require additional or different actions depending on the technical or legal framework applicable to a specific site.
The departmental and tanks Missouri Risk-Based Corrective Action guidance documents and related information are available online at www.dnr.mo.gov/env/hwp/mrbca/mrbca.htm and www.dnr.mo.gov/env/hwp/tanks/mrbca-pet/mrbca-pet-tanks.htm.
The Risk-Based Corrective Action Process rule, 10 CSR 25-18.010, is available online at www.sos.mo.gov/adrules/csr/current/10csr/10c25-18.pdf.
For More Information
Hazardous Waste Program
P.O. Box 176
Jefferson City, MO 65102-0176
800-361-482 or 573-751-3176