Natural Memorandum
Total Page：16
File Type：pdf, Size：1020Kb
TECHNICAL MEMORANDUM www.naturalrt.com No. 1 Date: September 17, 2009 Subject: Potable Well Survey, Hydrogeologic Assessment, and Modifications to the Groundwater Monitoring Program, Venice Ash Impoundment From: Bruce Hensel Background and Summary This technical memorandum was prepared in partial response to the April 10, 2009 letter from IEPA to AmerenEG requesting a hydrogeologic assessment and potable well survey at the Venice ash impoundments. Ameren provided an initial response on May 20, 2009; in that response they noted that a groundwater monitoring program is already in-place at this facility and that a hydrogeologic report had been submitted to IEPA in January 2000. Ameren concluded by stating that additional documentation to fulfill the request of the April 10, 2009 letter would be provided within four months (by September 20, 2009). The specific elements to be provided are: ■ A hydrogeologic assessment plan ■ A groundwater monitoring plan ■ A potable well survey In summary, the potable well survey revealed that one (1) potential industrial well is located within a 2,500-foot radius of the Venice ash impoundments (Figure 2; Table 1). Well #1, located south of the ash impoundments, was constructed in 1943 by the Missouri-Illinois Materials Company; it is unknown at this point in time if this well is still active. The hydrogeologic assessment and groundwater monitoring plans are not yet complete, because these elements were dependent on obtaining off-site access for installation of ground-water sampling points. Ameren has diligently worked with the property owners to obtain this access, which was granted for this final property just this week. We now anticipate completion of these items in November or early December 2009. VENICE INTERIM RESPONSE TECH MEMO.DOC 1 NATURAL RESOURCE TECHNOLOGY TECHNICAL MEMORANDUM No. 1 Potable Well Survey The Venice ash impoundments and search radius areas (Figure 2) are located in Madison County, Township 3 North, Range 10 West, south ¼ of Section 35; and St. Clair County, Township 2 North, Range 10 West, Section 2, west 1/8 of Section 1, and the north 1/16 of Sections 11 and 12. The following databases and sources of information were utilized to determine community water source and water well locations and construction details in the vicinity of the Venice ash impoundments. ■ Illinois State Geological Survey (ISGS) - Water Well Database. The ISGS website provides a viewer map as well as a database query for well logs. According to ISGS, one water well is located within the search radius. The well is numbered #1 on an aerial map (Figure 2) and summary Table 1; the ISGS database boring log and well construction information are provided in Appendix A. The ISGS database also contained stratigraphic, test borings, and environmental monitoring well logs located within the search radius. These borings and monitoring wells are not included within the search results presented in this report. ■ Illinois State Water Survey (ISWS) Private Well Database and Water Well Construction Reports. No private wells records were identified in the ISWS database within the search radius (Attachment A). Well construction reports, ordered from ISWS, did not include well logs for the ISGS wells nor were there additional wells located in the search radius. ■ Illinois EPA web-based Geographic Information System (GIS). The Illinois EPA database website provides ArcIMS Viewer Maps (Attachment A), which provide information on community (CWS), non-community (NCWS), and public water supply (PWS) wells. The Illinois EPA system indicates CWS, NCWS, and PWS wells are not located within the search radius or within the immediate vicinity outside of the search radius (Attachment A). The Illinois EPA system confirmed the location of Well #1 identified in the ISGS database. ■ Potable water for the City of Venice and the Village of Brooklyn is served by Illinois American Water Company – East St. Louis (Attachment A Illinois EPA SWAP Fact Sheet). The City of Venice has a groundwater ordinance prohibiting groundwater use for potable purposes; the Venice groundwater ordinance is not depicted on the Illinois EPA ArcIMS Viewer Map (Attachment A). Hydrogeologic Assessment and Groundwater Monitoring Plan Review of previous investigation reports indicates that the existing site monitoring wells conform with regulatory requirements or are otherwise consistent with industry practices. Key items not addressed in the previous investigations include: characterization of aquifer thickness, characterization of groundwater flow at depth, and characterization of groundwater off site. These items will be addressed in the hydrogeologic assessment. [VENICE INTERIM RESPONSE TECH MEMO.DOC] 2 NATURAL RESOURCE TECHNOLOGY TECHNICAL MEMORANDUM No. 1 In addition, regional data will be updated. ■ Regional & local geomorphology, stratigraphy, and hydrogeology will be updated as needed based on data presented in reports prepared by the Illinois State Geological and Water Surveys. ■ Upstream of the site, river stage statistics will be compiled based on records maintained by the St. Louis District of the US Army Corps of Engineers for the Mississippi River at L&D 27 (lower) Granite City, IL (MI7T/0185B) http://mvs-wc.mvs.usace.army.mil/archive/mi/mi7t/ ■ Downstream of the site, river stage statistics will be compiled based on records maintained by the St. Louis District of the US Army Corps of Engineers for the Mississippi River at St. Louis, MO (MISL/0179A) http://mvs-wc.mvs.usace.army.mil/archive/mi/misl/ The Field Investigation will provide information needed to complete the hydrogeologic assessment and to develop a final groundwater monitoring plan. Field work will occur in two phases. Phase I will consist of soil borings and groundwater grab samples used to estimate the extent of the plume. The hydrogeologic assessment and groundwater monitoring plan will be based on pre-existing data and data collected during Phase I. Phase II will consist of implementation of the groundwater -monitoring plan and will involve installation of new monitoring wells to complete the well network used to define the horizontal and vertical extent of impacts. During Phase I, ten geologic borings will be completed through the perched zone, if present, into the water table for collection of groundwater grab samples (Figure 1). The borings will be advanced using direct push (e.g., Geoprobe®) drilling methods. Groundwater grab samples will be collected using a Geoprobe® Screen Point groundwater sampler (or equivalent) and submitted to a laboratory for analysis of dissolved boron and sulfate, ash indicator parameters that can be used to delineate plume extent. The data gathered during Phase I will be used to finalize monitoring well locations and screen elevations for Phase II. The Phase I soil borings radiate out from the southern end of the former ash ponds (orange triangles, Figure 1) to sample groundwater downgradient of the property. The borings are positioned to assess downgradient groundwater during normal groundwater flow conditions (near MW-3), reversed groundwater flow conditions (near MW-5), and the areas between. The boring location marked “vp” near MW-7 will extend to the base of the aquifer (estimated at 100 feet below grade), or refusal of the direct push equipment. A groundwater grab sample will be collected from the top of the water table and once every 10 feet thereafter (assumed 7 samples at this location). Two [VENICE INTERIM RESPONSE TECH MEMO.DOC] 3 NATURAL RESOURCE TECHNOLOGY TECHNICAL MEMORANDUM No. 1 groundwater grab samples will be collected at the remaining nine boring locations: one grab sample will be taken near the water table; the other will be collected approximately 20 feet below the water table (approximately 50 feet below grade). Approximately 25 total grab samples will be submitted to the lab for analysis plus additional samples for QA/QC. Figure 1. Proposed Phase I Soil Boring Locations. Access Agreements Ameren Services Company’s Real Estate Department has secured access to neighboring properties. The existing well (MW-7) and several of the proposed soil borings are located on property owned by Terminal Rail Road Association (TRRA) (Figure 1) south of the former impoundments. Existing wells (MW-8 and MW-9) and several of the proposed soil boring are located on property owned by Norfolk Southern Railway Company (NSRC) east of the former impoundments. The Representative made contact with both TRRA and NSRC to inquire about conducting the proposed soil borings. Subsequent site visits in [VENICE INTERIM RESPONSE TECH MEMO.DOC] 4 NATURAL RESOURCE TECHNOLOGY TECHNICAL MEMORANDUM No. 1 August 2009 confirmed placement of sample locations that would minimize interference with railroad activities on each site. Since the site visit in August, both Norfolk Southern and TRRA have agreed to provide access. Schedule A contractor will be selected to install the soil borings, sample bottles will be ordered, and NRT will mobilize to the site as soon as possible, likely in October. The soil borings and groundwater samples are anticipated to take 4 days to collect. The groundwater analysis will take approximately 4 weeks under standard turn-around times. Data interpretation, discussion, and reporting are expected to take 2 weeks after receipt from the laboratory. Given this time frame, we anticipate completion of the first phase of the hydrogeologic assessment and groundwater-monitoring plan in November or early December 2009. [VENICE INTERIM RESPONSE TECH MEMO.DOC]