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HomeMy WebLinkAboutRoyal Golf Res Dev. EAW_MDH Comment Letter Minnesota Department of Health PROTECTING, MAINTAINING AND IMPROVING THE HEALTH OF ALL MINNESOTANS November 23rd, 2016 Stephen Wensman Planning Director City of Lake Elmo 3800 Laverne Avenue North Lake Elmo, MN 55042 Dear Mr. Wensman, Thank you for providing the Minnesota Department of Health (MDH) with the opportunity to comment on the Environmental Assessment Worksheet (EAW) for the Royal Golf Club Residential Development project. The mission of MDH is to protect, maintain, and improve the health of all Minnesotans. The careful planning and development of projects such as this one supports this mission and is an important step in ensuring health in all policies. MDH does have several comments regarding groundwater, water quality, and soil contamination at and near the site: Section 10—"Geology" Although no sinkholes have been identified on the project property, the Minnesota Geological Survey (MGS) karst inventory does map one sinkhole less than one mile northeast of the project property, just north of the intersection of Manning Avenue and 27th St. N. (UTM coordinates 510846/4981836). Depth to carbonate bedrock is an important factor in the potential for karst development, with that potential increasing significantly where depths are less than 50 feet (Alexander, et al. , 2003, "Sinkholes, Sinkhole Probability, and Springs and Seeps", Goodhue County Atlas, County Atlas Series, Atlas C-12,Part B,Plate 10). Well logs near the east property boundary of the project area indicate depth to bedrock is approximately 47-59 ft. (unique well numbers:442166,447252,431201,and 503306). Two infiltration areas and two stormwater ponds are planned near the northeast corner of the project property(as shown on Figure 7). Consideration should be given to potential karst development beneath these infiltration areas and whether any mitigation measures are needed, particularly given the proximity of these areas to planned home construction. Section 11 —"Water Resources" The groundwater discussion should include more information regarding the perfluorochemical (PFC) contamination in the groundwater in this area. Groundwater has been impacted by PFCs from the former Washington County Landfill and 3M-Oakdale Disposal Site. Due to groundwater flow, surface water-groundwater interactions, and stormwater management activities, the groundwater east of Lake Elmo has been impacted by PFCs emerging from these disposal areas. Recent MDH sampling has detected PFCs at concentrations above the new Environmental An equal opportunity employer Stephen Wensman The Royal Golf Club Residential Development Page 2 November 23rd, 2016 Protection Agency (EPA) Lifetime Health Advisory levels of 70 parts per trillion for PFOS and PFOA in the surface water in Lake Elmo,the unnamed creek that discharges from Lake Elmo onto the project property, Horseshoe Lake, and the series of ditches and stormwater ponds further downstream. Surface water ponds on the property that are part of the Project 1007 drainage system are almost certain to be similarly impacted. The full extent and distribution of PFCs in this portion of Lake Elmo are still being determined. Use of surface water or groundwater at the project site should be carefully managed to avoid human exposure and prevent further spreading of the contamination. MDH further recommends landscaping options be implemented to create significant buffers in order to restrict public access to Horseshoe Lake. Preliminary data suggests PFC contamination is primarily in the Prairie du Chien aquifer(OPDC), but excessive use of Jordan aquifer (CJDN) wells may cause downward migration of the contamination, potentially placing downgradient CJDN wells at risk. MDH recommends the project proposer work with MDH,MPCA, and DNR to evaluate water quality in the existing wells and surface waters on the project property and determine appropriate use of these to mitigate for these potential impacts. Section 12—"Contamination/Hazardous Materials/Wastes" The sub-section titled"Investigation History"indicates a"disposal area"is located on an adjoining property to the southeast. The location is not shown on any figures and no information is provided regarding this disposal area and its proximity to the project property. The sub-section titled "Response Action Plan" indicates that contaminated soils excavated at the site are to be managed in a"Regulated Soil Management Area"beneath a 2 ft. cover. The figure shown in the Phase II Investigation Report (Appendix D) indicates the area proposed for this management area has a significant slope and may be prone to erosion. MDH assumes MPCA will be consulted in the design and construction of this facility to ensure it provides long-term encapsulation of these soils to prevent exposures. The sub-section titled"PFCs and Area Groundwater Contamination" (page 27) should be revised to reflect that PFCs above levels of health concern are present in the groundwater in this part of Lake Elmo. Although the concentrations detected in the CJDN wells on the property do not exceed levels of health concern, as noted above continued extraction of water from the CJDN may result in increased PFCs in this aquifer over time. Appendix D—Table 3 Although the table correctly identifies the current MDH Health Risk Limits for PFOS, PFOA, PFBA, and PFBS, it should be noted that MDH now uses the new EPA health advisory levels of 70 ng/L for PFOS and PFOA when evaluating health risks. Health starts where we live, learn, work, and play. To create and maintain healthy Minnesota communities, we have to think in terms of health in all policies. Thank you again for the opportunity to provide comments on this EAW for the Royal Golf Club Residential Development project. Feel free to contact me at (651) 201-4907 or david.belIgstate.mn.us if you have any questions regarding this letter. Sincerely, Stephen Wensman The Royal Golf Club Residential Development Page 3 November 23rd, 2016 )--t David Bell Environmental Review Coordinator Environmental Health Division Minnesota Department of Health PO Box 64975 Saint Paul, MN 55164-0975