20160506_Memo to KA and PO regarding brownfieldc:\users\jennyp\appdata\local\microsoft\windows\temporary internet files\content.outlook\hj6yfgnq\20160506_memo to ka
and po regarding brownfield.docx
MEMORANDUM
TO: Kate Aanenson, Community Development Director
Paul Oehme, Director of Public Works/City Engineer
FROM: Terry Jeffery, Water Resources Coordinator
DATE: May 9, 2016
SUBJ: Chick-fil-A Brownfield Remediation
On April 28, 2016, HR Green, the consultant for Chick-fil-A, provided Barr Engineering,
the district engineer for Riley Purgatory Bluff Creek Watershed District, with a draft
limited Phase II Environmental Site Assessment (ESA). This was provided to the City on
May 1, 2016. The Phase I ESA identified three potential contaminant sources within 175
feet of the current property. The Phase II ESA identified the following contaminants on
site above Minnesota groundwater standards. These include benzene, 1-
methylnaphthalene and naphthalene. Other volatile organic compounds (VOCs) and
semi-volatile organic compounds (SVOCs) were detected but were below Minnesota
groundwater standards. In addition, Resources Conservation and Recovery Act (RCRA)
metals were detected within the soil.
Based upon these findings, the environmental professional made a number of
recommendations. Some of the more germane recommendations are as follows:
Soils should be treated as hazardous materials and should be disposed of
accordingly.
Two permanent groundwater monitoring wells should be installed.
The MN Pollution Control Agency (PCA) should be notified of the VOCs,
SVOCs, RCRA metals and gasses detected above the respective regulatory
threshold according to MN Statute 115.061.
State and Federal laws prohibit infiltration in areas where, among other criteria, there is
less than three (3) feet of separation from the bottom of the infiltration feature and the
elevation of seasonally saturated soils and areas where high levels of contaminants in
soils and groundwater will be mobilized by infiltrating stormwater. Staff cannot
determine if these conditions exist based upon the evidence provided. Staff has already
made it a Condition of Approval that the applicant provide adequate evidence that the
mottled and gleyed soils were not created by saturated soil conditions, which is the most
likely cause. The Phase II findings have been provided to the MN PCA for their review
and the development of a Response Action Plan (RAP).
This site is located within the Drinking Water Surface Management Area (DWSMA) for
Chanhassen. The site is also within the composite 1-year capture zone for nine (9) city
wells.
Because of these recent revelations, the following conditions should be added to the staff
report:
Chick-fil-A Brownfield Remediation
May 9, 2016
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The applicant shall, as part of the RAP, get guidance from the MN Pollution Control Agency on
whether infiltration would be allowed in the area.
In the event that infiltration is not allowed, the applicant must redesign the storm sewer
management system so that the following conditions are met:
o There shall be no increase in rates leaving the site.
o Abstraction is achieved to the maximum extent practicable. Other abstraction methods
such as reuse must be evaluated.
o Water is treated to achieve 90% removal of Total Suspended Solids and 60% removal of
Total Phosphorus.
In the event that infiltration is not allowed, the Surface Water Connection Fee credit shall be
modified to reflect the amount of abstraction achieved on the site. If no abstraction is achieved
the credit shall be $0.00 and the fee due shall be $39,994.68.
This concludes my amended review. Please contact me at extension 1168 with any questions.