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May 4, 2020 Thomas Paschke City Planner City of Roseville 2660 Civic Center Drive Roseville, MN 55113 Re: Twin Lakes Station Environmental Assessment Worksheet Dear Thomas Paschke: Thank you for the opportunity to review and comment on the Environmental Assessment Worksheet (EAW) for Twin Lakes Station project (Project) in the city of Roseville, Ramsey County, Minnesota. The Project consists of a mixed-use redevelopment. Regarding matters for which the Minnesota Pollution Control Agency (MPCA) has regulatory responsibility or other interests, the MPCA staff has the following comments for your consideration. Water Resources (Item 11) Wastewater Design wastewater flow calculations should be included for average daily flow and peak flow. The total number of each development type and the design flow per unit should be itemized. A table, similar to Table 9 for traffic volume, should be included showing number of units, average flow, and peak flow per unit. A map showing the connection to the city sewer and the sewer route to the wastewater treatment plant would be useful. A brief discussion of the Metropolitan Council Environmental Services (MCES) wastewater treatment plant, where the flow will ultimately be treated, should be included. Currently the EAW only mentions that the wastewater will be treated at one of the nine MCES facilities. Questions on the wastewater should be directed to Dave Sahli at 651-757-2687 or David.Sahli@state.mn.us. Stormwater It is strongly advised that the redevelopment consider improving existing stormwater conditions by incorporating green infrastructure practices that will help the development resist the impacts from increasing rainfall in Minnesota and protect the water quality of the downstream receiving waters. Examples include maximizing green space and planting trees, creating bioinfiltration areas, constructing narrower streets and sidewalks to reduce impervious surfaces, creating infiltration trenches in parking lots or tree boxes, using pervious pavements and reusing stormwater during dry spells. Additional information on these practices can be found in Minnesota’s Stormwater Manual. Please direct questions regarding construction stormwater to Roberta Getman at 507-206-2629 or Roberta.Getman@state.mn.us. Contamination/Hazardous materials/Wastes (Item 12) It appears that the Phase I and Phase II Environmental Site Assessments were conducted only on the northern portion of the Project site. Therefore, it is not clear if there is the potential for contamination on the southern portion of the site, or if the Response Action Plan/Construction Contingency Plan will be implemented on the southern portion of the Project Site. Please clarify.