08-11-11 Planning Comm. Agenda - Laserfiche WebLink

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Planning Commission July 29, 2011 Page Two 3. The final plan should provide details on how the watermain testing will be completed. If a new valve is not installed at the connection, the existing valve must be inspected and any deficiencies corrected at the time of the connection. The connection to the existing watermain must be coordinated with Agropur, formerly Schroeder Milk, as they are a high volume user and typically run 24 hours a day. 4. All storm water entering infiltration areas must be pretreated for sediment removal prior to discharge to the practice. Sumps or sediment removal structures should be added to accommodate this requirement. Civil Details 1. The top barrel section of all manholes should be a 1 -foot section. 2. Retaining glands, megalug or equal, can be used in lieu of rodding for hydrants. Operating and cap nuts shall be to Little Canada standard. Landscape Plan 1. A planting plan for the 10 -foot bench area of the large pond should be included in the landscape plan. 2. Seeding is proposed for the large pond slope and we would recommend plug planting be utilized to ensure sufficient establishment since the pond areas will receive stormwater shortly after construction. A seed mixture should be indicated for the snow melt pond in the northeast corner of the site. 3. The boulevard area between the Park & Ride facility and the public streets is proposed to be largely trap rock. The applicant should specify if the rock will be placed on the ground or if a plastic barrier will be used as this will affect the stormwater runoff from the site. Drainage Calculations 1. A post construction drainage area map was provided as part of the submittal but an existing drainage area map should be provided for comparison. Pre existing rates of discharge should be provided for each drainage direction. 2. The existing area is slightly higher that the proposed area. Both areas should be equal. 3. The site consists of silty clay and silty sand soil types. A type C soil and associated curve number should be utilized in HydroCAD modeling. 4. The proposed pond 2S is modeled as wet pond and therefore any area below the normal water level (NWL) should have a curve number of 100. 5. A detail should be provided for the outlet structure for Pond 2P and the underground system outlet for verification of modeling. 6. Infiltration /exfiltration rates from imported sand should be modeled at 0.8- inches per hour. 7. The post condition discharge rates should be determined without the use of infiltration to ensure rate control will be accomplished in the event the infiltration systems fail. Ltr- 072911 -PC 10062 Flanders Court NE, Blaine, MN 55449 - Phone: (763) 780 -0450 - Fax: (763) 780 -0452