08/28/2002 Env Bd Packet - Laserfiche WebLink

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. The lighting plan submitted identifies proposed lighting fixtures. These fixtures are not consistent with our ordinance requirements. • • Analysis: • The high water elevation of the large basin on the west is indicated at 897.2. The West infiltration basin on the site is proposed to have a base elevation of 897.0. There needs to be at least a 3 -foot separation between the bottom of the basin and the seasonally high ground water level. The applicant should demonstrate that adequate separation exists or redesign the improvements to achieve this separation. This 3 -foot separation is consistent with MPCA's guidelines for septic systems. In addition, given this is a light industrial site, the applicant should submit a soil sensitivity test for designed systems to evaluate potential effects on groundwater. If runoff water could contain a significant concentration of soluble pollutants, infiltration basins should not be used. Proximity to drinking wells must be evaluated. Basins should be at least 150 feet from any wells and be situated at least 10 feet down - gradient and 100 feet up- gradient from building foundations • Basins should be designed with pretreatment features such as grit chambers, swales with check dams, filter strips, or sediment fore bays. Traps should be a component of any infiltration system. Desirable side slope dimensions of the basin should be no greater than 3H: 1V. Flatter slopes are preferred. The basin water depths should be no more than 2 feet to eliminate compaction to the basin, and the ponding time no more than 72 hours. A desirable length to width ratio for an infiltration basin should be 3:1 or greater. Overflow should include check dams, level bars or other structures to ensure sheet washing. Access to the site for maintenance should be addressed. • Swale areas should be kept to a 1% to a 2% slope. Recommend that the design of these swales be modeled after Met Council /Barr engineering design standards. • Sequencing and Construction Sequencing Plans (BMP's) should be submitted. Suggested guidelines are in the Minnesota Urban Small Sites BMP Manual. (Attachment 10). • A Maintenance Plan should be submitted with the BMP Plan. (Attachment 11). • The landscape plan seems to have appropriate materials. All soil areas in the landscape, and surface water treatment train, should follow written and approved BMP's. There are no trees that will be saved on this site. The City native plant seed schedule (Attachment 12), should be used in and around the basins and swales, unless