(A) Site design process.
(1) Whenever possible, new development projects shall be designed using the “better site design techniques” of the current version of the Minnesota Stormwater Manual available at: http://stormwater.pca.state.mn.us/index.php/Better_site_design.
(2) Better site design involves techniques applied early in the design process to preserve natural areas, reduce impervious cover, distribute runoff and use pervious areas to more effectively treat stormwater runoff. Site design should address open space protection, impervious cover minimization, runoff distribution and minimization, and runoff utilization through considerations such as:
(a) Open space protection and restoration:
1. Conservation of existing natural areas (upland and wetland);
2. Reforestation;
3. Re-establishment of prairies;
4. Restoration of wetlands;
5. Establishment or protection of stream, shoreline and wetland buffers; and
6. Re-establishment of native vegetation into the landscape.
(b) Reduction of impervious cover:
1. Reduce new impervious cover through redevelopment of existing sites and use of existing roadways, trails, etc.;
2. Minimize street width, parking space size, driveway length, sidewalk width; and
3. Reduce impervious surface footprint (e.g. two-story buildings, parking ramp).
(c) Distribution and minimization of runoff:
1. Utilize vegetated areas for stormwater treatment (e.g. parking lot islands, vegetated areas along property boundaries, front and rear yards);
2. Direct impervious surface runoff to vegetated areas or to designed treatment areas (roofs, parking, driveways drain to pervious areas, not directly to storm sewer or other conveyances);
3. Encourage infiltration and soil storage of runoff through grass channels, soil compost amendment, vegetated swales, rain gardens, etc.; and
4. Plant vegetation that does not require irrigation beyond natural rainfall and runoff from the site.
(d) Runoff utilization. Capture and store runoff for use for irrigation in areas where irrigation is necessary.
(3) Stormwater criteria. The following general criteria shall be incorporated in site design for stormwater runoff to protect surface and ground water and other natural resources by maintaining pre-development hydrological conditions:
(a) Reduce impacts on water;
(b) Protect soils;
(c) Preserve vegetation;
(d) Decrease runoff volume;
(e) Decrease erosion and sedimentation;
(f) Decrease flow frequency, duration, and peak runoff rates;
(g) Increase infiltration (groundwater recharge);
(h) Maintain existing flow patterns;
(i) Reduce peak flows;
(j) Store stormwater runoff on-site; and
(k) Avoid channel erosion.
(4) Erosion and sediment control criteria. The following general criteria shall be incorporated in site design for erosion and sediment control:
(a) Minimize disturbance of natural soil cover and vegetation;
(b) Minimize, in area and duration, exposed soil and unstable soil conditions;
(c) Protect receiving water bodies, wetlands, and storm sewer inlets;
(d) Protect adjacent properties from sediment deposition;
(e) Minimize off-site sediment transport on trucks and equipment;
(f) Minimize work in and adjacent to water bodies and wetlands;
(g) Maintain stable slopes;
(h) Avoid steep slopes and the need for high cuts and fills;
(i) Minimize disturbance to the surrounding soils, root systems and trunks of trees adjacent to site activity that are intended to be left standing; and
(j) Minimize the compaction of site soils.
(B) Other design standards.
(1) All volume control for water quality and quantity and site design specifications shall conform to the current version of the Minnesota Stormwater Manual.
(2) All erosion and sediment control requirements shall conform to the current requirements of NPDES/SDS construction stormwater general permit.
(3) Public stormwater detention facilities must be located on public property and accessed by a 30 foot easement.
(4) It is the responsibility of the applicant to obtain from adjacent property owners any necessary easements or other property interests concerning flowage of water.
(Ord. 20220120-01, passed 1-20-22)