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f) A plan for maintenance of the system must be submitted that identifies the maintenance activities and frequency of activities for each infiltration practice on the site. A signed maintenance agreement will be required by the City. 6) Pond and Additional Infiltration System Design Criteria. Newly constructed or expanded/modified ponds and basins shall be designed and constructed to meet the following: a) All ponds or basins shall: 1) Have a 4:1 maximum slope (above the normal water level [NWL] and below the 10:1 bench, if a wet pond); 2) Maximize the separation between inlet and outlet points to prevent short-circuiting of storm flows; 3) Have an emergency overflow spillway identified and designed to convey storm flows from events greater than the 100-year event; and 4) Be made accessible for maintenance and not be entirely surrounded by steep slopes or retaining walls which limit the type of equipment that can be used for maintenance. Vehicle access lane(s) of at least ten (10) feet shall be provided, at a slope less than fifteen percent (15%) from the access point on the street or parking area to the pond, to accommodate maintenance vehicles. Maintenance agreements will be required when the pond is not located on City property. b) All wet ponds shall: 1) Have an aquatic bench having a 10:1 (H:V) slope for the first ten (10) feet from the NWL into the basin; 2) Have inlets be placed at or below the NWL; 3) Have a skimming device designed to remove oils and floatable materials up to a five (5) year frequency event. The skimmer shall be set a minimum of twelve (12) inches below the normal surface water elevation and shall control the discharge velocity to 0.5 feet per second. 4) Have an average four (4) feet of permanent pool depth (dead storage depth). This constraint may not be feasible for small ponds (less than about three [3] acre-feet in volume or less). In such cases, depths of three to four (3-4) feet may be used. To prevent development of thermal stratification, loss of oxygen, and nutrient recycling from bottom sediments, the maximum depth of the permanent pool should be less than or equal to ten (10) feet. 7) Erosion and Sediment Control (Roseville City Code Chapter 803.04) a) The City's Erosion Control Ordinance shall be followed for all projects, including those not regulated under the NPDES construction permit. b) Prior to the start of any excavation or land disturbing activity for the site, the Applicant or contractor must have in place a functional and approved method of erosion and sediment control. The contractor must have received authorization from the City prior to commencing construction activities. c) Development projects subject to the NPDES Construction Permit shall meet the requirements of the NPDES permit program, including the requirement to prepare and follow a storm water pollution prevention plan (SWPPP). The Applicant shall submit proof of receipt and approval by Minnesota Pollution Control Agency and/or watershed district of the permit application prior to commencing construction if required. A copy of the SWPPP prepared in accordance with the NPDES permit requirements, shall be submitted to the City if requested by the City Engineer. Page 6 of 8 DRAFT