Stormwater Management in the NWA The City's Surface Water Management Plan for the Northwest Area applies a "treatment train" approach designed to mimic the natural hydrology of the existing system. This approach is more holistic in that its application begins at the planning stages of development and applies a number of Better Site Design Drawdown within 48-hours or 72-hours from the end of the storm event for surface or sub-surface features, respectively; 3. A minimum of 12-inches of organic material or sand above the rock trench or drain tile system; and. 4. Drain tile system must be designed above the seasonal high water table. (d) Stormwater ponds. Infiltration practices are susceptible to clogging by suspended solids in stormwater runoff. Therefore, infiltration trenches and basins require pretreatment to remove a portion of the solids load before entering the infiltration practice. Where infiltration or filtration facilities, practices or systems are proposed, 1. pretreatment of runoff must be provided in accordance with the guidance in the Minnesota Stormwater Manual5and will not be credited toward compliance with the criteria in subsection 3.1c. 2. Pretreatment plays an important role in stormwater treatment. Pretreatment structures, installed immediately upgradient to a stormwater control, Minnesota Pollution Control Agency (MPCA). (2016). Operation and maintenance of infiltration trench. In Minnesota stormwater manual. New Hampshire Department of Environmental Services (NHDES). (2011). this online version of the manual offers cadd images, as well as detailed presentations and discussions of the following and other relevant aspects of infiltration basin design considerations: physical feasibility, including drainage, topography and soils. practice and site considerations, such as conveyance, underdrains, pretreatment, … Arlington Pascal Stormwater Improvement Project Original Project Cost: $2.5 Million 60" Storm Sewer Pipe No Water Quality Benefits Final Project Cost: $2.0 Million 18 Stormwater BMPs Stormwater Volume and Pollutant Reduction Benefits *Costs do not include bond interest Final Total Project Capital Cost: $2.7 Million • Projects must comply with standards listed in the Minnesota Stormwater Manual, City Specifications, and the Dakota County Low Impact Development Standards • Unless otherwise approved by the Director of Public Works/City Engineer, projects shall not be located within rights-of-way or easements. The City discourages the installation of Pretreatment . plays an important role in stormwater treatment. Pretreatment structures, installed immediately upgradient to a stormwater control, reduce flow rates and remove sediment and debris before stormwater enters a stormwater control. This helps to improve the stormwater control's pollutant removal efficiency and reduces maintenance flow that could result from stormwater infiltration. See MnDOT Geotechnical Manual, Appendix H for additional background information and minimum • Provide pretreatment before discharging into an infiltration BMP. Technical Memorandum No. 14-06-ENV-01 • From MN Stormwater Manual . Source: Stormwaterpartners.com . Pretreatment: Vegetated Buffer Strips and Flow-Through Structures : MIDS Work Group . April 19, 2013 . p-gen3-15f. Title: April MIDs Work Group Presentations (multiple) Author: Barr Engineering-Minnesota Pollution Control Agency (Barb Olafson-PDF on