The URL can be used to link to this page

1. Surface Water Management Plan UpdateCity of Chanhassen Local Stormwater Management Plan Update Planning Commission November 19, 2013 :7=1 Background Chanhassen has begun updating our Surface Water Management Pan. As we update this plan we will be coming to this body to discuss necessary changes to our local controls. These changes will predominately apply to stormwater management. Changes may also be required for erosion control and wetland protection. Attached you will find a table comparing the regulatory requirements of each agency with jurisdiction in Chanhassen. This table will be updated prior to the November 19, 2013 meeting. Plan Contents Contains three major sections: an inventory, goals and policies, and an Implementation Plan. 1) Inventory • Inventory of physical environment and water resources • Updated stormwater modeling • Condition assessment: water quality, stream conditions, pond inventory, wetland data • Information from other studies or reports • TMDLs, Use Attainability Analyses • Watershed District requirements • NPDES - stormwater permit requirements • Wetland inventory • Bluff Creek Watershed Natural Resources Management Plan • Wellhead protection plan • Other agency requirements 2) Goals and Policies • Holistic water management — stormwater, lakes and streams, wetlands, groundwater 3) Implementation Plan • Programs, including education and outreach program • Capital projects • Maintenance actions • Ordinance revisions • Assessment of adequacy of funding City of Chanhassen Local Water Management Plan Update "= 44Wenck November 19, 2013 Engineers • Scientists Business Professionals 6IZ5 . Development and Redevelopment Project Review /Permit Requirements of Various Agencies 11/19/2013 Chanhassen NPDES MS4 Permit NPDES Construction Permit Carver County WMO Riley- Purgatory —Bluff Cr WD Lower Minnesota River WD Minnehaha Creek WD Plan: Plan: January 26, 2011 Plan: December 14, 2011 Plan: July 5, 2007 Rules: Rules: In development Rules: Cities Rules: May 2011 Threshold: single family Disturb >1 acre of land, or Disturb >1 acre of land, or a. Land - disturbing activities Disturb >1 acre of land 21 acre where more than 20% residential new development part of common development part of common development that will disturb 50 cubic yards of site is or will be impervious >1 acre >1 acre or more of earth; b. Land - disturbing activities that will disturb 5,000 square feet or more of surface area or vegetation; or c. Subdivision of a parcel into three or more residential lots. Threshold: non - residential Disturb >1 acre of land, or Disturb >1 acre of land, or a. Land - disturbing activities Disturb >1 acre of land 21 acre where more than 20% new development part of common development part of common development that will disturb 50 cubic yards of site is or will be impervious >1 acre >1 acre or more of earth; b. Land - disturbing activities that will disturb 5,000 square feet or more of surface area or vegetation; or Threshold: single family Disturb >1 acre of land, or Disturb >1 acre of land, or Same as above, except where Disturb >1 acre of land 151 acre; requirements vary by residential redevelopment part of common development part of common development redevelopment of more than size, change in >1 acre >1 acre 50% of site or that increases imperviousness, and % impervious by more than 50 %, disturbance applies to entire site; less than 50% of site, applies only to disturbed area /new impervious Threshold: non - residential Disturb >1 acre of land, or Disturb >1 acre of land, or Same as above, except where Disturb >S acre of land :51 acre; requirements vary by redevelopment part of common development part of common development redevelopment of more than size, change in >1 acre >1 acre 50% of site or that increases imperviousness, and % impervious by more than 50 %, disturbance applies to entire site; less than 50% of site, applies only to disturbed area /new impervious Threshold: grading and erosion Disturb >1 acre of land, or Disturb >1 acre of land, or a. Land - disturbing activities As required by the General All land disturbing activity control part of common development part of common development that will disturb 50 cubic yards Permit for Construction except agriculture and >1 acre >1 acre or more of earth, disturbances of less than b. Land- disturbing activities 5,000 sq ft moving less than that will disturb 5,000 square 50 cu yd feet or more of surface area or vegetation Water quality: new No net increase in TP or TSS Wet pond with 1,800 cu ft Provide for at least 75% Treatment as required by the No net increase in TP, except development annual load dead storage per contributing removal of TP and 90% General Permit for where land use was row acre and live storage of 1" of removal of TSS from all runoff Construction; NURP pond crop /feedlot, must be runoff from new impervious from impervious surface designs apply modeled as if meadow surface Development and Redevelopment Project Review /Permit Requirements of Various Agencies 11/19/2013 Chanhassen NPDES MS4 Permit NPDES Construction Permit Carver County WMO Riley- Purgatory —Bluff Cr WD Lower Minnesota River WD Minnehaha Creek WD Plan: Plan: January 26, 2011 Plan: December 14, 2011 Plan: July 5, 2007 Rules: Rules: in development Rules: Cities Rules: May 2011 Water quality: redevelopment Decrease in TP and TSS annual Wet pond with 1,800 cu ft Provide for at least 75% Treatment as required by the Varies based on size and load dead storage per contributing removal of TP and 90% General Permit for whether impervious is acre and live storage of 1" of removal of TSS from all runoff Construction; NURP pond increased or decreased runoff from new impervious from impervious surface designs apply surface Rate control No specific requirement No more than 5.66 cfs per No increase over 2-, 10 -, and No increase over 1 -or 2-, 10-, No increase over 1 -, 10-, and acre pond surface area 100 -year rates or 100 -year rates 100 -year rates, except where land use was row crop /feedlot, must be modeled as if meadow Infiltration: new development No net increase in annual If more than 1 acre of new 1.1" abstraction from all 0.5" runoff from new 1" from impervious surface. runoff volume impervious, infiltrate /abstract impervious surface impervious surface Where 1" infeasible, must do 1" from new impervious at least 0.5" plus additional TP surface reduction Infiltration: redevelopment Decrease in annual runoff If more than 1 acre of new 1.1" abstraction from all 0.5" runoff from new 1" from impervious surface. volume impervious, infiltrate /abstract impervious surface impervious surface Where 1" infeasible, must do 1" from new impervious at least 0.5" plus additional TP surface reduction Wetland buffer No specific requirement 100 feet from a special water 20 to 100 feet from wetlands, a. <2 acres, 25' minimum; 16 to 75 feet, depending on depending on mgmt. class; 50 b..2 acres, 25' minimum, wetland mgmt class feet from a water basin; 50 average 50' feet from the greater of the centerline of watercourse or edge of meander belt; 30 feet from a first -order stream Linear projects Disturb >1 acre of land; may Disturb >1 acre of land If project creates more than No specific requirement Projects creating >10,000 sq ft be excepted from some or all 5,000 square feet of new or new impervious surface infiltration requirement if lack additional impervious surface. sufficient right of way Applies only to all new and reconstructed impervious surface. Bluff requirements No specific requirement No specific requirement Unknown No removal of vegetation in No specific requirement the Bluff Impact Zone and Bluff Face; new structure setback 30 ft top of bluff, SSTS setback 50 ft TP -40 or Atlas 14 TP -40 No specific requirement No specific requirement Atlas 14 Cities Will adopt Atlas 14 as part of current rule revision