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HomeMy WebLinkAbout190730 2 MCWDimpervioussummarySummary: Impervious Cover Requirements for cities in Minnehaha Creek Watershed District City Impervious Cover Requirement – Shoreland Impervious Cover – Single Family Land use outside shoreland zone Number of variances for impervious cover Notes Chanhassen 25% impervious in Shoreland Management District (Sec. 20-485) 25% maximum coverage for all structures and paved surfaces [Sec. 20- 615]. Gravel is considered impervious. 6 BMPs may be required if granted a variance – varies by case. Deephaven 25% only in shoreland district no impervious cover limits out of the shoreland district 3 BMPs required if granted a variance – on advice of city engineer. Edina The city does not have any impervious surface limitations in or out of the shoreland zone. If a property exceeds impervious cover limits, the BMP requirements are determined through the city's variance permit. N/A Excelsior 35% Anything greater than 35% would require a variance permit (in general, the city does not regularly allow impervious cover >35%) 3 - two were for commercial properties to meet ADA requirements and 1 was for a residential home that exceeded the impervious surface requirement but decreased some of their impervious surface as part of their development proposal. Shoreland: Rate of runoff cannot increase with any new development on property; A stormwater management review is required with any land disturbing activity; There is only a small piece of the city of Excelsior that is out of the shoreland district (1000' from OHWL); If a property exceeds impervious cover limits, the BMP requirements are determined through the city's variance permit; green space minimum=60%, and 60% of the lot shall be free of above ground construction of any kind; The city's variance permit encourages the use of pervious pavers, redirecting downspouts to green areas, raingardens, etc. Greenwood 30% 30% impervious limit for the entire city 2 BMPs required if granted a variance – on advice of city engineer. Golden Valley 50% (11.21 Subd. 10) 11.21 Subd. 19--No more than 40% of the front yard may be covered by concrete, bituminous pavement, or pavers. They encourage raingardens when they can, but the city has clay soils so its not always logical. But generally, BMPs are not required on a single family lot (they are required for single family subdivisions)[Al Lundstrom] Hopkins 35% 35% is the limit for building coverage only. No impervious cover limitations. 0 Hopkins only has a floodplain ordinance (no shoreland ordinance). The info from the shoreland ordinance section is actually from their zoning code; Contact stated they had not granted a variance in years ('not how they operate') Independence 25% See Sec 505.13 subd. due to the 2 1/2 acre minimum, there 0 When development density, etc can't meet or isn't sufficient to 2 table is no impervious cover limitation on non-shoreland lots handle stormwater runoff adequately, then BMPs such as diversions, settling basins, etc. See Sect 505.23, subd. 6 (b) Long Lake 30% for "R2" - Lakeshore SF [sec. 8 p. 1] Seems like there are only limitations for "R2" Lakeshore Single Family District (see shoreland ordinances). Per conversation with city officials, there are no impervious cover limits, but there are building coverage limits (principle + accessory structures) Conditional use permits granted under the conditions: 1. The smallest amount of bare ground is exposed for as short a time as feasible, 2. Temporary ground cover is used and permanent ground cover is planted, 3. Methods to prevent erosion and trap sediment are employed, 4. Fill is stabilized to accept engineered standards [sec. 8 p. 2]; Conditions that may be attached to Conditional Use permits: 1. Increased setbacks from OHWL, 2. Limitations on natural vegetation to be removed or the requirement that additional veg be planted, 3. Special provisions for the location, design and use of structures, watercraft launching and docking areas [sec. 17A p. 10]; A copy of approved amendments granting variances must be sent to the DNR [sec. 17A p. 3] Maple Plain No shoreland district None. At least 3 The idea the city has is if someone wants to exceed a regulation, they can as long as it is made up for through the use of LID technologies or other BMPs. Medina 25% 40% in most districts; Especially in area within MCWD (which is mostly Rural Residential [RR]) 1 single family residential; 1 commercial For the RR zoning district, up to 50% impervious may be allowed with LID features and/or BMPs incorporated (this is formatted similar for other zoning districts as well [i.e. 20% impervious limit for RR-UR, can go up to 30% with BMPs/LID]); Sec. 840.1.05, Subd. 9, R1 (single family) Lot Standards:"Impervious surface coverage may exceed this amount [40%] if stormwater management practices are implemented on the lot which, according to the City Engineer, reduce runoff below that which would occur if abiding by the maximum impervious surface regulation. However, in no case shall impervious surface coverage exceed 60 percent of the lot area remaining after wetlands and stormwater ponds have been excluded." Minneapolis No mention of impervious limitation in shoreland overlay district section; must just be the same as No more than 65% in R1-R3 (546.150) in residential zoning (65%) Minnetonka Currently there is no impervious surface rule for non-shoreland districts. The city has a draft impervious surface limitation rule that is being reviewed by their city council (still "bruised" after recent issues with new wetland buffer rules, so they are not expecting an impervious surface rule to be passed very soon. If/when passed, the new one would be more restrictive than shoreland district impervious cover limit). 6 Applicants can exceed impervious cover limitations with the use of BMPs (pervious pavers, raingardens, etc.). Also, the Stormwater Management requirements do apply to single family lots if the triggers are reached. BMPs are required for stormwater management. On a parcel, there is a 30% impervious limit only for land within 150' of OHWL. If there is land on that same parcel that is more than 150' from the OHWL, there is a 75% limit for that area. Minnetonka Beach 30% 30% 0 Minnetrista 25% 25% impervious max in all zoning districts 0 (pavers have been exempted from hard cover until 2008) Non-pervious pavers have been exempted from hard cover until 2008--now they are not exempt. Pervious pavers count for 50% of what impervious surface counts for. Mound 30% for lots in or out of shoreland zone (up to 40% for lots of record) 40% for lot of record, 30% all others 0 BMPs are used on a case by case basis (if there is any indication of drainage problems, then they would be required) Orono 0 to 75 feet - only steps on steep banks and minimal driveway if no other access, 75 to 250 feet - 25%, 250 to 500 feet -30%, 500 to 1,000 feet - 35% No more than 15% of a lot smaller than 2 acres can be covered by buildings About 160 variances have been granted but we are unable to easily determine how many were for impervious cover. No formal requirement to install BMPs if granted a variance. Plymouth 25% within Shoreland Management Overlay District No impervious limitations outside of shoreland district 8 were applied for; 1 was denied and 7 were approved. All 7 that were approved were for sunroom additions onto existing townhomes within the same development Shoreland: "Requests for variances to this Section shall include one or more BMPs for controlling/improving stormwater runoff, as may be determined by the city council. Examples of BMPs include, but are not limited to, rain gardens, infiltration basins, and riparian buffers." Sec. 21665.10 Subd. 3; No requirements to (Cimarron Ponds), where the size of the "unit lot" is only slightly larger than the size of the actual dwelling unit. In this development, the requirement for these variances is more of a technicality, because if the pro-rated share of the "base lot" for the development (dedicated common open space providing a natural buffer to protect Gleason Lake) was included in the impervious cover calculation, none of these variances would have been required. install BMPs in non-shoreland districts. However, the city contact stated that there is an increasing number of residents interested in installing raingardens on their "single family" property, even out of the shoreland district. The Plymouth Home & Garden Expo has workshops on raingarden installation/maintenance that are popular with residents. The city contact himself even has one installed on his property. Richfield maximum of 45% impervious None Nothing in their zoning code about requiring BMPs on single family lots, but all development plans must comply with the city's Stormwater Management Plan Shorewood 25% maximum 33% for residential; Commercial and govt = 66% 1 Variances are not granted very often. Spring Park 30% or 3,000 square feet 30% or 3,000 square feet None Shoreland Variance: up to 40% with BMPs; If there is a setback variance granted, things like water diversion away from the lake, water retention features, and raingardens may be required; There is no separate zoning code for non-shoreland districts--All the areas in the entire city that are not in the shoreland district are portions of parcels that are in the shoreland district. St. Bonifacius No Shoreland District 35% None St. Louis Park none 35% for single family homes. This is for the structure only, it does not include driveways, patios, detached garages less than 15 feet in height, sheds, etc. Driveways are limited to an average width of 22 feet in the front yard. None Typically the city does not require BMPs on single family lots, but it is considered on a case-by-case basis (i.e. if they are exceeding other regulations) Tonka Bay 25% allowed; 26-35% with Admin/Engin. 25% allowed; 26-35% with Admin/Engin. Approval; 36% over 5 (of 16 additions, 22 rebuild) Engineer decides when BMPs are necessary (case-by-case basis) Approval; 36% over requires public hearing requires public hearing Victoria 25% for residential 25%; 30% for PUD One in 2005 for a handicap acessibility ramp and owner was required to redirect runoff to street versus lake The city does not usually require BMPs on single family lots in general, but people try to propose the use of BMPs (i.e. raingardens) so they can increase impervious cover limits. In order for the city to approve something like that the applicant need to prove the effectiveness of the proposed BMPs with stormwater calcs & pictures, and their proposed plan must be approved by the city engineer. One situation someone wanted to put interlocking pervious pavers on their driveway and exceed impervious cover limitations. The city approved the variance since it was a relatively permanent feature (unlike a raingarden that can be filled in easily). They still had to prove the effectiveness of the pavers prior to the project being approved. Wayzata 25% 20% – 35% depending on zoning district Zero - City offers Conditional Use permit on Shoreland properties (12 CUP's since 2005) Single family lots are allowed up to 75% impervious with innovative stormwater management techniques--but overall it is the discretion of the city engineer. The BMPs that would be required would depend on the extent of the variance (i.e. 20% over the impervious limit--city might require a pervious driveway; 2% over the impervious limit--city might require a rain barrel). In general, if someone proposes an exceedence of the impervious surface limit, the city first asks them to minimize impervious surfaces and/or reduce the extent of the project, or install BMPs.; Woodland 25% 25% 2 The entire city is in the "shoreland district" (25% impervious limit for entire city); BMPs required if granted a variance – on advice of city engineer.