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B Surface Water-Related City Code Updates CITY OF CHANHASSEN 7700 Market Boulevard PO Box 147 Chanhassen, MN 55317 Administration Phone: 952.227.1100 Fax: 952.227.1110 Building Inspections Phone: 952.227.1180 Fax: 952.227.1190 Engineering Phone: 952.227.1160 Fax: 952.227.1170 Finance Phone: 952.227.1140 Fax: 952.227.1110 Park & Recreation Phone: 952.227.1120 Fax: 952.227.1110 Recreation Center 2310 Coulter Boulevard Phone: 952.227.1400 Fax: 952.227.1404 Planning & Natural Resources Phone: 952.227.1130 Fax: 952.227.1110 Public Works 1591 Park Road Phone: 952.227.1300 Fax: 952.227.1310 Senior Center Phone: 952.227.1125 Fax: 952.227.1110 Web Site www.ci.chanhassen.mn.us ~ MEMORANDUM To: Todd Gerhardt, City Manager From: Lori Haak, Water Resources Coordinator ()tf(C~ , Date: January 22, 2007 Re: Surface Water-Related City Code Updates BACKGROUND At the regular Council meeting on January 8, 2007, City staff presented the recommended ordinances that would revise City Code to bring it into compliance with the City's Second Generation Surface Water Management Plan. The City Council requested the opportunity to discuss the recommended changes at a work session. DISCUSSION The text of the proposed code revisions was included in the City Council packet for January 8, 2007. That item also included brief explanations of why the changes were proposed. The entire staff report is attached for your reference (City Council only via Agenda Manager). Two main items were brought up by council members at that meeting and a representative from the development community prior to the Council meeting. Additional information is provided below and in the attachments to this staff report. 1. Definition of Impervious Surface. Staff recommendation is to amend the definition of "impervious surface" found in the City Code to incorporate items as they are currently interpreted by City staff. Staff has compiled a list of definitions for "impervious surface" from other communities. The results of a survey on how impervious surfaces are regulated and interpreted in different communities are also being compiled. Any additional information obtained by the time of the work session will be provided at the work session. 2. Wetland Buffer and Setback Requirements. Attached are several documents that provide background on the existing and proposed wetland regulations. Additionally, staff has compiled a spreadsheet that compares wetland buffer strip and setback requirements between Chanhassen, 11 metro communities and a watershed district. The City of Chanhassen · A growing community with clean lakes, quality schools, a charming downtown, thrivin!J businesses, winding trails, and beautiful parks. A great place to live, work, and play. Todd Gerhardt January 22, 2007 Page 2 of 2 Staff will be able to answer additional questions on this information during the work session. RECOMMENDED ACTION The Council should review and discuss the proposed code revisions and recommend any changes to staff. The City Code updates should be scheduled for a City Council meeting agenda in the near future so they can be adopted and implemented as soon as practical. ATTACHMENTS 1. Definitions of Impervious Surface from Chanhassen and Other Communities. 2. Comparison of Imperviousness by Community. 3. Existing and Proposed Wetland Classifications, Buffer Strips and Setbacks. 4. Proposed Wetland Buffer Strips and Setbacks. 5. Comparison of Wetland Buffer and Setback Requirements. 6. City of Excelsior Ordinance No. 393 Pertaining to Green Space and Impervious Surface Coverage Maximums. G:\ENG\Lori\Surface Water\2006 SWMP Update\Code Updates\Misc\012207 CC Work Session Memo.doc Impervious Surface Definitions Chanhassen: Existing definition: Impervious surface means any material that substantially reduces or prevents the infiltration of storm water. It shall include, but not be limited to, gravel driveways, parking area, buildings and structures. Proposed definition: Impervious surface means any material that reduces or eliminates water infiltration when compared to local native soil surface and structure. Impervious surfaces include, but are not limited to: bituminous and concrete driveways, pavers of all material, compacted aggregate, non-porous landscape underlayment, retaining walls, buildings, rooftops, patios, landscape stepping stones or flagstones, driveways, pool decking and any other structures. Exemptions include decks when installed without impervious surface below, landscape rock or mulch with pervious underlayment. Bloomin2ton: Impervious Surface: Any surface which prevents absorption of storm water into the soil. Ea2an: Impervious Surface: A material providing a hard surface which prevents normal absorption of water into land. It shall include, but not be limited to gravel driveways, parking areas, buildings and structures. Maple Grove: Impervious surface means an artificial or natural surface through which water, air, or roots cannot penetrate, except that a swimming pool shall not be considered an impervious surface to the extent of the surface area of any water that may be used to fill the pool. Minnetonka: Impervious surface: A material providing a hard surface which prevents normal absorption of water into land. Ramsev: Impervious surface: A properly maintained artificial surface through which water cannot easily penetrate. Shoreview: Impervious Surface Coverage: Any surface that prevents substantial infiltration of precipitation and prohibits the growth of vegetation. Such surfaces include, but are not limited to, driveways, parking lots, patios, roofs, sidewalks, streets, swimming pools and tennis courts. Impervious materials include asphalt; brick; concrete; crushed rock or stone; gravel; plastic; and stone. The City Manager or his/her designee shall determine whether any proposed surface or material is pervious or impervious. The use of the material shall be considered when making a determination of the pervious or impervious nature of any material, i.e., areas subject to repeated pedestrian and vehicular traffic become compacted and are considered impervious. G:\ENG\Lori\Surface Water\2006 SWMP Update\Code Updates\Misc\Other Communities Impervious.doc ~ :: c ::s E E o o ~ .c tn tn CI) C tn ::s o .:; ... CI) c. E c: ca C) ca W Q) C) ct3 CD > o () C) '# en C::LOQ) 32C\1>- '5 .0 '# eno Q)C\1 >- c: o ~ c: "e o o in '# ,#LOen LO(")Q) (")0>- ~ en Q) >- CD c: "m in o Z c: CD en en ca .c c: ca .c o ~ LO C\I ~ C5 CD '# en C::LOQ) Q)C\I>- ..9 en Q) en '~ Q)> >- - ('" 'C c: ca CD .. o .c ('. en mm +::+:: c: c: CD CD 'C'C "U; "U; CD CD .. .. ~~ "e "e J!!J!! CD CD ('. 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LO ~C\I I 00 C\I~ ..-. 0 ~~ I 00 C') 0> 0> ~ "'0 0) II 0 C C ~ ~ a: City of Excelsior Ordinance No. 393 An Ordinance Amending the Zoning Ordinance of the Excelsior City Code Pertaining to Green Space and Impervious Surface Coverage Maximums THE CITY OF EXCELSIOR DOES HEREBY ORDAIN: SECTION ONE: Purpose: Prior to September of 2004, the City followed an informal policy that exempted paver bricks from impervious surface calculations. The exemption was based on the assumption that storm water would not run off of areas covered by paver bricks. In the fall of 2004, the Excelsior City Council declared a moratorium on the policy of exempting paver bricks from impervious surface calculations in order to allow the Planning Commission to study the effect of paver bricks on storm water runoff. After studying the issue, the Planning Commission found that, although some types of paver bricks reduced the rate of storm water runoff, many resulted in little or no reduction in runoff. Based on these findings, the Planning Commission recommended that the policy of exempting pavers from impervious surface calculations be discontinued. As a result of the Planning Commission's study and recommendation, the City Council is adopted this ordinance. In addition, this ordinance is intended to update the City's regulations related to green space and impervious surface coverage for development within the community. SECTION TWO: The City of Excelsior has determined it must update its regulations related to green space and impervious surface coverage for development within the community. With this Ordinance, the City is defining green space, impervious surface coverage, and pavers. The lot requirements and setback sections of each of the zoning districts are also being updated to add specifications for green space. SECTION THREE: Section 2-2, Definitions of the Zoning Ordinance of the Excelsior City Code is amended to read as follows: 2-2 DEFINITIONS: GREEN SPACE: An area not occupied by structures or impervious surface coverage. It includes open or landscaped areas which are covered by vegetation or decorative landscape materials with permeable landscape barrier material, or water bodies (lakes, ponds, and streams) which have a natural bottom. In residential districts. Ogecorative walkways, retaining walls for planting areas, and decorative water features are included in this definition but shall account for, in total, not more than five (5) percent of the total lot area devoted to green space. Not to be included in this definition are swimming pools and walkways that are designed for more than incidental pedestrian use. Any other impervious surface coverage shall not be considered green space. Ordinance No. 393 Page 2 IMPERVIOUS SURFACE COVERAGE: Any surface impervious or resistant to the free flow of water or surface moisture. Impervious coverage shall include, but not be limited to, all paved sidewalks, patios, driveways, parking areas, underlying impermeable landscape barrier material, tennis courts, and swimming pools. Open decks and stairways, which are fifty (50) percent or more open surface, shall not be counted as impervious surface coverage, provided they are installed over a permeable surface. Aggregate Base Class 5 or rock surfaces shall be counted as fifty (50) percent impervious, provided they are installed over a permeable surface. Pavers. bricks. blocks. or similar materials used to provide around surfaces shall be considered impervious surface coveraae. PAVERS: An interlocking pavement system. The City shall maintain a list of allowable paving systems and installation specifications as periodically reviewed and approved by the City Council. SECTION FOUR: Section 41-7, R-1, Single Family Residential District of the Zoning Ordinance of the Excelsior City Code is amended as follows: 41-7: LOT REQUIREMENTS AND SETBACKS: The following minimum requirements shall be observed in a R-1 District subject to the following additional requirements, exceptions, and modifications set forth in this Ordinance: Lots Having Lots Created After Legal Standing on February 9,2003 February 9,2003 Lot Area 6,000 square feet 10,000 square feet Lot Width 42 feet 70 feet Front Yard Setback1 25 feet 25 feet Side Yard Setback 1 1 0 feet 1 0 feet Side Yard Abutting a Street 15 feet 15 feet Right-of-Wa/ Rear Yard1 35 feet 35 feet Building Height 2 30 feet 30 feet Green Space Minimum 600/0 600/0 Impervious Surface Coverage 350/0 350/0 Maximum3 NOTES: 1 Setback allowances and exceptions are found in Section 17-6 of this Ordinance. 2 Building height exceptions and limitations are found in Section 17-4 of this Ordinance. 3 Impervious surface coverage requirements of the Shoreland Management District are found in Article 60 of this Ordinance.