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HomeMy WebLinkAbout9C - BMP Report to Mitigate Impervious Surfaces MEETING DATE: AGENDA #: PREPARED BY: AGENDA ITEM: DISCUSSION: CITY COUNCIL AGENDA REPORT JUNE 16, 2008 9C JEFF MATZKE, PLANNER CONSIDER APPROVAL OF A REPORT CONSIDERING BEST MANAGEMENT PRACTICES (BMP) TO MITIGATE IMPERVIOUS SURFACES Introduction The purpose of this agenda item is to discuss possible mitigation alternatives for impervious surfaces. Historv In February 2008 a variance appeal was presented to the City Council requesting the use of mitigation alternatives to allow for an increase of impervious surfaces above the maximum allowed by the current ordinance. The variance was denied due to lack of hardship; however, the City Council directed City Staff to review the current impervious surface requirements and research possible mitigation alternatives. The following information includes details regarding the current ordinance requirements, a memorandum from City Staff related to possible Best Management Practice alternatives for impervious surfaces, and comments from recent Lake Advisory Committee and Planning Commission discussions. Current Circumstances Current Ordinance Recuirements The current definition of impervious surface is as follows: Impervious Surface. The portion of the buildable parcel which has a covering which does not permit water to percolate into the natural soil. Impervious surface shall include, but not be limited to, all driveways and parking areas, whether paved or not, sidewalks greater than 3 feet in width, patios, tennis and basketball courts, swimming pools, covered decks and other structures. Decks open to the sky and having open joints of at least 1/4 inch, areas beneath overhangs less than 2 feet in width, and sidewalks 3 feet in width or less shall be exempted from the calculation of impervious surface. The impervious surface of a lot shall be documented by a certificate of survey unless exempted from this requirement by the Zoning Administrator. Section 1104.306 (1) of the Shoreland Ordinance states the following: Imoervious Surface Coverage: Impervious surface coverage for lots in all Use Districts shall not exceed 30% of the lot area, except as provided in the following sections. Such impervious surface coverage shall be documented by a certificate of survey at the time of any zoning or building permit application, according to the definitions of impervious surface as listed in subsection 1101.400. (1) An existing site which is being altered, remodeled, or expanded without expanding the existing impervious surface may be allowed, provided that where appropriate and where necessary, structures and practices for the www.cityofpriorlake.com Phone 952.447.9800 / Fax 952.447.4245 treatment of storm water runoff are in compliance with the Prior Lake Storm Water Management Plan and approved by the City Engineer. Alternative Best Manacement Practices IBMPs\ The attached memorandum from the City's Water Resource Engineer details the current statutory limits for impervious surface, as well as an engineering background and technical explain of various Best Management Practice methods to handle stormwater. Details regarding possible procedures for monitoring and managing these installed methods are also included at the end of the memorandum and in the Issues section of this agenda report. Lake Advisorv Committee Discussion The Lake Advisory Committee discussed these mitigation alternatives at their May 21, 2008 meeting. The following are comments from their discussion: . With high prices of lakeshore properties it would be nice to offer alternative methods for the small lots that need a greater amount of impervious surface to gain the high value of the property. . In regards to a possible escrow or letter of credit to be held by the City on properties with a mitigation system, this could place a burden on a residential property owner. The mitigation systems will already incur a large cost for its installation and maintenance. . A method of reviewing/regulating maintenance schedules of the mitigation systems would need to be very clear and objective so that current and any future residents of a property and the City Staff are well aware of the req u irements. . Startup and implementation of managing and monitoring methods of the mitigation systems could be a serious undertaking for the City both financially and practically. . Since our 30% ordinance already allows for a 5% more impervious surface than the DNR regulation of 25% and our water quality has not really improved over the last few years, the DNR may not be very receptive to additional impervious surface allowances. . Impervious surface is not only looked at from a stormwater perspective (which the mitigation BMPs may address) but also its impact on aesthetic values and natural wildlife in our lake community. It is difficult for these other factors to be addressed by specific mitigation regulations because they are more arbitrary than stormwater quality and runoff statistics. Plannina Commission Discussion The Planning Commission discussed the BMP alternatives at their May 27, 2008 meeting. For your reference, the Planning Commission meeting draft minutes are included as an attachment. The Commissioners are interested in the flexibility that a mitigation program may allow, however; they also expressed concerns related to the time and financial resources required for City Staff's implementation, monitoring, and maintenance of the various BMP systems. ISSUES: The purpose of the Shoreland Regulations Ordinance is to preserve and enhance the quality of surface waters, preserve the economic and natural environmental values of shorelands, and provide for the wise utilization of waters and related land resources. Through development agreements BMP stormwater methods are currently used for commercial, industrial, and large scale residential PUD projects in the City of Prior Lake (both within and outside of the Shoreland District). City Staff believes a program to allow for increased impervious surface could be developed and managed. However there are several issues related to a change in the impervious surface ordinance that should be considered carefully. The City Council may want to consider the following questions: 1) Is this ordinance change consistent with the 2030 Vision? 2) Is the implementation of a mitigation program a priority for the City Council? 3) Should City Staff look into reallocating time for a mitigation program or possibly replace an existing program? To assist the Council in evaluating these questions, City Staff has identified the following pros/cons related to an ordinance modification: Pros . Existing Conditional Use Permit system could be utilized . Improves the stormwater quality of an area in a way that could be quantitatively identified . Provides greater flexibility for property owners for developing properties . Encourages the use of innovative storm water technologies . City Staff has the skills to develop a program (provided there is a reallocation of staff resources) . May encourage ordinance compliance by providing options Cons . Increased City Staff time will be necessary for program development, individual project review, construction, compliance review and enforcement . Reallocation of staff resources or consultant time are necessary to develop and manage the program . A revised ordinance could be complicated for individual residents, leading to a greater potential for misunderstandings and miscommunication . Potential for negative impacts on wildlife habitat and natural aesthetics of the shoreland area . Due to the uniqueness of residential properties, individual BMP designs will vary and require additional review time . The dissemination of information and conditions of a CUP to future property owners could be problematic, requiring greater communication and code enforcement . The City has other initiatives currently not being pursued that may have more value at this time (Le. easement management program) Initially staff believes the majority of staff time will be spent on developing the program as the number of initial applications will be small. However it is expected that most new construction and remodeling projects on the lake will pursue this ordinance flexibility over time eventually resulting in hundreds of individual CUP's that need to be monitored and enforced. FINANCIAL IMPACT: ALTERNATIVES: Reviewed by: \~J Frank BOYlepM Any possible ordinance change will need to be reviewed by the DNR for approval as well as require a public hearing at the Planning Commission and approval by the City Council. If the City Council chooses to implement a mitigation program (BMP techniques), it will likely result in a need for increased staff time in order to review, monitor, and, in the event of non-compliance, participate in litigation. The unique nature of these individual mitigation applications may require a time frame and financial cost similar to the staff time allocated to the Hines variance review and analysis. This project involved a cost to the City in the amount of $3,321.00 and 71 hrs of staff time. 1. Direct staff to pursue a specific ordinance change. 2. Maintain the current impervious surface ordinance. 3. Defer this item and provide staff with specific direction. '- Engineering Department MEMORANDUM City of Prior Lake 16200 Eagle Creek Avenue S.E. TO: FROM: DATE: RE: Prior Lake, MN 55372 Danette Walthers-Moore, Community Development and Natural Resources Director Ross Bintner, Water Resources Engineer. April 18, 2008 BMP Credits for Impervious Surface Requirement. In a recent meeting with a DNR hydrologist, the possibility was floated of allowing a higher cap in the impervious limit if equivalent structural practices were put in place. Currently the City of Prior Lake enforces a maximum impervious surface limit of 30% on residential lots within 1000' of a lake. The purpose of this memorandum is threefold: I. Statutory background - Explain state planning process and statutory limit. 2. Engineering background - Explain thought process behind requiring impervious limit. 3. Technical exploration - Look into possibility of allowing credit mechanism. Statutorv Backe'round The concept of a 1000 foot "shore land zone" and its impervious cover limitation are a product of State Rules and Statute. Minnesota rule 6120.330 Subp 11 part B sets a limit of 25% maximum impervious on shoreland zone lots. The State planning processes that lead to this rule creation was complete in 1989. The impervious limit was one of many mechanisms put into place as a part of statewide rules to mitigate urbanization's detrimental affect on water quality. The impervious limit was also enacted to provide enhanced wildlife habitat and a natural visual appearance though increased tree canopy and vegetative cover, however these reasons will not be explored in this memorandum. Enl!ineerine Backe'round The urbanization of a watershed leads to increased impervious surfaces. A more impervious watershed causes more direct nutrient transfer, higher peak runoff rates and larger runoff volumes. This increased pollutant load and connectivity of the watershed is difficult to manage in the shore land zone, due to the proximity of the lake. As impervious surfaces increase, groundwater recharge, evaporation and transpiration decrease and runoff increases. The use of Best Management Practices (BMPs) is common in water resource management, as engineers attempt to design a sustainable series of treatment devices and practices that route and treat stormwater to mimic the hydrology of an area before development. A practical 35.~ Impen,rioul U*,f :!;O"l4,dl lo..2~ Im,.1'\IIou1 ~S'* E ~D% tI. .... 15%1 example of this practice: A forested area along the Lake is planned to be developed as housing. In the existing condition only 10 percent of rainfall will run off the site. In the proposed condition 30 percent of rainfall will run off the site. Since housing and roads generate additional runoff, water quality and rate control ponds are planned with the development to slow the additional water runoff and settle out sediments and debris generated by the increased impervious surfaces. All BMPs require monitoring and maintenance to continue functioning and providing a consistent level of service. While all BMPs provide public and private benefit, to prevent public degradation of water, not all are publicly maintained. IIHm in't" S.o.mr,t'~ llt';HlS4tJiC'..tgt!- f:."'1~"'nl" Lh.'f.,flu.... 100 "'hulll!\h \I'..r", In..1 ~ IWrIll<lJWotff ~ - ~ 4'~IIrp, tll (KJ"~ . -!len,ll <In'''' JUUII1<<tl.. ~rowllwf..rm'f!:'.nl ""1-....( <II k.u. - Maxilull('di<>1 iltI,t' /J('r\\V1i'1I th.' (IUrl1i" Jrlld a.lHnl1i"" ropn'\'f111 ..borl clmiltlJl!:offHm,,>. ''Jh^It~''\ iI"1i ,-"",n' 'f'IJII'Hdhi 2. SEH lqU'cd ~..t4:"'* "''''HI ( ,,""'.. ""'llll;fl The above diagram shows a pond cut-section with normal, IOO-year and sediment volumes pictured. Water quality ponds are generally development-scale BMPs. In the technical section of the memorandum, private home-scale BMPs will be explored. Technical Exoloration This section will explore the possibility of providing a credit system that would allow a homeowner to exceed the 30% limit by providing structural BMPs. First; potential structural BMPs will be detailed, highlighting benefits, intended use, maintenance liability, and, monitoring and inspection protocol.. Next; water quality issues will be explored to detail a potential credit system. Finally; a monitoring and maintenance system will be theorized and issues detailed. Type: Infiltration Trenches . Description: A trench dug with filter fabric placed around the excavation enclosing an open graded aggregate that provides space to store water. A observation well is provided to monitor system function. . Purpose: To provide surface water flow a place to collect and a path to disburse to the groundwater. . Benefit: Moderate benefit to volume control and groundwater recharge. Small benefits for water quality and rate control exist as well. ~\OflotP Fl",f1o nHW1lIl :$II~ . Suitability: This EMP is not suitable for From; le""MN' 1m tight soils such as clay and may be a risk to groundwater quality in sandy soils or wellhead protection areas. . Maintenance: Sediment frequently clogs the surface layer and over the long term clogs the storage throughout the system. Raking and replacement of surface to maintain flow is required ANNUALLY. Monitoring is required QUARTERLY. . Design life: A infiltration trench system can be expected to last 3 to 7 years. Potential BMPs 0\, . '. Wf4Il Type: Underground Storage I Rainwater Cistern · Description: A storage chamber made of Plastic or Corrugated Metal provides a place to temporarily store water. · Purpose: Water is directed from roofs or driveways and is stored under lawn or pavement until it is needed for irrigation. · Benefit: Substantial benefit for volume control. Moderately benefit for groundwater recharge, and rate control. Small benefit to water quality. . Suitability: This BMP is suitable for many applications. . Maintenance: Tanks must be inspected for sediment QUARTERLY. Sediment must be cleanedfrom tanks BIYEARLY. Pump must be maintained on an as needed basis. . Design life: With regular cleaning and pump replacement a system can be expected to last 45 years. Type: Pervious Pavements . Description: A permeable pavement surface that allows rainwater to soak into the ground Previous surfaces such as the one pictured to the left can also be planted with vegetation. · Purpose: To promote groundwater recharge while providing a stable pavement surface for light vehicle traffic and parking . Benefit: Moderate benefit to groundwater recharge and volume control. Some benefit to rate control and water quality. . Suitability: This BMP is not suitable for tight soils such as clay, or may require additional under drains in such situations. . Maintenance: Pores need cleaning in situations where sedimentation can occur. ANNUAL sweeping and reseeding is required Freeze thaw cycle can cause heaving and damage if drainage is not functioning. Shoveling and plowing may cause damage. . Design life: A pervious pavement system can be expected to last 25 years. Type: Green Roofs . Description: A roofwith special reinforcement and planting media that allows plant growth on top of homes, garages, or sheds. . Purpose: Provide a unique architectural aesthetic that also provides benefit to water quality. . Benefit: Substantial Benefit to water quality and volume control. Moderate benefit to rate control. Added benefit of habitat and reduced heat. . Suitability: This BMP is suitable to a wide variety of situations but can be very cost prohibitive. . Maintenance: Frequent maintenance is required to establish vegetation. Weeding and replanting can be a challenge at heights and slopes. . Design life: A green roof can be expected to last 15 years. Type: Raingardens . Description: A shallow depression planted with flowering perennial plants and native grasses. . Purpose: Raingardens collect water from nearby impervious surfaces and allow it to infiltrate. Rain gardens use the deep rooted plants to provide a path for groundwater recharge. . Benefit: Substantial benefit to volume control and groundwater recharge. Moderate benefit to water quality and rate control. . Suitability: Rain gardens are suitable for a wide variety of situations but may not work well on tight soils such as clay, or in excessive sediment conditions or groundwater sensitive areas. . Maintenance: Vegetation management is required MONTHLY. Sediment cleaning is required ANNUALLY. Tilling and replanting is required BIANNUALLY. . Design life: A properly maintained rain garden can be expected to last 20+ years before major soil amendments are needed. Type: Buffer Zones . Description: A near shore zone planted with deep rooted native vegetation. . Purpose: Buffer zones stabilize the shoreline and near shore area soil by providing a thick cover of native vegetation and root growth both upland and in the water. . Benefit: Substantial benefits to water quality and shoreline stabilization exist. Small benefits for volume and rate control also present. . Suitability: Buffers are suitable for all shorelines. Heavy tree canopy can reduce ground plants thickness and limit species, but tree roots serve the same purpose for soil retention. . Maintenance: Establishing a buffer zone can take MONTHLY maintenance in the first 5 years. After vegetation is established, minimal maintenance is required. . Design life: A diverse plant community is self repairing and can be expected to last indefinitely. Protection is required from encroachment. Some vegetation management may be desired to promote wildflower growth. Type: Boulevard Trees . Description: Trees planted near impervious surfaces with canopy overlapping planned. . Purpose: Boulevard Trees intercept rainwater that would otherwise fall onto impervious surfaces. This concept of "canopy intercept and evaporation" can have a applicable effect on total runoff in small storms. . Benefit: Some volume control benefit exists. . Suitability: This is a natural process and can be taken advantage of in all near-pavement tree plantings. . Maintenance: This practice depends on the size and health of the tree. Proper tree care is required. . Design life: Variable based on number of trees, tree age and health. $HADE TREES ORNAMENTAL TllEES -!.- 15"- ~ ---r ~~~ .-.n~ -~ $T1IEE7I.NIH'T In this first portion of the technical exploration, the following potential BMPs were detailed: Infiltration trenches, underground storage / rainwater cistern, pervious pavements, green roofs, raingardens, buffer zones, and boulevard trees. In the next section the BMPs will be compared with the potential trade off of increased site impervious balance water quality issues. Potential Credit Svstem If a credit system were allowed, a homeowner would be able to apply for a permit to build roofs, driveways, sheds, patios and other impervious surfaces that would amount to greater than the current 30% impervious limit. In exchange for this increased impervious the homeowner would agree to design, construct, monitor and maintain a series of BMPs that would provide equivalent or greater public benefit to water quality. (Aesthetic and habitat public benefits would be lost, or mitigated through another, unexplored method) To craft a credit system and figure out what methods would be required to mitigate the affects of a hypothetical impervious addition on a small scale basis, first we must look at what is lost by adding more impervious. RELATIONAL TREHDS OF FRESHWATER FISH ACTIVllYlO TURBlDllY VALUES AND TIME 1100,000 The addition of impervious causes the following: . Increased runoff volumes. . Increased runoff rates. . Increased pollutant loads. o Phosphorus (organic matter) o Turbidity (suspended sediment) o Heavy metals (pavement and roof) o Salts and household chemicals o Hydrocarbons (cars) . Decreased soil stability. . Decreased Groundwater Recharge. These five items each could be mitigated for using a series of BMPs such as those described above. To steam line the planning design and approval process a fixed credit system with strict design standards could be created. A ~ l-- e. ~ Q ~ 1100 , 110 HOURS DAVS TIME WEEKS ...... MO NT HS This fixed credit system would call out how-much and which methods could be used mitigate increased impervious. The following is a concept: POTENTIAL CREDIT SYSTEM Per 1000 SF Requirement Infiltration Cistern Pervious Pavement O.SC / SF Green roof O.SC / SF 2C/ SF 2C/ SF N/A Volume 104C IC / CF 1 C / CF Rate 1000C 10C / CF (credits) 1000C SC / CF (credits) Stabilize N/ A Shore and Runoff path 1:1 w/ Increase (1000C) 42C .2SC/SF N/A 10C / CF 3C / CF SC / SF 2C / SF Pollutant Soil N/A N/A Groundwate r O.SC / CF O.SC/CF In this concept, a hypothetical 1000SF impervious surface would need to meet the S requirements (volume, rate, pollutant, soil, and groundwater) by mixing the 7 BMPs credit systems; an example. 1000SF of new impervious would require the following per storm: . 104 Cubic Feet of volume control . 1000 Credits of rate control . 1000 Credits of Pollutant removal . 1000 Credits of Soil Stabilization . 42 Credits of groundwater recharge Here is an example of a mix of BMPs installed to meet the credit requirements. (In this example, all BMPs are used, but this is not required) . Green roof on 80SF shed . 10CF rain barrels/cistern . 30CF Infiltration trench . 30SF Pervious path . S Boulevard/Driveway Trees . 12CF Raingarden Raingarden Buffer Trees 1 C / CF N/A 1 C/ea 20C / CF O.OSC/S F 0.6C/SF N/A 10C / CF 10C/ea N/A 1 C/SF lSC/ea l.SC / CF N/A N/A Requiremen t (C=credits) Infiltratio Cister Pervious Green Raingarde n n Pavement roof n Total DESIGN lOCF 80SF 30SF 30CF I Volume I Rate I Pollutant I Soil I Groundwater lSC lS0C 60C 40C 160C 160C 104C 1000C 1000C 1000C 42C 30C 300C lS0C 10C 100C 30C lSC SC 7.SC Buffer Tree s 12CF 925S F 5 12C 240C 120C SC 112C lOOOC I 1125C I lOOOC I 45.5C I SOC SSSC 92SC SOC 7SC 18C Sustainable Monitorinll and Maintenance Protocols Because benefits provided by the homeowner-installed and maintained BMPs would need to be sustainable indefinitely, there would need to a program to ensure that monitoring and maintenance was taking place a regular intervals. The following will detail a recommended protocol for successful implementation and monitoring ofBMPs: The recommended protocol has 3 parts: Homeowner agreements, Design review and construction verification, and Program manager duties, 1. Homeowner Agreements: A legally enforceable tool will be required such that the City can compel current and future owners of BMPs to maintain all BMPs to an agreed upon level of service. The agreement must be easily enforceable allowing the City to enter onto private property and must be a part of the property Deed so that future buyers are bound to the requirements as well. 2. Design Review and Construction Verification: The design and construction must be approved and witnessed by City Staff to ensure proper methods are used and BMPs will function as planned. The agreement will need to spell out liability issues, such that a failed BMP that causes damage to property or financial hardship does not expose the City to liability since Staff will review and approve design and construction. 3. Program Manager: To maintain the promised level of service, City Staff must regularly inspect and test BMP function. A program manager will be needed to coordinate program documentation, record keeping, notification correspondence, and other duties. The startup costs of creating a sustainable monitoring and maintenance protocol would be significant, due to the technical and legal nature of the agreement and BMPs. This protocol only puts a basic outline to the program and more thought it needed if a credit system is offered. DRAFT PLANNING COMMISSION MINUTES TUESDAY, MAY 27, 2008 B. Impervious surface discussions. Planner Jeff Matzke presented the staff report dated May 27,2008, on file in the office of the Community Development and Natural Resource Department. As part of the Zoning Ordinance Update project City Staff has been directed by City Council to review the current impervious surface requirements and research possible mitigation alternatives. The Lake Advisory has also reviewed and forwarded on their comments to staff. Ross Bintner, Water Resource Engineer, presented his report which included the Lake Advisory comments and concerns. Comments from the Commissioners: Billington: . This looks like staff would be a lot busier with this package. · Questioned soil conditions for the homeowner- If someone has highly porous soil conditions which would absorb an amount of precipitation perhaps greater than someone else, how is that taken into account for credit? The water would be absorbed and not drained off as impervious surface. Bintner responded there is a credit built in with the design would take care of that on nice sandy soil. When the DNR wrote their rules they knew all shorelines are different with a wide variety of soil types. They knew there would be more run off from the clay and more pollutants coming from the silty erosive soils. The 30% is already an artificial baseline as it is. They have said a one acre lot can have this much impervious surface, we know its causing a detriment to the lake however it's allowable because people have a right to use their property. But that's where they drew a line. Ringstad: . Looks like a lot of work has gone into this report. I have a couple of broad comments. · The DNR is already granting the City of Prior Lake 5% impervious surface above other lake communities- hearing and looking at other issues you've talked about and our (the Commissioner's) background - Bintner brought up 3 excellent points in his summary of recommendations. Looking at the program manager section, the City staff would regularly inspect and test properties - it would be a cost the City currently does not budget for in regulating the homeowner's granted impervious surface. · I also see potential for increases of lot variance requests for impervious surface, which we have on the many small nonconforming lots. It would make the problem even bigger. · I would be very cautious and look at this real seriously - I think the DNR allowed Prior Lake the 30% impervious surface is because we have a 75 foot setback compared to other cities with a 50 foot setback. Again, that is aesthetics. We have seen many variance requests who want to creep a little closer to the lake. . We have been consistent with our rulings. . Very interesting information - glad Ross came tonight. It was a good report. . From my perspective I would be very very cautious.. . Perez: . Is there any reason sidewalks are exempt from the impervious surface? Matzke responded our ordinance has been that way for some time. Prior Lake is one of the very few communities, if any, that have that type of stipulation. Many communities count all hard surfaces including areas less than 3 feet in width. Staff would like you (Commissioners) to consider this issue with the upcoming zoning review discussions. . Question for Ross on the 25% maximum - Do you know what the limits were prior to '89? Bintner responded he was not sure before that date but the State did impose the 25% at that time as the maximum. The reason the City got to do a little more is because they let us exercise a portion of the State Statute called "Implementing Flexibility". At that time we had a conversation with the DNR about other mitigating factors that the City could be put in place that would allow us that extra 5%. · Has this gone through the DNR's review? Bintner responded the DNR has not seen this report. · How do the impervious pavers work in the winter with shoveling? Bintner responded it is a rougher surface for shoveling but as far as how they function - they have an area underneath that is open graded aggregate, larger stones that actually produce a better melting surface. The water will actually melt because of the air that is allowed to flow. · Agree with Commissioner Ringstad - this is an added cost for city staff and if we were to go forward I would put the entire burden on the property owner. They get all the benefit and should bear the brunt of the expense. . Ross did a good job presenting the checks and balances. · Prior Lake is a 5% above the rest of the State and should leave it. . I agree with Commissioner Ringstad - I would be leery. Fleming: · Do we have a sense of how many cities are at 30%? Matzke said Prior Lake is one ofa few above 25%. · Is it fair to surmise some of them might not be implementing some of the BMP? Matzke responded that would probably be correct. Most of the other lake communities, Minnetonka as one of them, are implementing a buffer zone or other mitigation alternatives similar to BMPs. Whether it was a mitigation to change their impervious surface, I don't believe that was the case. · For-many of the same reasons mentioned, I really think the scope of this has a level and a degree of constant complexity, I'm not sure we are ready or should we manage if we had the capacity to do so. Lemke: · Questioned the 3' sidewalk exemption - Walthers-Moore responded in one of the most recent zoning ordinance reviews by the Planning Commission, a reduction was one of the recommendations made. Originally that was meant for a smaller 3' sidewalk. It has gotten to the point now where staff sees much longer sidewalks expanding into patios. It does not function as a 3' sidewalk. · Perez questioned if the length (of the sidewalk) should be limited. Walthers-Moore replied that was a good consideration and should be looked into. · Soils are also a concern - are we trying to fix a problem that doesn't exist? I think we should approach this very carefully. What if a house goes into foreclosure, who is going to maintain these practices? There may be other homes not on the lake; we may not have any legal recourse. . I think we are moving in the wrong direction. We should be limiting impervious surface to 25% and mitigate to 30% if mitigation is provided. . At this point in time with current technology as explained by our water resource engineer, we are not comfortable certain mitigations will solve the problems on all properties. That's a flexibility cities and ordinances, rules and regulations don't always have. Perez: · What is Ross's/statT's recommendation? Bintner stated "BMPs if designed right and maintained correctly would be effective, but to build and maintain on a private home with a thousand different contacts (BMPs) would be overwhelming. It could be developed but would need additional staff and would be a political and tricky undertaking at every step. It would be a significant cost to the City." Billington: · The Lake Advisory would be in favor of increasing the impervious surface for smaller lake lots. Bintner thought that came out of a discussion because a number of the small lake lots have already been grandfathered in to the 30% impervious surface. The Lake Advisory wanted to promote the BMPs but did not want it as "fix" approach, but rather an incentive. The Commissioners thanked staff for their reports. This will go before the City Council on June 16th.