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HomeMy WebLinkAboutItem 4.14.1 TOWN OF LOS ALTOS HILLS September 6, 2007 Staff Report to the Planning Commission SUBJECT: DEVELOPMENT AREA POLICY AMENDMENT FROM: Nicole Horvitz, Assistant Planner' APPROVED BY: Debbie Pedro, AICP, Planning Director 'D? RECOMMENDATION That the Planning Commission: Forward a recommendation to the City Council to approve the proposed revisions to the Development Area Policy with regard to credit for the use of semi permeable materials for driveways, turnarounds and required parking. (Attachment 1) BACKGROUND At their July 26, 2007 meeting, City Council discussed the proposed amendments to the Development Area Policy and noted that development area credits from using semi -permeable materials should not be limited to just constrained lots. The City Council directed staff to further research and prepare revisions to the Town's Development Area Policy. (Attachment 2). Staff is seeking Planning Commission comments and suggestions on revisions to the Development Area Policy to allow credit for certain surface materials for driveways, turnarounds, and required parking. DISCUSSION The Town's current Development Area Policy provides guidelines that limit development area on a property in order to protect the natural features and rural character of the Town and minimize run off and erosion related to construction on slopes. The current policy does not give credit for the use of semi -permeable materials on any of the following: • Tennis or sports courts • Driveways • Required parking areas • Turnarounds • Above ground decks Grasscrete pavers, permeable concrete and permeable pavers can be an excellent alternative to plain concrete surfaces for driveway, turnarounds, and parking areas because they can be used to locally infiltrate rainwater, reduce water mnoff, and minimize erosion. Planning Commission Development Area Policy Amendment September 6, 2007 Page 2 of 3 The maximum square footage that an applicant may gain with the use of semi -permeable materials is approximately 2,100 square feet, using grasscrete pavers for the driveway, required parking, and fire truck turnaround However, more than likely applicants will choose to use permeable concrete or pavers for the driveway and a combination of permeable pavers, concrete or grasscrete for the turnaround and parking. This would result in an average development area credit between 900-1,400 square feet EXAMPLE: 200+180+660=1,040 sq. ft. Using the Town's MDA/MPA formula a one acre property with a slope of 10% or less has an allowable MDA of 15,000 sq. ft. or 34% lot coverage. A one acre property with a 25% slope has an allowable MDA of 7,500 sq. ft. or 17% lot coverage. The MDA of a property will not change. However, the percentage of lot coverage using both impervious and semi -permeable materials could potentially increase by 2%-5%. Grasscrete Pavers Permeable Concrete Permeable Pavers % of Allowable Lot (50% credit) (30% credit) (10% credit) Two Required Outdoor MDA Coverage Coverage with approx. Parking Spaces 120 sq ft 40 sq ft (10x20 each)= 400 sq ft 900-2,100 sq. ft. of Surfaces) Development Area Credit Fire Truck Turnaround 900 sq ft 540 sq ft 15,000 =1,800 sq ft (approx) 36%-39% 1 Acre 25% rriv,,,y00 sq ft (approx) 1,000 sq ft WM 220 sq ft Using the Town's MDA/MPA formula a one acre property with a slope of 10% or less has an allowable MDA of 15,000 sq. ft. or 34% lot coverage. A one acre property with a 25% slope has an allowable MDA of 7,500 sq. ft. or 17% lot coverage. The MDA of a property will not change. However, the percentage of lot coverage using both impervious and semi -permeable materials could potentially increase by 2%-5%. The proposed development area credit for semi -permeable surfaces will increase the amount of development on a property. However, the amendment is consistent with the intent of the Development Area Policy to "minimize runoff and erosion concerns related to construction on slopes". The potential impacts for runoff and erosion from the increased development is mitigated because the semi permeable materials have storm water management benefits including: % of Allowable Lot Maximum Potential Lot Acreage Slope MFA MDA Coverage Coverage with approx. (Impervious 900-2,100 sq. ft. of Surfaces) Development Area Credit 1 Acre >10% 6,000 15,000 34% 36%-39% 1 Acre 25% 5,000 7,500 17% 19%-22% The proposed development area credit for semi -permeable surfaces will increase the amount of development on a property. However, the amendment is consistent with the intent of the Development Area Policy to "minimize runoff and erosion concerns related to construction on slopes". The potential impacts for runoff and erosion from the increased development is mitigated because the semi permeable materials have storm water management benefits including: Planning Commission Development Area Policy Amendment September 6, 2007 Page 3 of 3 • Reduce the amount of untreated runoff • Increase the amount of filtered groundwater • Eliminate puddling or standing water • Prevent erosion. To ensure that the additional paving will not increase storm water runoff, applicants who choose to utilize semi -permeable materials for driveways, turnarounds, and required parking will be required to provide manufacturer's specifications and data for the materials including water absorption rate, installation procedure, and maintenance requirement guidelines. In addition, the applicant will be required to provide hydrologic calculations to demonstrate that post - development peak discharge value for water runoff does not exceed the existing pre -development peak discharge value of the property. CEQA STATUS The project is categorically exempt under Section 15306 of the State CEQA Guidelines ATTACHMENTS 1. Amended Development Area Policy 2. Minutes from the July 26, 2007 City Council Meeting - 3. Staff Report to City Council dated July 26, 2007 Attachment 1 Policy Re: Development Area and Tennis/Sports Courts, Driveways, and Pervious Surfaces Code Sections: Section 10-1.502(b) of the Zoning Code defines "development area" to include floor area as well as other coverage, including parking areas, patios, decks, walkways, swimming pools, tennis courts, and other surfaces comprised of artificially emplaced building materials (paving, roofing, masonry, stone or wood) Intent: The purposes of limiting development area on a site are twofold: 1) to protect natural features and rural character of the Town; and 2) to minimize runoff and erosion concerns related to construction on slopes. The City Council finds that tennis/sports courts, driveways and parking areas appear as development regardless of the surface used, and generally require considerable land alteration to be accommodated on a site. Policy: No development credit will be granted for the use of semi -permeable material(s) on any of the following: a. Tennis or sports courts b. Driveways* c. Required parking areas* d. Turnarounds* e. Above ground decks 2. In other development areas, partial credit for the use of semi -permeable material(s) may be granted depending on the permeability and appearance of the surface. Make an appointment with the Planning Department at (650) 941-7222, to discuss material selections with a Planner. *Applicant must provide manufacturer's specifications and data for the materials including water absorption rate, installation procedure, and maintenance requirement guidelines. *Applicant must provide hydrologic calculations to demonstrate that post -development peak discharge value for water runoff does not exceed the existing pre -development peak discharge value of the property. Attachment 2 his property and was able to move forward on his subdivision which could prove to be a very profitable development. Councihnember O'Malley commented that this was one of the few times that he disagreed with staff. He noted that Mr. O'Keeffe had received a letter from former City Engineer Henry Louie stating that the Town would provide him sewer connections. He then proceeded with his application to LAFCO and the County. Subsequently, the Town reversed its opinion. O'Malley suggested that it would be appropriate to waive the legal fees and only charge staff costs. He believed that the review had been a higher level than necessary and added that the Town bad an interest in providing and encouraging sewer connections. Councilmember Warshawsky stated that he concurred with the recommendation of staff. MOTION MADE AND FAILED: Moved by O'Malley to waive Mr. O'Keeffe's $5,000 legal charges and limit the charges to the $2,000 fees associated with the staff charges. Motion failed due to lack of a second. 19. Consideration of Resolution Establishing a Preferential Puking District in the Town of Los Altos Hills for Crescent Lane Planning Director Debbie Pedro introduced the item to Council. Staff had received an application from the residents on Crescent Lane to establish a preferential parking district on their private street. The application had been signed by a majority of the residents. The applicants had reported problems with Foothill College students parking, loitering and littering on their street and then using the neighborhood path to access the college. Mike Weimar, Crescent Lane, spoke on behalf of the applicants. He offered that the students were using his street to avoid parking fees charged by the campus. Weimar spoke to the disruption the students caused to their neighborhood. A letter from the President of Foothill College supporting the application had accompanied their request. Resident, Crescent Lane, stated that she supported the request for the Preferential Parking District. She had not bad an opportunity to sip the petition. Mayor Jones advised that the Town would incur a minimal fiscal impact in association with the application. The residents would pay all costs associated with the signage. Council directed staff to use the same template that had been used previously for the Dawnridge preferential parking district. MOTION SECONDED AND CARRIED: Moved by Mordo, seconded by Kerr and passed unanimously to adopt Resolution No. 57-07 Establishing a Preferential Puking Area (Crescent Lane). 20. Consideration of Amendment to the Town's Development Area Policy Planning Director Debbie Pedro introduced the item to Council. Council at their May 24, 2007 meeting had directed staff to research and prepare proposed amendments to the Town's Development Area Policy to allow additional development area, particularly for 12 City Council Meeting Meares Suly 26, 2007 constrained lots (one acre properties with maximum development area (MDA) of 7,500 square feet or less). The Town's original policy had been approved by Council in 1995 and had a two fold purpose: 1) to protect natural features and the rural character of the Town; and, 2) to minimize runoff and erosion concerns related to construction on slopes. Pedro reviewed the list of items that previously had been identified as areas where development credits could not be granted for the use of semi -permeable materials due to aesthetic concerns and the potential amount of grading that would be required. They included tennis or sports courts, driveways, required parking areas, turnarounds and above ground decks. However with the development of newer materials and technology, Pedro suggested that erosion and runoff concerns could potentially be addressed. The Planning Commission had considered the revisions to the Development Area Policy at their June 28, 2007 meeting and recommended approval of development area credits when semi -permeable materials were used for three areas. Specifically; driveways, required parking, and turnarounds on constrained lots. Pedro proceeded with a PowerPoint presentation that included slide representations of the acceptable materials and their respective credits. They included Grasscrete (50% credit), permeable concrete (30% credit), permeable pavers (10% credit), and artificial turf (90% credit). Pedro explained the artificial turf market had varied products -both in quality and appearance. For this reason, staff was recommending that the use of artificial turf be limited to the side and rear yards of a property. Pedro reviewed slides of different development scenarios and examples where semi -permeable materials could be used for the outdoor parking, fine truck turnaround and driveway. For example, if grasscrete was used in a 400 square foot area for outdoor parking, it would result in a development area credit of 200 square feet. Pedro explained that the MDA of the constrained lot was not being changed with the new proposed Policy and was still governed by the formula of acreage and slope but the way that the area was counted where the semi -permeable products were used would result in a development area "credit". Pedro concluded her report with a chart that summarized the proposed revisions and included: the four products under discussion, the percentage of development area credit that would be gained with their use, the areas where they could be used and if they could be used in the setback Pedro noted that under the constrained lot scenario (1 acre minimum and a MDA of 7,500 or less) the maximum "credit" for the use of the semi- permeable materials was 2,200 square feet Council discussion ensued. The consensus was that the proposed amendment to the Development Area Policy was a step in the right direction. Council questioned if the credits for the semi -permeable materials should be extended to other lots with restrictions beyond constrained lots with possible higher limits. It was suggested that the location of s the property might be a factor in the review process and their proclivity to runoff. Af OPENED PUBLIC COMMENT Richard Partridge, Briones Lane, suggested that it was positive for Council to be encouraging the use of semi -permeable materials but believed that the policy amendment 13 City Council Meeting Minutes July 26, 2007 was too significant not to have a wider review. He questioned what would happen if someone had 7,600 square feet of development and could not take advantage of the proposed policy. CLOSED PUBLIC COMMENT MOTION SECONDED AND CARRIED: Moved by Mordo, seconded by Warshawsky and passed by a 4-1 voice vote (Councilmember O'Malley -No) to approve the revised Development Area Policy as presented in the staff report. Councilmember O'Malley offered that he would prefer to review the proposed policy inconsistencies and revisit the application to include additional lots with a threshold determined by Council. MOTION TO RECONSIDER: MOTION SECONDED AND CARRIED: Moved by Kerr, seconded by O'Malley and passed by the following roll call vote to rescind the prior action of Council. AYES: Mayor Pro Tem Mordo, Councihnember Ker, Councilmember O'Malley NOES: Mayor Jones, Councilmember Warshawsky ABSENT: None ABSTAIN: None Jitze Couperus, Page Mill Road, commented that he was concerned with coupling the use of semi -permeable materials with a reward of more increased development. He suggested Council consider different reward options. CLOSED PUBLIC COMMENT Council consensus was to direct staff to draft a revised Development Area Policy that would expand the allowance for development credits to other lots not directly in the definition of the constrained lots and as a more general policy for the Town. The revised policy would be reviewed by the Planning Commission and ultimately considered by the City Council. 21. Designation of Voting Delegate and Alternates — League of California Cities Annual Conference Scheduled for September 5-8, 2007 MOTION SECONDED AND CARRIED: Moved by Mordo, seconded by Ker and passed unanimously to appoint City Manger Carl Cahill as the Town's voting delegate to the League of California Cities Annual Conference. 22. Consideration of Date for City Council Strategic Goal Setting Session 14 City Council Meeting Minutes My 26, 2007 Attachment 3 TOWN OF LOS ALTOS HILLS July 26, 2007 Staff Report to the City Council SUBJECT: AMENDMENT TO THE DEVELOPMENT AREA POLICY FROM: Debbie Pedro, Planning Duectol- APPROVED: Carl Cahill, City Manager r— c-, RECOMMENDATION: That the City Council Approve the amendments to the Development Area Policy with regard to credit for the use of semi permeable materials, as contained in Attachment 1. BACKGROUND: At the May 24, 2007 meeting, City Council directed staff to research and prepare amendments to the Town's Development Area Policy to allow additional development area for one acre properties with maximum development area (MDA) of 7,500 sq. ft. or less. The Council suggested allowing partial development area credit for materials that did not result in an increase of water runoff from the property. At their meeting of June 28, 2007, the Planning Commission reviewed the Development Area Policy and unanimously voted to recommend approval of the proposed amendments. DISCUSSION The Planning Commission discussed revising the current Development Area Policy to allow constrained lots (one acre minimum with a MDA of 7,500 sq. ft. or less) to receive development area credit when semi -permeable materials are used on driveways, required puking, and turnarounds. Depending on the type of materials used and the total area affected, property owners with constraint lots could gain between 800 to 1,500 sq. ft. of additional development area. Furthermore, the Commission agreed that artificial turf should only count as 10% coverage. Eventhough the appearance of artificial turf has continued to improve, the quality of the product varies depending on the manufacturer. Therefore, it is recommended that artificial turf be installed only in the rear or side yards to minimize it visibility to neighboring properties. A chart detailing the material and credit percentage is included in the revised Development Area Policy. (Attachment 1) The Planning Commission staff report and meeting minutes dated June 28, 2007 are attached for Council review. (Attachments 2 and 3) FISCAL IMPACT There is no fiscal impact associated with this recommendation. CEOA REVIEW The proposed ordinance amendment is exempt from California Environmental Quality Act (CEQA) pursuant to Section 150611.3 of the CEQA Guidelines. ATTACHMENTS 1. Amended Development Area Policy 2. Staff Report to Planning Commission dated June 28, 2007 3. Draft Minutes from the June 28, 2007 Planning Commission Meeting Report prepared by: Nicole Horvitz, Assistant Planner Policy Re: Development Area and Tennis/Sports Courts, Driveways, and Pervious Surfaces Code Sections: Section 10-1.502(b) of the Zoning Code defines "development area" to include floor area as well as other coverage, including parking areas, patios, decks, walkways, swimming pools, tennis courts, and other surfaces comprised of artificially emplaced building materials (paving, roofing, masonry, stone or wood) Intent: The purposes of limiting development area on a site are twofold: 1) to protect natural features and rural character of the Town; and 2) to minimize runoff and erosion concerns related to construction on slopes. The City Council finds that tennis/sports courts, driveways and parking areas appear as development regardless of the surface used, and generally require considerable land alteration to be accommodated on a site. Policy: No development credit will be granted for the use of semi -permeable material(s) on any of the following: a Tennis or sports courts b. Driveways* c. Required parking areas* d. Turnarounds* e. Above ground decks 2. In other development areas, partial credit for the use of semi -permeable material(s) may be granted depending on the permeability and appearance of the surface. Make an appointment with the Planning Department at (650) 941-7222, to discuss material selections with a Planner. *For constrained lots (one acre minimum and a MDA of 7,500 or less) credit for the use of semi- permeable materials for the driveway, required parking, and turnaround will be granted based on the permeability of the material. *For constrained lots only =one acre minimum, MDA of 7500 90% Rrquir urnorounds, anti Credit for all olhvr'- Artificial Turf (i.e. 10o sq. it wverege Yes N/A Yes =10 sq. ft DA) 50% No Grasscrete Pavers (i.e. 100 sq. R coverage (ExcW for tornaromds Yes * Yes = 50 sq. ft DA) and driveways) Permeable 30% No Concrete (i.e. 100 sq. ft c°verage (Except for tvr .,mds Yes * No - 70 sq. R DA) and driveways) 10% No Permeable Pavers (i.e. 10D sq. R wverage (Exeept forwmaromds Yes* Yes = 90 sq. ft DA) end driveways) *For constrained lots only =one acre minimum, MDA of 7500 TOWN OF LOS ALTOS HILLS June 28, 2007 Staff Report to the Planning Commission SUBJECT: DISCUSSION TO CONSIDER AMENDING THE DEVELOPMENT AREA POLICY FROM: Nicole Horvitz, Assistant Planner APPROVED BY: Debbie Pedro, AICP, Planning Director RECOMMENDATION That the Planning Commission: Review and discuss the Development Area Policy with regard to credit for the use of semi permeable materials and direct staff to prepare tent amendments to the policy as determined to be necessary. WouO Ze -11161 ilX At their May 24, 2007 meeting, the City Council duetted staff to research and prepare proposed amendments to the Town's Development Area Policy to allow additional development area for constrained properties with maximum development area (MDA) of 7,500 sq. ft. or less. The Council suggested that semi -permeable materials used in landscape or hardscape improvements could receive partial credit for development area coverage because it will not result in an increase of runoff from the property. An additional idea mentioned was to consider not counting the second floor as development area on lots with steep slopes. (Attachment 2) Staff is seeking Planning comments and suggestions on revisions to the Development Area Policy to allow credit for certain surface materials. DISCUSSION The Tovm's current Development Area Policy provides guidelines that limit development area on a property in order to protect the natural features and rural character of the Town and minimize run off and erosion related to construction on slopes. The current policy (Attachment 1) does not give credit for the use of semi -permeable materials on any of the following: • Tennis or sports courts • Driveways • Required parking areas • Turnarounds • Above ground decks Planning Commission Development Area Policy Amendment ]me 28, 2007 Page 2 of 5 Given the advancements in technology, building techniques, and building materials on sloped lots, it is recommended that the Planning Commission review and consider allowing a development area credit for certain semi -permeable materials. Artificial Turf The appearance of artificial turf has continued to improve and many manufacturers have products that look like real grass. Maintenance to the artificial turf is minimal. An occasional brooming is recommended but not necessary. This will stand the fibers up and even out the infill materials. Debris like leaves and twigs can be easily removed with a leaf blower. As long as the leaf blower nozzle is not placed too close to the turf, the sand and rubber will stay in place while the debris is blown away. The long term effect of the sun does not harm the artificial turf lawnscape or make it fade. The fibers have a UV protection coating and can withstand the damaging affects of sun, heat, wind, snow, and ice. The drainage in the turf is very similar to natural grass. The turf backing has many perforated holes allowing for water to drain vertically. Pets cannot harm the turf. The turf is also installed strictly for dog ams. Urine is not a problem as it absorbs into the sand and rubber and eventually evaporates. You may also spray the soiled area with a hose. The cost comparison to installing artificial lawn or grass versus installing a sprinkler system, top soil, and the price of sod, combined with watering, mowing, weeding, and fertilizing, it can pay for itself in a few years. (Source; Back Nine Greens, Attachment 3) Staff recommends a 90% credit for artificial turf. (i.e. 100 sq. ft. of coverage counts as 10 sq. ft. of development area) and may encroach within the property line setbacks. The artificial turf should be installed in the rear or side yard of the property to minimize its visibility to neighboring properties. Planning Commission Development Area Policy Amendment June 28, 2007 Page 3 of 5 Grasscrete Pavers Grasscrete is a cast -in-place, monolithic, pervious concrete pavement that is continuously reinforced to provide superior structural integrity. After the concrete is sufficiently hardened, the voids are filled with topsoil and grass providing a free draining "pavement" with the structural capacity to handle most heavy vehicle loads. Grasscrete can be an excellent alternative to plain concrete surfaces for puking lots, driveways, and access roads for vehicles or fire trucks. Grasscrete can also be used for erosion control. Grasscrete drains at about the same rate as would an ordinary lawn in the same location. The presence of concrete has little effect on the drainage; the soil and the slope are the controlling factors. The surface area of Grasscrete is 47% concrete and 53% whole (to be filled with Grass). Grass usually covers much of the concrete in areas not subject to regular vehicle traffic. Holes may be filled and covered with crushed stone, seashells, etc. to provide drainage in cases where grass is not desired. (Source; Concrete Network, Attachment 4) Staff recommends a 50% credit for grasscrete. (i.e. 100 sq. ft. of coverage counts as 50 sq. ft. of development area). Grasscrete must be installed outside the required setbacks except for fire truck turnarounds and driveway backup areas. Planning Commission Development Area Policy Amendment Jmie 29, 2007 Page 4 of 5 Permeable Concrete Permeable concrete is a special structural concrete with the fine particles removed. This creates 15 to 20 percent voids so the concrete looks like a giant rice cake. The pavement will support traffic and allow water to pass through to a gravel layer underneath. The strength of pervious concrete is about 85 percent of conventional concrete, making it suitable for sidewalks, driveways, alleys, parking lots and residential streets. Permeable concrete is much more porous than underlying soils. Typical infiltration rates are 250 to 300 inches per hour; typical installations require soils with percolation rates of more than 1/2 - inch per hour. A gravel bed placed underneath the concrete stores water before it moves into the soil or can provide a channel for movement of water to storm water channels. A 4 -inch bed of rock or aggregate 3/4 inches or larger with 30 percent voids will store 1.2 inches of water. In addition to its water quantity benefits, pervious paving can remove some pollutants through absorption, straining and microbial decomposition. (Source; Puget Sound Online, Attachment 5) Staff recommends a 50% credit for permeable concrete (i.e. 100 sq. R of coverage counts as 50 sq. ft, of development area). Although permeable concrete has some benefits for drainage and water run-offs, due to its appearance as a solid, hardscape surface, the permeable concrete should qualify for development area credit only when used for required fire truck turnaround, parking, and driveway. Permeable Pavers Permeable pavers replicate natural storm water infiltration, provide treatment and eliminate the need for conventional detention/ treatment systems. Most of the paving over' in developed areas is due to common roads and parking lots, which play a major role in transporting increased storm water runoff and contaminant loads to receiving waters. Alternative paving materials can be used to locally infiltrate rainwater and reduce the Planning Commission Development Area Policy Amendment June 28, 2007 Page 5 of 5 runoff leaving a site. This can help to decrease downstream flooding, the frequency of combined sewer overflow events, and the thermal pollution of sensitive waters. The use of these materials can also eliminate problems with standing water, provide for groundwater recharge, control erosion of streambeds and riverbanks, facilitate pollutant removal, and provide for a more aesthetically pleasing site. The effective imperviousness of any given project is reduced while land use is maximized. Alternative pavers can even eliminate the requirement for underground sewer pipes and conventional storm water retention / detention systems. The drainage of paved areas and traffic surfaces by means of permeable systems is an important building block within an overall low impact development scheme that seeks to achieve a storm water management system close to natural conditions. (Source; Low Impact Development Center, Inc, Attachment 6) Staff recommends a 10% credit for permeable pavers. (i.e. 100 sq. ft. of coverage counts as 90 sq. ft. of development area). Permeable pavers must be installed outside the required setbacks except for fire truck turnarounds and driveway backup areas. CEOA STATUS The project is categorically exempt under Section 15306 of the State CEQA Guidelines ATTACHMENTS 1. Development Area Policy 2. Minutes From the May 24, 2007 City Council Meeting 3. Artificial Turf- Back Nine Greens, www.backnine¢eens.com 4. Grasscrete Pavers -Concrete Network, www.coneretenetwork.com/bomanite/green.htm 5. Permeable Concrete- Puget Sound Online, www.psat.wa.aov 6. Permeable Pavers- Low Impact Development Center, Inc, www.lid-stormwater.net 1117 Develop Comprehensive Plan for Expanded Recreational Facility Access and Begin Implementation of Acquisitions --Report of the Ad Hoc Committee on Recreational Facilities (To be Distributed at the Meeting) (Mayor Pro -Tem Jones) Mayor Pro Tem Jones reported that the Ad Hoc committee had met prior to the Council meeting (May 24, 2007) and were currently reviewing the alternatives for recreation. Jones summarized the featured article in the June Newsletter that bad outlined the Committee's activities. They included: 1) review of current recreation facilities; 2) responsiveness to recreation survey that showed a strong interest in a community park and possibly a sports field; and, 3) investigation of partnerships with private clubs and/or possiblejoint ventures for recreation opportunities. Jones reported that there were a series of projects at the Little League fields that were being assessed that could potentially enhance safety and improve the drainage problems at the site. This should reflect in a reduction of maintenance costs. To appropriately evaluate the drainage problems and move forward on any additional projects at the fields, the City Manager had authorized a topographical survey of the site at a cost of $8,000. Jones advised that the Committee would be developing a priority list of projects and budgets. The needs of the Westwind Bam Committee would be integrated into the overall recreation "master plan" with a projected multi-year capital improvement budget. COUNCIL MEETING RECESSED: 9:40 P.M. COUNCIL RECONVENED TO OPEN SESSION: 10:00 P.M. —106 12. 2007 Community Survey on Site Development and Zoning Standards Planning Director Debbie Pedro introduced this item to Council. The City Council at their February 8, 2007 meeting authorized the Town to conduct a community survey to gauge resident opinions on current site development and zoning standards. Godbe Research, a professional survey firm, was hired to conduct the telephone survey in April 2007. The survey consisted of sixteen questions with several culled from the 2001 mail - in Community Survey. Pedro proceeded with a PowerPoint Presentation that included: a comparison of responses of 2001 and 2007 survey on questions regarding allowable maximum development area and maximum floor area (MDA/MFA); estate homes; development review process; and, open space easements. The presentation also included a list of Planning Commission Comments and Recommendations from their May 3, 2007 review of the survey findings. Pedro noted that one of the key findings from the telephone survey was that the majority of residents polled were satisfied with the development regulations and believed that the status quo should be maintained. In comparing the results of the two surveys, there did not appear to be any major shift in opinion. There was a trend however that more people found the regulations too restrictive in 2007, particularly newer, younger residents. The survey findings indicated an increase in "newer residents" with 1-10 years residency in Town. Regular City Meeting Minutes May 24, 2007 Only a slight majority of responders believed that a cap or absolute maximum should be set on the size of a home (Estate Homes). However, a majority of residents did concur that setbacks should be increased for homes of 10,000 + square feet. With regards to open space (conservation) easements, a majority clearly favored the policy of requiring the dedication of open space. However, the majority of residents were not in favor of imposing more restrictive fence regulations and they were evenly divided on the issue of allowing taller deer fencing. Pedro reviewed the Planning Commissions comments and recommendations that included: 1) majority of residents felt the status quo should be maintained regarding site development issues; 2) high percentage of residents would like to see increased setback requirements for estate homes and recommended that staff return the Estate Home Ordinance (proposed) for review; 3) continued strong support for the open space easement policy; and, 4) in general, younger and newer residents (less than 15 years) were more likely to feel that development standards were too restrictive compared to the more established residents. The Conunission recommended that staff develop a "Property Improvement Information Booklet" to be included in the Town's welcome packet Council thanked Pedro for her presentation. Mayor Pro Tem Jones concurred that the survey's findings had strongly endorsed the status quo "on balance'. Jones commented that he had several issues that he wanted to address. He was in concurrence with the Planning Commission's recommendation to revisit the Estate Homes with regards to setback and possible restriction of 20,000 square feet Second, with regards to fencing, he believed that the survey language may have been confusing but there was an indication that there was support for deer fencing taller than 6 feet Third, was development on sloped property and the LUF penalty. Jones suggested that it appeared that people believed it was too restrictive. The final issue he proposed for discussion was the feasibility of an incentive for people to construct energy efficient homes. Jones added that the Council had previously requested this and he would like to have the issue revisited. Jones noted these were the issues/topics he would like to discuss and queried what the appropriate next step in the process would be. Councilmember Mordo commented on the suggested discussion topics. He noted that historically, there have been very few homes approved in the estate home classification of 20,000 square feet and did not believe it was necessary to set a maximum for house size. However, he did concur with a review of setback requirements for estate homes. Mordo agreed that deer fencing would be a more attractive, aesthetically pleasing fence option that would lend itself to a feeling of open space compared to a solid 6 foot fence and he would be open to discussion. He expressed his concern with opening discussions on MDA/MFA because it was an arbitrary number and preferred reviewing each special case individually and granting variances where warranted. Mordo suggested that the Council consider reviewing the calculations for permeable and semi permeable materials. Pedro offered that there was a currently a Council development policy adopted in 1999 that calls for discount in development area for the use of certain materials. Additional materials could be added. Mordo suggested that the table be reviewed. Regular City Meeting Minutes May 24, 2007 Jones concurred and requested that direction be given to the Planning Commission to investigate ways to make it easier for people to develop their yards with methods and materials that would not substantially increase the amount of run off from their properties. One suggestion was the exploration of second story homes on sloped lots. Councilmember Kerr supported relief for building on slope lots including credit for permeable driveways but believed that the current development allotment for flat lots was appropriate. He also supported the use of taller deer fencing especially to protect gardens and vineyards but did not want to see properties completely fenced. Councilmember O'Malley noted that he was comfortable with forwarding the topics to the Planning Commission for discussion. However, he was concerned with MDA being increased on sloped lots. O'Malley explained that the velocity of runoff from the lot potentially hurt the person residing below the property and could cause erosion but he was open to listening to proposals. Mayor Warshawsky thanked staff for the report. He believed that it was a good survey and he had gamered several key points from his review of the findings. Warshawsky noted the trend that new residents and younger residents believed the Town's development policies were too restrictive. There also was a clear indication that the long term resident population was decreasing. Warshawsky suggested that the new/younger residents might be more supportive of the Town's long term capital improvement projects. in review of the discussion items proposed by Mayor Pro Tem Jones, Warshawsky's comments included: no support for changes in the fence ordinance; support for green energy incentives as long as they were "carrots not sticks'; review of setback requirements for estate homes but no limit to the size of homes; and, he would support discussion of MDA/MFA requirements. City Attorney Steve Mattas advised the Council that they could refer the matters where there had been Council consensus back to the Planning Commission for further evaluation. He suggested that it would be preferable for the Council to give clear direction on rather they wanted the Commission to consider and refer recommendations to Council or consider, take action and then refer the matter to Council. Mayor Pro Tem Jones suggested that he would be interested in the Planning Commission's input on the issues being forwarded to Council for further Council consideration. He acknowledged that there was no clear consensus on the topics but Council had indicated they would like further discussion on the matters. He suggested the topics be referred to the Planning Commission for study, analysis and recommendations. The topics included: 1) Fencing: fence amendment to allow replacing 6 foot fences with 8 foot fences (open deer fencing only). 2) Slope properties: analysis of a set of recommendations of what development might be allowable given the advancements in technology, building techniques, and materials for 10 Regular City Meeting Minutes May 24, 2007 projects on sloped lots. This would include review of materials that did not result in an increase of runoff from the property and could be discounted on development calculations. An additional option to be considered was calculations for a second floor not being counted as development on a very steep slope. 3) Estate Homes: Review of setbacks for larger homes but no further study of maximum house size. 4) Definition of incentives for high- energy construction. Review to be forwarded to both the Planning Commission and Environmental Initiatives Committee. MOTION SECONDED AND CARRIED: Moved by Jones, seconded by Mordo and passed unanimously to refer the items identified to the Planning Commission and Environmental Initiatives Committee as appropriate. 13. Consideration of Sergeant William Sigua Memorial City Manager Cahill reported that at the direction of the Mayor, staff and Community Relations Committee representative Duffy Price had reviewed options for an appropriate tribute for Sgt. William Signa of Los Altos Hills who was killed in combat operations while serving in Iraq. Before Council was a proposal for their consideration to name one of the Town's Little League playing fields on Purissima Road in his honor. David Rock, Little League President, had advised the Board of the proposal. Council consensus was to move forward with the memorial. Staff was directed to work with the family and coordinate the dedication. NEW BUSINESS 14. Discussion of City Council Summer Meeting Schedule Following Council discussion, the June 28 and August 23, 2007 regular City Council meetings were cancelled. REPORTS FROM COMMITTEES SUB -COMMITTEES AND COUNCILMEMBERS ON OUTSIDE AGENCIES 15. Loan to the Friends of Westwind for the repair of the lower riding arena surface at Westwind Barn Councilmember Mordo introduced this item to Council. He summarized the recent successes of the Westwind Community Barn Committee (WCBC) that included: the new operating agreement between the Friends of Westwind and the Town; and, the Friends of Westwind's adoption of revised Bylaws. The Committee was now moving forward on renovation plans for the Barn. They would be submitting an agreement for architectural services and the development of a feasibility study to Council in the near future. The estimated project costs were between $500,000 and $1 million with funding to be divided 11 Regular City Meeting Minutes May 24, 2007 Back Nine Greens I Synthetic Turf Lawns I Artificial Grass Field Turf I Athletic Play SYNTHETIC TURF LAWNS I GRASS We use only the highest quality materials available; it's not like any synthetic or artffreial lawn or greas you have ever seen cr felt before. Though it looks, feels and plays so much like real lawn, it is incredibly durable and requires very little .maintenance. Maintenance to the synthetic bur€ is minimal. An cocasicnal brooming is recommended but not necessary. This will 53od rhe fibers up and even out the Infill materiels. Lebr's like leaves and twins can be easily removed with a leaf blower. As long as the leaf blower nozzles rot placed too close to the turf, fine sand and rubber will stay in place while the debris Is blown away. The icing `-em effect of the sun does not harm the sy oetic turf lawnseape or make it fade. The fibers have a 11V protection coating and can wiffistend the damaging 2fects of sun, hat, wind, snow aro Ice. Tne sy[rthatic turf comes with a limited d year rarranty; actual life expectancy is 15-25 years. The drainage in the turf is very similar to natural grass. The turf backing has many perforated holes allowing for water to train vertically. Pets cannot harm the tort. The turf is also installed strictly for dog runs. Urine is not a problem as It absorbs into the sand and ribber and eventually evaporates. You may also spray the soiled area with a hose. The cost comparison to installing synd is lawn or grass versus installing a sprinkler system, top soil, and the price of sod, combined with watering, mowing, weeding, and fertilizing, it can pay for Itself In a few years. S"thri lawns I Synthetk Putting Greens I About I Iii I Gaifery S SackNineGresns 2006. All Rights P.rwd. weh 511s peweloci by D,,ital base's Arnifilal Lawn 15yni Turf Lawns 5 Goss ,......n,..,.,-,..,., rrh' 6/21/2007 Grasscrete b Bomanite: A Functional Green Paving Solution - The Concrete Network Page 1 of 2 ATTACHMENT q Grasscrete by Bomanite: A Functional "Green" Paving Solution Blending architecture and landscape is sometimes a complicated task when functionality, aesthetic appeal and eoo-friendly criterion have to be considered. Grasscrete by Bomande provides a variety of landscape solutions while maintaining a sustainable "green" product design. Grasscrete is a cast -in-place, monolithic, pervious concrete pavement that is continuously minforced to provide superior structural integrity. After the concrete is sufficiently hardened, the voids are filled with topsoil and gmss, thus providing a free draining pavement'with the structure[ capacity to handle most heavy vehicle loads. Grasscrete is great for emergency access lanes, delivery access mutes, overflow parking areas, and for intermittent drainage channels to help prevent erosion. Available in a range of systems specific to the required use, Gresscrete is essentially a cellular reinforced concrete slab, the cells being voids created in the patented casting pmcess which am subsequently filled with soil and seeded with grass or other appropriate ground cover. The Grasscrete system selected can either be purely functional or be a concealed product that is both purposeful and pleasing in appearance. Grasscrete offers the end-user the ability to provide year round access for a variety of applications without compromising the aesthetics of their exterior landscaping and having to utilize traditional hard pavements, eliminating the need to contml storm water runoff. him 6/21/2007 Permeable Paving Information - The Concrete Network Page 1 of 1 Hnd a Grasscrete Contractor Grasscrete can be an excellent alternative to plain concrete surfaces for parking lots, driveways, and access roads for vehicles or fire trucks. Grasscrete can also be used for erosion control. Grasscrete drains at about the same rate as would an ordinary lawn in the same location. The presence of concrete has little effect on the drainage; the soil and the slope are the controlling factors. The surface area of Grasscrete is 47% concrete and 53% hole (to be filled with Grass). Grass usually covers much of the concrete in areas not subject to regular vehicle traffic. Holes may be filled and covered with crushed stone, seashells, etc, to provide drainage in rases where grass is not desired. Construction Details Construction Process Additional Data (Maintenance, Drainage, Load Test Report, Slope Paving, Etc) Section Sponsor BRTar® =64-- Lwxngnruc Find a Grasscrete Contractor http://www.mncretenetwork.wm/grassuete/ 6/21/2007 Grasscrete by Bomanite: A Functional Green Paving Solution - The Concrete Network Page 2 of 2 Grasscrete can also be employed as a stabilization product for areas that experience seasonal runoff, that require maximum water capacity to handle an adjacent hard surface or that require a structural base material prior to application. Gresscrete wn be customized to suit a0 variety of applications where the elimination of retention ponds, wales or other storm water management devices is desired. Gresscrete does not contribute to the heat island effect like other hard surfaces such as asphalt, does not allow contaminants to runoff during first flush" rainfall into potemially fragile eco -systems and allows for tree plantings in dose proximity. Gmsscrete is a very sustainable produd that can employ a large recycled material centent both in the form of aggregate and binder such as fly ash or slag- its Ifiespan is indefinite and can be recyded itself to form the aggregates for future Grasscrete applications. The plastic former utilized to create the void structure is designed to have a limitless number of reuses, the strength to accept live concrete loads, and capable to being removed during the concrete plastic state to create the voids. Structural analysis of the finished concrete section is based upon the bending moment of the mesh reinforcement contained within the slab, relatively to slab depth, contact area with base and an assumed allowable ground bearing of 45kN/m2 for its base. By using combinations of depth and different mesh types, the system can be tailored to provide the most economical solution. httu://www.conaetenetwork-com/bomanite/green.htin 6/21/2007 Permeable pavement 8c°Esau fia;n;2UBUCAInONS haifaet's Frt�k9e Natural Approaches W Stmmwater Manarement Home Pare /3rMM • n• Gress Parking --1--d Performance Area, Whidbey Island and Bellingham Pervious Concrete. multiple Locations pervious Concrete Alley. Bellingham Pervious Driveway. La Natural Approaches to Stormwater Management Permeable Pavement Country Lanes Vancouver, B. C. Background Alleys or back tares in Vancouver, B.C. provide access to garages and are used for public services such as garbage pickup. Consequently, both passenger vehicles and heavy trucks frequently use these lanes. The city of Vancouver developed an environmentally sustainable "Country Lane" design that makes back lanes greener and more attractive. This alternative to paving asphalt lanes to full width is a response to the city's goal to reduce er vi. onmental impacts and to create a more livable community. The city also hopes to increase public awareness of rtormwater issues. Description sties pvrtc m wMvn urs s Preparing structural grass. Country lanes feature two narrow wmra•amaamr�,m. strips of concrete that provide a Vancouver Country Lane smooth driving surface. A plastic grid is completed. placed between and beside these concrete strips and covered with topwil and grass. This structural grass can support vehicles and prevents the grass roots from being compacted and creating ruts in the wit. The road base is a mixture of aggregate, which provides structural stability, and a sand/wit mixture that allows for drainage and provides the soil components required for grass growth. Results Country Lanes provide several benefits: . Controlling stormwater at the source means less change to stream hydrology. . Surface water infiltration recharges groundwater. . Topsoil filters pollutants natumlly. . Adding green space improves air quality. • Replacing asphalt with grass reduces the "heat island effect," where warmer temperatures occur due to pavement hftn-//www.ncatwaeov/Publirafiom/LID studies/permeable pavementhtm 6/21/2007 Permeable pavement Vancouver is building three of these lanes as a demorsuation project. With the success of these demonstration projects, this design will become available as a standard local improvement lane project, Costs The costs are approximately 50 percent higher than conventional lane paving. However, as builders and regulators gain more experience with this approach, they wilt be able to refine the design and construction process and costs should drop. Contact Wally Konowalchuk City of Vancouver, B.C. (604) 873-7387 w Lly_kmm"lchuk@dty.vancow r.bc.ca Pervious Paving Parking Lots Modification Project The Evergreen State College, Olympia Background New building construction at The Evergreen State College requires additional parking capacity. The philosophy of Evergreen is to reduce the impact of the Campus on the erMmnment with every maintenance or redevelopment project, wherever practical. In addition to reducing the environmental impact, 'soft' drainage systems will puede monitoring and teaching opportunities for students in the college's environmental studies program. Based on a Zero Impact' Feasibility Study (see page 27), the college decided to intensify its use of existing parking areas rather than clearing more foresL Description The Parting lots Modification Project will provide additional parking in lots B and C on either side of the main entrance to the campus. Ruroff from the parking lots currently, discharges to the Fast Fork of Houston Creek without treatment or detention. The innovative design adds new parking by removing and reshaping planting islands and reorganizing laves. Pervious paving *stems Will replace approximately 34,DDD square feet of existing landscaping for naw parking stalls. The combination of adding new Pervious paving and converting existing paving to pervious surfaces will result in a net reduction of ruroff to Houston Creek. The paving bid package includes three alternative paving systems, including EcoStonew by UrdGroup, Gravel Pave 2", and a system of crushed rock with cellular confinement The design for the pavement Includes infiltration to the subgrade and storage in rock ballast under the pavement The objective is to 'Zero Impact is a project that adheres to the 6S/0 (65 percent forest cover preserved/zero effective impervious surface) development standard and is constrained by characteristics of a healthy watershed as described in the Salmon in the City Conference Abstracts. Approximately a mmmd. mately 9,OOD square feet of impervious parking area at The Evergreen State College vvill be converted to bloretentim areas (numbered in plan at right). Pervious sanouspaWngiasaw. g Page 2 of 7 rn ..,..a:e../..e....sol.l> ..noemmt hhn 6/21/2007 Permeable pavement Infiltrate the 100 -year, 24-hour storm materials vary according without surface runoff. A sand filter to the intensity of use providing water quality treatment is in parking lots. In the Located directly below, the paving above diagram, a system, cellular confine-ment system stabilizes a Approximately 9,000 square feet of parking surface of rkin lot access lanes will be crushed rock. P g converted to bioretention facilities. The design provides for soil restoration to a depth of two feet. The objective is to provide bloretention areas with sufficient surface and subsurface storage volume to infiltrate runoff from all events up to the 100 -year, 24 -tour storm. Evergreen may also build a motorcycle parking structure with a vegetated roof that will be a study focus for students in the environmental studies program. The motorcycle port will have approximately 6 inches of soil on the roof with plants selected for their tolerance to extreme wet and dry conditions. Challenges One complication of the project was old fill material found under the existing pavement. Because it is unsuitable for pavers or bioretention facilities, contractors had to remove and dispose of it. This cost would not have occurred with the asphalt paving alternative. Costs The cost of the zero discharge parking retrofits is the same as, or lower than, traditional alternatives using new treatment and detention systems. Costs for green roofing will be higher, but the increased life of the roof will help offset these costs. An important factor in choosing the pervious paving systems is that this approach negates the need to clear and grade surrouMing forest areas for detention ponds. Contacts Michel George The Evergreen State College ( " Thomas W. Holz Grass Parking Lot and Performance Area Whidhey Island and City of Bellingham Background A farmers' market and community hall at Bayview Comer on Whidbey Island needed weekend parking. 2020 Engineering designed a reinforced grass pavement system that makes the area look like open space when not used for parking. In Bellingham, the owner of the Boundary Bay Brewery wanted to expand the winter parking area and to Grass parking lot design meets standards for traditional traffic loads and resembles open space when not used for parking. Page 3 of 7 htt,r//w .ngat.wa.eov/Publicatiom/LID studies/vermeable. pavenmthlm 6/21/2007 Permeable pavement provide a summer beer garden and performance area. Description The grass parking lots use an interlocking plastic grid (GeoBlock" at Bayview Comer and Grassy Pavers" at Boundary Bay Brewery). The grid was filled with a mixture of sand and chicken compost and planted with grass. Results The parking lot designs meet standards for traditional traffic loading. The grass parking replicates natural conditions for slowing and infiltrating stormwater runoff and eliminates the need for conventional detention/treatment systems. Costs The cost for both lots was $3 to $4 per square foot, installed. Pervious Concrete Multiple Locations have used Pervious concrete nationally for than 20 years. In the 1980s, sereral projects used pervious concrete in the Puget basin, including at Musky Stadium and at xmcrpnm m emwm mrsa anir Rnere w.rcew of o,et umn�) Perviousete infiltratesinfiltrateswater extremely well— typically 250 to 300 inches per hour. sae•,raeumrde Bayview come, Whidbey Island. Top photo: ager construction. Lower photo: during construction. Boundary Bay Brewery, Bellingham. Top photo: during construction. Lower photo: after wre-truction. Page 4 of 7 bttn:/Avww.usatwa Rov/Publications/LID studies/permeable pavement.htm 6/21/2007 Permeable pavement a park in Redmond. in recent years, builders have used pervious concrete in several new projects and more are planned. Description Pervious concrete is a special structural concrete with the fine particles removed. This creates 15 to 20 percent voids so the concrete looks like a giant rice cake. The pavement will support traffic and allow water to pass through to a gravel layer undemeath. The strength of pervious concrete is about 85 percent of conventional concrete, maidng it suitable for sidewalks, driveways, alleys, parking lots and residential streets. Designers and irntallers need special training to ensure structural integrity and porosity. Post -placement testing is important Pervious concrete is much more porous than underlying soils. Typical infiltration rates are 250 to 300 inches per hour, typical installations require soils with percolation rates of more than 112 -inch per hour. A gravel bed placed underneath the concrete stores water before it moves into the soil or can provide a channel for movement of water to stormwater channels. A flinch bed of rock or aggregate 314 inches or larger with 30 percent voids will store 1.2 inches of water. In addition to its water quantity benefits, pervious paving can remove some pollutants through absorption, straining and microbial decomposition. Following are some of the locations of recent pervious concrete installatiow around Puget Sound: Four blocks of sidewalks on N. 145th Street, Seattle. • 400 feet of sidewalks at 100th Ave., Marysville. • Six parking lots at Fort Lewis. • Sidewalk on North Street in Olympia. Plaza at Greemvond Park, Seattle. • Alley In Bellingham. Parking lot for the Washington Aggregates a Concrete Association office, Des Moines. • Nine parking spaces at Bayview Comer, Whidbey Island. Planning is currently underway for a residential subdivision to demonstrate the usefulness of permeable concrete for residential streets, driveways and sidewatl¢. Costs The cost for pervious concrete is typically $6 to 9 per square foot This is comparable to conventional concrete. Contacts Bruce Chattin Pervious Concrete Alley City of Bellingham Background Page 5 of 7 http://www.psatw&gov/Publications/LID studies/permeable_pavementhtm 6/21/2007 Permeable pavement A residential homebuilder was interested in sustainable construction and decided to try pervious paving in an alley that provides access to homes. This was the first application of a pervious concrete roadway in a Whatcom County right-of- way. Description can µac W we.. m ager The alley provides access to two pervious concrete alley, residential properties while minimizing Bellingham. environmental impacts. Porous concrete allows for the infiltration of stonnwater runoff while providing the same structual capacity as conventional concrete. Engineers determined the depth of the coshed rock base material --sed to support the concrete—based upon the type of underlying soil conditions and amount of water storage area needed to accommodate stone events. No fine materials were used. Since this project was the first of its kind, the city of Bellingham wanted to know about durability, load, treatment and maintenance requirements. Results Stormwater treatment occurs as water flows through the pervious concrete road section and underlying snits. Other characteristics, such a maintenance issues, are comparable to conventional pavement systems. The engineer used the Department of Ecology's Stormwater Management Manual for Western Washington as one of the guides to document the Stormwater infiltration benefits of the project Costs materials cost approximately $1.50 per square foot Installation costs were similar to conventional paving. Contact 2020 Engineering, Inc. ( Pervious Driveway City of Bellingham Background Stormwater runoff causes pollution in the Lake Whatcom watershed in Bellingham, as it does in many other developed areas. Because Lake Malcom is the sole source of drinking water for the city of Bellingham, this can have serious wnsequences for the city's drinking water supply. A homeowner in � ri1O1°.vewmIew W the watershed wanted to demci strate pervious driveway, alternative sustainable building practices Bellingham. and decided to replace the edsting impervious asphalt driveway with a pervious one. Description The homeowner installed a pervious paving system composed of individual interlocking paving blocks placed on a http://www.psaLwa.gov/Publications/LID_ stadies/permeable pavementhtm 6/21/2007 Permeable pavement Page 7 of 7 bed of fine gravel. The configuration of the pavement blocks provides a series of voids to allow stonnwater to infiltrate. Results The new driveway has better structural Properties than the replaced asphalt surfaced driveway. The pervious paver system replicates natural conditions for stonnwater infiltration, provides treatment, and eliminates the need for conventional detention/treatment systems. The homeowner reports a significant reduction in the volume of stormwater flowing doom the driveway, and into the fake. The perviouspaNew avveerrvale system replicates natural stormwater infiltration, provides treatment and eliminates the need for comentional detentiord treatment systems. Costs The cost was approximately $5 per square foot installed. Contact 2020 Engineering, Inc. (36D) 6712020 Website: ,2020enelneeringxonn Home - About the Sound - Who We Are - Events Calendar - Publications - Rnpurces - Site Inde trTJ roves swnd AGim T. oMa of the Governor P.D.Ba iWW, ota,l; wa Mn 98SU-MW Tdldree(WW "W10: 1900151 -SOUND, outride WeNIn mIa601715 SH0 PRIVACY Non' Lwim,en6 m goq a VA gae7 Comet 90Y, Ccy+gM O Aua.¢t 10. NM M ROft Res d http://www.psaLw&gov/Publications/LID_studies/permeable_pavement.htn 6/21/2007 Watershed Benefits of Permeable Pavers Home I LID ftokaMUnd I Delon I Site Mao I D'sdaime[ — =,Watershed Benefits of Permeable Pavers Typical scenario... Most of the 'paving oveP in developed areas is due to common mads and parking lots, which play a major role in transporting increased stormwater runoff and contaminant loads to receiving waters. Alternative paving materials can be used to locally infiltrate rainwater and reduce the runoff leaving a site. This can help to decrease downstream flooding, the frequency of combined sewer overflow (CSO) events, and the thermal pollution of sensitive waters. Use of these materials can also eliminate problems with standing water, provide for groundwater recharge, control erosion of streambeds and riverbanks, facilitate pollutant removal, and provide for a more aesthetically pleasing site. The effective imperviousness of any given project is reduced while land use is maximized Alternative pavers can even eliminate the requirement for underground sewer pipes and conventional stormwater retention / detention systems. The drainage of paved areas and traffic surfaces by means of permeable systems is an important building block within an overall Low Impact Development scheme that seeks to achieve a stormwater management system close to natural conditions. ...with permeable pavers* Water Quality Some current studies on the effectiveness of permeable pavers for reducing Total Suspended Solid (TSS), nutrient, metal and thermal loadings are being conducted in Florida, Toronto, and Washington State. The puking lot of the Florida Aquarium in .•: �'`. ^ r " '� •'r� ` ° a , Tampa, which serves 700,000 visitors annually ;41 has been innovatively designed as a research http://www.lid-stonnwater.naVpermeable�pavers/p=pavers benefits.htm 6/21/2007 and demonstration project for the use of permeable pavers as part of a treatment train approach, comparing three paving surfaces in conjunction with swales.1 First-year results found that load removal efficiencies for metals (copper, iron, lead, manganese and zinc) ranged from 23 to 59% for asphalt pavement with a swale; 62 to 84% for cement pavement with a swale; and 75 to 92% for porous concrete with a Swale. In general, metals were measured at much higher concentrations in the basins paved with asphalt than those paved with cement products. The porous system with a Swale also achieved 91% removal efficiency for total suspended solids, higher than the other two paving systems. Studies at the University of Guelph in Canada have also observed greater pollutant loads from asphalt surfaces than from concrete or permeable pavers. There, a research team led by Professor William James has been performing field and laboratory tests since 1993 on the influence of permeable pavers on runoff pollutant levels and thermal characteristics. They have found that a permeable paver made up of interlocking concrete blocks can significantly reduce the surface runoff loads of such contaminants as nitrite, nitrate, phosphate, phosphorus, metals, BOD, and ammonium.2In addition, during a lab simulation, the permeable pavers were found toreducesurface runoff temperatures by 2 to 4 degrees Celsius compared to the runoff from asphalt paving. Since the permeable pavers also increase infiltration, the total heat content of runoff leaving a site is reduced substantially.3 Finally, surface and subsurface runoff samples are being collected by the Center for Urban Water Resources Management in Washington State from a test parking area, which contains five different surface materials.4 Constructed in 1996, the King County employee parking lot contains nine stalls, of which one is traditional asphalt, and the others are four pairs of alternative permeable pavement surfaces: gravel -filled interlocking concrete blocks, soil and grass -filled interlocking concrete blocks, gravel -filled plastic cell networks, and soil and grass -filled plastic cell networks. http://www.lid-stormwater.net/permeable�pavers/pe=pavers_bmefits.ht,n 6/21/2007 Pavers The project's primary goal is to determine the long-term water quality benefits of these systems under real world usage. A system of pipes, gutters and gauges collect and enable the measurement of the volume and chemistry of both the surface runoff and the subsurface infiltrate. A comprehensive water quality analysis is being conducted over the winter of 20012002. Preliminary results indicate that the subsurface runoff is consistently cleaner than the surface runoff, statistical analyses and reports will be produced in future months (Derek Booth, Feb. 2002, personal communication). For more specialized users, continuing research at Coventry University in England has been looking at applying nutrients to permeable pavers in order to support a microbial population that can serve as an in- situ bioreactor for oil degradation in highway and parking lot runoff= Studies have demonstrated the potential to maintain microbial activity for over 12 months from one application of a slow-release fertilizer, with warnings given about ensuring the effective use of the nutrients so that high effluent levels will not cause eutrophication in receiving waters. Water Quantity Most of the above studies have also examined the influence of permeable pavers on runoff volume, tending to show a marked reduction in the surface runoff that leaves a permeable paver site due to increased infiltration In the University of Guelph experiments, field sites with permeable interlocking concrete pavers demonstrated a 90% reduction in =off volume.1 The treatment train studies at the Florida Aquarium showed that, in general, the use of swales reduced runoff volume but that paving type also played a major role in runoff reduction, with permeable pavers being the most effective. The figure below demonstrates this fact as well as the caveat that the use of swales and permeable pavers has the most influence on runoff during small stotms.6 For high intensity rainfalls or when soil conditions are saturated, runoff is not reduced as substantially. Note the different scales on the two graphs; the first is for a rain event that produced just over 0.5 inch of rain in about 75 minutes, while the second is for an event producing almost 2.5 inches in under 2 hours and occurring less than 24 hours after four preceding days with rain http://www.lid-stormwater.net/permeable_pavers/permpavers bmefits.htm 6/21/2007 rage 4 or 5 The studies by the Center for Urban Water Resources Management in Washington State have looked for similar differences in the hydrologic response of pavers based on storm intensity or if the storm followed a long dry period versus a period of abundant rain. To date, however, results show a general absence of surface runoff from the permeable pavers regardless of conditions: "it all just infiltrates, all the time" (Derek Booth, personal communication). The figure below, representing a typical observation during the study's fust year, compares surface nmoff produced from traditional (asphalt) and permeable (Turfstone) pavements.! The Turfstone permeable paver is a 60% impervious surface made up of soil and grass -filled interlocking concrete blocks. The measured surface runoff from the Turfstone is less than 1 percent of the total rainfall and is probably a result of observed leaks in the, covering over the collection system. All other permeable pavement systems showed equivalent results. The asphalt paving, however, responds quickly to the rainfall, with most of the rain that hits the surface running off. It is likely that results are different from those in Florida due to differences in the two regions' rainfall regimes. The Washington rain event had a maximum rainfall intensity that was under 0.2 in/hr, this was typical of the storms recorded. In comparison, the heavier rain event presented in the Florida graph had http://www.lid-stormwater.net/permeable�__pavers/permpavers_benefits.htrn 6/21/2007 .storm NuvF�nsa>�'$`1`�,'3"�96•? SutFdva rtiv o>�1=rb vi Td+iiEon P;'vi`A'3pTablt v.ve s 7� a.di z L � s • k� v.ma a vv V..99 SOD.aa ffia0 5aa.'➢p It is likely that results are different from those in Florida due to differences in the two regions' rainfall regimes. The Washington rain event had a maximum rainfall intensity that was under 0.2 in/hr, this was typical of the storms recorded. In comparison, the heavier rain event presented in the Florida graph had http://www.lid-stormwater.net/permeable�__pavers/permpavers_benefits.htrn 6/21/2007 a maximum rainfall intensity of 1.5 in/hr. Rain events in Washington State are generally of a lower intensity and longer duration than those measured in Florida, where the rainfall, particularly in the summer, is dominated by short and more intense convective events. 4 all six photographs from UNI Eco -Stone® Permeable Concrete Pavers PowerPoint presentations, 02000 UNI -GROUP U.S.A. www.uni-grouousa org 1 Rushton, B.T., 2001: Low -impact parking lot design reduces runoff and pollutant loads. Journal of Water Resources Planning and Management, (May/June), 172-179. 2 James, W., ed, 1997: Advances in Modeling the Management of Stormwater Impacts Volume S. Proceedings of the Stormwater and Water Quality Management Modeling Conference, Toronto, Ontario, February 22-23, 1996, 520 pp. 3 James, W., 2002: Green roads: Research into Permeable Pavers. Stormwater, (March/April), 48-50. 4 Booth, D.B., J. Leavitt and IC Peterson, 1996: The University of Washington Permeable Pavement Demonstration Project. Background and First -Year Results, available online at bttp:/Mmt.washinelon.edu cuwrm/ under Research - 5 Pratt, C.J., A.P. Newman and P.C. Bond, 1999: Mineral oil bio -degradation within a permeable pavement: long tam observations. Wat. Sci. Tech., 39 (2),103-109. 6 Southwest Florida Water Management District, 2001: Florida Aquarium Parking Lot - A Treatment Train Approach to Stormwater Management. Final Report for FDEP Contract No. WM 662, Brooksville, Florida, 220 pp. 7 Booth, D.B. and J. Leavitt, 1999: Field evaluation of permeable paver systems for improved stormwater management Journal ofthe American Planning Association, 65(3), 314-325. Back to ton http://www.lid-stormwater.net/permeable—pavers/p=pavas_benefits.htm 6/21/2007 Planning Commission Minutes June 28, 2007 Page 3 NEW BUSINESS 5.1 Development Area Policy Nicole Horvitz, Assistant Planner, presented the staff report stating that at the May 24, 2007 City Council meeting, Council directed staff to research and prepare proposed amendments to the Town's Development Area Policy to allow additional development area for properties with a maximum development area of 7,500 feet or less. Semi -permeable materials used in landscape and hardscape improvements do not increase water run-off from the property and could receive a partial credit for development area coverage. The Town's current development policy does not award credit for use of semi -permeable materials on tennis or sport courts, driveways, required parking, above ground decks and turnarounds. The proposed credit would be given to constrained lots (one acre minimum with 7,500 square feet of development area or less) for the use of semi -permeable materials for turn-arounds, required parking and driveways. Staff recommends a credit of 90 percent for artificial turf because of the product's natural appearance and permeability. Artificial turf installation would be limited to rear and side yards to minimize visibility and allowed to encroach into the setback. Grasscrete pavers and permeable concrete are recommended to receive a 50 percent credit and permeable pavers a 10 percent credit. Commissioner Cottrell commented on the variety of artificial turf materials available and the different permeability capabilities. Commissioner Harpootlian bad concerns about subsurface drainage if artificial turf was installed over compacted soil. The ground surface should be prepared properly to accept drainage and allow the water to penetrate the soil. Sandy Humphries, Environmental Design Committee, commented on the strong fumes released on hot days from the astro-turf sports field installed at Pinewood School. She requested that if astro-turf is allowed in Town, the water runoff be required to be filtered either over a heavily vegetated area or a filtering system because of the turf s toxic nature. She also felt that pavers should not be installed over a concrete base nor solid concrete pavers allowed. Chairman Collins noted that some types of artificial turf use small particles of ground -up tires applied to the top surface to help the turf blades remain upright. This application is suitable for level areas but unsuitable for slopes as rain will cause the loose particles to be washed off the artificial turf and into the drainage system. Discussion ensued regarding the advantages and disadvantages of semi -permeable materials and possible development area credit granted to acre lots with a maximum development area of 7,500 feet and possible development area credit for all lots installing artificial turf. Debbie Pedro, Planning Director, summarized the staff recommendation to allow development area credit for semi -permeable materials and revise the development area policy to allow development area credit for driveways, turn-arounds and required parking spaces that utilize grasscrete, permeable concrete or permeable pavers on constrained lots with maximum development area of 7,500 feet or less. For a one acre lot that would support a 5,000 square foot house, only 2,500 square feet of development area would remain for the driveway, pool, patio, Planning Commission Minutes June 28, 2007 Page 4 DRAFT etc. The proposed credit would allow up to an extra 1,500 square feet of development area if permeable concrete, permeable pavers or grasscrete was utilized. MOTION SECONDED AND PASSED BY THE FOLLOWING ROLL CALL VOTE: Motion by Commissioner Carey and seconded by Commissioner Cottrell to forward a recommendation to City Council to adopt staff recommendations for development area credit with the exception of reducing the development area credit for permeable concrete to 30 percent. AYES: Chairman Collins, Commissioners Carey, Clow, Cottrell and Harpootlian NOES: none This decision will be forwarded to be heard at a future City Council meeting. 6. REPORT FROM THE CITY COUNCIL MEETING 6.1 Planning Commission Representative for June 10 -Commissioner Cary 6.2 Planning Commission Representative for June 28's -Cancelled 6.3 Planning Commission Representative for July 12`s -Chairman Collins 6.4 Planning Commission Representative for July 26u' -Commissioner Clow APPROVAL OF MINUTES 7.1 Approval of June 7, 2007 minutes PASSED BY CONSENSUS: To approve the June 7, 2007 minutes. REPORT FROM FAST TRACK MEETING — JUNE 12 AND JUNE 19, 2007 8.1 LANDS OF LANDS OF PAO AND CHAO, 14555 Harvard Court. File #18-07- ZP-SD; A request for a Site Development Permit for a 1,600 square foot two story addition (maximum height: 27') and interior remodel. CEQA Review: Categorical Exemption per Section 15303(a). (Staff -Nicole Horvitz). Approved with conditions. 8.2 LANDS OF MUNCH, 12758 Leander Drive; File #221-06-ZP-SD-GD; A request for a Site Development Permit for 1,753 two story addition and interior remodel (maximum height 23'). CEQA review -Categorical Exemption per Section per Section 15303(a). (Staff -Nicole Horvitz). Approved with conditions. 8.3 LANDS OF LEGATES, 11308 Magdalena Road; File #20-07-ZP-SD; A request for a Site Development Permit for a new 5,682 square foot single story residence (maximum height 25'4"). CEQA review -Categorical Exemption per Section 15303(a). (Staff -Nicole Horvitz). Approved with conditions. 8.4 LANDS OF COVELL, 26940 Orchard Hill Lane; File #46-07-ZP-SD-GD; A request for a Site Development Permit for a new 5,012 square foot two story residence with a 1,676 square foot basement, 450 square foot pool, and 135