2014-12-03_VB_Agenda - Laserfiche WebLink

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DPZA ETAILED ROPOSALAND ONING NALYSIS 1 Zawadski Homes proposes to build a newone-family, detachedresidence for a homeowner 2 client. The proposed improvements include 2,262 square feet of building area (i.e., house, porch, 3 and stoop) and 1,598 square feet of paved surfaces (i.e., driveway, sidewalk, and patio), which 4 would comprise 29.9% of the 12,908 square-foot parcel.The site plan and written narrative 5 detailing the proposal is included with this report as Attachment C. 6 City Code §1017.14 (Shoreland Lot Size) requires parcels in the shoreland district to be at least 7 15,000 square feet. City Code §1004.08(Improvement Area)limits the amount of built 8 improvements(e.g., buildings, driveways, pools, pergolas, etc.) to 50% of the area of a 9 residential parcel.The purpose of this provision is to allow for rather liberal development of 10 residential properties while establishing a maximum amount to prevent over-building. Below this 11 50% cap, however, paved surfaces and the footprints of enclosed buildings are limited to 25% of 12 a parcel area in locations, like the subject property, within the shoreland management district in 13 order to minimize the amount of storm water runoff that may negatively affect the nearby lake, 14 neighboring properties, or public storm water infrastructure. The requested variance is needed to 15 account for the fact that the building footprint and pavement area wouldequal about 30% of the 16 parcel area, which is about 635square feet more than the 25% limit would allowon this 17 substandard parcel.If the approximately1,270 square-foot proposed driveway can be built to be 18 at least 50% pervious, the overall imperviouscoverage of the site would be at or below the 25% 19 limit even though the total building footprint and pavement area would not change. 20 An important bit of nuance in the text of §1004.08, asdiscussed above,is the fact that it specifies 21 a limit on “building footprints and paved surfaces” and does not use the word “impervious.”In 22 theory, a driveway made of 100% pervious pavement—that is, a paving material that allows rain 23 water to infiltrate through the pavement and into the soils underneath instead of forcing the rain 24 water to run-off elsewhere—would not add to a property’s impervious coverageregardless of its 25 size. This kind of product can be especially helpful on smaller parcels where even moderately- 26 sized homes can approach 25% of the parcel area.If a pervious driveway isn’t properly 27 maintained, however, it can become less perviousover timeandthepercentage of impervious 28 surfaces can gradually increase beyond the established limit.City staff has long been supportive 29 ofpervious paving productsas a way to minimize storm water but,until recently, staff didn’t 30 have a good way to ensure that pervious pavement would be properly maintained. When this 31 “improvement area” provision was adopted in 2010, all paved surfaces, both pervious and 32 impervious, were treated the same so that impervious surfaces would still not exceed 25%even if 33 it included pervious pavement thatwas allowed tofail over time. 34 In 2013, however, Roseville created the Residential Storm Water Permit (ReSWP) which is an 35 administrative process of accommodating increased “building footprints and paved surfaces” by 36 reviewing and approving plans both for installing best management practices (BMPs) for storm 37 water mitigation and ensuring the proper, ongoing maintenance and functioning of those BMPs. 38 With the ReSWP, a driveway built with pervious pavement can be recognized as such, and the 39 driveway’s contribution to impervious surfaces can be calculated as something less than the total 40 driveway area, depending on the specified permeability of the pavement.Staff from Roseville’s 41 Planning and Engineering Divisions have been discussing amending the zoning codeso that it 42 benefits from the greater differentiation of paved surfaces,butthe present proposalis bound by 43 the existing code requirements. 44 The reason this topic is coming forward as a variance request rather than as a zoning amendment 45 is that Roseville’s EngineeringDivisionstaff is currently working on an amendment for pervious 46 PF14-030_RVBA_120314 Page 2of 5