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storm water control, or other conditions of approval often relieves those concerns and, 60 consequently, appeals are rare. 611 5.3 In reviewing Setback Permit applications, it must be determined that the structure or 62 driveway causing the encroachment won't have negative impacts on adjacent properties 63 and that the improvements will be consistent with the nature of a residential property. 64 6.0 ADMINISTRATIVE APPROVAL OF Ex SS IMPERVIOUS COVERAGE 6 1`5 6.1 Planning Division staff routinely receives questions about, or building permit 66 applications for, small residential additions which represent exactly the kind of 67 improvements the City wants to encourage but that would be prohibited because the 68 proposal would exceed the impervious coverage limit. Staff has to explain to many of 69 these homeowners that a variance for the excess impervious coverage cannot be approved 70 unless they can demonstrate the "hardship" required by state statute; this has the effect of 711 discouraging many of the projects. 72 6.2 The City Code allows typical lots to have impervious surfaces (e.g., driveways, patios, 73 and building footprints) covering up to 30% of the property; that is, an 11, 000-square- 74 foot lot may have 3,300 square feet of impervious surface area. Lakefront lots are 71") allowed impervious surfaces covering 25% of the property. These restrictions have three 76 main purposes: to preserve the residential quality of single- and two-family properties, to 77 protect sensitive lakes and wetlands, and to prevent rain water runoff from entering the 78 storm sewer in greater amounts than the infrastructure is designed to handle. 79 6.3 A review of all of the variance applications which have included excess impervious 80 coverage since the creation of the Variance Board in 2004 indicated that the average of 811 such variances approved impervious surface area equal to 117% of the maximum 82 allowance. That is, impervious surfaces were allowed to cover 34% (instead of 30%) of a 83 typical lot, and shoreland lots were allowed 29% coverage where the Code maximum is 84 25%. 8 1`5 6.4 The research also revealed a natural breakpoint in the variances at 120% of Code 86 allowances (i.e., approving up to 30% coverage on lakefront properties and up to 36% on 87 regular lots) . Only a relative few applications requested variances for more impervious 88 coverage than this, and these requests were for impervious surface area averaging 137% 89 of the amount allowed by the City Code (equal to 41 % coverage on a standard property 90 and 34% on a lake lot) . gii 6.5 All impervious coverage variances approved since the middle of 2006 have included the 92 condition that storm water runoff from the property could not exceed that which would 93 be generated by the maximum allowed impervious coverage. For example, the owner of a 94 standard lot that is granted a variance to have 35% coverage would have to implement 95� measures (e.g., install a rain water garden) to ensure that the storm water runoff 96 generated from the excess 5% lot coverage is infiltrated on site. This requirement ensures 97 that variance approvals do not cause problems on adjacent properties or overburden the 98 storm sewer infrastructure. 99 6.6 A rain water garden is a common choice for residential storm water mitigation because it 1100 is essentially a shallow, landscaped excavation. Depending on the soils, it might be about 11011 1 O'x 15' in area and 8 " deep at the deepest point; rain water is directed toward the PROJO015—RCA-072808 (5).doc Page 3 of 6