16.80.090 Impervious and partially pervious surface limits.
A. Residential Single Development. One of two development “methods” can be selected, as described below and further detailed in BMC 15.42.060.
1. Fully Engineered Method. See full requirements in BMC 15.42.060(A)(3) and (B)(3); or
2. Forested Method.
a. Impervious surface limits not to exceed 2,000 square feet or 20 percent of the gross lot area, whichever is lesser.
b. Partially pervious surface limits not to exceed 1,000 square feet or 10 percent of the gross lot area, whichever is the lesser.
c. Together, the total impervious surface and partially pervious surfaces shall not exceed 25 percent of the gross lot area nor exceed 2,500 square feet.
d. See full requirements in BMC 15.42.060(A)(3)(b) and (B)(3)(b).
B. Redevelopment of an existing nonconforming lot with regard to impervious and partially pervious surface area limits. When an owner of a lot that exceeds the impervious limits expressed in BMC 16.80.090(A) desires to remodel or add on to an existing building or impervious area or partially pervious surface, they shall comply with BMC 15.42.060(B)(3) or may:
1. Add an additional story to any existing portion of the residential building that will not change the footprint, subject to height limitations in BMC Title 20.
C. Reconstruction of a building that is nonconforming with regard to impervious area limits is allowed on a like-for-like basis when damaged by earthquake, fire, vehicular collision or similar accidental causes. Owners of nonconforming lots with regard to impervious area may not rebuild buildings that have been abandoned or are more than 50 percent destroyed by reason of neglect unless they conform to impervious limits in BMC 16.80.090(A).
D. Impervious Limits for Residential Multi and Commercial Development. The maximum impervious limit for residential multi and commercial development shall be determined during the SEPA review process. The SEPA process shall consider stormwater impacts, ambient water quality, contaminant and nutrient loading and the adopted goals and policies for the Lake Whatcom watershed in effect at the time of application. All residential multi and commercial development review shall emphasize best management practice prevention efforts over treatment strategies for the minimization of water quality impacts and a finding of fact must be made that no increase in phosphorus or fecal coliform loading will result from the approval of the development. [Ord. 2009-06-040; Ord. 2001-01-001].