RES 15810 - Laserfiche WebLink

Significant Impact Impact 4.3-5: Project construction would require the filling of seasonal drainage channels and in-channel wetlands. Finding Changes or alterations have been required in, or incorporated into,the project which mitigate or avoid the significant effects on the environment. Facts in Support of Finding The City of Pleasanton has adopted the following measures which will reduce potential impacts to seasonal drainage channels and in-channel wetlands to a less-than-significant level: Mitigation Measure 4.3-5: The proposed project would impact approximately 0.022 acre of Waters of the United States(0.016 acre and 243 lineal feet of drainage channel waters,and 0.006 acre of in-channel wetlands). The connection to Sunset Creek Lane would require approximately 100 linear feet(400 square feet)of additional impact. While compensation for impacts to Waters of the United States shall occur at a minimum of a 1:1 replacement ratio,the CDFW and RWQCB generally require a replacement ratio of 2:1 or better. To the degree possible,the applicant shall replace lost wetland resources in kind. Thus,the project would create at least 343 feet of channel(1:1 ratio)and 0.031 acres of waters of the US (seasonal drainage channel), of which would be at least 0.006 acres of seasonal wetlands on the Lund Ranch property. Creation of new channels can be logistically difficult as there are finite areas within a site to accomplish this type of mitigation. Therefore, some mitigation for the seasonal channel may have to be out-of-kind. This could be accomplished by creating additional seasonal wetlands. The creation of not less than 0.031 acre of wetland and/or seasonal channel would be required. The site supports sufficient opportunities to accommodate creation of wetland habitat. Even if the project could not create 243 feet of channel,there are a number of areas along Drainage Areas A and B and within the non jurisdictional drainage swales on the site that could easily accommodate this type of constructed wetland mitigation. The goal of this mitigation should be to create new wetlands and enhance existing wetlands in a way that replaces the functions and values of the wetlands that are proposed to be filled. A qualified biologist should develop a restoration plan that identifies the full extent of the impact, location of suitable sites to create or enhance wetlands of the necessary acreage, and develop success criteria specific to the actual wetland creation design. The mitigation site should be monitored for at least five years. A detailed wetland restoration plan should be developed for this mitigation area during the regulatory permitting phase of the project. The plan will be subject to review by the City of Pleasanton and acquisition of the required permits through City consultation with the USACE, RWQCB, CDFW. This plan should incorporate additional studies and details, including the following: • Type and acreage of wetland to be impacted and goals for wetland creation • Detailed assessment of soil suitability for wetland creation • Description of site hydrology, including depth and duration of inundation, potential for scour or deposit of sediments, etc. • Site preparation measures, including grading methods,to relieve compaction and/or ensure low potential for scouring of soils • Revegetation and erosion control on slopes surrounding the mitigation site • Description of buffer areas around the mitigation • Maintenance program • Long term monitoring program, including performance and success criteria. LUND RANCH II(PUD-25)RESIDENTIAL PROJECT 9 FINDINGS