DEPARTMENT: Development Services
SUBJECT: TPV 17-017 Tree Preservation Variance for SAWS Lift Station 225 & 227 Removal
SUMMARY:
Request by Mr. Miles Stanley, P.E., for approval of a tree preservation variance request from Unified Development Code 35-523 (h), “significant trees shall be preserved at eighty (80) percent and heritage trees at one hundred (100) percent preservation within both the 100-year floodplains and environmentally sensitive areas.” The applicant is requesting a Variance Request to mitigate for removal of tree stand within the 100-year floodplain in excess of the 80% minimum preservation of protected trees in place under the 2015 Tree Preservation Ordinance for the elimination of Lift Stations 225 & 227 as part of a SAWS’ consent decree with the United States Environmental Protection Agency and part of SAWS 2017 Lift Station Elimination Program. The required mitigation for the 100-year floodplain will be met by paying a total of 652 diameter inches, or $130,400.00, into the Tree Mitigation Fund. In addition, the contractor will be required to seed all disturbed area with a native grass seed mix consisting of grasses, legumes and wildflowers native to the San Antonio area. (Herminio Griego, (210) 207-6042, herminio.griego@sanantonio.gov, Development Services Department)
BACKGROUND INFORMATION:
Project A/P# 2278574
Council District: Outside City Limits
Consultant: Miles Stanley, P.E. of Ford Engineering
Staff Coordinator: Herminio Griego, Assistant City Arborist, (210) 207-6042
ANALYSIS:
The Development Services Department (DSD) has reviewed the information presented in Mr. Miles Stanley’s letter dated September 14, 2017.
The Unified Development Code (UDC) - Article V, Section 35-523 (h), 100-Year Floodplain(s) and Environmentally Sensitive Areas states that, “Significant trees shall be preserved at eighty (80) percent preservation within both the 100-year floodplains and environmentally sensitive areas. Mitigation shall be prohibited in floodplains and environmentally sensitive area except when a variance is granted by the Planning Commission.”
The applicant is requesting a Variance Request to mitigate for removal of tree stand within the 100-year floodplain in excess of the 80% minimum preservation of protected trees in place under the 2015 Tree Preservation Ordinance for the elimination of Lift Stations 225 & 227 as part of a SAWS’ consent decree with the United States Environmental Protection Agency and part of SAWS 2017 Lift Station Elimination Program. SAWS staff has coordinated with city staff to ensure that the proposed tree mitigation meets desired criteria. The project team has also coordinated with the contractor for this project to ensure that the contractor can preserve as many trees as possible while maintaining a safe work environment and delivering a high quality product. DSD staff does agree with the applicant’s request to mitigate for tree stand below 80% preservation for the following reasons:
1. Project Information - This project will eliminate two long force mains and lift stations and replace them with new gravity sanitary sewer pipeline. This project will install approximately 2.8 miles of 24-inch PVC sanitary sewer pipeline and demolish two existing lift stations. The pipeline alignment runs along the Medio Creek Floodplain. SAWS and the project team have worked diligently to provide the required infrastructure while complying with the City’s Tree Ordinance. As an example, the location of the temporary construction easement was placed in a way to minimize the removal of trees and the alignment of this pipeline was located outside of the most heavily wooded areas within the floodplain.
2. Tree Preservation - Due to the proposed scope of work, the project is unable to preserve the minimum 80% of significant trees within the 100-year floodplain and Environmentally Sensitive Area (ESA). Tree preservation percentages within the floodplain and ESA area are 44.7% and 24%, respectively. One 25-inch Mesquite tree will also be removed within the floodplain due to the alignment of the proposed sanitary sewer line. Since replanting within the floodplain and ESA areas are impractical, a 50% native seed mix credit was given to the project for proposing to re-seed all disturbed areas with a native seed mix to help return the ESA area to pre-development conditions. After applying the 50% native seed mix, the required tree mitigation for heritage trees, ESA and floodplain equates to 652 diameter inches.
3. Tree mitigation - A grand total of 652 diameter inches of trees will be mitigated by paying in to the Tree Mitigation Fund $130,400.00 (652 inches x $200 per inch). In addition, the contractor will be required to seed all disturbed area with a native grass seed mix consisting of grasses, legumes and wildflowers native to the San Antonio area. Where trees have been removed, the contractor is required to forgo using hydromulching in favor of a more robust drilled seed method to establish the native seed mix. In places where trees are to be preserved, the contractor will also make efforts to preserve the native understory as well.
DSD staff supports the applicant’s request to fall below 80% of tree stand preservation requirements based on the project type, conditions of the site and design constraints. The proposed Variance Request meets the intent and spirit of the Tree Ordinance therefore, staff recommends approval.