DEPARTMENT: Development Services
SUBJECT: TPV 18-018 Tree Preservation Variance for Davis Ranch/Silver Canyon Off-Site Sewer
SUMMARY:
Request by Mr. Chris Dice, 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.” Staff recommends approval. (Herminio Griego, (210) 207-6042, herminio.griego@sanantonio.gov, Development Services Department)
BACKGROUND INFORMATION:
Project A/P# 2352542
Council District: Outside City Limits
Consultant: Chris Dice, P.E. of Cude Engineers
Staff Coordinator: Herminio Griego, Assistant City Arborist, (210) 207-6042
ANALYSIS:
The Development Services Department (DSD) has reviewed the information presented in Mr. Chris Dice’s letter dated May 16, 2018.
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. Heritage trees shall be preserved at one hundred (100) 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 significant and heritage trees within both the 100-year floodplain and Environmentally Sensitive Area in excess of the 80% significant and 100% heritage minimum preservation of protected trees in place under the 2010 Tree Preservation Ordinance for construction of an off-site sewer for Davis Ranch and Silver Canyon Subdivisions. DSD staff does agree with the applicant’s request to mitigate for significant trees below 80% and heritage trees below 100% preservation for the following reasons:
1. Project Information - The scope of this project is located within the City of San Antonio’s ETJ, south of Silver Oaks Unit 5 and west of Silver Oaks Unit 6 (see attached exhibits). This is a SAWS sewer infrastructure project that is utilizing existing sewer easements or reservations. Additional required easements to complete the sewer alignment are being created by separate instrument and thus this project does not have a plat ID. The alignment for the proposed gravity sewer main primarily runs along drainage channels, floodplain and drainage lows therefore; most of the limits for this project are either within the 100 year floodplain or 60’ riparian buffer.
2. Tree Preservation - Due to the proposed scope of work, the project is unable to preserve the minimum 80% of significant trees and 100% heritage trees within the 100-year floodplain and Environmentally Sensitive Area (ESA). Given the limited width restraints due to the use of an existing sewer easement, the design team made numerous efforts to route the new sewer alignment in such a way as to maximize the number of trees preserved. Currently there is total of 1,202.5 inches of significant trees and 206 inches of heritage trees existing within the 100-year floodplain. Post development there will be 395.5 inches (32.89%) of significant trees and 118 inches (57.28%) of heritage trees preserved within the 100-year floodplain. Within the ESA, there is currently a total of 230 inches of significant trees. There are no heritage trees located within the ESA. Post development there will be 26 inches (11.3%) of significant trees preserved within the ESA. Required mitigation for these categories includes: 566.5 inches for significant trees within the 100-year floodplain, 235.9 inches for heritage trees within the 100-year floodplain, and 159 inches for significant trees within the ESA. Since replanting within the floodplain and ESA areas are impractical, the applicant proposed to re-seed all disturbed areas with a native seed mix to help return the ESA area to pre-development conditions.
3. Tree mitigation - A grand total of 961.4 diameter inches of trees will be mitigated by paying in to the Tree Mitigation Fund $192,280.00 (961.4 inches x $200 per inch). In addition, the contractor will be required to seed all disturbed areas 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.
DSD staff supports the applicant’s request to mitigate for significant trees below 80% and heritage trees below 100% preservation requirements based on the conditions of the site, design constraints, and exceeding mitigation requirements. The proposed Variance Request meets the intent and spirit of the Tree Ordinance therefore, staff recommends approval.