DEPARTMENT: Development Services
SUBJECT: TPV 20-024 Tree Preservation Variance for SAWS W-6 Upper Segment Sanitary Sewer Project
SUMMARY:
Request by Mr. Jeff Farnsworth for approval of a tree preservation variance request from Unified Development Code Section 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”, located Highway 90 to Southwest Military Drive. Staff recommends approval. (Herminio Griego, (210) 207-6042, herminio.griego@sanantonio.gov, Development Services Department)
BACKGROUND INFORMATION:
Project A/P# 2564579
Council District: 4
Consultant: Mr. Jeff Farnsworth
Staff Coordinator: Herminio Griego, Assistant City Arborist, (210) 207-6042
ANALYSIS:
The Development Services Department (DSD) reviewed the information presented in Mr. Jeff Farnsworth’s letter dated February 14, 2020.
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 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 the removal of tree survey delineated significant trees in the Environmentally Sensitive Areas and Floodplain in excess of 80% minimum preservation of tree survey delineated trees in place under the 2010 Tree Preservation Ordinance for development of San Antonio Water System (SAWS) W-6 Upper Segment Sanitary Sewer project (the Project). DSD staff does agree with the applicant’s request to mitigate via enhanced revegetation and payment into the Tree Mitigation Fund for tree stand determined to be below 80% tree survey preservation in the floodplain and buffer areas for the following reasons:
1. Existing site conditions - The W-6 Upper Segment Sanitary Sewer project is required pursuant to the agreement between the City of San Antonio and the United States Environmental Protection Agency to address capacity constrained sewer infrastructure across the City of San Antonio. The Project is essential for the health and welfare of San Antonio’s citizenry. The Project consists of replacing approximately 31,000 linear feet of 8” to 104” gravity sewer mains. The sewer mains will be installed predominantly via tunneling. The Project will also include nine tunnel access shaft sites and open cut sewer line installation. The open cut excavation is limited to only 1,140 linear feet of open cut trench. The Project is constrained by the existing sewer alignment and connections, and existing permanent easements. The tree impacts were minimized by using tunneling as an installation technique and limiting the length of the open cut trenches. The shaft sites, which are necessary to support the tunnel efforts, resulted in the majority of the tree impacts.
The Tree Survey Delineation Plan indicates that fifty-one (51%) and fifty-seven (57%) percent of the significant tree inches surveyed in the buffer and floodplain respectively will be preserved. All of the heritage trees will be preserved in the buffer and the floodplain.
2. Tree mitigation and canopy diversity - The applicant proposes to meet the Buffer and Floodplain Tree Survey Delineation mitigation requirements as follows:
a. Boring approximately 29,860 linear feet to minimize tree impacts;
b. Minimizing the length of the open cut trench;
c. Re-seeding 25.4 acres of disturbed area, both inside and outside of the floodplain;
d. Reclaiming disturbed areas by drill seeding with a native seed mix and ensuring 85% establishment; and
e. Mitigation Evaluation:
i. Total Buffer +Floodplain mitigation = 232.6 inches
ii. Mitigation balance for implementing items a, b, c and d = 116.3 inches
iii. Tree Mitigation Fund Payment = 116.3 inches @ $200.00 per inch $23,260.
DSD staff supports the applicant’s request to fall below 80% Tree Survey Delineation requirements in the floodplain and environmentally sensitive area based on the conditions of the site, design and construction efforts to minimize tree impacts and the need to address the current capacity constrained sewer lines. The proposed Variance Request meets the intent and spirit of the Tree Ordinance therefore, staff recommends approval.