DEPARTMENT: Development Services
SUBJECT: TPV 18-017 Tree Preservation Variance for SAWS 15-4802 Martinez Creek Sewer Line Replacement Project
SUMMARY:
Request by Mr. Curt Raabe, 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# 2333423
Council District: 1
Consultant: Curt Raabe, P.E. of CDS Muery
Staff Coordinator: Herminio Griego, Assistant City Arborist, (210) 207-6042
ANALYSIS:
The Development Services Department (DSD) has reviewed the information presented in Curt Raabe’s letter dated June 8, 2018 (revised).
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 surveyed trees within the 100-year floodplain in excess of the 80% minimum preservation of protected trees in place under the 2015 Tree Preservation Ordinance for development of the SAWS 15-4802 Martinez Creek Sewer Line replacement project. DSD staff does agree with the applicant’s request to mitigate for tree stand canopy below 80% preservation for the following reasons:
1. Existing site conditions - The project is a sewer replacement with lines ranging in diameter up to fifty-four (54”) inches. The entire project is located within the Martinez Creek floodplain. No potion of the project is in the Environmentally Sensitive Areas or the non-floodplain areas. The project extends from Fredericksburg Road to Perez Road along Martinez Creek. However, trees will be impacted only in the reach between Ruiz Street and Delgado Street. The sewer line replacement was also coordinated with the San Antonio River Authority (SARA) projects. The SAWS and SARA coordination will allow Martinez Creek to be included in SARA’s Westside Creek projects. The project is constrained by the need to maintain the proper sewer grade to control flows, to connect with downstream reaches and stay above the hike and bike trail along the creek. Due to existing site conditions, design and layout requirements the project is unable to preserve the minimum 80% of trees surveyed along the project. No heritage trees will be removed. The project and preservation data are presented in the table below:
|
|
Floodplain |
Units |
|
Tree Survey Data |
|
|
|
Preserved Inches |
83.5 |
Inches |
|
Removed Inches |
84 |
Inches |
|
Total Inches |
167.5 |
Inches |
|
Preserved % |
50 |
% |
|
Required % |
100 |
% |
|
|
|
|
|
Required Mitigation Calc |
|
|
|
Preserved (Inches) |
83.5 |
Inches |
|
Required (Inches) |
167.5 |
Inches |
|
Mitigation (Inches) |
84 |
Inches |
2. Required mitigation for the tree survey is 84 inches as depicted in the table above:
3. Tree mitigation and canopy diversity - The applicant opted to provide 100% mitigation instead of 80% as part of going above the minimum requirements in the Unified Development Code. Therefore the mitigation is based on 100% x 167.5 inches (total) - 83.4 inches (preserved) = 84 inches (mitigated). The project will meet the floodplain tree survey mitigation requirements as follows:
a. A total of 84 inches will be mitigated by a combination of reseeding the disturbed areas and paying into the Tree Mitigation Fund.
b. Reseeding - A total of 42,000 Ft2 will be replanted;
i. Using the drill seeding technique;
ii. A native seed mixture, and
iii. Ensuring eighty-five (85%) establishment.
c. Offset:
i. The reseeding received fifty (50%) percent credit, and
ii. Reduced the 84 inches of tree survey mitigation to 42 inches.
d. The owner will pay $8,400.00 into the Tree Mitigation Fund as follows:
i. Tree Survey Mitigation: 42 diameter inches X $200.00 per inch = $8,400.00.
DSD staff supports the applicant’s request to fall below 80% preservation requirements in in the floodplain and Environmentally Sensitive Area based on the conditions of the site, design constraints, and exceeding mitigation and tree survey requirements. The proposed Variance Request meets the intent and spirit of the Tree Ordinance therefore, staff recommends approval.