20251203-002: Arbor View Variance Applicant Form (LDC 25-8-302) — original pdf

Backup

November 17, 2025 ENVIRONMENTAL COMMISSION VARIANCE APPLICATION FORM PROJECT DESCRIPTION Applicant Contact Information Name of Applicant Street Address City State ZIP Code Work Phone E-Mail Address Terry Irion 13215 Bee Cave Parkway, Suite A-2320 Austin, Texas 78738 512-615-6653 Terry.irion@sprouselaw.com Variance Case Information Case Name Case Number Address or Location Environmental Reviewer Name Environmental Resource Management Reviewer Name Applicable Ordinance Watershed Name Watershed Classification Arbor View Subdivision C8-2025-0085.0A 4316 Far West Blvd., Austin, Texas 78731 Mohamad Abdulkader Liz Johnston 25-8-302 Bull Creek Watershed ☐Urban ☐Water Supply Rural ☐ Suburban █ Water Supply Suburban ☐ Barton Springs Zone City of Austin | Environmental Commission Variance Application Guide 1 November 17, 2025 Edwards Aquifer Recharge Zone ☐ Barton Springs Segment ☐ Northern Edwards Segment █ Not in Edwards Aquifer Zones Edwards Aquifer Contributing Zone Distance to Nearest Classified Waterway ☐ Yes █ No 1,300 lineal feet Water and Waste Water service to be provided by City of Austin Request The variance request is as follows (Cite code references: Variance 25-8- 302 Impervious cover square footage: acreage: percentage: Existing 0 0 0 Proposed 3,900 0.09 15.89 % Provide general description of the property (slope range, elevation range, summary of vegetation / trees, summary of the geology, CWQZ, WQTZ, CEFs, floodplain, heritage trees, any other notable or outstanding characteristics of the property) The parcel is a 0.56-acre parcel that fronts on a curbed and guttered public street. All utilities necessary to serve the tract are already built underground in public right-of -way or PUE. There is a storm sewer inlet on the western end of the parcel that discharges storm water from Far West Blvd onto the parcel. The ERI identifies a potential seep in the NW corner of the parcel that will be isolated in a Lot 2 “no build” conservation and drainage easement lot and further protected by a 75’ CEF buffer zone. There is no classified waterway or floodplain on the parcel. The nearest classified waterway and FEMA floodplain is Bull Creek, which is 1,300 lineal feet from the subject Property, as depicted in Exhibit 7. No water quality is proposed for this one lot single family residence because there will be less than 5,000 sqft of proposed impervious cover. The parcel has steep slopes which fall somewhere over 50’ from the front of the parcel to the rear of the parcel. Accordingly, net site area as calculated in Section 25-8-62 is negligible and cannot meet the impervious cover requirements of Section 25-8-423, nor can the Property be developed with a residence that is not constructed on a slope less than 25% without building it to a pier and beam platform above the natural gradient. The parcel has no allowed use that can be made of it without a variance. Please see Exhibit 5 (slope map). City of Austin | Environmental Commission Variance Application Guide 2 November 17, 2025 Clearly indicate in what way the proposed project does not comply with current Code (include maps and exhibits) The proposed plan is to build a single-family home, garage, and access driveway on a raised platform supported by 8 piers as shown on Exhibit 7 (attached). The only site disturbance of the natural gradient will be for construction of the 8 concrete pads for the piers. Storm water will be captured and detained on the driveway and discharged through a pipe to the west end of the Property that will go through an energy dissipator and release at a very low velocity of 0.46 fps which is far lower than requested by the ECM to prevent erosions at the point of discharge. FINDINGS OF FACT As required in LDC Section 25-8-41, in order to grant a variance the Land Use Commission must make the following findings of fact: Include an explanation with each applicable finding of fact. Project: Ordinance: A. Land Use Commission variance determinations from Chapter 25-8-41 of the City Code: 1. The requirement will deprive the applicant of a privilege available to owners of similarly situated property with approximately contemporaneous development subject to similar code requirements. Yes / No – The ordinance does not allow the construction of a residential structure on a slope with a gradient in excess of 25%. There is not an available site on the entire tract that does not exceed 25% slope gradient and re-grading the site with cuts and fills is neither practical nor permitted by other sections of the code. Applicant proposes construction of a building platform supported by 8 piers, including the driveway bridge, which will be elevated above the natural grade and by a pier supported platform. See Exhibit 7. 2. The variance: a) Is not necessitated by the scale, layout, construction method, or other design decision made by the applicant, unless the design decision provides greater overall environmental protection than is achievable without the variance; City of Austin | Environmental Commission Variance Application Guide 3 November 17, 2025 Yes / No – The proposed design of a pier supported platform on which the house, garage, driveway will be built (see 25-8-301) will achieve overall environmental protection greater than without a variance by eliminating the need for cut, fill, and stabilized structural supports for the construction of the building pad. The pier supported platform will be elevated above the natural gradient and the only site disturbance will be for the construction of the 8 piers. Hillside vegetation will not be disturbed except as necessary during construction of the piers supporting the platform elevated above the natural grade. Disturbed areas during construction of the piers will be restored with native and adopted vegetation as prescribed by the ECM. There will be no cut or fill utilized in construction of the building platform. b) Is the minimum deviation from the code requirement necessary to allow a reasonable use of the property; Yes / No – Given the topography of the site there is no way that compliance with strict reading of the code can be achieved without a variance. The property is left without any legal use for development and will constitute a regulatory taking of the Property. While deviating from the code requirement which contemplates a home built on natural grade, the result of the pier supported building platform is that there will be very minimal contact with the natural grade. The requested variance is the minimum deviation from the code requirements necessary to achieve a reasonable use of the Property. c) Does not create a significant probability of harmful environmental consequences. Yes / No – The variance will not create a significant probability of harmful environmental consequences but rather will avoid harmful environmental consequences from constructing on steep slopes. The ordinance only allows a calculated 232 sqft of net site area impervious cover. By building all the impervious cover on a platform of eight piers as shown in Exhibit 7, the Project is able to avoid destabilization of the steep limestone slopes by utilizing piers to build above the natural grade instead of altering the natural grade. The Staff has raised concerns with the stability of the slopes under the building eroding over time as the vegetation under the building will eventually not survive. Applicant has confirmed with a Geotech expert that the soil type is stable limestone and is not likely to slough over time if properly protected. As additional protection of the slopes under the building, Applicant proposes to add perimeter rock beams or gabion baskets (per COA detail 6395-1) around the building platform shadow as needed to prevent rainwater hitting pervious areas outside of the building footprint from conveying storm water under the building footprint shadow. This will prevent any erosion from occurring from storm water conveyed under the building from the undisturbed slope areas. The Project will have on onsite “detention pond” sized to capture and detain the 100-year storm event utilizing City of Austin | Environmental Commission Variance Application Guide 4 November 17, 2025 Atlas 14 rainfall assumptions. (See Exhibit 8). The “detention pond” will be constructed onsite in the driveway and capture 100% of the storm water runoff of the building footprint. The total detention volume is sufficient to contain 100- year storm event. It will drain into the overflow aperture. Per City Drainage Criteria Manual the calculated depth of water in a 100-year storm in this detention facility will be 3.12” at the deepest point. In a 100-year storm event the rate of discharge will be Q100 = 0.55 cfs with a velocity V100 = 0.46 fps, which is very low. The City Drainage Criteria Manual 7.3.0 and Environmental Criteria Manual 1.4.6(A7) determines that in order to prevent erosion, discharge from a detention pond outlet needs to be kept below a velocity of 4.0 fps (feet per second). The fps proposed rate of velocity is more than 8x lower than the allowed velocity rate of release by the ECM. The runoff from the driveway will be captured in a storm pipe. Virtually every square foot of the 3,900 sqft of the impervious cover on the site will be captured, stored and slowly released through a gravel medium at the outflow from the energy dissipator and rock berm. 3. Development with the variance will result in water quality that is at least equal to the water quality achievable without the variance. Yes / No – Development with a variance will result in water quality that is at least equal to the water quality achievable without a variance because natural gradient site disturbance will be limited to less than 130 sqft of concrete pads for the 8 piers and total impervious cover will be limited to 3,900 sqft of shadow impervious cover above the piers. Furthermore, the driveway detention pond will capture 100% of the surface runoff from this development and convey it through a control aperature to a 15” storm pipe located under the building. The release rate can be adjusted but will generally be set to drain over a 48-hour period at a rate of 0.46 fps during a 100-year storm event, which is well below the ECM design criteria for maximum velocity fps release. The stormwater runoff from the driveway will be captured in a storm pipe and diverted to the energy dissipator and rock berm. Accordingly, every square foot of impervious cover runoff from improvements on this site will be captured, stored, and slowly released. B. NOT APPLICABLE Additional Land Use Commission variance determinations for a requirement of Section 25-8-422 (Water Quality Transition Zone), Section 25-8-452 (Water Quality Transition Zone), Article 7, Division 1 (Critical Water Quality Zone Restrictions), or Section 25-8-368 (Restrictions on Development Impacting Lake Austin, Lady Bird Lake, and Lake Walter E. Long): 1. The criteria for granting a variance in Subsection (A) are met; Yes / No [provide summary of justification for determination] City of Austin | Environmental Commission Variance Application Guide 5 November 17, 2025 2. 3. The requirement for which a variance is requested prevents a reasonable, economic use of the entire property; Yes / No [provide summary of justification for determination] The variance is the minimum deviation from the code requirement necessary to allow a reasonable, economic use of the entire property. Yes / No [provide summary of justification for determination] **Variance approval requires all above affirmative findings. City of Austin | Environmental Commission Variance Application Guide 6 November 17, 2025 A Exhibits for Commission Variance 1. Aerial photos of the site 2. Site photos 3. Aerial photos of the vicinity 4. Context Map (Tax Parcel Map) – A map illustrating the subject property to developments in the vicinity to include nearby major streets and waterways 5. Topographic Map - A topographic map is recommended if a significant grade change on the subject site exists or if there is a significant difference in grade in relation to adjacent properties. 6. Proposed Concept Plan for single-family residence 7. Proposed Site Plan Pier Configuration 8. Site and Drainage Plan (4 pages) 9. Maps showing distance of site from qualified water way and floodplain (2 pages) 10. An Environmental Resource Inventory pursuant to ECM 1.3.0 (33 pages) City of Austin | Environmental Commission Variance Application Guide 7 EXHIBIT 1 EXHIBIT 2 EXHIBIT 3 EXHIBIT 4 EXHIBIT 5 EXHIBIT 6 1 OF 2 2 OF 2 EXHIBIT 7 DRAINAGE SUMMARY TABLE (PRE & POST CONDITIONS) S N DRIVEWAY CROSS SECTION NO:1 SCALE 1"=5'-0" NW NE W E SW SE P P P E P E E E P P P E P E E E . C N I , I I S R E E N G N E L I V C U R T S L A N O S S E F O R P I S R E E N I G N E L A R U T C U R T S D N A L I V I C G N I T L U S N O C i m o c . c n e c s p @ e c s p | 2 2 4 6 . 8 3 2 . 2 1 5 L E T | 7 2 7 8 7 X T , I N T S U A , 0 1 2 E T U S I , E N A L R E M R A P T S E W 5 0 2 2 CONTROL OPENING SECTION SCALE 1"=2'-6" E P P P P E P E E E SITE PLAN AND ROOF DETENTION POND SCALE 1"=10'-0" CURB P E P E N NW NE W E SW SE S P P P E P E E E P P P E P E E E CURB PRE DEVELOPED CONDITIONS SCALE 1"=30'-0" CURB POST DEVELOPED CONDITIONS SCALE 1"=30'-0" DRAINAGE SUMMARY TABLE (PRE & POST CONDITIONS) SITE INFORMATION TABLE DETENTION POND SUMMARY TABLE DETENTION POND AREA & VOLUME OFF SITE DRAINAGE AREA MAP SCALE 1"=80'-0" . C N I , I I S R E E N G N E L I V C U R T S L A N O S S E F O R P I S R E E N I G N E L A R U T C U R T S D N A L I V I C G N I T L U S N O C i m o c . c n e c s p @ e c s p | 2 2 4 6 . 8 3 2 . 2 1 5 L E T | 7 2 7 8 7 X T , I N T S U A , 0 1 2 E T U S I , E N A L R E M R A P T S E W 5 0 2 2 E P P P P E P E E E P E P E N NW NE W E SW SE S CURB THIS SURVEY WAS PERFORMED WITHOUT THE BENEFIT OF AN ABSTRACT OF TITLE. Land urveying THIS PROPERTY DOES NOT LIE WITHIN THE 100 YEAR FLOOD- PLAIN, AND HAS A ZONE RATING AS SHOWN ON THE FLOOD INSURANCE RATE MAPS F.I.R.M. MAP NO. PANEL: DATED: P P P E P E E E P P P E P E E E . C N I , I I S R E E N G N E L I V C U R T S L A N O S S E (cid:41) O R P I S R E E N I G N E L A R U T C U R T S D N A L I V I C G N I T L U S N O C i m o c . c n e c s p @ e c s p | 2 2 4 6 . 8 3 2 . 2 1 5 L E T | 7 2 7 8 7 X T , I N T S U A , 0 1 2 E T U S I , E N A L R E M R A P T S E W 5 0 2 2 E P P P P E P E E E P E P E P P P E P E E E P P P E P E E E . C N I , I I S R E E N G N E L I V C U R T S L A N O S S E (cid:41) O R P I S R E E N I G N E L A R U T C U R T S D N A L I V I C G N I T L U S N O C i m o c . c n e c s p @ e c s p | 2 2 4 6 . 8 3 2 . 2 1 5 L E T | 7 2 7 8 7 X T , I N T S U A , 0 1 2 E T U S I , E N A L R E M R A P T S E W 5 0 2 2 E P P P P E P E E E P E P E BUILDING CROSS SECTION NO:2 SCALE 1"=5'-0" EXHIBIT 9 EXHIBIT 10 CITY OF AUSTIN ENVIRONMENTAL ASSESSMENT 0.56-ACRE UNDEVELOPED LOT RESIDENTIAL LOT 4316 FAR WEST BLVD. AUSTIN, TRAVIS COUNTY, TEXAS 78731 Prepared For Professional StruCIVIL Engineers, Inc. 12710 Research Blvd., Suite 390 Austin, Texas 78759 Prepared By M. Trojan & Associates Environmental Consultants 8244 Lime Creek Road Leander, Texas 78641 MTA Project No. SE-13-015 October 31, 2013 M. TROJAN & ASSOCIATES Environmental Consultants M. TROJAN & ASSOCIATES Environmental Consultants Mirza Tahir Baig, PE Professional StruCIVIL Engineers, Inc. 12710 Research Blvd., Suite 390 Austin, Texas 78759 October 31, 2013 Subject: Report of City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot (Tabrizi Subdivision) 4316 Far West Blvd. Austin, Travis County, Texas 78731 MTA Project No. SE-13-015 Mirza: This report provides the environmental information required for the City of Austin (COA) submittal for proposed subdivision of a 0.56-acre undeveloped residential lot (Tabrizi Subdivision) located at 4316 Far West Blvd. in Austin, Travis County, Texas. The information provided herein addresses certain “environmental elements” and other environmental factors that the COA may require as part of your Plan submittal as well as for potential future re-submittals. This Environmental Assessment was prepared in accordance with the COA Environmental Criteria Manual, Water Quality Management Section 1.3.0 and the COA Land Development Code (LDC) Sections 25-8-121 through 25-8-125. Thank you for providing me with the opportunity to assist you in environmental matters associated with the proposed project. Should you have any questions or require additional information, please feel free to contact me at 258-6606 or forward an email to mtrojan@austin.rr.com. Respectfully, Michael Trojan, CPG M. TROJAN & ASSOCIATES c: MTA Project File SE-13-015 Licensed Professional Geoscientist #1109 M. TROJAN & ASSOCIATES 8244 Lime Creek Road, Leander, Texas 78641 Office: (512) 258-6606 / E-mail: mtrojan@austin.rr.com CITY OF AUSTIN ENVIRONMENTAL ASSESSMENT 0.56-ACRE UNDEVELOPED RESIDENTIAL LOT 4316 FAR WEST BLVD. AUSTIN, TRAVIS COUNTY, TEXAS 78731 Prepared For Professional StruCIVIL Engineers, Inc. 12710 Research Blvd., Suite 390 Austin, Texas 78759 Prepared By M. Trojan & Associates Environmental Consultants 8244 Lime Creek Road Leander, Texas 78641 MTA Project No. SE-13-015 October 31, 2013 City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot 4316 Far West Blvd. Austin, Travis County, Texas 78731 MTA Project SE-13-015 October 31, 2013 TABLE OF CONTENTS 1.0 OVERVIEW ............................................................................................................................1 1.1 STUDY AREA..........................................................................................................................1 1.2 PROPOSED SITE DEVELOPMENT...............................................................................................1 1.3 PREVIOUSLY PUBLISHED REPORTS ............................................................................................1 2.0 ENVIRONMENTAL ELEMENTS...............................................................................................2 2.1 HYDROGEOLOGIC ELEMENT...................................................................................................2 2.1.1 Topography and Surface Water Hydrology.........................................................2 2.1.2 Soils ............................................................................................................................2 2.1.3 Geology ....................................................................................................................3 2.2 VEGETATIVE ELEMENT.............................................................................................................4 2.3 UTILITIES ELEMENT ..................................................................................................................5 2.4 POLLUTION ATTENUATION PLAN ..............................................................................................5 3.0 CRITICAL ENVIRONMENTAL FEATURES ..............................................................................6 3.1 ONSITE FEATURES...................................................................................................................6 3.1.1 Springs/Seeps ............................................................................................................6 3.1.2 Bluffs............................................................................................................................6 3.1.3 Canyon Rimrock .......................................................................................................7 3.1.4 Caves .........................................................................................................................7 3.1.5 Sinkholes and Other Recharge Features...............................................................7 3.1.6 Wetlands ....................................................................................................................7 3.1.7 Other Features...........................................................................................................7 3.2 OFFSITE FEATURES ..................................................................................................................8 4.0 ENDANGERED SPECIES .......................................................................................................9 5.0 CONCLUSIONS AND RECOMMENDATIONS ...................................................................10 6.0 REFERENCES .......................................................................................................................12 APPENDIX A: FIGURES APPENDICES Figure 1 – Site Location Map Figure 2 – Site Aerial Photograph Figure 3 – Site Subdivision Plan Figure 4 – Site Topographic Map Figure 5 – Site Soils Map Figure 6 – General Geologic Map M. TROJAN & ASSOCIATES Environmental Consultants page i City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot 4316 Far West Blvd. Austin, Travis County, Texas 78731 MTA Project SE-13-015 October 31, 2013 Figure 7 – Site Vegetation Map Figure 8 – Site Geologic/CEFs Map APPENDIX B: SITE PHOTOGRAPHS Photographs Taken During the Field Reconnaissance APPENDIX C: CITY OF AUSTIN CRITICAL ENVIRONMENTAL FEATURES WORKSHEET M. TROJAN & ASSOCIATES Environmental Consultants page ii City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot 4316 Far West Blvd. Austin, Travis County, Texas 78731 MTA Project SE-13-015 October 31, 2013 1.0 OVERVIEW M. Trojan & Associates was retained to conduct a City of Austin (COA) Environmental Assessment for proposed subdivision of a 0.56-acre undeveloped residential lot located at 4316 Far West Blvd. in Austin, Travis County, Texas (refer to Figures 1 and 2 of Appendix A). The information provided herein addresses certain “environmental elements” and other environmental factors that the COA may require as part of the Plan submittal. The essential environmental elements include: (1) hydrogeologic element, (2) vegetative element, (4) Pollution Attenuation Plan, and (5) Critical Environmental Features (CEFs) – as defined by the COA. In addition, rare plant species are addressed as part of the vegetative element and endangered species are This Environmental Assessment was prepared in addressed at the end of the report. accordance with the COA Environmental Criteria Manual, Water Quality Management Section 1.3.0 and the COA Land Development Code (LDC) Sections 25-8-121 through 25-8-125. (3) utilities element, The field reconnaissance for this Environmental Assessment was conducted on October 23, 2013 by Mr. Michael Trojan, a Professional Geologist/Hydrogeologist certified by the Texas Board of Professional Geoscientists. Mr. Trojan has 29 years of experience in all aspects of the environmental field and 19 years (1994 – present) direct experience in conducting vegetation surveys, geologic assessments over the Edwards Aquifer Recharge Zone and other karst terrain, CEFs assessments, and endangered species habitat assessments for land developers in the Central Texas area. 1.1 Study Area The subject property is located on the north side of Far West Blvd., just west of the Far West Blvd. and Mesa Drive intersection (refer to Figures 1 and 2 of Appendix A). The property consists of approximately 0.56 acres of undeveloped land. The landscape represents relatively steep slopes with large rock outcrops and dense vegetation (refer to photographs in Appendix B). There are no improvements on the lot. 1.2 Proposed Site Development Based on review of a draft subdivision plan provided by Professional StruCIVIL Engineers, Inc., as of the writing of this COA Environmental Assessment the lot will be a stand-alone residential lot for potential future construction of two single-family home structure (refer to Figure 3 of Appendix A). 1.3 Previously Published Reports No previously published, site-specific technical reports were reviewed as part of this Environmental Assessment. M. TROJAN & ASSOCIATES Environmental Consultants page 1 City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot 4316 Far West Blvd. Austin, Travis County, Texas 78731 MTA Project SE-13-015 October 31, 2013 2.0 ENVIRONMENTAL ELEMENTS 2.1 Hydrogeologic Element Environmental Criteria Manual, Water Quality Management, Section 1.3.1 Land Development Code Section 25-8-122 2.1.1 Topography and Surface Water Hydrology Based on a topographic survey provided by Professional StruCIVIL Engineers, Inc. and site reconnaissance, the lot slopes generally toward the north (refer to Figure 4 of Appendix A). Topographic elevations on the lot range between approximately 768 and 810 feet above mean sea level (msl), with the highest elevations located at the eastern-most extent of the lot and the lowest elevations within an ephemeral drainage way crossing of the north-northeast property boundary. Topographic slopes on the southern half of the lot are generally steep while slopes on the northern half are moderate to moderately steep. As is depicted in Figure 4 of Appendix A, all stormwater runoff generated on the lot flows toward the north and northwest and either discharges directly offsite to the neighboring property or to an onsite ephemeral drainage way that channels runoff offsite to the north-northeast. The ephemeral drainage way also collects upstream stormwater runoff via an underground culvert located at the southwest property corner – at Far West Blvd. The property is located within the upper part of the Bull Creek watershed. Bull Creek lies approximately 0.75 miles southwest of the lot and the creek flows to the Lake Austin segment of the Colorado River. According to review of a FEMA Flood Insurance Rate Map and the COA GIS, no portion of the lot lies within the 100-year floodplain. Moreover, no portion of the lot lies within an area designated by the COA as a Critical Water Quality Zone (CWQZ) and Water Quality Transition Zone (WQTZ). 2.1.2 Soils According to the Soil Survey of Travis County, Texas, the soils that are reported to be on the subject property are as follows (also refer to Figure 5 of Appendix A for soil type locations): Soil Component Name: Brackett soils and Rock outcrop, steep (BoF) Soil Surface Texture: Light brownish gray gravelly clay loam to approximately 4 inches with about 60 percent coarse fragments, underlain by pale brown clay loam to about 15 inches Permeability is moderately slow; available water Hydrologic Group: M. TROJAN & ASSOCIATES Environmental Consultants page 2 City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot 4316 Far West Blvd. Austin, Travis County, Texas 78731 MTA Project SE-13-015 October 31, 2013 Soil Drainage Class: capacity is low Well drained Based on the Soil Survey and as is depicted on Figure 5 of Appendix A, the Brackett soils and Rock outcrop is the soil type reported to cover the entire lot. Shallow excavations were made at various locations across the property and observations of the soil characteristics confirmed the presence of soils similar to those described in the Soil Survey. However, true soils were found to be located generally on the northern half of the lot and were observed to be relatively thin (up to approximately 12 inches). Where present, soils were observed to be mostly fine-grained, and were noted to exhibit a minor to moderate fraction of limestone rock fragments. In addition, given the relatively steep topographic slopes on many portions of the lot, soils exhibit moderate to high erosion. No soils were observed within the ephemeral drainage way on the western part of the lot. 2.1.3 Geology Based on the Geologic Map of the Austin Area, Texas (Bureau of Economic Geology (1992) and review of other available geologic/hydrologic publications, the outcropping (near surface) geologic material beneath the subject property is reported to be the Walnut Formation (Kwa) (refer to Figure 6 of Appendix A). The Walnut Formation is described as follows: Walnut Formation The Walnut Formation consists of limestone, marl and marly limestone. The formation is generally gray to tan, soft to hard, fine to medium grained, thick to thin bedded, and massive to nodular. The Glen Rose Formation (Kgr) is reported to outcrop directly north and east of the lot, while the Edwards Limestone (Ked) is reported to outcrop to the east of the lot. In stratigraphic sequence, both the Walnut and Glen Rose Formations underlie the Edwards. An abundance of rock outcrops were observed over most of the lot, primarily along steep topographic breaks and along the ephemeral drainage way on the western portion of the lot (refer to photographs in Appendix B). Given partial soil cover of the northern half of the lot – areas of medium topographic slopes – rock outcrops are less In addition, large rock slabs were found to have fallen into the lot from the abundant. eroded portions of the property boundary. All limestone outcrops were observed to be tan/gray, slightly marly and indurated. M. TROJAN & ASSOCIATES Environmental Consultants page 3 City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot 4316 Far West Blvd. Austin, Travis County, Texas 78731 2.2 Vegetative Element MTA Project SE-13-015 October 31, 2013 Environmental Criteria Manual, Water Quality Management, Section 1.3.2 Land Development Code, Section 25-8-123 This section describes the general vegetation on the subject property as well as the presence of rare plant species, if any are present. Plant communities on the property were characterized according to the dominant plant taxa present. Qualitative observations of plant cover, structure, and spatial changes in vegetation species composition were also used to determine areas of common communities (if present). Large vegetation and related information associated with the subject property is discussed below (also refer to Figure 7 of Appendix A for a vegetation map and Appendix B for photographs, and the Subdivision Plan for a tree survey). Large Vegetation: Ashe juniper (Juniperus ashei); 0.5- to 18-inch trunk diameters Cedar elm (Ulmus crassifolia); 0.5- to 12-inch trunk diameters Hackberry (Celtis occidentalis); 05.- to 15-inch trunk diameters Chinaberry (Melia azedarach); 1- to 12-inch trunk diameters Live oak (Quercus fusiformis); 1- to 3-inch trunk diameters Miscellaneous unidentified intrusive trees; 0.5- to 4- inch trunk diameters Canopy: 100% medium to high closed canopy. Ground Cover: Very sparse ground cover of unspecified native grasses and small brush. Notes: The lot represents landscape with steep to medium-steep topographic slopes and dense large vegetation. Large vegetation consists of a variety of trees dominated by cedar, cedar elm, hackberry and chinaberry trees. A relatively small number of trees exceed a trunk diameter of seven inches. For completeness, the subject property was also inspected for eight rare plant species These include Texas amorpha (Amorpha that are known to occur in Travis County. M. TROJAN & ASSOCIATES Environmental Consultants page 4 City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot 4316 Far West Blvd. Austin, Travis County, Texas 78731 MTA Project SE-13-015 October 31, 2013 (Philadelphus ernestii), Buckley roemerana), Texabama croton (Croton alabamensis var. texensis), Glass Mountains coral-root (Hexalectris nitida), Heller marbleseed (Onosmodium helleri), Canyon mock- orange tridens (Tridens buckleyanus), Bracted twistflower (Streptanthus bracteatus), and Tobusch fishhook cactus (Ancistrocactus The survey was accomplished by walking 25-foot (approximate) spaced tobuschii). transects across the entire property. Based on the inspection, rare plant species were not observed. As is discussed in Section 1.2, the lot will be divided into a single lot (refer to Figure 3 of Appendix A). The subdivision will have no impact on existing trees. Potential future construction of a single-family home on the lot will likely require removal of selected mature trees; however, it is assessed that existing old-growth trees can be protected to the greatest extent practicable (refer to tree survey in the Subdivision Plan). 2.3 Utilities Element Environmental Criteria Manual, Water Quality Management, Section 1.3.3 Land Development Code, Section 25-8-124 The intent of this element is for the wastewater report to provide environmental justification for a sewer line location in a CWQZ. As there is no underground infrastructure proposed within a CWQZ, this section does not apply. 2.4 Pollution Attenuation Plan Land Development Code, Section 25-8-125 According to the COA administrative and environmental criteria manuals, an applicant proposing an industrial use, as defined in LDC Section 25-2-5, that is not completely enclosed in a building shall provide a Pollutant Attenuation Plan (PAP). The intent of the PAP is to provide information regarding water quality best management practices for open-air industrial activities and to establish criteria for site development and reclamation. As the Subdivision Plan does not propose an industrial use that is not completely enclosed in a building, this section does not apply. M. TROJAN & ASSOCIATES Environmental Consultants page 5 City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot 4316 Far West Blvd. Austin, Travis County, Texas 78731 MTA Project SE-13-015 October 31, 2013 3.0 CRITICAL ENVIRONMENTAL FEATURES According to the Environmental Criteria Manual, Water Quality Management, Section 1.3.0(B), an Environmental Assessment must identify CEFs and propose protective measures for such features. Accordingly, the field reconnaissance of the tract included search for and identification of CEFs, including springs/seeps, bluffs, canyon rimrock, caves, sinkholes, and other This was types of potential accomplished by walking 25-foot (approximate) spaced transects across the entire property. The findings of this inspection are summarized below. recharge features. 3.1 Onsite Features 3.1.1 Springs/Seeps The COA Environmental Criteria Manual defines a spring as a point or zone of natural groundwater discharge in upland and/or riparian zones which produce measurable flow down gradient of the source, or a pool, or both, or (during drought conditions) an area characterized by the presence of a mesic plant community. Based on observations made across the entire lot, a series of seeps was identified on the north-northwestern part of the property. The seep area is described below. Seep Area S-1 Latitude: Longitude: 30.361052 (approximate center of area) -97.773269 (approximate center of area) Seep Area S-1 represents a series of seep conduits along a 20- to 30-foot segment of the ephemeral drainage way on the western portion of the lot (refer to Figure 7 of Appendix A and the CEF Worksheet of Appendix C). The seep area appears to be active following periods of precipitation and inactive during droughts. The seeps were observed active at the time of the site reconnaissance. 3.1.2 Bluffs The COA Environmental Criteria Manual defines a bluff as an abrupt vertical change in topography of more than 40 feet with an average slope steeper than four feet of rise for one foot of horizontal travel (approximately 75 degrees). Based on observations made across the entire property, no bluffs were identified. M. TROJAN & ASSOCIATES Environmental Consultants page 6 City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot 4316 Far West Blvd. Austin, Travis County, Texas 78731 3.1.3 Canyon Rimrock MTA Project SE-13-015 October 31, 2013 The COA Environmental Criteria Manual defines canyon rimrock as an abrupt vertical rock outcrop of more than 60 percent slope (31 degrees), greater than four feet vertically, and a horizontal extent equal or greater than 50 feet. Based on observations made across the entire property, no canyon rimrock was identified. 3.1.4 Caves The COA Environmental Criteria Manual defines a cave as an underground void large enough for an adult to enter. Based on observations made across the entire property, no caves were identified. 3.1.5 Sinkholes and Other Recharge Features The COA Environmental Criteria Manual defines a sinkhole as a circular or oblong depression formed in soluble rock by the action of subterranean water which is a potential point of significant recharge (with or without a surface opening). The Environmental Criteria Manual also observes other features such as faults, solution cavities and enlarged fractures as potential points of recharge. Based on observations made across the entire property, no sinkholes or other recharge features were identified. 3.1.6 Wetlands The Environmental Criteria Manual defines a wetland as land transitional between terrestrial and aquatic systems where the water table is usually at or near the surface or the land is covered by shallow water. An area is classified as a wetland if it meets the Army Corps of Engineers (USACE) three parameter technical criteria as outlined in the USACE 1987 Wetlands Delineation Manual. Based on observations made across the entire property, no wetland features were identified. 3.1.7 Other Features Based on observations made across the entire property, no other identified. features were M. TROJAN & ASSOCIATES Environmental Consultants page 7 City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot 4316 Far West Blvd. Austin, Travis County, Texas 78731 3.2 Offsite Features MTA Project SE-13-015 October 31, 2013 The field reconnaissance also included inspection of neighboring properties a distance of approximately 150 to 200 feet (as practicable) from all boundaries of the subject property for identification of offsite CEFs that could be deemed as significant in terms of development on the property. Based on the offsite reconnaissance, no features were identified. M. TROJAN & ASSOCIATES Environmental Consultants page 8 City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot 4316 Far West Blvd. Austin, Travis County, Texas 78731 MTA Project SE-13-015 October 31, 2013 4.0 ENDANGERED SPECIES With the exception of inspecting the subject property for eight rare plant species, no formal endangered (wildlife) species “survey” was conducted as part of this Environmental Assessment. However, for completeness the property was inspected for suitable habitat for primarily the Golden-cheeked Warbler as well as for endangered cave species that are common to certain parts of Travis County. The Golden-cheeked Warbler and endangered cave species are addressed below. Golden-cheeked Warbler Based on Travis County Balcones Canyonlands Conservation Preserve (BCCP) habitat maps, it is noted that the subject property lies on the fringe of Golden-cheeked Warbler – Zone 2 (unconfirmed habitat). While the lot lies in this designated zone, reconnaissance of vegetation on the property did not identify suitable habitat for the Golden-cheeked Warbler. Suitable habitat was observed directly north of the lot. Endangered Cave Species Based on BCCP endangered species maps, the subject property lies in an area designated as Endangered Cave Species Habitat – Karst Zones 1 and 2. While the lot lies in these zones, field reconnaissance of the property confirmed the absence of CEFs that could provide habitat for such endangered cave species. M. TROJAN & ASSOCIATES Environmental Consultants page 9 City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot 4316 Far West Blvd. Austin, Travis County, Texas 78731 MTA Project SE-13-015 October 31, 2013 5.0 CONCLUSIONS AND RECOMMENDATIONS M. Trojan & Associates has conducted a COA Environmental Assessment for proposed subdivision of a 0.56-acre undeveloped residential lot located at 4316 Far West Blvd. in Austin, Travis County, Texas. Based on research and field reconnaissance conducted as part of this Environmental Assessment, this report provides the following conclusions and recommendations:  Characteristics of soils that cover the tract are the primary factors that influence potential subsurface recharge on the property. Areas of the lot that exhibit soil cover have soils that are relatively thin (up to approximately 12 inches), fine-grained and with reported moderately- slow permeability. It is suggested that these areas have moderate recharge potential; however, steep to medium-steep topographic slopes on the lot provide for rapid runoff, with only short periods of runoff residence time that would allow for significant infiltration.  No CEFs were identified as specific points of subsurface recharge that would require protection in light of any potential development.  According to the Subdivision Plan, the lot is proposed to be subdivided into a single lot. The subdivision will have no impact on existing trees. Potential future construction of a single-family home on the lot will likely require removal of selected mature trees; however, it is assessed that existing old-growth trees can be protected to the greatest extent practicable.    Seep Area S-1 represents a series of seep conduits along a 20- to 30-foot segment of the ephemeral drainage way on the western portion of the lot. The seep area appears to be active following periods of precipitation and inactive during droughts. The seeps were observed active at the time of the site reconnaissance. The subject property lies on the fringe of Golden-cheeked Warbler – Zone 2 (unconfirmed habitat). While the lot lies in this designated zone, reconnaissance of vegetation on the property did not identify suitable habitat for the Golden-cheeked Warbler. Suitable habitat was observed directly north of the lot. Based on BCCP endangered species maps, the subject property lies in an area designated as Endangered Cave Species Habitat – Karst Zones 1 and 2. While the lot lies in these zones, field reconnaissance of the M. TROJAN & ASSOCIATES Environmental Consultants page 10 City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot 4316 Far West Blvd. Austin, Travis County, Texas 78731 MTA Project SE-13-015 October 31, 2013 property confirmed the absence of CEFs that could provide habitat for such endangered cave species. M. TROJAN & ASSOCIATES Environmental Consultants page 11 City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot 4316 Far West Blvd. Austin, Travis County, Texas 78731 MTA Project SE-13-015 October 31, 2013 6.0 REFERENCES The following primary references/resources were utilized during the course of conducting this COA Environmental Assessment:  City of Austin GIS Viewer. (www.ci.austin.tx.us/GIS/developmentwebmap/Viewer.aspx).   Edwards Aquifer Recharge Zone information – Texas Commission on Environmental Quality online information sources. FEMA Flood Insurance Rate Map.  Garner, L. E. and Young, K. P. 1992. Environmental Geology of the Austin Area; an Aid to Urban Development. Bureau of Economic Geology (Report of Investigations No. 86), University of Texas, Austin, Texas.  Geologic Map of the Austin Area, Texas. 1992. Bureau of Economic Geology, the University of Texas at Austin, Bureau of Economic Geology.  Groundwater hydrology – Texas Water Development Board online information resources.     Personal communications with representatives of Professional StruCIVIL Engineers, Inc. Site subdivision plan – provided by Professional StruCIVIL Engineers, Inc. Soil Conservation Service STATSGO soils information. Soil Survey of Travis County, U.S. Department of Agriculture – Natural Resources Conservation Service, dated 1980.  U.S. Geological Survey topographic map.  Travis County Balcones Canyonlands Conservation Preserve information sources.  U.S. Fish & Wildlife Service information sources. M. TROJAN & ASSOCIATES Environmental Consultants page 12 SUBJECT PROPERTY 0.56-Acres; Undeveloped Far West Blvd. MoPac Mesa Drive M. TROJAN & ASSOCIATES Environmental Consultants 8244 Lime Creek Road Leander, Texas 78641 (512) 258-6606 Scale: Date: Project: MTA Project: No Scale October 31, 2013 City of Austin EA SE-13-015  NORTH FIGURE 1 SITE LOCATION MAP 0.56-ACRE UNDEVELOPED RESIDENTIAL LOT 4316 FAR WEST BLVD. AUSTIN, TRAVIS COUNTY, TEXAS 78731 Single-Family Residence SUBJECT PROPERTY 0.56-Acres; Undeveloped Single-Family Residence Note: August 1, 2012 Aerial Photograph M. TROJAN & ASSOCIATES Environmental Consultants 8244 Lime Creek Road Leander, Texas 78641 (512) 258-6606 Scale: Date: Project: MTA Project: 1” = 60’ (approx.) October 31, 2013 City of Austin EA SE-13-015  NORTH FIGURE 2 SITE AERIAL PHOTOGRAPH 0.56-ACRE UNDEVELOPED RESIDENTIAL LOT 4316 FAR WEST BLVD. AUSTIN, TRAVIS COUNTY, TEXAS 78731 Source: Professional StruCIVIL Engineers, Inc. M. TROJAN & ASSOCIATES Environmental Consultants 8244 Lime Creek Road Leander, Texas 78641 (512) 258-6606 Subdivision Plan – Single Lot Scale: Date: Project: MTA Project: No Scale October 31, 2013 City of Austin EA SE-13-015  NORTH FIGURE 3 SITE SUBDIVISION PLAN 0.56-ACRE UNDEVELOPED RESIDENTIAL LOT 4316 FAR WEST BLVD. AUSTIN, TRAVIS COUNTY, TEXAS 78731 Ephemeral Drainage Way (Heavily Eroded Bedrock) Bull Creek Watershed Underground Culvert Discharge Far West Blvd. Source: Professional StruCIVIL Engineers, Inc. Stormwater Runoff Direction  NORTH M. TROJAN & ASSOCIATES Environmental Consultants 8244 Lime Creek Road Leander, Texas 78641 (512) 258-6606 Scale: Date: Project: MTA Project: 1” = 40’ (approx.) October 31, 2013 City of Austin EA SE-13-015 FIGURE 4 SITE TOPOGRAPHIC MAP 0.56-ACRE UNDEVELOPED RESIDENTIAL LOT 4316 FAR WEST BLVD. AUSTIN, TRAVIS COUNTY, TEXAS 78731 Entire Property is Covered by Brackett Soils and Rock Outcrop, Steep (BoF) Source: Soil Survey of Travis County Note: Selected onsite soils have been altered due to erosion M. TROJAN & ASSOCIATES Environmental Consultants 8244 Lime Creek Road Leander, Texas 78641 (512) 258-6606 Scale: Date: Project: MTA Project: 1” = 60’ (approx.) October 31, 2013 City of Austin EA SE-13-015  NORTH FIGURE 5 SITE SOILS MAP 0.56-ACRE UNDEVELOPED RESIDENTIAL LOT 4316 FAR WEST BLVD. AUSTIN, TRAVIS COUNTY, TEXAS 78731 SUBJECT PROPERTY The Subject Property is Underlain by the Walnut Formation (Kwa) Ked Far West Blvd. Mesa Drive Kgr Kwa NOTE: Subject property location is approximate Sources: (1) Geologic Map of the Austin Area, Texas, The University of Texas at Austin, Bureau of Economic Geology, dated 1992, (2) TCEQ  NORTH M. TROJAN & ASSOCIATES Environmental Consultants 8244 Lime Creek Road Leander, Texas 78641 (512) 258-6606 Scale: Date: Project: MTA Project: No Scale October 31, 2013 City of Austin EA SE-13-015 FIGURE 6 GENERAL GEOLOGIC MAP 0.56-ACRE UNDEVELOPED RESIDENTIAL LOT 4316 FAR WEST BLVD. AUSTIN, TRAVIS COUNTY, TEXAS 78731 Property Exhibits a Variety of Medium- to Old-Growth Tree Types; Primary Types Include Cedar, Cedar Elm, Hackberry and Chinaberry M. TROJAN & ASSOCIATES Environmental Consultants 8244 Lime Creek Road Leander, Texas 78641 (512) 258-6606 Largest old-growth trees (refer to tree survey of the Site Plan)  NORTH Scale: Date: Project: MTA Project: 1” = 60’ (approx.) October 31, 2013 City of Austin EA SE-13-015 FIGURE 7 SITE VEGETATION MAP 0.56-ACRE UNDEVELOPED RESIDENTIAL LOT 4316 FAR WEST BLVD. AUSTIN, TRAVIS COUNTY, TEXAS 78731 Ephemeral Drainage Way (Eroded Bedrock) FEATURE S-1 (Seep Area) Underground Culvert Discharge Far West Blvd. M. TROJAN & ASSOCIATES Environmental Consultants 8244 Lime Creek Road Leander, Texas 78641 (512) 258-6606 Scale: Date: Project: MTA Project 1” = 40’ (approx.) October 31, 2013 City of Austin EA SE-13-015  NORTH FIGURE 8 SITE GEOLOGIC/CEFs MAP 0.56-ACRE UNDEVELOPED RESIDENTIAL LOT 4316 FAR WEST BLVD. AUSTIN, TRAVIS COUNTY, TEXAS 78731 PHOTOGRAPHIC REPORTING DATA SHEET [ PHOTOGRAPH 1 ] Project: Site: City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot Location: 4316 Far West Blvd., Austin, Travis County, Texas 78731 Date Taken: October 23, 2013 Photographer: Michael Trojan, CPG Description: View of the southern (front) portion of the property, with Far West Blvd. in the foreground. Photograph taken from Far West Blvd. facing northwest. M. TROJAN & ASSOCIATES Environmental Consultants Page 1 of 7 PHOTOGRAPHIC REPORTING DATA SHEET [ PHOTOGRAPH 2 ] Project: Site: City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot Location: 4316 Far West Blvd., Austin, Travis County, Texas 78731 Date Taken: October 23, 2013 Photographer: Michael Trojan, CPG Description: View of typical steep topographic slopes and large vegetation along the southern extent of the lot. M. TROJAN & ASSOCIATES Environmental Consultants Page 2 of 7 PHOTOGRAPHIC REPORTING DATA SHEET [ PHOTOGRAPH 3 ] Project: Site: City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot Location: 4316 Far West Blvd., Austin, Travis County, Texas 78731 Date Taken: October 23, 2013 Photographer: Michael Trojan, CPG Description: View of typical large vegetation on the central and northern portions of the lot. M. TROJAN & ASSOCIATES Environmental Consultants Page 3 of 7 PHOTOGRAPHIC REPORTING DATA SHEET [ PHOTOGRAPH 4 ] Project: Site: City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot Location: 4316 Far West Blvd., Austin, Travis County, Texas 78731 Date Taken: October 23, 2013 Photographer: Michael Trojan, CPG Description: View of typical bedrock exposed at ground surface on the lot. M. TROJAN & ASSOCIATES Environmental Consultants Page 4 of 7 PHOTOGRAPHIC REPORTING DATA SHEET [ PHOTOGRAPH 5 ] Project: Site: City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot Location: 4316 Far West Blvd., Austin, Travis County, Texas 78731 Date Taken: October 23, 2013 Photographer: Michael Trojan, CPG Description: View of the stormwater culvert discharge (onto the lot) at the southwest corner of the lot. The culvert discharges stormwater runoff to an ephemeral drainage way that trends along the western portion of the lot. M. TROJAN & ASSOCIATES Environmental Consultants Page 5 of 7 PHOTOGRAPHIC REPORTING DATA SHEET [ PHOTOGRAPH 6 ] Project: Site: City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot Location: 4316 Far West Blvd., Austin, Travis County, Texas 78731 Date Taken: October 23, 2013 Photographer: Michael Trojan, CPG Description: View of groundwater seeps along the ephemeral drainage way that trends along the western portion of the lot. M. TROJAN & ASSOCIATES Environmental Consultants Page 6 of 7 PHOTOGRAPHIC REPORTING DATA SHEET [ PHOTOGRAPH 7 ] Project: Site: City of Austin Environmental Assessment 0.56-Acre Undeveloped Residential Lot Location: 4316 Far West Blvd., Austin, Travis County, Texas 78731 Date Taken: October 23, 2013 Photographer: Michael Trojan, CPG Description: Second view of groundwater seeps along the ephemeral drainage way that trends along the western portion of the lot. M. TROJAN & ASSOCIATES Environmental Consultants Page 7 of 7 CITY OF AUSTIN CEF WORKSHEET 1 2 3 4 9 Project Name: 0.56 Undeveloped Residential Lot Project Address: Date: Environmental Assessment Date: 4316 Far West Blvd. Austin, Travis County, Texas 78731 10/31/2013 10/23/2013 5 6 7 8 Primary Contact Name: Mirza Tahir Baig, PE Professional StruCIVIL Engineers, Inc. Phone Number: (512) 238-6422 Prepared By: Michael Trojan, CPG CEFS Located? {yes,no} : Yes FEATURE TYPE {Wetland, Rimrock, Recharge Feature, Seep, Spring} FEATURE ID (e.g. S-1) FEATURE LONGITUDE (WGS 1984 in Meters) In Decimal Degrees e.g. - 97.77128 FEATURE LATITUDE (WGS 1984 in Meters) WETLAND DIMENSIONS (ft) RIMROCK DIMENSIONS (ft) In Decimal Degrees e.g. 30.26356 X Y Length Avg Height Seep Area S-1 -97.773269 30.361052 City of Austin Use Only WPDRD CASE NUMBER: