Geologic Assessment

TABLE OF CONTENTS

1.0 Introduction ...... 1 2.0 Methodology ...... 1 3.0 Results ...... 1 3.1 Site Overview ...... 1 3.2 Geology ...... 1 3.3 Soils ...... 2 3.4 Site Hydrogeologic Assessment ...... 3 4.0 References...... 4

LIST OF APPENDICES

Appendix A: Texas Commission on Environmental Quality (TCEQ) Forms and Attachments

• Attachment A – Geologic Assessment Table

• Attachment B – Stratigraphic Column

• Attachment C - Narrative Description of Site Geology

• Attachment D – Location Map, Site Geologic Map, and Soils Map

• Attachment E – Photographic Documentation

Geologic Assessment Report, US 79 from IH35 to east of FM 1460

LIST OF PREPARERS

Crystal Allgood Project Manager Philip C. Pearce, P.G. Senior Geoscientist Debbie Duran, G.I.T. Environmental Specialist Ben Dilly, G.I.T. Environmental Specialist Jason Kainer Geographic Information Systems Specialist

Geologic Assessment Report, US 79 from IH35 to east of FM 1460

1 1.0 Introduction

2 SWCA Environmental Consultants (SWCA) was contracted by LAN to conduct a Geologic 3 Assessment for the presence of potential recharge features for the proposed improvements 4 along US 79 from IH-35 to east of FM 1460, located in Round Rock, Williamson County, 5 Texas (“project site”) (Appendix A, Attachment D). This report includes the Texas Commission 6 on Environmental Quality (TCEQ) Geologic Assessment form #TCEQ-0585.

7 2.0 Methodology

8 SWCA geologists conducted a field survey for a Geologic Assessment on 23 March 2018, 12 9 July 2018,10 July 2019 and 20 November 2019. The pedestrian survey was completed by 10 walking parallel transects spaced approximately 50 feet apart as directed by the TCEQ in the 11 Instructions to Geologists for Geologic Assessments on the Edwards Aquifer 12 Recharge/Transition Zones (Rev. 10-01-04). Closer spacing was used where vegetation 13 inhibited clear observation. All potential karst features, including depressions, holes, and 14 animal burrows, were carefully examined for evidence of subsurface extent. A number of 15 techniques were used for this effort, including probing with a digging implement to 16 determine the thickness and consistency of fill material and feeling for the presence of air 17 flow, which may indicate the presence of a sub-surface void space. Other techniques 18 included making observations of any notable characteristics of the feature site such as the 19 presence of various types of vegetation or a semi-circular burrow mound produced by the 20 activities of small mammals.

21 3.0 Results

22 3.1 Site Overview

23 The project site lies within the Edwards Aquifer Recharge Zone and Edwards Aquifer Transition 24 Zone. The subject property generally slopes to the southwest. The surface elevations range 25 from 700 to 750 feet above mean sea level (amsl). The property consists of a paved road and 26 parkway areas, and includes areas of adjacent proposed right-of-way (ROW) expansion. 27 Residential and commercial properties are adjacent to the project site.

28 3.2 Geology

29 The subject property is underlain by Eagle Ford Group (Kef), Buda Limestone (Kbu), Del Rio 30 Clay (Kdg), Georgetown Formation (Kgt), and Edwards Formation (Ked). The Ked is exposed 31 west of IH-35. The Kef is composed of claystone, shale, flaggy limestone, and marl. The Kbu 32 is comprised of nodular, soft and hard limestone and is very fossiliferous. The Del Rio Clay 33 (Kdg) formation is composed of claystone and contains pyrite and selenite. The Kgt is 34 comprised of thin, fine-grained limestone (Housh 2007). Quaternary-age terrace and alluvial

Geologic Assessment Report, US 79 from IH35 to east of FM 1460 1

35 deposits cover the bedrock units in portions of the site (Collins 1997). A Stratigraphic 36 Column is included as Appendix A, Attachment B.

37 The subject property occurs within the Balcones Fault Zone (BFZ) within the Edwards Aquifer 38 Recharge Zone. During the middle Tertiary, structural down-warping occurred to the 39 southeast associated with the formation of the ancestral Gulf of Mexico. The earth’s crust 40 was stretched in response, and the BFZ formed along a zone of weakness, which today 41 marks the boundary between the Edwards Formation and the Gulf Coastal Plain throughout 42 central Texas. This zone consists of a series of northeast trending, predominantly normal, 43 nearly vertical, en echelon faults. A fault identified as Chandler Fault crosses the project 44 area west of Egger Avenue (Housh 2007).

45 The project area is within the Edwards Aquifer Recharge Zone. Recharge into the Edwards 46 Aquifer primarily occurs in areas where the Edwards Formation and Georgetown Formation 47 are exposed at the surface. Most recharge is from direct infiltration via precipitation and 48 streamflow loss. Recharge occurs predominantly along secondary porosity features such as 49 faults, fractures, and karst features (caves, solution cavities, sinkholes, etc.). Karst features 50 are commonly formed along joints, fractures, and bedding plane surfaces in the Edwards 51 Formation and Georgetown Formation.

52 3.3 Soils

53 A review of soils data from the U.S. Department of Agriculture Natural Resources 54 Conservation Service (NRCS) indicates that eleven soil map units are present within the 55 Project Area (NRCS 2018): Krum silty clay (1 to 3 percent slopes) (KsB); Fairlie clay (0 to 1 56 percent slopes) (FaA); Branyon clay (0 to 1 percent slopes) (BrA); Crockett fine sandy Loam 57 (1 to 3 percent slopes) (CfB), Doss silty clay (1 to 3 percent slopes) (DoC Krum silty clay (0 to 58 1 percent slopes) (KsA); Oakalla silty clay (0 to 2 percent slopes) (Of); Queeny clay loam (1 to 59 5 percent slopes) (QuC); Houston Black clay (3 to 5 percent slopes)(HuC2); Branyon Clay 60 (BrB) (1 to 3 percent slopes); and Georgetown stony clay (1 to 3 percent slopes)(GsB).

61 The KsB and KsA consist of very deep to clayey alluvium, well drained soils and are in the 62 “C” hydrologic soil group, which has a slow infiltration rate when thoroughly wetted.

63 The FaA is composed of deep, moderately well drained, very slowly permeable soils. The BrA 64 and BrB soils consist of very deep, moderately well drained, slow permeable soils. The Of 65 soils are very deep, well drained soils that form in loamy alluvium. The QuC soils consist of 66 well drained soils. The HuC2 and GsB soils consist of moderately well drained soils. The 67 FaA, BrA, BrB, CfB, DoC, Of, QuC, HuC2, and GsB soil types are in “D” classification of the 68 hydrologic soil groups, which have a very slow infiltration rate when thoroughly wetted (NRCS 69 2018). A map displaying the locations of the soil types is included in Appendix A, 70 Attachment D.

Geologic Assessment Report, US 79 from IH35 to east of FM 1460 2

71 3.4 Site Hydrogeologic Assessment

72 Overall, the potential for fluid movement to the Edwards Aquifer at the site is moderate. Two 73 potential recharge features were identified on site, and terrace and alluvial deposits cover 74 much of the project site.

75 The depth to water in the western portion of the project site appears to be relatively shallow 76 (less than 50 feet) based on depth to water measurements in nearby well number 58-27- 77 810 and the presence of Brushy Creek Spring, which is located in the eastern portion of the 78 site. Well 58-27-810 has had water levels ranging from 605 to 687.64 feet in elevation 79 (Texas Water Development Board [TWDB] 2018). The ground elevation near the western end 80 of the project site is approximately 730 feet.

81 Brushy Creek Spring is located within the Lake Creek Watershed inside a storm water culvert 82 that runs under highway 79 (N 30.516834°, W 97.661271°). Spring flow is ephemeral, but 83 when present, water emerges from three spring diversion pipes and several cracks in the 84 concrete culvert. Water flows from the culvert over a large riprap structure and into a deep 85 pool, which then constricts into a spring run that empties directly into Brushy Creek. The 86 spring is located within the Transition Zone portion of the project approximately 0.5 miles 87 east of the Edwards Aquifer Recharge boundary. It discharges at an elevation of roughly 700 88 feet. Construction of the culvert beneath US 79 is believed to have intercepted some of the 89 flow from the original Brushy Creek Spring orifice, which might have been previously located 90 somewhat south or east of the current spring location.

91 To the east of Chandler Fault within the project site, the Edwards Aquifer appears to be 92 confined and water moves upward under artesian conditions into the overlying Buda 93 Limestone and possibly alluvial deposits before discharging at Brushy Creek. Housh (2007) 94 mapped an unnamed fault south of the project site. Fractures or an extension of the fault 95 potentially cross US 79 in the area of Brushy Creek Spring. The fractures or an extension of 96 the fault possibly serve as a conduit for water moving up through upper confining units of 97 the Edwards Aquifer to discharge at the surface as spring flow.

98 The potential exists for encountering karst voids during construction within the Edwards 99 Aquifer Recharge Zone portion of the project. The potential is possibly greatest in the vicinity 100 of the Chandler Fault, which is the functional boundary between the Recharge and 101 Transition Zones.

102 Feature Descriptions

103 SWCA identified two features described below.

104 S-1 Feature S-1 is Brushy Creek Spring which is located within a storm water culvert that 105 runs beneath US Hwy 79 underneath the project site. The concrete culvert includes three 106 diversion pipes which feed into Brushy Creek Spring. During the site visit, it appeared water

Geologic Assessment Report, US 79 from IH35 to east of FM 1460 3

107 was emerging from several cracks within the concrete culvert. Because the spring is 108 hydrogeologically connected to the Edwards Aquifer, and the potential for rapid infiltration 109 exists when the spring is not flowing, the feature is ranked as sensitive.

110 S-2 Feature S-2 is Chandler Fault which intersects the project area to the west of Egger 111 Avenue. Due to fine infilling at the surface throughout the project area, the probability of 112 rapid infiltration is low.

113 A prominent off-site recharge feature is present within the bed of Brushy Creek 114 approximately 1200 feet south of US 79. The feature is a collapse sinkhole referred to in 115 this report as the Brushy Creek Sinkhole at Veterans Park. The sinkhole is approximately 30 116 feet in diameter and is aligned with the Chandler Fault. According to Heather Beatty, P.G., 117 formerly of the Texas Department of Transportation (Beatty 2018 Personal Communication) 118 the sinkhole is visible when flow in Brushy Creek is low. At such times the sinkhole captures 119 nearly all the stream flow. A photograph from November 1999 is included in Attachment E.

120 4.0 References

121 Beatty, Heather, 2018. Personal Communication.

122 Collins, E.W. 1997. Geologic Map of the Round Rock Quadrangle, Texas. University of Texas, 123 Bureau of Economic Geology Open-File Map OFM0013, scale 1:24,000

124 Housh, T.B., 2007, Bedrock Geology of Round Rock and Surrounding Areas, Williamson and 125 Travis Counties.

126 Natural Resource Conservation Service (NRCS). 2018. Official soil survey descriptions. U.S. 127 Department of Agriculture, Natural Resources Conservation Service, Soil Survey Staff. 128 Available online at: https://soilseries.sc.egov.usda.gov/osdname.asp. Accessed 129 March 2018 & July 2018.

130 Texas Water Development Board. 2018. Water Data Interactive website, 131 http://www2.twdb.texas.gov/apps/waterdatainteractive/groundwaterdataviewer, 132 accessed April 25, 2018.

Geologic Assessment Report, US 79 from IH35 to east of FM 1460 4

APPENDIX A

TEXAS COMMISSION ON ENVIRONMENTAL QUALITY (TCEQ) FORMS

Geologic Assessment Report, US 79 from IH35 to east of FM 1460

4. Attachment A - Geologic Assessment Table. Completed Geologic Assessment Table (Form TCEQ-0585-Table) is attached. 5. Soil cover on the project site is summarized in the table below and uses the SCS Hydrologic Soil Groups* (Urban Hydrology for Small Watersheds, Technical Release No. 55, Appendix A, Soil Conservation Service, 1986). If there is more than one soil type on the project site, show each soil type on the site Geologic Map or a separate soils map.

Table 1 - Soil Units, Infiltration Soil Name Group* Thickness(feet) Characteristics and Thickness Branyon clay (0 to 1 percent Soil Name Group* Thickness(feet) slopes) (BrA) D <1.5 Krum silty clay (1 Queeny clay to 3 percent loam ( 1 to 5 slopes) (KsB) percent slopes) Krum silty clay (0 (QuC) D <1.5 to 1 percent slopes) (KsA) C <1.5 * Soil Group Definitions (Abbreviated)

Fairlie clay (0 to A. Soils having a high infiltration 1 percent rate when thoroughly wetted.

slopes)(FaA) D <1.5 B. Soils having a moderate infiltration rate when thoroughly Oakalla silty clay wetted. (0 to 2 percent C. Soils having a slow infiltration slopes)(Of) D <1.5 rate when thoroughly wetted. D. Soils having a very slow infiltration rate when thoroughly wetted.

6. Attachment B – Stratigraphic Column. A stratigraphic column showing formations, members, and thicknesses is attached. The outcropping unit, if present, should be at the top of the stratigraphic column. Otherwise, the uppermost unit should be at the top of the stratigraphic column. 7. Attachment C – Site Geology. A narrative description of the site specific geology including any features identified in the Geologic Assessment Table, a discussion of the potential for fluid movement to the Edwards Aquifer, stratigraphy, structure(s), and karst characteristics is attached. 8. Attachment D – Site Geologic Map(s). The Site Geologic Map must be the same scale as the applicant's Site Plan. The minimum scale is 1”: 400' Applicant's Site Plan Scale: 1" = 100' 2 of 3 TCEQ-0585 (Rev.02-11-15)

Site Geologic Map Scale: 1" = 100' Site Soils Map Scale (if more than 1 soil type): 1" = 250' 9. Method of collecting positional data: Global Positioning System (GPS) technology. Other method(s). Please describe method of data collection: 10. The project site and boundaries are clearly shown and labeled on the Site Geologic Map. 11. Surface geologic units are shown and labeled on the Site Geologic Map. 12. Geologic or manmade features were discovered on the project site during the field investigation. They are shown and labeled on the Site Geologic Map and are described in the attached Geologic Assessment Table. Geologic or manmade features were not discovered on the project site during the field investigation. 13. The Recharge Zone boundary is shown and labeled, if appropriate. 14. All known wells (test holes, water, oil, unplugged, capped and/or abandoned, etc.): If applicable, the information must agree with Item No. 20 of the WPAP Application Section. There are (#) wells present on the project site and the locations are shown and labeled. (Check all of the following that apply.) The wells are not in use and have been properly abandoned. The wells are not in use and will be properly abandoned. The wells are in use and comply with 16 TAC Chapter 76. There are no wells or test holes of any kind known to exist on the project site. Administrative Information 15. Submit one (1) original and one (1) copy of the application, plus additional copies as needed for each affected incorporated city, groundwater conservation district, and county in which the project will be located. The TCEQ will distribute the additional copies to these jurisdictions. The copies must be submitted to the appropriate regional office.

3 of 3 TCEQ-0585 (Rev.02-11-15)

ATTACHMENT A

GEOLOGIC ASSESSMENT TABLE

Geologic Assessment Report, US 79 from IH35 to east of FM 1460

ATTACHMENT B

STRATIGRAPHIC COLUMN

Geologic Assessment Report, US 79 from IH35 to east of FM 1460

Stratigraphic Column

Note: The shaded areas represent the lithology that outcrops on the property.1

Navarro and Taylor Groups, undivided; 600 feet thick

Austin Group; 325–420 feet thick

Upper Confining Units Eagle Ford Group; 25–65 feet thick

Buda Limestone; 40–50 feet thick Upper Cretaceous

Del Rio Clay; 40–70 feet thick

Georgetown Formation; 30–80 feet thick

Edwards Edwards Formation; Up to 200 feet thick Aquifer

Comanche Peak Formation; 80 feet thick

Walnut Formation; Up to 120 feet thick

Lower Cretaceous

Lower Confining Units Upper member of Glen Rose Limestone; 500 feet thick

Note: The shaded areas represent the lithology that outcrops in the Project Area.

Geologic Assessment Report, US 79 from IH35 to east of FM 1460

ATTACHMENT C

NARRATIVE DESCRIPTION OF SITE GEOLOGY

Geologic Assessment Report, US 79 from IH35 to east of FM 1460

PLEASE REFER TO SECTION 3.0 OF THIS REPORT

Geologic Assessment Report, US 79 from IH35 to east of FM 1460

ATTACHMENT D

LOCATION MAP, SITE GEOLOGIC MAP, AND SOILS MAP

BURNET BELL

WILLIAMSON

LEE TRAVIS HAYS BASTROP

Path: N:\Projects\42000\42648 US 79 Round Rock TXDOT\MXD\US 79 Round Rock TXDOT 42648.aprx

US 79 FROM I35 1:48,000 R TO FM 1460 Created By: J. Kainer Project Number: 42648 Project Site Date: 11/21/2019 PROJECT LOCATION MAP 0 2,000Feet

0 400Meters 720 750

720

730

740 Kgt

Edwards Aquifer Recharge Zone

Service Layer Credits: World Topographic Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri Japan, METI, Esri China (Hong Kong), (c) OpenStreetMap contributors, and the GIS User Community World_Imagery: TX Orthoimagery Program, Williamson County TX, DigitalGlobe, Microsoft World Transportation: Esri, HERE, Garmin, (c) OpenStreetMap contributors

730

720

710

Ked Ked

Path: N:\Projects\42000\42648 US 79 Round Rock TXDOT\MXD\US 79 Round Rock TXDOT 42648.aprx

US 79 FROM I35 Project Site Geologic Unit 1:1,200 Kau - Austin Chalk TO FM 1460 ") Feature Created By: J. Kainer Kbu - Buda Limestone Project Number: 42648 Date: 11/21/2019 GEOLOGIC Edwards Aquifer Boundary Kdr - Del Rio Clay ASSESSMENT 0 200Feet 10-Foot Contour Line Kgt- Geogretown Formation MAP 1 Inch = 100 Feet Ked - Edwards Limestone Page 1 of 4 0 50Meters 710

Kau

700 720

S-2

700

Kbu

720

Kgt 710

Edwards Aquifer Recharge Zone Edwards Aquifer C h a n d le r F a u lt Transition Zone

720

Kbu

690

Brushy Creek Sinkhole 680 ") Kdr Ked

690

Path: N:\Projects\42000\42648 US 79 Round Rock TXDOT\MXD\US 79 Round Rock TXDOT 42648.aprx

US 79 FROM I35 Project Site Geologic Unit 1:1,200 Kau - Austin Chalk TO FM 1460 ") Brushy Creek Sinkhole Created By: J. Kainer Kbu - Buda Limestone Project Number: 42648 Date: 1/10/2020 GEOLOGIC Edwards Aquifer Boundary Kdr - Del Rio Clay ASSESSMENT 0 200Feet 10-Foot Contour Line Kgt- Geogretown Formation MAP 1 Inch = 100 Feet Ked - Edwards Limestone Page 2 of 4 0 50Meters 720 Kau

710

700 Edwards Aquifer S-1 Transition Zone ")

700

690 Kbu

Service Layer Credits: World Topographic Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri Japan, METI, Esri China (Hong Kong),680 (c) OpenStreetMap contributors, and the GIS User Community World_Imagery: Williamson County TX, USDA FSA, DigitalGlobe, GeoEye, CNES/Airbus DS World Transportation: Esri, HERE, Garmin, (c) OpenStreetMap contributors

670

Kdr

Kbu

680

690 680 700

710

Path: N:\Projects\42000\42648 US 79 Round Rock TXDOT\MXD\US 79 Round Rock TXDOT 42648.aprx

710

700

Service Layer Credits: World Topographic Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster 700 NL, Ordnance Survey, Esri Japan, METI, Esri China (Hong Kong), (c) OpenStreetMap contributors, and the GIS User Community World_Imagery: Williamson County TX, USDA FSA, DigitalGlobe, GeoEye, CNES/Airbus DS World Transportation: Esri, HERE, Garmin, (c) OpenStreetMap contributors

Edwards Aquifer Transition Zone

700 690

Kbu 700

690

680

Path: N:\Projects\42000\42648 US 79 Round Rock TXDOT\MXD\US 79 Round Rock TXDOT 42648.aprx

PHOTOGRAPHIC DOCUMENTATION

Geologic Assessment Report, US 79 from IH35 to east of FM 1460 US 79 from IH35 to east of FM 1460, Texas Geologic Assessment Photographic Log

Photograph 1. Representative photo depicting the project area, facing east.

Photograph 2. Representative photo of the project area, facing east.

SWCA Project No. 42648 F-1 US 79 from IH35 to east of FM 1460, Texas Geologic Assessment Photographic Log

Photograph 3. View of the project area, facing west.

Photograph 4: View of upstream location of drainage pipes.

SWCA Project No. 42648 F-2 US 79 from IH35 to east of FM 1460, Texas Geologic Assessment Photographic Log

Photograph 5: View of inside box culvert drainage facing upstream.

Photograph 6: View of Brushy Creek Springs downstream US Hwy 79.

SWCA Project No. 42648 F-3

This report was written on behalf of the Texas Department of Transportation by

SWCA ENVIRONMENTAL CONSULTANTS 6200 UTSA Boulevard, No. 102 San Antonio, Texas 78249 www.swca.com

Geologic Assessment Report, US 79 from IH35 to east of FM 1460