Cotton Belt Corridor Regional Rail

Transcription

1 Cotton Belt Corridor Regional Rail Geology and Soils Existing Conditions Technical Memorandum December 2013 Prepared for Dallas Area Rapid Transit General Planning Consultant Managed by URS Corporation

2 Cotton Belt Corridor Regional Rail Geology and Soils Existing Conditions Technical Memorandum December 2013 Prepared by Cox McLain Environmental Consulting, Inc. Prepared for Dallas Area Rapid Transit General Planning Consultant Managed by URS Corporation

3 Document Revision Record Project/Report Name: Geology and Soils Existing Conditions Technical Memorandum PM: Dan Meyers URS Project Number: PIC: Jerry Smiley Revision Number Date Draft Version 1 August 27, 2013 Draft Version 2 Originator: Sign: Date: Cox McLain, AICP,CM August 27, 2013 Comments by: Nancy Stavish, AICP, URS September 1, 2013 Reggie Herman, AICP, URS December 26, 2013 Task Manager Approval: Date: Verified/Approved by: Date: Distribution Name Title Firm Geology and Soils Existing Conditions

4 TABLE OF CONTENTS 1.0 INTRODUCTION AND METHODOLOGY DESCRIPTION OF EXISTING CONDITIONS Geology Soils DISCUSSION OF POTENTIAL IMPACTS Geology Soils Literature/Sources Cited...14 LIST OF TABLES Table 3-1 Soil Characteristics Related to Construction LIST OF FIGURES Figure 2-1 Geologic Features... 3 Figure 2-2 East-West Cross-section of Geology of Dallas County... 4 Figure 2-3 Soils... 6 LIST OF PHOTOS Photo 2-1 Exposed Austin Chalk... 2 Photo 2-2 Approximately 15 feet of alluvial deposits over Austin Chalk formation along a creek... 2 Geology and Soils Existing Conditions

5 1.0 INTRODUCTION AND METHODOLOGY This memorandum addresses geology and soils for the Cotton Belt Regional Rail Corridor Project (Cotton Belt Project) study area. The proposed Cotton Belt Project would provide connectivity between the Dallas/Fort Worth International Airport (DFW Airport) and the communities of Grapevine, Coppell, Carrollton, Addison and Dallas, eventually connecting to the existing Dallas Area Rapid Transit (DART) Red Line Light Rail Transit (LRT) corridor in Plano and Richardson, Texas. The project study area used for the assessment of potential impacts includes a one-quarter-mile corridor centered on the project centerline of the Cotton Belt Corridor right-of-way (Cotton Belt Corridor). Existing literature and mapping were reviewed for the project area to assess geology and soils. Maps examined include Aerials Express Dallas 2010 Aerial Imagery, the Geologic Atlas of Texas Dallas Sheet (UT-BEG, 1987), and U.S. Department of Agriculture Natural Resource Conservation Service (NRCS) Soil Surveys for Dallas County (NRCS, 1980), Collin County (NRCS, 1969) and Tarrant County (NRCS, 1981). 2.0 DESCRIPTION OF EXISTING CONDITIONS This section describes the existing conditions with respect to geology and soils within the project study area. 2.1 Geology Four geologic types underlie the project area the Eagle Ford Formation, alluvium, fluviatile terrace deposits, and Austin Chalk. These are discussed below and depicted on Figure 2-1. Figure 2-2 shows an east-west cross-section of the geology of Dallas County. The Eagle Ford Formation, comprised of shale, siltstone, and limestone of late Cretaceous origin, underlies approximately the western one-third of the project area and is also found in the central portion of the project area (UT-BEG, 1987). This formation has an average thickness of 475 feet (The Dallas Geological Society, 1965). Fossils are rarely found in the Eagle Ford Formation, but fish bones and teeth are occasionally found (Shuler, 1918). Concretions are common throughout the formation. Alluvium consists of sand, silt, clay and gravel of variable thickness and recent origin. This geologic feature is generally associated with major streams. Within the project area, alluvium is found in the vicinity of the Elm Fork of the Trinity River and its tributaries (UT-BEG, 1987). Alluvial deposits result in rich soils, and sand and gravel deposits contribute economic value (Shuler, 1918). Fossils are commonly found in these deposits (Shuler, 1918). Fluviatile terrace deposits include sand, gravel, silt, clay, or mud of recent origin. It is generally associated with floodplains and is found on terraces. These deposits are found in the central portion of the project area, in association with alluvium (UT-BEG, 1987). Sand deposits in terrace areas have economic value, and fossils are commonly found in them (Shuler, 1987). Austin Chalk, of late Cretaceous origin, is comprised of chalk (microgranular calcite), with some interbedded calcareous clay and hard lime mudstone. It underlies approximately the eastern one-half of the project area (UT-BEG, 1987). Austin Chalk often overlies the Eagle Ford Formation (The Dallas Geological Society, 1965). This formation is an average of 500 feet thick Geology and Soils Existing Conditions 1

6 (Shuler, 1918). The formation includes approximately 85 percent limestone (calcium carbonate), with lesser amounts of silica, zinc oxide, aluminia, and magnesia; iron pyrite concretions are common in the lower layers (Shuler, 1918). Small-scale faulting is a characteristic feature of Austin Chalk; during faulting, the chalk breaks into irregular blocks by fissure planes along which slight movements have taken place (Shuler, 1918). Photo 2-1: Exposed Austin Chalk (stock photo) Photo 2-2: Approximately 15 feet of alluvial deposits over Austin Chalk formation along a creek (stock photo) Geology and Soils Existing Conditions 2

7 Cotton Belt Corridor Regional Rail Project Geology and Soils Existing Conditions 3

8 Geology and Soils Existing Conditions 4 Cotton Belt Corridor Regional Rail Project

9 2.2 Soils Seven soil associations are found within the project study area. These include (from west to east): Houston Black-Navo-Heiden association gently sloping, deep, clayey and loamy soils of uplands; Houston Black-Heiden association deep, nearly level to strongly sloping, clayey soils of uplands; Wilson-Rader-Axtell association deep, nearly level to gently sloping, loamy soils of uplands; Trinity-Frio association deep, nearly level, clayey soils of floodplains; Eddy-Stephen-Austin association very shallow, shallow, and moderately deep, gently sloping to moderately steep, loamy and clayey soils of uplands; Austin-Houston Black association moderately deep and deep, nearly level to sloping, clayey soils of uplands; and Houston Black-Austin associations gently sloping to sloping, clayey soils of uplands that are over deep marl and chalk. A total of 55 soil series are found within the proposed right-of-way. Ten of these series are found in Tarrant County, 37 are found in Dallas County, and the remaining eight are found in Collin County. Descriptions of each of these are found below (grouped by main soil series type, as appropriate) and depicted on Figure 2-3. Altoga silty clay, 5 to 12 percent slopes This soil series consists of deep, well drained, clayey soils found on escarpments of stream terraces. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Arents These soils are comprised of discarded overburden from gravel and sand mining operations. They are found in Dallas County and are not classified as prime farmland (NRCS 1980; NRCS, 2012). Arents, loamy, gently undulating These areas have been smoothed following discard of mined material and pits have been filled with soil (NRCS, 1980). Arents, loamy, hilly These areas have not been smoothed, and overburden has been left in mounds and ridges (NRCS, 1980). Austin silty clay This soil type consists of deep, calcareous, clayey soils that are gently sloping to sloping (NRCS, 1969; NRCS, 1980). Austin silty clay, 1 to 3 percent slopes This soil series is found in Collin County and Dallas County and is classified as prime farmland (NRCS, 1969; NRCS, 1980; NRCS, 2012). Austin silty clay, 3 to 5 percent slopes, eroded This soil series is found in Collin County and is not classified as prime farmland (NRCS, 1969; NRCS, 2012). Geology and Soils Existing Conditions 5

10 Cotton Belt Corridor Regional Rail Project Geology and Soils Existing Conditions 6

11 Austin-Urban land complex This complex is made up of nearly level and gently sloping, welldrained soils and areas of Urban land on uplands. These soils are found in Dallas County and are not classified as prime farmland (NRCS, 1980; NRCS, 2012). Austin-Urban land complex, 0 to 2 percent slopes Austin soil makes up approximately 50 percent of the complex, urban (developed) land makes up about 40 percent, and the rest is comprised of minor soils (NRCS, 1980). Burleson clay This soil type includes deep, nearly level to moderately sloping clays that have a crusty surface when dry. They are found on uplands and old alluvial terraces along major streams (NRCS, 1969; NRCS, 1980; NRCS, 1981). Burleson clay, 0 to 1 percent slopes This soil series is found in Collin County, Dallas County and Tarrant County and is classified as prime farmland (NRCS, 1969; NRCS, 1980; NRCS, 1981; NRCS, 2012). Burleson clay, 1 to 3 percent slopes This soil series is found in Collin County and Dallas County and is classified as prime farmland (NRCS, 1969; NRCS, 1980; NRCS, 2012). Crosstell fine sandy loam, 1 to 3 percent slopes This soil type is made up of deep, gently sloping, loamy soil on convex ridges and side slopes (NRCS, 1981). This soil is found in Tarrant County and is not classified as prime farmland (NRCS, 2012). Crockett fine sandy loam This soil type is made up of deep, moderately well drained, nearly level to gently sloping loamy soils on uplands (NRCS, 1980). Crockett fine sandy loam, 1 to 3 percent slopes These soils are found in Dallas County and are not classified as prime farmland (NRCS, 1980; NRCS, 2012). Crockett fine sandy loam, 2 to 5 percent slopes These soils are found in Dallas County and are not classified as prime farmland (NRCS, 1980; NRCS, 2012). Dalco clay, 1 to 3 percent slopes This is a moderately deep, gently sloping, moderately well drained soil of uplands (NRCS, 1980). This soil is found in Dallas County and is classified as prime farmland (NRCS, 1980; NRCS, 2012). Dalco-Urban land complex, 0 to 3 percent slopes This complex includes moderately deep, moderately well drained, nearly level and gently sloping soils and areas of urban land. Dalco soil comprises approximately 50 percent of the complex, urban land comprises 30 percent, and minor soils make up the rest. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Dutek loamy fine sand, 1 to 5 percent slopes This soil series is deep, gently sloping, and well drained. It is found on old stream terraces on uplands. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Eddy clay loam, 3 to 8 percent slopes This soil series consists of very shallow to shallow, well drained, gently sloping to sloping soil overlying the Austin Chalk formation. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Eddy-Stephen complex, 1 to 5 percent slopes This complex consists of gently sloping, well drained, very shallow and shallow soils over the Austin Chalk formation (NRCS, 1980). Eddy soils Geology and Soils Existing Conditions 7

12 make up approximately 60 percent of the complex, Stephen soil makes up about 30 percent, and minor soils make up the rest. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Eddy-Urban land complex This complex includes gently sloping, shallow and very shallow, well drained soils and areas of urban land. These soils are found in Dallas County and are not classified as prime farmland (NRCS, 1980; NRCS, 2012). Eddy-Urban land complex, 4 to 8 percent slopes This complex is made up of approximately 50 percent Eddy soil, 30 percent urban land, and 20 percent minor soils (NRCS, 1980). Ferris-Heiden complex This complex includes deep, well drained, gently rolling and rolling soils on hillsides (NRCS, 1980; NRCS, 1981). Ferris-Heiden complex, 2 to 8 percent slopes This complex is comprised of approximately 50 percent Ferris soil, 45 percent Heiden soil, and 5 percent other, similar soils. This soil series is found in Tarrant County (NRCS, 1981). This soil is not classified as prime farmland (NRCS, 2012). Ferris-Heiden complex, 5 to 12 percent slopes This complex is comprised up approximately 60 percent Ferris soil, 20 percent Heiden soil, and 20 percent minor soils (NRCS, 1980). It is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Ferris-Urban land complex, 5 to 12 percent slopes This complex is made up of deep, well drained, sloping and strongly sloping soil and area of urban land (NRCS, 1980). Ferris soil comprises approximately 60 percent, urban land comprises approximately 25 percent, and the remainder is minor soils. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Frio silty clay These soils are deep, well drained, nearly level soils found on floodplains. They soils are found in Dallas County (NRCS, 1980). Frio silty clay, occasionally flooded This soil is classified as prime farmland (NRCS, 1980; NRCS, 2012). Frio silty clay, frequently flooded This soil is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Frio-Urban land complex This complex includes deep, nearly level, well drained soils and areas of urban land on floodplains of small streams (NRCS, 1980). Frio soil makes up approximately 70 percent of the complex, urban land makes up approximately 15 percent, and the rest is minor soils. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Heiden clay These soils are deep, well drained, gently sloping soils on uplands (NRCS, 1980). Heiden clay, 1 to 3 percent slopes This soil series is found in Tarrant County and is classified as prime farmland (NRCS, 1981; NRCS, 2012). Heiden clay, 2 to 5 percent slopes This soil is found in Dallas County and is classified as prime farmland (NRCS, 1980; NRCS, 2012). Geology and Soils Existing Conditions 8

13 Houston Black clay This soil type includes deep, calcareous, clayey soils found on uplands or old alluvial terraces. These soils form cracks to a depth of more than 30 inches when dry (NRCS, 1969; NRCS, 1980; NRCS, 1981). Houston Black clay, 0 to 1 percent slopes This soil series is found in Collin County and Dallas County and is classified as prime farmland (NRCS, 1969; NRCS, 1980; NRCS, 2012). Houston Black clay, 1 to 3 percent slopes This soil series is found in Collin County, Dallas County, and Tarrant County and is classified as prime farmland (NRCS, 1969; NRCS, 1980; NRCS, 1981; NRCS, 2012). Houston Black clay, 2 to 4 percent slopes This soil series is found in Collin County and is not classified as prime farmland (NRCS, 1969; NRCS, 2012). Houston Black-Urban land complex, 0 to 4 percent slopes This complex includes deep, moderately well drained, nearly level and gently sloping soils and areas of urban land. In Tarrant County, the complex is comprised of percent Houston Black soils, percent Urban land, and less than 25 percent other, similar soils (NRCS, 1981). In Dallas County, the complex is made up of approximately 40 percent Houston Black soil, 35 percent urban land, and 25 percent minor soils (NRCS, 1980). This soil is not classified as prime farmland (NRCS, 2012). Justin loam, 1 to 3 percent slopes This is a deep, well drained, gently sloping soil found on convex ridges on uplands. This soil is found in Tarrant County (NRCS, 1981). It is classified as prime farmland (NRCS, 2012). Leson clay, 1 to 3 percent slopes This is a deep, gently sloping soil on uplands. This soil series is found in Tarrant County (NRCS, 1981). It is classified as prime farmland (NRCS, 2012). Lewisville silty clay These soils consist of deep, well drained, calcareous clays that are gently to moderately sloping. They are found on stream terraces and areas that slope to streams (NRCS 1969; NRCS, 1980). Lewisville silty clay, 1 to 3 percent slopes This soil is found in Collin and Dallas Counties (NRCS, 1969; NRCS, 1980). It is classified as prime farmland (NRCS, 2012). Lewisville silty clay, 3 to 5 percent slopes, eroded This soil is found in Collin County and is not classified as prime farmland (NRCS, 1969; NRCS, 2012). Lewisville-Urban land complex This complex is made up of deep, well drained, nearly level and gently sloping soils and areas of urban land (NRCS, 1980). These soils are found in Dallas County and are not classified as prime farmland (NRCS, 1980; NRCS, 2012). Lewisville-Urban land complex, 0 to 4 percent slopes This complex is comprised of approximately 55 percent Lewisville soil, 30 percent urban land, and 15 percent minor soils (NRCS, 1980). Lewisville-Urban land complex 4 to 8 percent slopes Lewisville soil makes up approximately 60 percent of this complex, urban land makes up 30 percent, and 10 percent is minor soils (NRCS, 1980). Mabank fine sandy loam, 0 to 1 percent slopes This soil type is a deep, nearly level, somewhat poorly drained soil in depressions on uplands (NRCS, 1980). These soils are found in Dallas County and are not classified as prime farmland (NRCS, 1980; NRCS, 2012). Geology and Soils Existing Conditions 9

14 Navo clay loam, 1 to 3 percent slopes This is a deep, gently sloping, loamy soil found on side slopes and low ridges along drainageways. This soil series is found in Tarrant County (NRCS, 1981). It is not classified as prime farmland (NRCS, 2012). Seagoville clay, occasionally flooded This soil series is deep, moderately well drained, and nearly level (NRCS, 1980). It is found on floodplains. This soil is found in Dallas County and is classified as prime farmland (NRCS, 1980; NRCS, 2012). Silawa fine sandy loam, 3 to 8 percent slopes This soil is deep, well drained, gently sloping to sloping, and is found on uplands (NRCS, 1980). This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Stephen-Urban land complex, 1 to 4 percent slopes This complex includes shallow, well drained, gently sloping soils and areas of urban land over the Austin Chalk formation. Stephen soil comprises approximately 60 percent of the complex, urban land makes up 30 percent, and minor soils make up the rest. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Trinity clay This soil type includes deep, somewhat poorly drained, calcareous, clayey soils on floodplains of major streams and their tributaries. When dry, these soils can crack to a depth of up to 20 inches (NRCS, 1969; NRCS, 1980). Trinity clay, occasionally flooded This soil is found in Collin and Dallas Counties (NRCS, 1969; NRCS, 1980). In Collin County, it is associated with Pittman Creek. In Dallas County, it is found in association with the Elm Fork of the Trinity River. This soil is classified as prime farmland (NRCS, 2012). Trinity clay, frequently flooded This soil series is found in Tarrant County, in association with Cottonwood Branch (NRCS, 1981), and in Dallas County, in association with Grapevine Creek (NRCS, 1980). This soil is not classified as prime farmland (NRCS, 2012). Trinity-Urban land complex This complex is made up of deep, nearly level, somewhat poorly drained soils and areas of urban land on floodplains. It is comprised of approximately 60 percent Trinity soil, 20 percent urban land, and 20 percent minor soil. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Wilson clay loam This is a deep, somewhat poorly drained soil on uplands (NRCS, 1980). Wilson clay loam, 0 to 1 percent slopes This soil is nearly level. It is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Wilson clay loam, 0 to 2 percent slopes This is a nearly level to gently sloping, loamy soil. It is found on upland ridges and in slightly depressed areas above drainageways. This soil is found in Tarrant County (NRCS, 1981). This soil is not classified as prime farmland (NRCS, 2012). Wilson clay loam, 1 to 3 percent slopes This is a gently undulating soil. It is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Wilson-Urban land complex, 0 to 2 percent slopes This complex includes nearly level to gently sloping, deep, somewhat poorly drained soils and areas of urban land. Wilson soils make up approximately 60 percent of the complex, urban land makes up 30 percent, and the rest is Geology and Soils Existing Conditions 10

15 minor soils. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). 3.0 DISCUSSION OF POTENTIAL IMPACTS This section addresses potential impacts to geology and soils. 3.1 Geology One proposed design profile option for the Cotton Belt Project includes a Tunnel Profile Option which would pass through the Austin Chalk formation, as shown on Figure 2-1. As previously discussed, Austin Chalk is known for producing small-scale faulting. The formation is also susceptible to weathering due to erosion. The occurrence of fossils in this formation is not common. Because Austin Chalk is a hard formation with soft layers and faulting/weathered sections, special structural design measures may be needed to strengthen tunnel walls in the vicinity of faults or layers (if the Tunnel Profile Option is selected). 3.2 Soils The Farmland Protection Policy Act (FPPA), as detailed in Subtitle I of Title XV of the Agricultural and Food Act of 1981, provides protection to the following: 1) prime farmland; 2) unique farmland; and 3) farmland of local or statewide importance. FPPA defines prime farmland as land that has the best combination of physical and chemical characteristics for producing food, feed, forage, fiber, and oilseed crops, and is also available for these uses (not urban built-up land or water). It has the soil quality, growing season, and moisture supply needed to economically produce sustained high yields of crops when treated and managed, including water management (irrigation), according to acceptable farming methods. Unique farmland is farmland that is used for production of specific high value food, feed, and fiber crops. Farmland of local or statewide importance is determined by the appropriate state or local government agency or agencies. The project study area contains 14 prime farmland soils, comprising approximately 1,550 acres of the project study area. See Figure 2-3. No unique farmland or farmland of local or statewide importance is found within the project study area. The project study area is mostly committed to urban use. The FPPA exempts from consideration those lands committed to urban use (within city limits or zoning boundaries). Thus, NRCS, FPPA coordination would not be required for project development activities within the study area. Potential soil erosion and sedimentation during construction will be addressed in a Stormwater Pollution Prevention Plan (SWPPP), to be prepared prior to beginning construction activities. The SWPPP will detail best management practices (BMPs) to be incorporated into the project design related to erosion control, sedimentation control, and post-construction total suspended solids (TSS) removal. Table 3-1 lists soil characteristics, including shrink-swell potential, risk of erosion, risk of corrosion, and constraints related to construction/excavation. Detailed geotechnical borings would be completed prior to the final design stage in order to identify and avoid through design any potential structural stability issues. Geology and Soils Existing Conditions 11

16 General Soil Type Altoga Table 3-1 Soil Characteristics Related to Construction Shrink- Risk of Corrosion Risk of Swell Uncoated Erosion Concrete Potential Steel Moderate -high Arents None Low, except on slopes Construction/ Excavation Constraints Severe High Low Shrink-swell, low strength, erosivity, corrosivity High Low Slope, floods, corrosivity Austin High Moderate High Low Shrink-swell, low strength, unstable material, corrosivity, erosivity Axtell Burleson High-very high Moderate Shrink-swell, low strength, corrosivity, erosivity High Low Shrink-swell, unstable material, corrosivity, cutbanks cave, erosivity Low-high Moderate Moderatehigh Slightmoderate Crockett Moderate -high Slight Moderatehigh Low Shrink-swell, low strength, corrosivity Dalco Very high Moderate High Low Shrink-swell, low strength, corrosivity, cutbanks cave, erosivity Dutek Very lowlow Slight (water)- moderate (wind) Lowmoderate Moderate -high Corrosivity Eddy clay loam Low Severe High Low Shallow depth to rock, slope, corrosivity, erosivity Eddy gravelly clay loam Low Severe Moderate Moderate Erosivity, chalky limestone within a depth of 3-8 inches Frio Moderate Slight High Low Floods, low strength, corrosivity Heiden Very high Moderate -severe High Low Shrink-swell, low strength, corrosivity, cutbanks cave, erosivity Houston Black Very high Slight- High Low Shrink-swell, low Geology and Soils Existing Conditions 12

17 General Soil Type Shrink- Swell Potential Table 3-1 Soil Characteristics Related to Construction Risk of Corrosion Risk of Erosion Concrete moderate Uncoated Steel Construction/ Excavation Constraints strength, very plastic material Houston Very high Severe Very high Very high Shrink-swell, erosivity, corrosivity, very plastic material Justin Lowmoderate Moderate Moderate Low Shrink-swell, erosivity Leson High Moderate High Low Shrink-swell, low strength, corrosivity, erosivity Lewisville High Severe High Low Shrink-swell, low strength, corrosivity, erosivity Mabank Low-high Slight Moderatehigh Moderate Shrink-swell, low strength, corrosivity, wetness Navo Moderate -high Moderate High Low Shrink-swell, low strength, corrosivity, erosivity Seagoville Low-high Slight Low-high Low Floods, shrink-swell, Silawa Very lowlow Moderate (wind)- severe (water) Lowmoderate cutbanks cave Moderate Corrosivity, erosivity Stephen Moderate Severe High Low Chalky limestone at a depth of 8-20 inches, corrosivity, erosivity Trinity Very high Slight High Low Low strength, wetness, floods, shrink-swell, cutbanks cave, corrosivity Wilson Low-high Slightmoderate Sources: NRCS, NRCS, NRCS, High Low Low strength, wetness, shrink-swell, corrosivity Geology and Soils Existing Conditions 13

18 4.0 Literature/Sources Cited Aerials Express Dallas 2010 Aerial Imagery. Dallas Geological Society The Geology of Dallas County: Symposium on Surface and Subsurface Geology, Gravity, Physiography, Underground Water Supply, Economic Geology and Engineering Geology of Dallas County. Dallas, Texas. Natural Resources Conservation Service (NRCS) Soil Survey for Collin County, Texas. NRCS Soil Survey for Dallas County, Texas. NRCS Soil Survey for Tarrant County, Texas. NRCS Web Soil Survey. Soil reports for Collin, Dallas, and Tarrant Counties, Texas. Accessed June 2, Shuler, E.W The Geology of Dallas County. University of Texas Bulletin No. 1818: March 25, Bureau of Economic Geology and Technology, Division of Economic Geology. University of Texas Bureau of Economic Geology (UT-BEG) Geologic Atlas of Texas: Dallas Sheet. Geology and Soils Existing Conditions 14

19 Alliance Transportation Group Arredondo, Zepeda & Brunz Bowman Engineering Connetics Transportation Group Cox McLain Environmental Consulting CP&Y Criado & Associates Dunbar Transportation Consulting HMMH KAI Texas K Strategies Group Legacy Resource Group Mas-Tek Engineering & Associates Nathan D. Maier Consulting Engineers Pacheco Koch Consulting Engineers Parsons Schrader & Cline Spartan Solutions Stantec Consulting Services Inc.

20 Cotton Belt Corridor Regional Rail Geology and Soils Existing Conditions Technical Memorandum December 2013 Prepared for Dallas Area Rapid Transit General Planning Consultant Managed by URS Corporation

21 Cotton Belt Corridor Regional Rail Geology and Soils Existing Conditions Technical Memorandum December 2013 Prepared by Cox McLain Environmental Consulting, Inc. Prepared for Dallas Area Rapid Transit General Planning Consultant Managed by URS Corporation

22 Document Revision Record Project/Report Name: Geology and Soils Existing Conditions Technical Memorandum PM: Dan Meyers URS Project Number: PIC: Jerry Smiley Revision Number Date Draft Version 1 August 27, 2013 Draft Version 2 Originator: Sign: Date: Cox McLain, AICP,CM August 27, 2013 Comments by: Nancy Stavish, AICP, URS September 1, 2013 Reggie Herman, AICP, URS December 26, 2013 Task Manager Approval: Date: Verified/Approved by: Date: Distribution Name Title Firm Geology and Soils Existing Conditions

23 TABLE OF CONTENTS 1.0 INTRODUCTION AND METHODOLOGY DESCRIPTION OF EXISTING CONDITIONS Geology Soils DISCUSSION OF POTENTIAL IMPACTS Geology Soils Literature/Sources Cited...14 LIST OF TABLES Table 3-1 Soil Characteristics Related to Construction LIST OF FIGURES Figure 2-1 Geologic Features... 3 Figure 2-2 East-West Cross-section of Geology of Dallas County... 4 Figure 2-3 Soils... 6 LIST OF PHOTOS Photo 2-1 Exposed Austin Chalk... 2 Photo 2-2 Approximately 15 feet of alluvial deposits over Austin Chalk formation along a creek... 2 Geology and Soils Existing Conditions

24 1.0 INTRODUCTION AND METHODOLOGY This memorandum addresses geology and soils for the Cotton Belt Regional Rail Corridor Project (Cotton Belt Project) study area. The proposed Cotton Belt Project would provide connectivity between the Dallas/Fort Worth International Airport (DFW Airport) and the communities of Grapevine, Coppell, Carrollton, Addison and Dallas, eventually connecting to the existing Dallas Area Rapid Transit (DART) Red Line Light Rail Transit (LRT) corridor in Plano and Richardson, Texas. The project study area used for the assessment of potential impacts includes a one-quarter-mile corridor centered on the project centerline of the Cotton Belt Corridor right-of-way (Cotton Belt Corridor). Existing literature and mapping were reviewed for the project area to assess geology and soils. Maps examined include Aerials Express Dallas 2010 Aerial Imagery, the Geologic Atlas of Texas Dallas Sheet (UT-BEG, 1987), and U.S. Department of Agriculture Natural Resource Conservation Service (NRCS) Soil Surveys for Dallas County (NRCS, 1980), Collin County (NRCS, 1969) and Tarrant County (NRCS, 1981). 2.0 DESCRIPTION OF EXISTING CONDITIONS This section describes the existing conditions with respect to geology and soils within the project study area. 2.1 Geology Four geologic types underlie the project area the Eagle Ford Formation, alluvium, fluviatile terrace deposits, and Austin Chalk. These are discussed below and depicted on Figure 2-1. Figure 2-2 shows an east-west cross-section of the geology of Dallas County. The Eagle Ford Formation, comprised of shale, siltstone, and limestone of late Cretaceous origin, underlies approximately the western one-third of the project area and is also found in the central portion of the project area (UT-BEG, 1987). This formation has an average thickness of 475 feet (The Dallas Geological Society, 1965). Fossils are rarely found in the Eagle Ford Formation, but fish bones and teeth are occasionally found (Shuler, 1918). Concretions are common throughout the formation. Alluvium consists of sand, silt, clay and gravel of variable thickness and recent origin. This geologic feature is generally associated with major streams. Within the project area, alluvium is found in the vicinity of the Elm Fork of the Trinity River and its tributaries (UT-BEG, 1987). Alluvial deposits result in rich soils, and sand and gravel deposits contribute economic value (Shuler, 1918). Fossils are commonly found in these deposits (Shuler, 1918). Fluviatile terrace deposits include sand, gravel, silt, clay, or mud of recent origin. It is generally associated with floodplains and is found on terraces. These deposits are found in the central portion of the project area, in association with alluvium (UT-BEG, 1987). Sand deposits in terrace areas have economic value, and fossils are commonly found in them (Shuler, 1987). Austin Chalk, of late Cretaceous origin, is comprised of chalk (microgranular calcite), with some interbedded calcareous clay and hard lime mudstone. It underlies approximately the eastern one-half of the project area (UT-BEG, 1987). Austin Chalk often overlies the Eagle Ford Formation (The Dallas Geological Society, 1965). This formation is an average of 500 feet thick Geology and Soils Existing Conditions 1

25 (Shuler, 1918). The formation includes approximately 85 percent limestone (calcium carbonate), with lesser amounts of silica, zinc oxide, aluminia, and magnesia; iron pyrite concretions are common in the lower layers (Shuler, 1918). Small-scale faulting is a characteristic feature of Austin Chalk; during faulting, the chalk breaks into irregular blocks by fissure planes along which slight movements have taken place (Shuler, 1918). Photo 2-1: Exposed Austin Chalk (stock photo) Photo 2-2: Approximately 15 feet of alluvial deposits over Austin Chalk formation along a creek (stock photo) Geology and Soils Existing Conditions 2

26 Cotton Belt Corridor Regional Rail Project Geology and Soils Existing Conditions 3

27 Geology and Soils Existing Conditions 4 Cotton Belt Corridor Regional Rail Project

28 2.2 Soils Seven soil associations are found within the project study area. These include (from west to east): Houston Black-Navo-Heiden association gently sloping, deep, clayey and loamy soils of uplands; Houston Black-Heiden association deep, nearly level to strongly sloping, clayey soils of uplands; Wilson-Rader-Axtell association deep, nearly level to gently sloping, loamy soils of uplands; Trinity-Frio association deep, nearly level, clayey soils of floodplains; Eddy-Stephen-Austin association very shallow, shallow, and moderately deep, gently sloping to moderately steep, loamy and clayey soils of uplands; Austin-Houston Black association moderately deep and deep, nearly level to sloping, clayey soils of uplands; and Houston Black-Austin associations gently sloping to sloping, clayey soils of uplands that are over deep marl and chalk. A total of 55 soil series are found within the proposed right-of-way. Ten of these series are found in Tarrant County, 37 are found in Dallas County, and the remaining eight are found in Collin County. Descriptions of each of these are found below (grouped by main soil series type, as appropriate) and depicted on Figure 2-3. Altoga silty clay, 5 to 12 percent slopes This soil series consists of deep, well drained, clayey soils found on escarpments of stream terraces. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Arents These soils are comprised of discarded overburden from gravel and sand mining operations. They are found in Dallas County and are not classified as prime farmland (NRCS 1980; NRCS, 2012). Arents, loamy, gently undulating These areas have been smoothed following discard of mined material and pits have been filled with soil (NRCS, 1980). Arents, loamy, hilly These areas have not been smoothed, and overburden has been left in mounds and ridges (NRCS, 1980). Austin silty clay This soil type consists of deep, calcareous, clayey soils that are gently sloping to sloping (NRCS, 1969; NRCS, 1980). Austin silty clay, 1 to 3 percent slopes This soil series is found in Collin County and Dallas County and is classified as prime farmland (NRCS, 1969; NRCS, 1980; NRCS, 2012). Austin silty clay, 3 to 5 percent slopes, eroded This soil series is found in Collin County and is not classified as prime farmland (NRCS, 1969; NRCS, 2012). Geology and Soils Existing Conditions 5

29 Cotton Belt Corridor Regional Rail Project Geology and Soils Existing Conditions 6

30 Austin-Urban land complex This complex is made up of nearly level and gently sloping, welldrained soils and areas of Urban land on uplands. These soils are found in Dallas County and are not classified as prime farmland (NRCS, 1980; NRCS, 2012). Austin-Urban land complex, 0 to 2 percent slopes Austin soil makes up approximately 50 percent of the complex, urban (developed) land makes up about 40 percent, and the rest is comprised of minor soils (NRCS, 1980). Burleson clay This soil type includes deep, nearly level to moderately sloping clays that have a crusty surface when dry. They are found on uplands and old alluvial terraces along major streams (NRCS, 1969; NRCS, 1980; NRCS, 1981). Burleson clay, 0 to 1 percent slopes This soil series is found in Collin County, Dallas County and Tarrant County and is classified as prime farmland (NRCS, 1969; NRCS, 1980; NRCS, 1981; NRCS, 2012). Burleson clay, 1 to 3 percent slopes This soil series is found in Collin County and Dallas County and is classified as prime farmland (NRCS, 1969; NRCS, 1980; NRCS, 2012). Crosstell fine sandy loam, 1 to 3 percent slopes This soil type is made up of deep, gently sloping, loamy soil on convex ridges and side slopes (NRCS, 1981). This soil is found in Tarrant County and is not classified as prime farmland (NRCS, 2012). Crockett fine sandy loam This soil type is made up of deep, moderately well drained, nearly level to gently sloping loamy soils on uplands (NRCS, 1980). Crockett fine sandy loam, 1 to 3 percent slopes These soils are found in Dallas County and are not classified as prime farmland (NRCS, 1980; NRCS, 2012). Crockett fine sandy loam, 2 to 5 percent slopes These soils are found in Dallas County and are not classified as prime farmland (NRCS, 1980; NRCS, 2012). Dalco clay, 1 to 3 percent slopes This is a moderately deep, gently sloping, moderately well drained soil of uplands (NRCS, 1980). This soil is found in Dallas County and is classified as prime farmland (NRCS, 1980; NRCS, 2012). Dalco-Urban land complex, 0 to 3 percent slopes This complex includes moderately deep, moderately well drained, nearly level and gently sloping soils and areas of urban land. Dalco soil comprises approximately 50 percent of the complex, urban land comprises 30 percent, and minor soils make up the rest. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Dutek loamy fine sand, 1 to 5 percent slopes This soil series is deep, gently sloping, and well drained. It is found on old stream terraces on uplands. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Eddy clay loam, 3 to 8 percent slopes This soil series consists of very shallow to shallow, well drained, gently sloping to sloping soil overlying the Austin Chalk formation. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Eddy-Stephen complex, 1 to 5 percent slopes This complex consists of gently sloping, well drained, very shallow and shallow soils over the Austin Chalk formation (NRCS, 1980). Eddy soils Geology and Soils Existing Conditions 7

31 make up approximately 60 percent of the complex, Stephen soil makes up about 30 percent, and minor soils make up the rest. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Eddy-Urban land complex This complex includes gently sloping, shallow and very shallow, well drained soils and areas of urban land. These soils are found in Dallas County and are not classified as prime farmland (NRCS, 1980; NRCS, 2012). Eddy-Urban land complex, 4 to 8 percent slopes This complex is made up of approximately 50 percent Eddy soil, 30 percent urban land, and 20 percent minor soils (NRCS, 1980). Ferris-Heiden complex This complex includes deep, well drained, gently rolling and rolling soils on hillsides (NRCS, 1980; NRCS, 1981). Ferris-Heiden complex, 2 to 8 percent slopes This complex is comprised of approximately 50 percent Ferris soil, 45 percent Heiden soil, and 5 percent other, similar soils. This soil series is found in Tarrant County (NRCS, 1981). This soil is not classified as prime farmland (NRCS, 2012). Ferris-Heiden complex, 5 to 12 percent slopes This complex is comprised up approximately 60 percent Ferris soil, 20 percent Heiden soil, and 20 percent minor soils (NRCS, 1980). It is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Ferris-Urban land complex, 5 to 12 percent slopes This complex is made up of deep, well drained, sloping and strongly sloping soil and area of urban land (NRCS, 1980). Ferris soil comprises approximately 60 percent, urban land comprises approximately 25 percent, and the remainder is minor soils. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Frio silty clay These soils are deep, well drained, nearly level soils found on floodplains. They soils are found in Dallas County (NRCS, 1980). Frio silty clay, occasionally flooded This soil is classified as prime farmland (NRCS, 1980; NRCS, 2012). Frio silty clay, frequently flooded This soil is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Frio-Urban land complex This complex includes deep, nearly level, well drained soils and areas of urban land on floodplains of small streams (NRCS, 1980). Frio soil makes up approximately 70 percent of the complex, urban land makes up approximately 15 percent, and the rest is minor soils. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Heiden clay These soils are deep, well drained, gently sloping soils on uplands (NRCS, 1980). Heiden clay, 1 to 3 percent slopes This soil series is found in Tarrant County and is classified as prime farmland (NRCS, 1981; NRCS, 2012). Heiden clay, 2 to 5 percent slopes This soil is found in Dallas County and is classified as prime farmland (NRCS, 1980; NRCS, 2012). Geology and Soils Existing Conditions 8

32 Houston Black clay This soil type includes deep, calcareous, clayey soils found on uplands or old alluvial terraces. These soils form cracks to a depth of more than 30 inches when dry (NRCS, 1969; NRCS, 1980; NRCS, 1981). Houston Black clay, 0 to 1 percent slopes This soil series is found in Collin County and Dallas County and is classified as prime farmland (NRCS, 1969; NRCS, 1980; NRCS, 2012). Houston Black clay, 1 to 3 percent slopes This soil series is found in Collin County, Dallas County, and Tarrant County and is classified as prime farmland (NRCS, 1969; NRCS, 1980; NRCS, 1981; NRCS, 2012). Houston Black clay, 2 to 4 percent slopes This soil series is found in Collin County and is not classified as prime farmland (NRCS, 1969; NRCS, 2012). Houston Black-Urban land complex, 0 to 4 percent slopes This complex includes deep, moderately well drained, nearly level and gently sloping soils and areas of urban land. In Tarrant County, the complex is comprised of percent Houston Black soils, percent Urban land, and less than 25 percent other, similar soils (NRCS, 1981). In Dallas County, the complex is made up of approximately 40 percent Houston Black soil, 35 percent urban land, and 25 percent minor soils (NRCS, 1980). This soil is not classified as prime farmland (NRCS, 2012). Justin loam, 1 to 3 percent slopes This is a deep, well drained, gently sloping soil found on convex ridges on uplands. This soil is found in Tarrant County (NRCS, 1981). It is classified as prime farmland (NRCS, 2012). Leson clay, 1 to 3 percent slopes This is a deep, gently sloping soil on uplands. This soil series is found in Tarrant County (NRCS, 1981). It is classified as prime farmland (NRCS, 2012). Lewisville silty clay These soils consist of deep, well drained, calcareous clays that are gently to moderately sloping. They are found on stream terraces and areas that slope to streams (NRCS 1969; NRCS, 1980). Lewisville silty clay, 1 to 3 percent slopes This soil is found in Collin and Dallas Counties (NRCS, 1969; NRCS, 1980). It is classified as prime farmland (NRCS, 2012). Lewisville silty clay, 3 to 5 percent slopes, eroded This soil is found in Collin County and is not classified as prime farmland (NRCS, 1969; NRCS, 2012). Lewisville-Urban land complex This complex is made up of deep, well drained, nearly level and gently sloping soils and areas of urban land (NRCS, 1980). These soils are found in Dallas County and are not classified as prime farmland (NRCS, 1980; NRCS, 2012). Lewisville-Urban land complex, 0 to 4 percent slopes This complex is comprised of approximately 55 percent Lewisville soil, 30 percent urban land, and 15 percent minor soils (NRCS, 1980). Lewisville-Urban land complex 4 to 8 percent slopes Lewisville soil makes up approximately 60 percent of this complex, urban land makes up 30 percent, and 10 percent is minor soils (NRCS, 1980). Mabank fine sandy loam, 0 to 1 percent slopes This soil type is a deep, nearly level, somewhat poorly drained soil in depressions on uplands (NRCS, 1980). These soils are found in Dallas County and are not classified as prime farmland (NRCS, 1980; NRCS, 2012). Geology and Soils Existing Conditions 9

33 Navo clay loam, 1 to 3 percent slopes This is a deep, gently sloping, loamy soil found on side slopes and low ridges along drainageways. This soil series is found in Tarrant County (NRCS, 1981). It is not classified as prime farmland (NRCS, 2012). Seagoville clay, occasionally flooded This soil series is deep, moderately well drained, and nearly level (NRCS, 1980). It is found on floodplains. This soil is found in Dallas County and is classified as prime farmland (NRCS, 1980; NRCS, 2012). Silawa fine sandy loam, 3 to 8 percent slopes This soil is deep, well drained, gently sloping to sloping, and is found on uplands (NRCS, 1980). This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Stephen-Urban land complex, 1 to 4 percent slopes This complex includes shallow, well drained, gently sloping soils and areas of urban land over the Austin Chalk formation. Stephen soil comprises approximately 60 percent of the complex, urban land makes up 30 percent, and minor soils make up the rest. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Trinity clay This soil type includes deep, somewhat poorly drained, calcareous, clayey soils on floodplains of major streams and their tributaries. When dry, these soils can crack to a depth of up to 20 inches (NRCS, 1969; NRCS, 1980). Trinity clay, occasionally flooded This soil is found in Collin and Dallas Counties (NRCS, 1969; NRCS, 1980). In Collin County, it is associated with Pittman Creek. In Dallas County, it is found in association with the Elm Fork of the Trinity River. This soil is classified as prime farmland (NRCS, 2012). Trinity clay, frequently flooded This soil series is found in Tarrant County, in association with Cottonwood Branch (NRCS, 1981), and in Dallas County, in association with Grapevine Creek (NRCS, 1980). This soil is not classified as prime farmland (NRCS, 2012). Trinity-Urban land complex This complex is made up of deep, nearly level, somewhat poorly drained soils and areas of urban land on floodplains. It is comprised of approximately 60 percent Trinity soil, 20 percent urban land, and 20 percent minor soil. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Wilson clay loam This is a deep, somewhat poorly drained soil on uplands (NRCS, 1980). Wilson clay loam, 0 to 1 percent slopes This soil is nearly level. It is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Wilson clay loam, 0 to 2 percent slopes This is a nearly level to gently sloping, loamy soil. It is found on upland ridges and in slightly depressed areas above drainageways. This soil is found in Tarrant County (NRCS, 1981). This soil is not classified as prime farmland (NRCS, 2012). Wilson clay loam, 1 to 3 percent slopes This is a gently undulating soil. It is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). Wilson-Urban land complex, 0 to 2 percent slopes This complex includes nearly level to gently sloping, deep, somewhat poorly drained soils and areas of urban land. Wilson soils make up approximately 60 percent of the complex, urban land makes up 30 percent, and the rest is Geology and Soils Existing Conditions 10

34 minor soils. This soil is found in Dallas County and is not classified as prime farmland (NRCS, 1980; NRCS, 2012). 3.0 DISCUSSION OF POTENTIAL IMPACTS This section addresses potential impacts to geology and soils. 3.1 Geology One proposed design profile option for the Cotton Belt Project includes a Tunnel Profile Option which would pass through the Austin Chalk formation, as shown on Figure 2-1. As previously discussed, Austin Chalk is known for producing small-scale faulting. The formation is also susceptible to weathering due to erosion. The occurrence of fossils in this formation is not common. Because Austin Chalk is a hard formation with soft layers and faulting/weathered sections, special structural design measures may be needed to strengthen tunnel walls in the vicinity of faults or layers (if the Tunnel Profile Option is selected). 3.2 Soils The Farmland Protection Policy Act (FPPA), as detailed in Subtitle I of Title XV of the Agricultural and Food Act of 1981, provides protection to the following: 1) prime farmland; 2) unique farmland; and 3) farmland of local or statewide importance. FPPA defines prime farmland as land that has the best combination of physical and chemical characteristics for producing food, feed, forage, fiber, and oilseed crops, and is also available for these uses (not urban built-up land or water). It has the soil quality, growing season, and moisture supply needed to economically produce sustained high yields of crops when treated and managed, including water management (irrigation), according to acceptable farming methods. Unique farmland is farmland that is used for production of specific high value food, feed, and fiber crops. Farmland of local or statewide importance is determined by the appropriate state or local government agency or agencies. The project study area contains 14 prime farmland soils, comprising approximately 1,550 acres of the project study area. See Figure 2-3. No unique farmland or farmland of local or statewide importance is found within the project study area. The project study area is mostly committed to urban use. The FPPA exempts from consideration those lands committed to urban use (within city limits or zoning boundaries). Thus, NRCS, FPPA coordination would not be required for project development activities within the study area. Potential soil erosion and sedimentation during construction will be addressed in a Stormwater Pollution Prevention Plan (SWPPP), to be prepared prior to beginning construction activities. The SWPPP will detail best management practices (BMPs) to be incorporated into the project design related to erosion control, sedimentation control, and post-construction total suspended solids (TSS) removal. Table 3-1 lists soil characteristics, including shrink-swell potential, risk of erosion, risk of corrosion, and constraints related to construction/excavation. Detailed geotechnical borings would be completed prior to the final design stage in order to identify and avoid through design any potential structural stability issues. Geology and Soils Existing Conditions 11