corridor - dart.org

Preliminary Engineering / Environmental Impact StatementNorthwest Corridor LRT Line to Irving and DFW Airport

Final Environmental Impact Statement 3 - 100Chapter 3 Affected Environment

Rappole 1995). These birds could also occur transiently wherever suitable habitat is present, suchas creek crossings or forested areas.

Of the 774 species of nongame birds covered by the MBTA, 122 nongame migratory birds havebeen currently identified as being of management concern at the national level because of:

(1)Documented or apparent population declines,(2)Small populations or limited distribution,(3)Dependence on restricted or vulnerable habitats, and(4)Specific threats. Habitat loss (e.g., fragmentation, breeding ground, stopover/wintering

ground) caused by a variety of human activities is overwhelmingly viewed as the greatestthreat facing these species.

Fifty-four species are listed as occurring or potentially occurring in USFWS Region 2, with 30species occurring or potentially occurring within Dallas County as resident, transient, migrant, orneotropical migrants (Pulich 1988; USFWS 1995b).

CorridorThree species in Table 3-36 would have a low to moderate potential of occurrence within theProject Corridor based on habitat availability. The Arctic peregrine falcon normally nests in theArctic tundra with a migration range from Northern Alaska, Canada, and Greenland to Central andSouth America during the fall months (USFWS 1999b). This species has been delisted federally;however, it is still listed as threatened by the State of Texas. A peregrine falcon (Falco peregrinus)could potentially occur within the project area. Areas, such as downtown skyscrapers, and foodresources, such as rock doves (pigeons), are somewhat abundant in the downtown Las Colinasarea; however, no known nesting sites for the falcon have been documented. The northernpopulation of the migrant loggerhead shrike, also has potential habitat present within the studyarea and is listed as rare by the State of Texas. Without conducting seasonal surveys, it is difficultto ascertain whether the shrikes that were observed were migratory or nonmigratory. However, ifpresent, migratory loggerhead shrikes would be transitory in the area and feeding resources areabundant (Pulich 1988).

A third species, the Texas garter snake, is listed as rare in Texas and depends upon habitatconsisting of wet or moist areas (TPWD 2001a). This species could potentially occur along riparianareas or near wetlands. Migrating bird species may use the riparian areas, wetland areas, orforest stands in the Project Corridor as stopping points on their way to and from wintering grounds.During the field surveys, several species of wading birds and ducks were observed usingpermanently ponded areas.

StationsSpecific field studies for wildlife and threatened and endangered species were not conducted at thestation areas. The probability of occurrence of threatened, endangered, and rare species within thestations area is dependent upon the habitat present, but should be similar to the probability ofoccurrences for the corridor. Some protected species could occur transiently in riparian andwooded habitats if sufficient food resources are available.

3.12 GEOLOGY AND SOILS

3.12.1 GeologyThe Study Area lies within the Blackland Prairie physiographic region. This category consists oflow rolling terrain with chalk and marl bedrock tilting to the south and east. The bedrock of DallasCounty is of Upper Cretaceous age. Thick sedimentary beds underlie the northwestern quadrantof Dallas County and are covered with Quaternary terrace deposits consisting of sand, gravel, silt



and clay, but no rock outcroppings. Along the Trinity River, these Quaternary soils are Alluviumfloodplain deposits and Fluviatile terrace deposits. The remainder of the project area contains theCretaceous shale, sandstone, and limestone of the Eagle Ford Group (BEG, 1972). Geologicinformation in the Project Corridor is shown in Figure 3-38.

Fossils are common throughout Dallas County and include occasional gastropods (snails),pelecypods (clams and oysters), cephalopod (ammonite and squid) shells, crayfish, and shark andskate teeth.

3.12.2 SoilsThe Project Corridor traverses many distinct soil types with varying patterns of drainage and relief.The Soil Survey of Dallas County, Texas was used to identify and characterize the soils thatoccur in the Study Area (USDA, 1980). A total of 16 soil types intersect the alignment, these arelisted, along with characteristics, potential and limitations of each soil type in Table 3-37. Soilsinformation for the Project Corridor is shown in Figures 3-39 and 3-40.

Soils consist mainly of nearly level to gently sloping clay soils. The soils immediately intersectingthe proposed alignment have varying potential for urban development. Seven of these 16 soiltypes are of high or moderate potential for urban uses, and the remaining nine are of low or verylow potential. The soils of low and very low potential for urban development are the most commonalong the length of the alignment, covering over 80 percent of the alignment. Limitations todevelopment in these low potential soils most commonly include frequent flooding and severeerosion hazards.

Prime Farmland SoilsPrime farmland is defined by the Department of Agriculture in Section 7 of CFR §658.2 as land thathas the best combination of physical and chemical characteristics to support farming. Primefarmland within the study area was identified using the 1980 Dallas County Soil Survey.Approximately 22 percent of the study area contains prime farmland soils, consisting of Houstonblack clay, Burleson clay, Frio silty clay, Silawa fine sandy loam, Trinity clay (occasionally flooded),and Heiden clay. Not all of these soils intersect the alignment, but all are found within the studyarea.

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Figure 3-38

NW Corridor LRT Line to Irving/DFWEnvironmental Impact Statement

GeologySource: Geologic Atlas of Texas, 1986

´0 4,000 8,0002,000Feet

LegendGeologic Formations

Eagle Ford Formation

Alluvium and QuaternaryFluviatile Terrace Deposits

Proposed Station!!Proposed LRT Line to Irving/DFWStudy Area

KefQtQal



TABLE 3-37SOIL TYPES INTERSECTING THE ALIGNMENT

Soil Type Soil Characteristics Soil Potential and LimitationsArents

(clayey,gently

undulating)

Consists of clayey soil material removed from nearby roadcuts, borrow pits, or drainange ditches. The soil is typicallydark brown, calcareous clay, containing many clods andbodies of very dark brown and grayish brown fragments ofsurface soil.

Permeability is slow to very slow, runoff ismedium, and sloping areas erode easily.These soils have a very low potential forurban development. Limitations are a highcontent of clay, wet spots and ponding.

Bastsil-Urban land

complex

(0% to 2%slopes)

Nearly level to gently sloping, well drained soils and areasof Urban land. The Bastsil soil comprises approximately 40percent of the complex, while Urban land comprisesapproximately 35 percent. Typically, the surface layer ismoderately acid, brown fine sandy loam to yellowish red tored sandy clay loam to a depth of about 34 inches. To 68inches, the soil is mottled dark red, yellowish red, and lightgray sandy clay loam.

Permeability is moderate, runoff is medium,and the hazard of erosion is moderate. Thesesoils have a high potential for urbandevelopment. The only limitation is corrosivityto uncoated steel.

Burlesonclay

(0% to 1%slopes)

Deep, nearly level, moderately well drained soils along oldstream terraces. The surface layer, to a depth of 4 inches,is typically neutral, very dark gray clay. To about 46 inches,the soil is slightly acid, very dark gray clay above a neutrallayer of grayish brown clay to about 64 inches. To a depthof 80 inches, the soil is moderately alkaline, grayish brownclay.

Permeability is very slow, available watercapacity is high, runoff is slow, and the hazardof erosion is slight. The surface layer of thesesoils tends to crush. The soil has highpotential for crop and pastureland and lowpotential for urban development. Limitationsinclude high shrink-swell potential, corrosivity,and low strength of the soil.

Ferris-Heidencomplex

(5% to 12%slopes)

Deep, well drained, gently rolling and rolling soils onhillsides. Ferris soil comprises about 60 percent of thecomplex and Heiden soils comprise about 20percent. Thesurface layer of the Ferris soil is moderately alkaline, lightyellowish brown clay to 3 inches. To 28 inches, the soil ismoderately alkaline, olive clay over moderately alkaline,light brownish gray clay to 41 inches. The soil is mottledlight brownish gray, light olive brown, and gray shaly clay toabout 72 inches. Heiden soils are moderately alkaline, darkgrayish brown clay to 19 inches. To a depth of 45 inches,the soil is moderately alkaline, grayish brown clay above alayer of mottled brownish gray, olive yellow, and brownishyellow, moderately alkaline shaly clay to 78 inches.

In the Ferris and Heiden soils, permeability isvery slow, available water capacity is high,runoff is rapid, and the hazard of erosion issevere. The potential of this soil complex forurban uses is low. A very high shrink-swellpotential, low strength, corrosivity, unstableslopes and erosion hazard are limitations todevelopment.

Frio siltyclay,

occasionallyflooded

Deep, well drained, nearly level soil on floodplains. Thesurface layer, to 7 inches, is moderately alkaline, very darkgrayish brown silty clay. To a depth of 53 inches, the soil ismoderately alkaline, very dark grayish brown silty clay. Inthe lower layer to 74 inches, the soil is moderately alkaline,brown silty clay loam.

Permeability is moderately slow, availablewater capacity is high, runoff is slow, and theerosion hazard is slight. This soil has a lowpotential for urban use because of the hazardof flooding, low soil strength, and corrosivity.

Heiden clay

(1% to 3%slopes)

Deep, well drained, gently sloping soil on uplands.Typically, the first 6 inches are a moderately alkaline, darkgray clay. To about 37 inches, the soil is very dark grayishbrown clay progressing to grayish brown clay with gray andyellowish brown mottles to 56 inches. The bottom 22inches are composed of shaly clay mottled in shades ofgray and yellow.

Permeability is very slow, available watercapacity is high, runoff is medium and thehazard of erosion is moderate. This soil hashigh potential for use as cropland andpastureland and low potential for urban uses.The very high shrink-swell potential,corrosivity, and low strength of the soil are itsprimary limitations.

Heiden clay

(2% to 5%slopes,eroded)

Deep, well drained, gently sloping soils on uplands.Typically, the first 6 inches are a moderately alkaline, darkgray clay. To 56 inches, the soil is a dark grayish brownclay. The bottom 22 inches are composed of shaly claymottled in shades of gray and yellow.

Permeability is very slow, available watercapacity is high, runoff is rapid and the hazardof erosion is severe. The soil has mediumpotential for pasture and low potential forurban uses. The very high shrink-swellpotential, corrosivity, low strength of the soil,and severe hazard of erosion are limitations.



TABLE 3-37 - continuedSOIL TYPES INTERSECTING THE ALIGNMENT

Soil Type Soil Characteristics Soil Potential and Limitations

Normangeeclay loam

(1% to 3%slopes)

Deep, moderately well drained, gently sloping soil onuplands. The surface layer is typically neutral, dark grayishbrown clay loam to a depth of 9 inches. To 14 inches, thesoil is a dark brown clay. Slightly acid, grayish brown claywith light olive brown mottles is found to depths of 25inches. To 41 inches, the soil is olive clay with commonyellowish brown mottles. To a depth of 66 inches, it ismoderately alkaline clay, mottled with shades of brown,olive and gray over fine platy shale.

Permeability is very slow, available watercapacity is high, runoff is medium, and thehazard of erosion is moderate. The soil hasmedium potential for urban development.Limitations include high shrink-swell potential,low strength, corrosivity, and the hazard oferosion.

Ovan clay,frequently

flooded

Deep, moderately well drained, nearly level soils onfloodplains. This soil is moderately alkaline, very darkgrayish brown clay to 15 inches thick. Dark grayish brownclay is found to 35 inches with moderately alkaline, lightolive brown clay to a depth of 80 inches.

Permeability is very slow, available watercapacity is high, runoff is slow and there is aslight erosion hazard. This soil has a very lowpotential for urban uses due to frequentflooding, high shrink-swell potential, clayeytexture and corrosivity of the soil.

Silawa finesandy loam

(1% to 3%slopes)

Deep, well drained, gently sloping soil on uplands. Typicallythe surface layer is neutral, brown fine sandy loam 10inches thick. To a depth of 19 inces, the soil is slightly acid,yellowish red sandy clay loam. To a depth of 34 inches, it ismedium acid, reddish yellow sandy clay loam. To a depth of44 inches, the soil is strongly acid, reddish yellow finesandy loam, and to a depth of 80 inches, it is medium acid,reddish yellow loamy fine sand.

Permeability is moderate, and the availablewater capacity is medium. Runoff is slow.Water and wind erosion are moderatehazards. The soil has high potential forpasture, medium potential for use ascropland, and high potential for urban uses.

Silawa Urbanland complex

(2% to 6%slopes)

This complex is made up of deep, well drained, gentlysloping and sloping soils and areas of Urban land. TheSilawa soil makes up about 50% of this complex; Urbanland makes up 25%. Typically, the surface layer of theSilawa soil is slightly acid, grayish brown fine sandy loamsix inches thick.

Permeability is moderate, and the availablewater capacity is medium. Runoff is medium.Water and wind erosion are moderatehazards. This soil has a high potential forurban uses.

Silstid loamyfine sand

(0% to 3%slopes)

This is a deep, well drained, nearly level to gently slopingsoil on uplands. Typically, the surface layer is neutral,brown loamy fine sand 10 inches thick.

Permeability is moderate, and the availablewater capacity is low. Runoff is slow, andwater erosion is a slight hazard. Wind erosionis a severe hazard if the surface is bare. TheSilstid soil has medium potential for pasture,low potential for use as cropland, and highpotential for urban uses.

Trinity clay,occasionally

flooded

Deep, nearly level, somewhat poorly drained soil onfloodplains. Typically, the surface layer is moderatelyalkaline, very dark grayish brown, very dark gray and blackclay. Between 48 and 68 inches, the soil is black clay thathas brownish mottles.

Permeability is very slow, available watercapacity is high, runoff is very slow, and thehazard of erosion is slight. This soil has avery low potential for urban uses. Limitationsinclude the hazard of flooding and wetness,corrosivity, and very high shrink-swellpotential.

Trinity clay,frequently

flooded

Deep, nearly level, somewhat poorly drained soil onfloodplains. Typically, the surface layer is moderatelyalkaline, dark gray, grayish brown and very dark gray clay.

Permeability is very slow, runoff is slow, andthe hazard of erosion is slight. This soil has avery low potential for urban use. Limitationsinclude the frequent flooding and wetness,corrosivity, very high shrink-swell potential,and clayey texture of the soil.

Urban landExtensively built up areas where 75 percent or more of thesurface is covered with buildings and pavement. Nativesoils have been altered or covered by urban development.

This mapping unit is extensively used forurban development.

Wilson-Urban land

complex

(0% to 2%slopes)

Nearly level to gently sloping, deep, somewhat poorlydrained soils and areas of Urban land. The Wilson soilmakes up about 60 percent of this complex and Urban landmakes up about 30 percent. The surface layer of theWilson soil is typically mildly to moderately alkaline, darkgrayish brown clay loam, and dark gray and olive brown tolight olive brown clay.

Permeability is very slow, runoff is slow, andthe hazard of erosion is slight. The Wilsonsoil has medium potential for urbandevelopment. The high shrink-swell potential,corrosivity, and low strength of the soil are themain limitations to urban use.

Source: Soil Survey for Dallas County, Texas (NRCS, 1980)

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LUNA RD

HARRY HINES BLVD

NORTHWEST HWY

UV114

UV183

UV354

&-482

&-348

REGAL ROW

TOM BRANIFF DR

WEB CHAPEL RD

STOREY LN

E AIRPORT FWY

CALIFORNIA CROSSING RD

")12

§̈¦35E

")12

§̈¦35E

Irving

Dallas Joes Creek

N O' CONNOR RD

JOHN CARPENTER FWY

DENTON DR

BNSF

RR

E lm Fork Tr i nit y Ri ver

ROCHELLE BLVD

NORTHGATE DR

Bachman

56

UV348

University of Dallas

Lake Carolyn

North Las Colinas

Loop 12 (deferred)

South Las Colinas (deferred)

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Figure 3-39


SoilsEast Section 0 2,000 4,0001,000

Feet ´Source: Ssurgo Soil Data - USDA, 1975

Legend

Proposed StationProposed LRT Line to Irving/DFWCarrollton-Farmers Branch LRT Line

SoilsAxtell-Urban (13)Bastsil-Urban (15)Burleson Clay (18)Arent Loamy (2)Arent Loamy Hilly (3)Ferris-Heiden (34)Ferris-Heiden (34)Frio Silty Clay (36)Frio Silty Clay (37)Arent Clayey (4)Heiden Clay (41)Heiden Clay (42)Houston Black Clay (43)Houston Black Clay (44)Houston Black-Urban (45)

Normangee Clay (53)Ovan Clay (55)Pits and Dumps (56)Silawa Fine Sand (60)Silawa Fine Sandy Loam (61)Silawa-Urban (63)Silstid Loamy Fine Sand (64)Silstid-Urban (65)Trinity Clay (72)Trinity Clay (73)Trinity-Urban (74) Urban Land (75)Vertel Clay (77)Wilson-Urban (80)Water (W)

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ROYAL LN

JOHN CARPENTER FWY

LUNA RD

WALNUT HILL LN

ESTERS RD

STORY RD

RIVERSIDE DR

HIDDEN

RIDGE DR

UV114

UV161

&-348

Hackberry Creek

Cottonwood Bran ch

VALLE

Y VIEW

LN

ROCHELLE BLVD

PRESIDENT GEORGE BUSH TPKE

MACARTHUR BLVDN MACARTHUR BLVD

WALNUT HILL LN

BELT LINE RD

Irving

Dallas

HURD DR

LAS COLINAS BL VD

N O' CONNOR RD

CARBON RD

DFW InternationalAirport

Belt LineRoad

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342 41Lake Carolyn

Carpenter Ranch

North Las Colinas

North Lake College

Figure 3-40


SoilsWest Section 0 2,000 4,0001,000

Feet ´Source: Ssurgo Soil Data, USDA 1975

SoilsAxtell-Urban (13)Bastsil-Urban (15)Burleson Clay (18)Arent Loamy (2)Arent Loamy Hilly (3)Ferris-Heiden (34)Ferris-Heiden (34)Frio Silty Clay (36)Frio Silty Clay (37)Arent Clayey (4)Heiden Clay (41)Heiden Clay (42)Houston Black Clay (43)Houston Black Clay (44)Houston Black-Urban (45)

Normangee Clay (53)Ovan Clay (55)Pits and Dumps (56)Silawa Fine Sand (60)Silawa Fine Sandy Loam (61)Silawa-Urban (63)Silstid Loamy Fine Sand (64)Silstid-Urban (65)Trinity Clay (72)Trinity Clay (73)Trinity-Urban (74) Urban Land (75)Vertel Clay (77)Wilson-Urban (80)Water (W)

LegendProposed StationProposed LRT Line to Irving/DFW

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