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1813141516171818 1314151613 17141516 17

COLLAPSIBLE-SOIL SUSCEPTIBILITYZION NATIONAL PARK GEOLOGIC-HAZARD STUDY AREA

EXPLANATION

T 38 ST 39 S

37 30'

113 7' 30"

2010

DISCUSSION

USING THIS MAP

SYMBOLS

ByWilliam R. Lund, Tyler R. Knudsen, and David L. Sharrow

Plate 6Utah Geological Survey Special Study 133

Zion National Park Geologic-Hazard Study Area, Washington and Kane Counties, Utah

Camp

Creek

Creek

Horse RanchMountain

Taylor Fork

North

Fork

Middle

Fork

South

LeePass

NaguntMesa

BuckPastureMountain

Creek

Timber

Kolob

CanyonsRoad

ShuntaviButte

GregoryButte

KolobArch Langston

Mountain

Creek

La Verkin

WillisCreek

BEAR CANYONTRAP

KO

LO

B

CA

NY

ON

S

BurntMountain

HO P

VA L L E Y

FirepitKnoll

PineValleyPeak

NorthgatePeaks

NorthGuardian

Angel

SouthGuardianAngel

Kolob

Terrac

eRo

ad

Kolob

Terrace

Road

North

Creek

Right

Fork

Left

Fork

Blue

Creek

Goose

Creek

LavaPoint

Kolob

Creek

DeepCr

eek

Coalp

itsWa

sh

Wash

Scoggins

Altar ofSacrifice

The WestTemple

MeridianTower The

Sentinel

MountKinesava

Wash

Hube

r

Creek

Oak

The Watchman

JohnsonMountain FORK

EAST

RIVER

VIRGIN

P A R U N U W E A P

C A N Y O N

BridgeMountain

The EastTemple

MountSpry

CraterHill

TwinBrothers

Mountainof the Sun

The GreatArch

The GreatWhite Throne

LadyMountain

CastleDome

Mount

AngelsLanding

ObservationPoint

Mountainof Mystery

WynopitsMountain

IvinsMountain

Timber

HU

RR

I CA

NE

CL I

FF

S

Death Point

Tucupit Point

Paria Point

Beatty Point

Top

Mountain

Herbs

Po

intLA

NGST

ON

CANYO

N

Currant

Creek

Cane

Creek

POLE

CANYON

L OW

E R

K OL O

B

P L A T E A U

UP P E R

K OL O

B

P L A T E A U

HO

RS

EP A

ST

UR

E

PL A

TE

AU

ZI O

N

CA

NY

ON

O R D E R V I L L E C A N Y O N

TheSubway

GREAT

WEST

CANYON

COUG

A R MO U N TA I N

CourtPatriarchsTheof

CreekBirch

Creek

Pine

Creek

Pine

Creek

Clear

Chec

kerbo

ard

Mes

a

Creek

Clear Creek

Co-op

GIFFORDCANYON

FORK

NORTH

RIVE

R

VIRGIN

ZION-MOUNT CARMEL TU NN EL

TUNNEL

Wash

Terry Wash

Jennin

gs

Wash

Coalpits

TheBishopric

HEAPS

CANYON

ECHO

CANYON

CableMountain

Temple ofSinawava

TELEPHONE

CANYON

IMLAY

CANYON

BULLOCH

GULC

HT H E

N A R R OWS

FORK

NORT

H

RIVER

VIRGIN

WILDCAT

CANYON

RUSSELLGULCH

North

Creek

North

Creek

Zion

Cany

on

Scen

icDr

ive

9

9

The Grotto

Zion CanyonVisitor Center

ZionLodge

Little

Creek

Grapevine

Wash

TOW

E RS

V I R G I NT H E

O F

Abraham Isaac

Jacob

ChurchMesa

PHANTOM VALLEY

CORRAL

HOLLOW

KolobCreek

WeepingRock

Cathedral Mountain

Majestic

Kolob CanyonsVisitor Center

WASH

INGT

ON C

OKA

NE C

O

IRON COWASHINGTON CO

Neag

le R

idge

BullpenMountain

Pocket Mesa

OAK SPRING VALLEY

PINE

VALLEYLEE

VALLEY

CaveKnoll

CAVE

VALLEY

TabernacleDome

Wash

SpringPine

TRAIL

CANYONGrea

theart

Mesa

BEHUNIN

CANYON

Creek

Shunes

Shunesburg Mountain

Wash

Hepworth

Wash

DennettCanyon

Bee HivePeak

HIDDENCANYON

CANYON

MYSTERY

R 12 W R 11 W

T 38 ST 39 S

R 11 W R 10 W

T 40 ST 41 S

T 41 ST 42 S

T 39 ST 40 S

T 41 ST 42 S

T 39 ST 40 S

T 40 ST 40.5 S

T 41 ST 42 S

R 11 W R 10 W

R 10 W

R 12 W R 11 W

R 10 W R 9.5 W R 9.5 W R 9 W

37 27' 30"

37 25'

37 22' 30"

37 20'

37 17' 30"

37 15'

37 12' 30"

37 10' 37 10'

37 12' 30"

37 15'

37 17' 30"

37 20'

37 22' 30"37 22' 30"

37 25'

113 5'

113 2' 30"

113

37 22' 30"

112 57' 30" 112 55'

112 52' 30"

112 52' 30"

112 55'112 57' 30"

113

113 2' 30"113 5'

113 7' 30"

113 10'

113 12' 30"

113 12' 30"

Zion National Park Geologic-Hazard Study Area boundaryZion National Park boundaryCounty boundaryState highwayMinor roadFoot trailExisting park structureArea not studied

37 27' 30"

MAP LIMITATIONSThis map is based on limited geologic and geotechnical data; site-specific investigations are required to producemore detailed geotechnical information. The map also depends on the quality of those data, which may varythroughout the study area. The mapped boundaries between susceptibility categories are approximate andsubject to change as new information becomes available. The susceptibility may be different than shown at anyparticular site because of variations in the physical properties of geologic deposits within a map unit, gradationaland approximate map-unit boundaries, and the small map scale. The map is not intended for use at scales otherthan the published scale, and is designed for use in general planning and design to indicate the need for site-specific investigations.

This map shows the location of known and suspected collapsible-soil conditions in the Zion National ParkGeologic-Hazard Study Area. The map is intended for general planning and design purposes to indicate wherecollapsible-soil conditions may exist and special investigations should be required. Site-specific investigationscan resolve uncertainties inherent in generalized mapping and help identify the need for special design, sitegrading and soil placement, and/or mitigation techniques. The presence and severity of collapsible soil alongwith other geologic hazards should be addressed in these investigations. If collapsible soil is present at a site,appropriate design and construction recommendations should be provided.

HAZARD REDUCTIONAlthough potentially costly when not recognized and properly accommodated in project design and construction,problems associated with collapsible soil rarely are life threatening. As with most geologic hazards, earlyrecognition and avoidance are the most effective ways to mitigate potential problems. However, collapsible soilis widespread in the study area, and avoidance may not always be a viable or cost-effective option.In Utah, soil-test requirements are specified in chapter 18 (Soils and Foundations) of the 2009 InternationalBuilding Code (IBC) (International Code Council, 2009a) and chapter 4 (Foundations) of the 2009 InternationalResidential Code for One- and Two-Family Dwellings (IRC) (International Code Council, 2009b), which areadopted statewide. IBC Section 1803.3 contains requirements for soil investigations in areas where questionablesoil (soil classification, strength, or compressibility) is present. IRC Section R401.4 states that the building officialshall determine whether to require a soil test to determine the soil’s characteristics in areas likely to haveexpansive, compressible, shifting, or other unknown soil characteristics. IBC table 1613.5.2 identifies collapse-prone soils as Site Class F. Site Class F soils require a site-specific investigation to determine the proper seismicdesign category and parameters for a proposed facility (see chapter 5 – Earthquake Hazards in accompanyingtext).Where the presence of collapsible soil is confirmed, possible mitigation techniques include soil removal andreplacement with noncohesive, compacted backfill; use of special foundation designs such as drilled pier deepfoundations, grade beam foundations, or stiffened slab-on-grade construction; moisture barriers; and careful sitelandscape and drainage design to keep moisture away from buildings and collapse-prone soils (Nelson andMiller, 1992; Pawlak, 1998; Keller and Blodgett, 2006).

UTAH GEOLOGICAL SURVEYa division of Utah Department of Natural Resourcesin cooperation withNational Park Service

This geologic-hazard map was funded by the Utah Geological Survey and theU.S. Department of the Interior, National Park Service. The views andconclusions contained in this document are those of the authors and should notbe interpreted as necessarily representing the official policies, either expressedor implied, of the U.S. Government.Although this product represents the work of professional scientists, the UtahDepartment of Natural Resources, Utah Geological Survey, makes no warranty,expressed or implied, regarding its suitability for a particular use. The UtahDepartment of Natural Resources, Utah Geological Survey, shall not be liableunder any circumstances for any direct, indirect, special, incidental, orconsequential damages with respect to claims by users of this product.For use at 1:24,000 scale only. The Utah Geological Survey does notguarantee accuracy or completeness of data.

www.geology.utah.gov

Base map consists of U.S. Department of Agriculture 2006 National AgriculturalImagery Program natural color aerial photography and shaded relief generatedfrom digital elevation data acquired from the Utah Automated GeographicReference Center.

Universal Transverse Mercator Projection, zone 12North American Datum of 1983

Unconsolidated geologic units with reported collapse values of >3 percent.

Geologically young (Holocene) unconsolidated geologic units with no available geotechnical data, butwhose genesis or texture is permissive of collapse (chiefly geologically young alluvial, colluvial, andeolian deposits).

Older unconsolidated geologic units (Pleistocene) with no available geotechnical data, but likecategory CSB have a genesis or texture permissive of collapse. Because of their age, these depositshave had greater exposure to natural wetting and collapse may have occurred, and/or the depositsmay be cemented by secondary calcium carbonate or other soluble minerals.

Geologic Deposits Known or Likely to Have a Significant Potential for Soil Collapse

Type ofDeposit

Collapsible SoilCategory

Stream andTerraceAlluvium

LacustrineDeposits

FanAlluvium

Eolian Deposits

Qa1, Qal1, Qat2, Qat3, Qath

1Refer to UGS geologic quadrangle maps (see Sources of Information and References in accompanyingtext) for descriptions of map units.

Qa, Qaly, Qay, Qa2, Qat4, Qat5, Qat6, Qas, QasoQato, Qav

Qafc, Qafco, Qmsc (alluvial parts)Qae, Qac, Qaes, Qaeo, Qaf, Qaf1, Qaf2, Qafy,

Qao, Qafo, Qage, Qmcp1, Qmcp2 Qaco, Qaec, Qap2, Qmcp3

Qea, Qer, Qes, Qed, Qre

ColluvialDeposits

Qc, Qmt, Qmts, Qce, QcesQco

Qla, QlsQlbc

Map Units1

CSA

CSB

CSC

CSA

CSB

CSC

CSB

CSB

CSC

CSB

CSC

Approximate meandeclination, 2009

12 9'o

TRUE

NOR

THMA

GNET

IC N

ORTH

Map Location

1 0 10.5 MILE

1000 0 1000 2000 3000 4000 5000 6000 7000 FEET1 0 10.5 KILOMETER

SCALE 1:24,000

CSA

CSB

CSC

Collapsible (hydrocompactible) soils have considerable dry strength and stiffness in their dry natural state, butcan settle up to 10 percent of the susceptible deposit thickness when they become wet for the first time followingdeposition (Costa and Baker, 1981; Rollins and Rogers, 1994) causing damage to property and structures.Collapsible soils are common throughout the arid southwestern United States and are typically geologicallyyoung materials, chiefly debris-flow deposits in Holocene-age alluvial fans, and some wind-blown, lacustrine, andcolluvial deposits (Owens and Rollins, 1990; Mulvey, 1992; Santi, 2005).Collapsible soils typically have a high void ratio and corresponding low unit weight (<80 to 90 lb/ft ; Costa andBaker, 1981; Walter Jones, consulting engineer, written communication, 2007) and a relatively low moisturecontent (<15%; Owens and Rollins, 1990), all characteristics that result from the initial rapid deposition anddrying of the sediments. Intergranular bonds form between the larger grains (sand and gravel) of a collapsiblesoil; these bonds develop through capillary tension or a binding agent such as silt, clay, or salt. Later wetting ofthe soil results in a loss of capillary tension or the softening, weakening, or dissolving of the bonding agent,allowing the larger particles to slip past one another into a denser structure (Williams and Rollins, 1991).In general, collapsible alluvial-fan and colluvial soils are associated with drainage basins that are dominated bysoft, clay-rich sedimentary rocks such as shale, mudstone, claystone, and siltstone (Bull, 1964; Owens andRollins, 1990). Bull (1964) found that the maximum collapse of alluvial-fan soils in Fresno County, California,coincided with a clay content of approximately 12 percent. Alluvial-fan deposits exhibiting dramatic collapsebehavior in Nephi, Utah, typically contained 10 to 15 percent clay-size material (Rollins and Rogers, 1994). Atclay contents greater than about 12 to 15 percent, the expansive nature of the clay begins to dominate and thesoil is subject to swell rather than collapse. Characteristically, collapsible soils consist chiefly of silty sands,sandy silts, and clayey sands (Williams and Rollins, 1991), although Rollins and others (1994) identified collapse-prone gravels containing as little as 5 to 20 percent fines at several locations in the southwestern United States.Soil composition is the primary indicator of collapse potential in alluvial-fan and colluvial soils. However, alongthe southern Wasatch Front, Owens and Rollins (1990) found that the degree of collapse generally increasedwith an increase in the ratio of fan area to drainage-basin area. In other words, alluvial fans (especially largealluvial fans) associated with small drainage basins had a greater likelihood of producing collapse-prone soils.Bull (1964) found a similar relation between fan and drainage-basin size in Fresno County.Loess—deposits of wind-blown clay, silt, and fine sand—typically has an extremely loose, open structure that ismaintained by water-soluble mineral cements or high-plasticity clay that act as a binder between larger grains(Gibbs and Holland, 1960; Costa and Baker, 1981). Like collapse-prone alluvial-fan soils, undisturbed loesstypically has a high void ratio, a correspondingly low in-place density, and is relatively dry. When wetted, loesswill collapse; the extent of the collapse largely depends on the texture (grain-size distribution) of the deposit.Gibbs and Holland (1960) found that clay-rich loess deposits tend to collapse less than those containing a higherpercentage of silt and fine sand.Naturally occurring deep percolation of water into collapsible deposits is uncommon after deposition due to thearid conditions in which the deposits typically form, and the steep gradient of many alluvial-fan and colluvialsurfaces. Therefore, soil collapse is usually triggered by human activity such as irrigation, urbanization, and/orwastewater disposal. Kaliser (1978) reported serious damage (estimated $3 million) to public and privatestructures in Cedar City, Utah, from collapsible soils. Rollins and others (1994) documented more than $20million in required remedial measures to a cement plant near Leamington, Utah, and Smith and Deal (1988)reported damage to a large flood-control structure near Monroe, Utah. In 2001, collapsible soils damaged theZion National Park greenhouse soon after it was constructed, as soils below and around the building were wettedby excess irrigation water. Park employees later reported that a wastewater treatment plant that had once beenlocated nearby had also had a history of damage from ground subsidence. Damage due to collapse of wind-blown deposits is not as well documented in Utah as damage associated with collapsible alluvial and colluvialdeposits; this may be due in part to the relatively lesser abundance of loess deposits in the state.For additional information about collapsible soil in the Zion National Park Geologic-Hazard Study Area, refer tothe Problem Soil and Rock Hazards chapter in this report.

3

REFERENCES

Survey Professional Paper 437-A, 70 p.

p.

Reclamation Engineering Monograph No. 28, 37 p.

Hills, Illinois, 870 p.

of Investigation 124, 130 p.

catastrophes: Upper Saddle River, New Jersey, Pearson Prentice Hall, 395 p.

Special Study 80, 23 p., 2 plates, scale 1:500,000.

engineering: New York, John Wiley & Sons, 259 p.

Geological and Mineral Survey Miscellaneous Publication 90-1, 38 p.

Colorado: Online, HP-Geotech, SLP paper, 4 p., <http://www.hpgeotech.com/Steve_Paper.htm >, accessedMay 4, 2008.

Journal of Geotechnical Engineering, v. 120, no. 9, p. 1533-1553.

collapsible gravels: Journal of Geotechnical Engineering, v. 120, no. 3, p. 528-542.

patterns [abs.]: Geological Society of America Abstracts with Programs, v. 37, no. 7, p. 326.

Proceedings 2 International Conference on Case Histories in Geotechnical Engineering, St. Louis, Missouri:University of Missouri at Rolla, p. 451-455.

Survey Contract Report 91-10, 44 p.

Bull, W.B., 1964, Alluvial fans and near-surface subsidence in western Fresno County, California: U.S. Geological

Costa, J.E., and Baker, V.R., 1981, Surficial geology, building with the earth: New York, John Wiley & Sons, 498

Gibbs, H.J., and Holland, W.Y., 1960, Petrographic and engineering properties of loess: U.S. Bureau of

International Code Council, 2009a, International building code: Country Club Hills, Illinois, 678 p.International Code Council, 2009b, International residential code for one- and two-family dwellings: Country Club

Kaliser, B.N., 1978, Ground surface subsidence in Cedar City, Utah: Utah Geological and Mineral Survey Report

Keller, E.A., and Blodgett, R.H., 2006, Natural hazards – Earth’s processes as hazards, disasters, and

Mulvey, W.E., 1992, Soil and rock causing engineering geologic problems in Utah: Utah Geological Survey

Nelson, J.D., and Miller, D.J., 1992, Expansive soils, problems and practice in foundation and pavement

Owens, R.L., and Rollins, K.M., 1990, Collapsible soil hazard map for the southern Wasatch Front, Utah: Utah

Pawlak, S.L., 1998, Evaluation, design, and mitigation of project sites in collapsible soil areas in western

Rollins, K.M., and Rogers, G.W., 1994, Mitigation measures for small structures on collapsible alluvial soils:

Rollins, K.M., Rollins, R.L., Smith, T.D., and Beckwith, G.H., 1994, Identification and characterization of

Santi, P., 2005, Recognition of collapsible soils based on geology, climate, laboratory tests, and structural crack

Smith, T.D., and Deal, C.E., 1988, Cracking studies at the Sand-H basin by the finite element method,

Williams, T., and Rollins, K.M., 1991, Collapsible soil hazard map for Cedar City, Utah area: Utah Geological

innd