SFUND RECORDS CTR

2095721

Sunrise Mountain LandfillClosure Plan

Prepared forDisposal Urban MaintenanceProcessing Company, Inc.

HLA

a Environmenla) Manager #IiM-1013

WXliff Yeckos. P.G.Managing Principal HydrogeologistNevada ICnvironmenlal Manager EM-1014

April 14. 1994

£76Harding Lawson AssociatesEngineering and Environmental Services4170 S. Decatur Boulevard. Suite A-1Las Vegas. Nevada 89103 - (702)251-5449

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AGREEMENT OF PARTIES

By signature below, the following entities agree to closing the Sunrise Mountain Landfill, located in ClarkCounty Nevada, in accordance with this Closure Plan and with the construction drawings andspecifications submitted with this document.

DISPOSAL URBAN MAINTENANCEPROCESSING COMPANY, INC.

Name

/-o~~t*£ts^/<Tide

CLARK COUNTY PUBLIC WORKS

Name (J 1

Title

Data

4- -Date

UNITED STATES BUREAU OFLAND MANAGEMENT

CLARK COUNTY HEALTH DISTRICT

Namo

Tiijo ^

HDato

2jf/^? T/

TiQo

Date

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TABLE OF CONTENTS

1.0 INTRODUCTION 21.1 Facility Operations 21.2 Landfill Closure 2

2.0 CLOSURE REQUIREMENTS AND RESPONSIBILITIES 22.1 Responsibility for Closure 22.2 Federal Closure Requirements 32.3 Property Lease Requirements 3

3.0 FINAL COVER CONSTRUCTION 33.1 Site Grade Modifications 33.2 Final Cover Description 33.3 Installation Methods and Procedures 4

4.0 HYDROLOGIC ANALYSIS 44.1 Surface Water 4

4.1.2 Offsite Runoff 44.1.3 On-site Runoff 5

4.2 Subsurface Water 5

5.0 SURFACE WATER MANAGEMENT SYSTEM 55.1 Surface Water Management Needs 55.2 Ero,«mn and Sediment Control Structures 6

6.0 MAXIMUM WASTE INVENTORY 6

7.0 FINAL CLOSURE SUMMARY 77.1 Closure Activities 77.2 Closure Schedule _ 7

8.0 POST-CLOSURE PLAN 78.1 Monitoring and Maintenance Activities 7

8.1.1 Inspection Plan 70.1.2 Monitoring Plan 88.1.3 Maintenance Plan 8

8.2 Post-Closure Contact 88.3 Post-Closure Land Use. . 8

9.0 CLOSURE REQUIREMENTS BASED ON BLM LEASE ANDCLARK COUNTY AGREEMENT 8

9.1 General 89.2 Methods for Limiting Disposal of Hazardous Wastes 99.3 Complianco with Applicable Laws and Regulations 109.4 Desert Tortoise Issues 119.5 Cultural and Paleontological Resources 119.6 Pesticides Use 119.7 Inspection Access 119.8 Response to Potential Regulatory Violations 119.10 Miscellaneous Requirements 11

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PLATES

1 Site Location Map2 Closure Schedule

APPENDICES

A Property Lease AgreementsD Municipal Wastes Management Plan

B-l 1991 Operations PlanB-2 Excerpts from 1986 Expansion Report Addressing Landfill Operations

C Regulated Wastes Management DocumentsC-l Asbestos Management DocumentsC-2 Medical Wastes Management DocumentsC-3 Septage Wastes Management DocumentsC-4 Soil Biotreatmont Management Documents

D Drilling Logs

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1.0 INTRODUCTION

1.1 Facility Operations

The Sunrise Mountain Landfill, in Clark County.Nevada is operated by Disposal UrbanMaintenance Processing Company. Inc.(D.U.M.P.Co.) under contract with Clark County.The landfill encompasses 720 acres of desert landalong the eastern edge of the Las Vegas Valley,and is approximately four miles east of Las Vegas(see Plato 1). Clark County has maintained leasesfor tlio landfill from the United States Bureau ofLand Management (BLM) since 1957.

Over the last two years, approximately 3,400 tonsof waste were accepted each day. The majority ofthis waste was municipal waste, but the landfillalso contained designated areas for disposed ofother wastes including asbestos, sanitary sludge,construction debris and medical wastes, andtreatment of septage waste and hydrocarboncontaminated soil. Locations of these areas areindicated on Sheet C-13 of the Closure Plandrawings incorporated as a part of this document.The 720-acre facility was designed with a refusecapaci'.y of 60,936,000 cubic yards and a servicelife of 31 years.

1.2 Landfill Closure

Closure of the landfill is a result 40 Code ofFederal Regulations (CFR), Part 258 (Subtitle D),which sots minimum performance standards for

all landfills. Although Subtitle D wont into effecton OcU-boi U. 1991, landfill operators had a Iwoyoar poriod to make modifications to bring thelandfills into compliance. These modificationsinclude installation of a liner system anddocumented plans to closo the landfill with acover designed to certain minimum standards.Although thoro is capacity for the landfill tocovilinuo accepting wastes, D.U.M.P.Co. and ClarkCounty have chosen to close the Sunrise facilityto comply with threshold deadline dates dictatedby Subtillo D. Notice of intent to close thefacility was appropriately filed with tho NevadaDivision of Environmental Protection. The finalload of waste was accepted prior to October 9,1993. Beginning October 9, 1993, all wastesformerly accepted by the Sunrise MountainLandfill have been disposed of at D.U.M.P.Co.'snow APEX Regional Waste Management Facility,

a landfill designed m accordance with Subtitle Dregulations.

The following document presents the plan forclosure (Plan), of the Sunrise Mountain LandfillFacility (Sunriso Facility). Incorporated byreference to the Plan are the Surface WaterManagement Plan (bound separately),Construction Quality Assurance Plan (boundseparately), and the accompanying Closure PlanDrawings.

The Plan's overall objective is to minimizepotential threats to human hnalth and theenvironment following the Sunrise MountainLandfill Facility closure. The conditions of theClosure Plan are the result of an agreementbetween Clark County (property lessee) andD.U.M.P.Co. (sito operator) as to the criteria andstandards for accomplishing site closure. Thedevelopment of the Plan was not a requirement ofSubtitle D. However, the Plan generally followsmany of criteria guidelines sot fourth in SubtitleD, including:

• Installation of a final cover systemdesigned to minimizu infiltiation auderosion by meeting the requirements of40 CFR. Part 258.60(a).

• Minimize the escape of waste cr waste•constituents to groundwater, surfacewater or UIH atmosphere.

• Design of the Closure Plan to minimizethe potential for extensive long-termmaintenance and controls.

2.0 CLOSURE REQUIREMENTSAND RESPONSIBILITIES

2.1 Responsibility for Closure

Per agreement with Clark County, as operator oftho Sunrise Mountain Landfill, D.U.M.P.Co. isobligated to close the landfill in accordance withapplicable federal. State and local laws andregulations existing at the time of closure, and tocomply with terms of two leases existing betweenClark County and the BLM. D.U.M.P.Co. will beresponsible for costs associated with closure ofthe landfill and, per applicable regulations and itsagreement with Clark County, will perform post-

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closure activities (monitoring, inspections, etc.)for five years after closure. Beyond this period,while not required by regulations, or agreement,any post-closure activities will be theresponsibility of either Clark County or BLM andwill not bo the responsibility of D.U.M.P.Co..

2.2 Federal ClosureRequirements

Subtitle D requires that a landfill accepting wasteafter October 9, 1991 be closed at the end of itsuseful life with a cover constructed of at least 18inches of material with a permeability greater thancr equal to 10"1 cm/sec, and no less than thepermeability of the underlying liner, if any.

Because the Sunrise Mountain Landfill accsptedits final load of waste prior to October 9.1993 andthero is no permanent linor system in place, acover that moots minimal Subtitle D requirements'will satisfy Federal Closure criteria listed in 40CFR. Part 258.60(a). The cover will beconstructed only over portions of the landfillfilled while Subtitle D was in effect (after October9, 1991). Other areas of the landfUl filled prior toOctober 9, 1991 are already considered closed inaccordance with Nevada regulations in effect atthat lima. Verification of cover thickness of areasclosed prior to October 9, 1991 was conducted byD.U.M.P.Co. as part of closure activities and isavailable for review al D.U.M.P.Co. facilities uponroquost.

2.3 Property Lease Requirements

Clark County holds I wo separate leases for theland occupied by the landfill. The 20-year leasefor Vho northern 320 acres of land is duo to expirein May 2002. A 2-year loaso for the southern 400acres of the site will end in May 1994. Currentcopies of thcso two leases are presented inAppendix A. The most significant condition ofthese leases is thai, the land may not bo used forthe disposal of hazardous materials. Discussion ofsite specific lease requirements is included inSection 9.

As operators of Sunrise Mountain, D.U.M.P.Co.also must moot certain requirements for closure asspecified by Clark County. There are listed in aModification Agreement to D.U.M.P.Co.'sfranchise agreement for solid waste collection and

disposal, dated October 5. 1993 (see Appendix A).Specific requirements in this agreement whichaffect this Closure Plan arc outlined in Section 9.

3.0 FINAL COVERCONSTRUCTION

3.1 Site Grade Modifications

The wastes and final cover will be graded to thecontours shown on the Closure Plan drawings.These grades have been designed with minimum3.5 percent slope and a maximum 3:1 slope topromote surface water drainage off of and awayfrom the landfill. Within areas to be blasted forinstallation of the stormwat«r diversion channel,along the eastern edge of the site, a steeper slopethan 3:1 may be utilized upon approval of agootechnical engineer. Final determination of cutslope steepness will bo determined at the time therock face is exposed during construction.

The grades are also intended to fill depressions onthe site and reduce ponding, particularly aroundthe asbestos disposal and scalehouse areas.Grading will begin in Iho southwest comer of thelandfill where waste was most recently placed.Grading will then proceed to other areas of thelandfill in which wasto was placed between 1991and 1993.

3.2 ' Final Cover Description

The final cover is designed per 40 CFR, Part258.60(a) to minimize infiltration, to reduceprosion and to function with a minimal amount ofmaintenance. Within areas receiving-final cover,an intermediate cover oxists consisting of aminimum of 12 inches of sod in place for dust,odor and litter control. This intermediate covermay be rogradod or stripped lo a minimumthickness of 6 inches before the final cover isinstalled. Final cover design will consist of thefollowing two layers:

• An infiltration layer consisting of aminimum of 18 inches of lowpermeability soil (K < 10'* centimetersper second). Extensive analysis of on-sitesoils has occurred and results ofgeotechnical tests indicate areas of on-site soils which can be processed oraugmented to achieve required

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permeability. Thus, materials salos orimportation is not anticipated. Results ofthis analysis aro not required as part ofclosure but are available for review uponrequest. Per Subtitle D requirements,this layer will bo less permeable thanuncompacted native soil at tho base ofthe landfill.

An erosion layer consisting of aminimum of 6 inches of native material.Soil for tlio erosion layer will be availablefrom on-site sources. This layor isdesigned to protect tho final cover fromerosion.caused by both wind and water.

Typically, in climates with a larger amount ofannual rainfall, a vegetative layer is included inthe final cover profile to help minimize erosion ofthe cover; however, the arid climate and nativesoils are not capable of naturally sustaining thedensity of plant growth required withoutirrigation and nutrient-rich soil. The installationof irrigation and the placement of top soil woulddefeat the intent of tho final cover to minimizeinfiltration. Therefore, the erosion layer soilmaterial will be placed lo minimize erosion of (hecover.

I3ased on analyses of on-site soils, the erosionlayer will generally be a sand with gravel and sillwith the gravel component approximately 15percent and tho silt component approximately 15lo 20 percent. Further details are discussed in thoConstruction Quali ty Assurance Plan submittodas a part of this document, lixperience ofD.U.M.P.Co. personnel has shown that these soilswill, ovor time, revcgale if they are not graded.There aro no plans for periodic grading onco thocover is in placo.

T!io final cover will bo constructed only overportions of the landfill in which waste was placedbetween the period of October 9, 1991 andOctober 9, 1993 (including those colls used forregulated wastes); this corresponds to an area ofapproximately 180 acres. The remaining portionsof the landfill already havo final cover placed inaccordance with Clark County Health District(CCHD) regulations governing solid waste sites,dated September 1990 (in effect prior lo SubtitleD) and aro therefore considered closed.

3.3 Installation Methods andProcedures

Prior to construction of tho final cover system, theintermediate cover will be inspected for thopresence of debris thai may adversely affectgrading and compaction activities. Constructionof the remainder of tho cover system may themproceed in accordance with design specifications.The first layer to be placed will be ihu low-permeability infiltration layer. Placement andgrading of final cover materials w i l l beaccomplished with typical earth-movingequipment. Additional detail of instillationmethods and procedures required for placementol the final cover and cap are included in thoConstruction Quality Assurance Plan developedfor closure of this site. D.U.M.P.Co. will obtain allnecessary Clark County Public Works (CCPW) andCCHD permits prior lo proceeding with applicableconstruction.

4.0 HYDROLOGIC ANALYSIS

4.1 Surface Water

To address erosion and runoff control issii^s. -ndetailed hydrologic analysis of tho site wasconducted. In addition, hydraulic dcsigu olrunoff control structures was also performed.Copies of these analyses are included in SurfaceWater Managemonl Plan, bound scparatoly Ageneralized summary of tho analysis follows.

4.1,2 Offsite Runoff

The U.S. Army Corps of Engineer.-' I I l iCM FloociHydrography Package was used to performcomputer modeling of off-site storm wali>r runoff .The purpose of this investigation was to ovalualo,the amount of runoff which on tors the l a n d f i l l si lofrom a watershed to tho north and oasV. Tho totalcontributing off-sito area of approximately 1100acres was divided into four smaller basins formodeling purposes. Tho six hour duration 25 and100-year frequency precipitation values of 2.53inches and 3.15 inches respectively were used.Results from the hydraulic analysis wore thenincorporated into the design of a runoff controldiversion channel located along the eastern edgeof the site. This structure is discussed further inSection 5 and in tho Surface Water ManagementPlan.

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4.1.3 On-site Runoff

Hydrologic analysis of on-site sources wasconducted using the HEC I Analysis Methods.Based on this evaluation, flows were estimatedand culverts, berms. swales and rundowns woredesigned to control surface runoff and direct itaway from covered areas. In general, structureswere placed at the grade breaks between the topareas of cover and tlio sloping faces. Rundownswore placed at periodic intervals to guide runoffdown the slope faces in a controlled fashion to thenearest accessible wash. These structures arediscussed in Section 5 and in the Surface WaterManagement Plan.

4.2 Subsurface Water

Subsurface hydrologic characteristics areinfluenced by two primary geological formationswhich underlie the site. Under the northernportion of the landfill, there is bedrock of theFrencliman Mountain complex, while to the souththere are alluvial valley fill sediments. Thosesediments vary from sands and gravels to silts andclays. Based on analysts of stockpiled fill materialtaken from various on-site areas, permeabilities at90 percent compaction vary from 3xlO's to over5x10"* cm/sec.

As observed in site excavations and duringdrilling in the area, alluvial sediments under thesouthern portion of the landfill consist ofapproximately 20 to 30 feet of loosesandy/gravelly material cemented with carbonateand gypsum. Drilling logs are included inAppendix D. Underlying soil has been describedas fine-grained deposits characteristic of theMuddy Creek Formation. This formation isrocogni/.ed regionally to underlie the southernportion of the landfill property. The occurrence ofgroundwater in the upper sandy layer is rare andis usually the result of rare major storm eventrunoff infiltration. Occasional damp areas of soilhave been found above the cement beds.

In the lower fine-grained layer, two wells havebeen previously installed in the past to explorethe possibility of developing a source of waterfrom the Muddy Creek Formation. These arelocated in the west-central portion of the site, justsouth of tho main facility access road. One well(depth of 100 feet) did not produce any water in

two years. Water was eventually found in thesecond well, but after being pumped dry, nearly amonth was required for recharge to original waterlevel. Due to potential surface water infiltrationand inappropriate construction techniques (thewells were originally designed for productionwells and not monitoring wells) these wells havebeen abandoned as part of site closure activities.Abandonment was in compliance with applicableregulations of the Nevada Division ofConservation and Natural Resources.

Water in the Muddy Creek Formation is thoughtto flow westward at a rale of 1 to 10 feet per year.This water is of poor quality with total dissolvedsolids of approximately 3500 mg/1 and isconsidered not fit for drinking without treatment.

Bedrock \inder the northeastern portion of tho siteis composed of sandstone and limestone. Existingsoil cover above the bedrock is typically only afew foe I thick. Because the bedrock material ishighly impermeable, the primary path for liquidmigration is through fractures in the surface of therock. The groundwater depth is unknown, but itis suspected that groundwater movement issouthwestward into neighboring alluvium.

5.0 SURFACE WATERMANAGEMENT SYSTEM

.<

5.1 Surface Water ManagementNeeds

Duo to the arid climate and resulting low orinfrequent runoff typical of the. ragion. IhoSunrise Facility has not required implementationof a formal surface water management system.However, surface water in the area tends lo flowdirectly over tho landfill as it travels from themountains to existing washes to the south. Tominimize erosion of tho cover, drainage swales,metal culvert rundowns and an off-silo stormwater diversion channel located along the easternboundary of the landfill will be constructed.These structures are designed on the basis ofClark County Regional Flood Control Districtprecipitation guidelines for the 25-year, 6-hourdesign storm. The 25-year storm is referenced byboth 40 CFR, Part 258 and Nevada Solid WasteRegulations (NRS 444) for stonnwater analysis oflandfill facilities. However additional capacity, up

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to Ihc expected 6-hour duration. 100 yearfrequency slonn water runoff discharge has beenincluded in tho main channel design. Thiscapacity is included without freeboard tolerance.Additional discussion of these structures isincluded in the Surface Water Management Plan.Structure design and location arc identified in theClosure Plan drawings, submitted with thisdocument. Upon termination of the land leases,any site improvements, including the erosion andrunoff control structures, will be owned andoperatod by tho BLM.

5.2 Erosion and Sediment ControlStructures

To minimize tho amount of cover erosion and tocontrol nonoff from the landfill, certain hydraulicstructures wili ho constructed on site. The mainstructure will consist of a trapezoidal oponchannel with a bottom width of ten (10) feet, 3:1side slopes, a total depth of approximately six (6)feet. This structure will be located along theeastern edge of the property in previouslydisturbed material. Thus no documentationrelated NEPA requirements is needed. Thechannel will be constructed to carry flows fromthe 25-yoar. 6-hour design storm withoutovertopping during the 100-year, 6-hour designstorm.

This clwnnol will route off-silo runoff from awatershed to thu north, tlirough the site, where itwill thnn drain into an existing wash to thesoutheast. Based on a review of historical areal1

photographs, this is tho historical flow channel for'his runoff in existence since at least the mid tolate 1900's. The channel invert will generally belocated below final design grade through its fulllength. It will bo rip-rap gabion lined for amajority of tho length with a low permeabilitygooloxlilo l iner placed below the rip-rap.Additional structures to bo constructed includechannelization at the entrance with rip-rap dropstructures located at the approximate mid-point.Plan drawings of the channel, submitted with thisClosure Plan, detail channel construction.Additional discussion is also included in theSurface Water Management Plan.

On-site erosion and runoff control structures willconsist of excavated swales, borms and corrugatedmetal structural plate pipe (half pipe sections).

Where necessary, duo lo velocity considerations,swales and berms will bo rip-rap lined. To theextent possible, structures will be placed tointercept runoff and divert it away from areas offinal cover material. Structures will also boplaced to intercept runoff at grade breaks betweenslope areas. On side slopes, rundowns, consistingof half sections of structural plate pipe, will beplaced to drain flows from upper cover areas, anddivert flow away from lower cover areas. At theedge of the site, flows will be directed to thenearest natural wash.

Upon termination of lease agreements,improvements made to tho site, including erosionand run-off control structures, would revert to theBLM as the land owners of record. All erosionand runoff control structures will bo installed aspart of closure activities, prior to October 9, 1994.Additional detail regarding scheduling ofconstruction is included in Plato 2.

6.0 MAXIMUM WASTE INVENTORY

The maximum inventory of wastes placed on-si*.eduring tho entire active life of the landfill cannotaccurately be determined as no records of dailyincoming volume wore maintained prior to 1991.Records available for tlio volume of waste placedbetween October 10, 1991 and October 9, 1993are available. A rough estimate of 2,500,000 tonshas been developed for this period of time, basedon estimated average daily waste volumes of 3,400tons per day. The landfill's original refusecapacity was designed for 60,936,000 cubic yardswith a service life of 31 years.

Based on estimates by D.U.M.P.Co., at the timeoperations ceased, there wore seven years oflandfill capacity remaining at this site. Thisoslimate assumed continued renewal of tho BLMlease for the southern 400-acros. Without thisrenewal, there was essentially no remainingcapacity duo to a lack of available soil for dailycover and fill. Taking this estimated remainingcapacity and utilizing the original design capacity,there has boon an estimated 47,000,000 cubicyards of total refuse deposited through the years.

For regulated non-hazardous wastes.Environmental Technologies of Nevada (ETN)generally maintained well documented, detailedrecords of incoming materials. Locations of waste

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colls for these materials are identified on sheetC13 of the Closure Plan drawings. A summary ofestimated volumes are as follows (additionaldescriptions of wastes and handling procedures isincluded in Section 9):

• Asbestos containing materials - Since1985. when records were required to bemaintained, logs indicate 91,178 cubicyards of material was disposed indesignated cells.

• Medical wastes - Since programinception in 1990. a total of 43,908 cubicyards of medical wastes have beenreceived arid placed into the medicalwastes cell.

• Septage Sludges - An approximation ofseptage sludge volumes, received fromCity and County municipal wastewaterfacilities, is 4 million tons since the1950's.

• Hydrocarbon Impacted Soils - Receipt ofhydrocarbon impacted soils for treatmentand subsequent use as fill and cover,began in 1989. Since that time, recordsindicate approximately 99,109 tons havebeen received.

7.0 FINAL CLOSURE SUMMARY

7.1 Closure Activities

Closure of the Sunrise Mountain Landfill beganon October 8, 1993 when tho final load of wastewas accepted. Activities to bo completed beforeI ho landfill is considered fully closed includesecuring tho landfill boundaries, grading thesurface of the landfill, installation of a final cover,installation of orosion and runoff controlstructures, and certification of closure by aprofessional engineer.

Securing of the landfill boundaries will consist ofestablishing fencing at roadways and berms and/orgates across roadways and other accessible points.This is considered adequate access control byD.U.M.P.Co. as a majority of the site is boundedby mountains which aro generally inaccessible tovehicular traffic. Evidence of the mountainousterrain is shown on sheot C3 of the Closure Plan

drawings. Existing tortoise fencing will bo loft inplace, although, por the leaso agreement withBLM, the site is no longer considered tortoisehabitat. Additional discussion is included inSection 9.

7.2 Closure Schedule

A schedule of the closure activities is presented inPlate 2. As noted on this schedule, closureactivities will be completed prior to October 9,1994. thus meeting the schodulo requirements asoutlined in Federal Register, Volume 58. No. 189,dated October 1,1993.

8.0 POST-CLOSURE PLAN

8.1 Monitoring andMaintenance Activities

8.1.1 Inspection Plan

During the first 5 years of closure, D.U.M.P.Co.will provide qualified personnel Lo inspect thoclosed landfill and surrounding areas on aperiodic basis. D.U.M.P.Co. anticipates theseinspections will be sufficient lo detect and repairdefects before they became major problem. Thefrequency of these inspections is subject to changebut will initially be at least every other month.During periods of precipitation, inspections willoccur more frequently to verify die integrity of thehydraulic structures and review the landfill coverfor signs of potential erosion. Por agreement withClark County, written summaries of theseinspections will be forwarded lo CCPW.

Inspections will be accomplished by walkingthroughout the closed areas and detailing inwriting, observations made by tho inspector.D.U.M.P.Co. will mako corrections to doteclcdproblems in an expedient manner.

The inspections will focus on integrity andoperability of the landfill closure system.Surveyed benchmarks will bo evaluated as to theirintegrity and visibility. Berms and fencing will beinspected as to their integrity. Likewise, thecondition, accessibility and visibility of all erosioncontrol structures will bo reviewed. Theengineered cover areas and older landfill areaswill be inspected for signs of orosion damage,

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sediment deposition, settlemont, subsidenco ordisplacement.

8.1.2 Monitoring Plan

The landfill ceased receiving wastes prior toOctober 9. 1993. Based on Subtitle D regulationsno monitoring of groundvvaler or methane gasmonitoring is required. However . in accordancewith the Modification Agreement betweenD.U.M.P.Co. and Clark County. D.U.M.P.Co. willconduct monitoring of methane gas along thofacility boundary. Monitoring will consist ofambient air readings utilizing a hand-held airpump. Such monitoring will occur somi-annually. Improvements permanently installedfor purposes of facility monitoring will revert toBLM ownership at the termination of the siteleases.

At present, there are two groundwaler wellslocated on-site. The deeper well remained

* uncapped for several years (exposed to dust andsurface infiltration) and is of questionablemonitoring value due to construction techniques(originally planned as construction well). Theshallow well has always remained dry. Thosewells have boon abandoned per applicable stateregulations. No additional groundwutermonitoring is planned at the facility.

8.1.3 Maintenance Plan

D.U.M.P.Co. will employ a series of preventiveand corrective maintenance procedures topreserve tho integrity of the closed landfill.Defects observed during inspection will beaddressed by D.U.M.P.Co. equipment andpersonnol. If the erosion layer of the cover hasboon eroded or damaged, or if other problemsresulting from settlement, subsidence ordisplacement are detected, tho cover will borepaired using similar on-sito material. If erosionoccurs to an extent necessitating repair of thecover due to concentrated surface runoff, a reviewof erosion/runoff control structures will occur todetermine if, due to subsidence or other alteredfiold conditions, revisions or additions to thestructures are required. Any changes or additionswill be noted in tho inspection reports submittedto CCPW. Similar inspection and repair activitieswill occur as necessary within the older landfillareas.

8.2 Post-Closure Contact

For the first five years of the post-closure period,the contact will be:

Disposal Urban MaintenanceProcessing Company, Inc.

770 East Sahara Ave.Las Vegas, Nevada 89104735-5151

After the five year period, tho BLM will bo thoprimary contact.

8.3 Post-Closure Land Use

Under Clark County's current lease with the BLM.the approved use of the property is for thesanitary landfill and related treatment anddisposal activities. Although none are planned,modifications to land use must be approved byClark County and the BLM. All sitsimprovements and erosion/runoff controlstructures remaining-at the termination of tho siteleases will revert to the BlJv-f unless otherarrangements authorization between Clark Countyand BLM are made.

9.0 CLOSURE REQUIREMENTSBASED ON BLM LEASE ANDCLARK COUNTY AGREEMENT•4

9.1 General

This section addresses special lease requirementsstipulated in Appendix A of the leasu betweenBLM and Clark County, dated May 21, 1992Those are in addition to standard leasorequirements set forth in all BLM leases and areintended to address tho use of tho area for landf i l land landfill related purposes. Each requirementin Appendix A of tho leaso is specificallyaddressed below. A copy of tho loa.se agreementis included in Appendix A of this report.

Also addressed in this Plan are requirements forclosure stipulated in the Modification Agreementto Franchise Agreement for collection anddisposal of solid waste, dated October 5, 1993,between Clark County and D.U.M.P.Co. A copyof this agreement is included in Appendix A.

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9.2 Methods for Limiting Disposalof Hazardous Wastes

Tho BLM lease specifically precludes the disposalof hazardous wastes on the site. To address this.D.U.M.P.Co. since 1991. had in place, anOperations Plan which described actions to limitdisposal of hazardous wastes within themunicipal colls and has addressed handlingrequirements for a variety of regulated and non-hazardous wastes (detailed below). A copy of theOperations Plan is included in Appendix B.

In addition, in 1986, as part of a document titled,"Sunrise Mountain Landfill Expansion,"procedures and requirements ware developed forhandling of regulated and non-hazardous wasteswhile excluding hazardous wastes. Theseprocedures were followed by D.U.M.P.Co.. Copiesof the appropriate sections of tliis document arealso included in Appondix B. All disposal loadswere checked at the gate and again at the edge oftho worlcing face of the landfill prior to dumping.Suspect materials were not allowed to beunloaded and the disposer was referred toEnvironmental Technologies of Nevada, Inc.(ETN). ETN was formed to handle disposal ofhazardous and regulated wastes for generators perfederal, State and local regulations. The presenceof ETN facilities and personnel at the SunriseLandfill has served to further minimize thopotential of regulated and hazardous materialsbeing placed into the municipal waste cells.

Additionally, community wido programs by ETNpertaining to disposal of household hazardouswastes and handling of commercial hazardouswastes at the generator's facility further serve toreduce the potential of hazardous wastes enteringthe silo. As a result of these efforts, thore havebeen no known incidents of suspect hazardouswiistes accepted at Sunrise Mountain Landfill.

Within areas designated for disposal or treatmentof non-hazardous, regulated wastes (asbestoswastes, medical wastes, septage sludges, andhydrocarbon impacted soils], specific procedureswore implemented to minimize the potential ofhazardous materials (as defined by applicableregulations at tho time of waste acceptance) fromentering the landfill. These included wastemanifesting, proscreening by analytical testing,testing after waste acceptance, and customer

education. Waste areas are designated on SheetC13 of the Closure Plan drawings, submitted withthis document. Appropriate permits andauthorizations for acceptance of these wastes areincluded in Appendix C. Wastes were processedas follows:

• Asbestos containing materials areconsidered regulated, non-hazardouswastes by the State of Nevada. Asbestoscontaining materials received byD.U.M.P.Co. were placed into adesignated cell located at thenorthwestern corner of the site. Fordisposal, asbestos wastes generators wererequired to seek permit by the CCHDprior to acceptance of the waste byD.U.M.P.CO.. In addition, asbestos wastemanifests were required. A copy of thestandard asbestos manifest is included inAppendix C. Specific procedures were

• also implemented for asbestos screening,acceptance, dumping, anddecontamination of equipment required.Since incoming wastes were generallyrequired to be solidified or encapsulatedprior to disposal, decontamination wasrarely required. When necessary, Ihedecontamination water was solidifiedwithin the asbestos cell and covered withsoil. A copy of these procedures is also'included in Appendix C. Theseprocedures also effectively reduced thepossibility of hazardous materialsentering into the asbestos cell. Theasbestos waste coll will receive a f i n a lcover and cap per 40 CFR. Part 258.GC(a).

• As a result of extensive rcqunsls (ranimedical facilities in the area, D.U.M.I3.Co.established a medical wnstos receiptprogram. Thus, medical wastes woveaccepted by D.U.M.P.Co. under a region-wide medical wastes handling program.No separate permit or regulatoryauthority was required for acceptance ofthe types of medical wastes disposed ofunder the program. Wastes handledunder this program included animalwastes, blood, blood impacted wastes,cultures, isolation wastes, sharps, andstocks. Under the contract with thegenerating entity, specific responsibilities

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for tho waste generator wore identified.These included prohibition of allchemical and radioactive wastes fromentering the faci l i ty . A copy of theservices provided under this program andof the waste generator's responsibilities isincluded in Appendix C. The medicalwastes cell will receive a final cover andcap po,v 40 CFR, Part 258.60 (a}.

Al the request of Clark County,D.U.M.P.Co. established a soptagehandling facility at the Sunrise MountainFacility. Seplage wastes from licensed,commercial haulers were accepted byD.U.M.P.Co. in designated ponds, locatedin the southeast corner of the site. Oncea pond was filled, activities were divertedto a new pond. Material in the old pondwas allowed to solidify. Monitoringbegan in July of 1991 and generallyconsisted of periodic sampling of driedwaste once the liquid had solidilied. andrandom periodic sampling of incomingwaste loads. Based on a November 16,1993 letter (included in Appendix C),Environmental Technologies of Nevada,Inc. (ETN) slated review of analyticaldata indicated only two periods whenregulatory action levels were exceeded.Rtjsulls from January 6, 1993, samplingindicated elevated levels of lead werefound to be 13 parts per million (ppm),abcwo the rogulatory level of 5 ppm. OnSeptember 2. 1993, tetrachloroethylunp(a common solvent) was found to be 3.4ppm. TU« regulatory acUon level for thiscons t i tuen t is 0.7 ppm. In bothinstances. CCHD was notified and as aresult, random sampling of incomingwastos was increased and follow-upsampling of the ponds indicated noanalyzed constituents above regulatoryaction levels were found. Analyticalresults are not included in this documentduo to the extensive amount of samplingwhich occurred. Records are availablefor review by appropriate regulatoryauthorities. Cells in which seplagewastos were placed will rocoivo a finalcover and cap per 40 CFR, Part 258.GO(a).

9.3

ETN has previously operated a soilbiotreaunont facility for hydrocarbonimpacted soil at tho Sunriso Facility,This was located in the west-centralportion of the site. The facility waspermitted by NDEP for zero discharge. Hwas also permitted by CCHD. Copies ofthose permits are included in AppendixC. Zoro-discharge was accomplished bylining tho bio-troalmont cells with HDPli.Potential soils wore pre-screonod throughanalytical testing prior to acceptance toverify no designated hazardous materialswera present. If potential hazardousmaterials were found in tho pre-screeriingprocess. ETN did not allow the materialto be placed into the treatment colls andwould coordinate disposal of the materialin a designated hazardous waste handlingfacility. A formal procedure for materialsscreening and acceptance was followedthroughout the life of the facil ity. A copyof pro-screening and acceptancedocuments and facility operationalprocedures is included in Appendix C.Once received, materials were treatedUirough physical and biological processesto reduce levels of hydrocarbons to belowregulatory action limits. Analyticaltesting of soil within the cells wasperiodically conducted to verify cleanup'prior' to removal of the soil from the cells.Sinco treated soils wore used as f i l l andcover in daily operations, this cell wasnot considorad a waste cell. Reporting ofactivit ies and results was mado to NDEPo\\ 'A regular basis and is available forinspection through NDEP upon request.This area will not receive a f inal coverand cap. Treated soils will be excavatedand used as f i l l material. The cell linerwill be removed and underlying soil willbo excavated to natural grade.

Compliance with Applicable Lawsand Regulations

The BLM lease requires compliance with CCHDSolid Waste Regulations, dated September 1990.and compliance with applicable federal. State, andlocal environmental and public health laws andregulations. The Sunrise Mountain Landfill wasoperated by D.U.M.P.Co. in compliance with local.

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SunrU* Mountain Landfill Closure Plan

Stale and federal regulations in placo at the timeof waste disposal. Further evidence of this actionis reflected in landfill inspection reportsconducted since the 1970's, completed by CCHDand Nevada Division of Environmental Protectionpersonnel. Copies of these reports are availableupon request. Closure of the facility will be incompliance with applicable RCRA Subtitle Drequirements, State solid waste closurerequirements, and applicable Clark Countyrequirements.

9.4 Desert Tortoise Protection

Items tliree through five of the additionalstipulations lists BLM concerns related topotential encounters with desert tortoises.D.U.M.P.Co. has on staff, individuals licensed indesert tortoise handling. These individuals havebeen responsible for training field andconstruction personnel in protocols associatedwith desert tortoise encounters. Should a tortoisebo encountered, appropriate BLM and/orD.U.M.P.Co. personnel will be notified forremoval and/or relocation.

9.5 Cultural and PaleontologicalResources

As the majority of the areas where closure activitywill bo occurring have previously bean disturbed,it is considered unlikely that any archeologicalobjects will bo encountered. No previous objectshave boon found in past activities. However,should any objects bo encountered during closureactivities, D.U.M.P.Co. will suspend operations inthat area and immediately notify BLM. Work inimpacted areas will not commence until clearedby BLM.

9.6 Pesticides Use

Under the BLM loose agreement, use of pesticidesis required to be cleared by BLM prior toapplication. There havo been no known past usesof pesticides on site. At present, there are noplans for uso of pesticides or herbicides afterclosure.

9.7 Inspection Access

BLM reserves the right to access the site at anytime for the purpose of inspecting the site forcompliance, without advance notice. Duringclosure of the site, the BLM or oilier regulatorypersonnel will have full access for the purpose ofverifying compliance with closure procedures.Once closed, no D.U.M.P.Co. personnel will bostationed on-site and access will be limited.D.U.M.P.CO. will provide to BLM copies of keysand/or codes for gates access to the site.

9.8 Response to PotentialRegulatory Violations

During closure activities and during the first fiveyears following closure, by written agreementwith Clark County, D.U.M.P.Co. is responsible forclosure and maintenance activities at the SunriseMountain Landfill. During this five year period,if a violation of regulations or laws (ill-place attime of closure) becomes evident, D.U.M.P.Co.will take appropriate, reasonable steps necessaryto correct the violation, including, assessment andremediation if necessary.

9.9 Insurance and Indemnification

Per the Modification Agreement with ClarkCounty, D.U.M.P.Co. will provide public liabilityand property damage insurance in the amountslisted in Section (i) of the County agreement tocover any claims arising from or related to closureor post-closure caro activities.

D.U.M.P.Co. will further indemnify and hold theCounty harmless for failure to close the SunriseMountain Landfill in accordanco with applicablelocal, state, and federal requirements and foractions of D.U.M.P.Co. as they relate to closureand post-closure caro activities on the site.

9.10 Miscellaneous Requirements

The modification agreement further requires thefollowing:

• D.U.M.P.Co. will stop receiving wastesprior to October 9,1993. This action wasaccomplished.

D.U.M.P.CO. agree to maintain tho site fora period of 5 years after final closure.

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rSunrls* Mountain Landfill Closure Plan

This is agreed to and discussed inSection 8.0.

D.U.M.P.Co. prepare and submit aclosure plan. This document serves asthe closure plan.

D.U.M.P.Co. conduct periodic inspectionand cleanup and maintain the integrity ofthe cover and erosion and runoff controlstructures. This is discussed in Section8.0 of this report.

D.U.M.P.Co. conduct sampling formethane gas and groundwater fromexisting wells. This is discussed inSection 8.1.2 of this report.

D.U.M.P.Co. make available records ofdisposal of waste at Sunrise Mountain, ifrequested by the County. If requested.D.U.M.P.Co. will supply the records inaccordance with conditions andstipulations listed in the ModificationAgreement.

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DISTRIBUTION

Sunrise Mountain LandfillClosure PlanLas Vegas. Nevada

April 14, 1994

Copies 1-3: Disposal Urban Maintenance Processing Company. Inc.770 East Sahara AvenueLas Vegas, Nevada 89104

Attention: Mr. George Rogers

Copies 4-5: Clark County Department of Public Works6655 Wast Sahara AvenueBuilding C-204Las Vegas, Nevada 89102

Attention: Mr. M. J. Manning

Copies 6-7: U.S. Department of the InteriorBureau of Land Management4765 Vegas DriveLas Vogas, Nevada 89126

Attention: Mr. Gary Ryan

Copy 8:

Copy 9:

Clark County Health District625 Shadow LaneLas Vegas, Nevada 89127

Attention: Mr. Clare SchmutzEnvironmental Health Director

Job File

Quality Control Reviewer:

Gerry A. Hester, P.E.Principal Engineer

WCY/kciyHLAOizs

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AGREEMENT OF PARTIES

By signature below, the following entities agree that the Sunrise Mountain Landfill, locatedin Clark County, Nevada, has been closed in accordance with the Sunrise Mountain LandfillClosure plan dated April 14, 1994.

DISPOSAL URBAN MAINTENANCEPROCESSING COMPANY, INC.

Name

Ot^Jt- P^J-J-t-AsCtj^-Sl

Title

/-IDatef

CLARK COUNTY PUBLIC WORKS

Name 7m' T-pi-trii- i~if Ptihlir Wnrlc.q

Title

Marrh ?Q.Date

UNITED STATES BUREAU OF LANDMANAGEMENT

Name

District. ManagerTitle

April 10, 1995Date

CLARK COUNTY HEALTH DISTRICT

Name

Environmental Health DirectorTitle

April 5, 1995

Date

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