UFC 3-280-02A Hazardous Waste Land Disposal/Land Treatment ...

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charts for determining the peak rate of discharge fromsmall watersheds, based on values for surface soil typesand antecedent moisture conditions. Basic informationand values are summarized in EPA 60012-79-165 anddetailed in the US Department of Agriculture’sengineering field manual.(4) Sedimentation basins are sized based onanalysis of settlement time for suspended solids, i.e.,sands, silts and clays. Sizing procedures are provided inTM 5-820-1 through TM 5-820-4. The trapping efficiencyof a basin is related to its surface area; the basin’s depthonly provides for sediment storage. The latter documentprovides an assessment of SCS sizing criteria, anddemonstrates that constructing basins to control claysizedparticles during peak flows may not be practicablebecause the basins would need to be ten times largerthat those used for control of silts.6-6. Gas control systems6-21a. Introduction. Gaseous emissions fromhazardous waste land disposal facilities-includinglandfills, surface impoundments, and land treatmentsites-generally fall into two categories: (1) methane gas,produced by the anaerobic decomposition of organicwastes, and (2) toxic vapors, produced by thevolatilization of chemical wastes. Methane gas,explosive in concentrations of 5 to 15 percent by volumein air, is generated mainly in landfills containing organicwastes; waste volatilization can occur at landfills, surfaceimpoundments and land treatment sites.(1) There are no specific regulations for controlof gaseous emissions at hazardous waste facilities. Inlandfills containing organic wastes, compliance with theRCRA solid waste criterion for explosive gases isrecommended (40 CFR section 257.3-8). This criterionstipulates that methane concentrations at the propertyboundary not exceed the lower explosive limit (LEL) of 5percent; in facility structures the limit is 25 percent of theLEL, or 1.25 percent methane.(2) EPA regulations do not specifically addressthe effects of hazardous waste land disposal facilities onair quality, due to the limited information on emissionsfrom such facilities and the fact that the problem iswaste-specific. However, 40 CFR 241.206-2recommends that the need for gas control should beassessed; if the need for control measures is warranted,the location and design elements for vents, barriers orrelated systems should be provided on design plans forthe facility. A collection system is not required at newfacilities if the owner/operator can demonstrate that nogas will be produced or, if produced, would neithercontribute any air pollutant to the atmosphere nor createa flammable or explosive environment.b. Control techniques. Control techniques for volatileemissions from surface impoundments and landtreatment sites are largely preventive in nature. Emis-TM 5-814-7sions from surface impoundments can be minimized byincreasing impoundment depth and decreasing surfacearea, and by constructing wind barriers. Removal ofvolatiles from the waste stream by stream stripping,distillation or incineration can also be used, wherepractical. In all cases, codisposal of reactive and/orincompatible wastes should be avoided. At landtreatment facilities, volatilization can be mitigated byinjecting volatile substances at least 6 inches below theground surface into moist but friable soils.(1) Venting is required at surface impoundmentsif gases accumulate beneath a liner and build uppressure. Sufficient gas pressure can lift the liner,creating an area where additional gas can accumulate.The higher the "gas bubble" rises, the more themembrane stretches and the less the hydrostaticpressure is able to restrain the membrane. If thiscondition is not controlled by venting, the liner couldrupture or float to the surface of the impoundment.(2) A number of control alternatives are availableat landfills. Choice of the appropriate control system willdepend on control objectives and involve determinationof the type of wastes present, the depth of fill, and thesubsurface characteristics of the sites and adjacentareas. In addition, field measurements should be usedto determine gas concentrations, positive and negativepressure, and soil permeability.(3) Atmospheric pipe vents, either of the "U" ormushroom configuration, can be used in landfills tocontrol vertical movement of gases; they are mosteffective in areas where gases are collecting andcausing pressure buildup. For example, venting iseffective in preventing uplift of the top liner followingclosure of a landfill. Forced ventilation, on the otherhand, provides an effective means of controlling bothlateral and vertical migration of gases. Such systemsusually employ a series of pipe vents or wells installedwithin lined landfills and are connected by a manifold to amotor blower. The effectiveness of vent trenches can beincreased by capping the trench with clay or otherimpervious material and employing lateral and riser pipesconnected by a manifold to a motor blower. The gas tobe vented or withdrawn from the landfill may requirecollection and treatment to control odors and to preventdischarge of volatile toxics to the atmosphere.c. Design considerations and constraints. Pipevents are usually constructed of perforated PVC pipeinstalled in a gravel pack to prevent clogging andencourage gas migration to the vent. They should besealed to prevent excess air from entering the systemand to prevent methane or volatile toxics from leakingout. The key design considerations in installation of pipevents, as part of either atmosphere or forced ventilationsystems, are proper placement and spacing. Anadditional consideration for forced ventilation sys-CANCELLED
tems is the gas flow rate. Flow rates should be at leastequal to the rate of gas production but low enough toprevent excess oxygen from being drawn into thesystem. Details concerning proper design of pipe ventsystems are contained in Methane Generation andRecovery from Landfills, EMCON Associates (1980).(1) Vent trenches are constructed by excavatinga deep trench which is backfilled with gravel to provide apath of least resistance through which gases can migratevertically. Design considerations in constructing venttrenches include ensuring proper ventilation by backfillingwith sufficiently permeable material and avoidinginfiltration of precipitation and clogging by solids. Inpassive closed vent trenches, ventilation can beenhanced by proper design of laterals and risers.(2) In active vent trenches with forced ventilation,the equations and design criteria for active control wellsapply, with allowances for the smaller area and greaterpermeability of the trench backfill. The key designconsideration for vent trenches is that the depth of thetrench extend to the ground-water table or anunfractured impervious stratum to prevent gas frommigrating under the trench.6-7. Final covera. Regulatory requirements. Final cover isrequired for closure of all hazardous waste landfills,surface impoundments developed for waste disposal,and those surface impoundments and waste piles atwhich all contaminated subsoils cannot be removed ordecontaminated at closure.TM 5-814-7(1) Specific regulations concerning final coverare summarized in table 6-6. The prime function offinmal cover is to minimize infiltration of precipitation.Other functions include preventing contamination ofsurface water run off, wind dispersion of hazardouswaste, and direct contact with hazardous waste byanimals or humans. To prevent liquid accumulationwithin closed disposal units, the regulations specify finalcover must have a permeability less than or equal to thepermeability of any bottom liner system or naturalsubsoils present.(2) For long-term performance with minimummaintenance, the final cover must be designed topromote drainage, minimize erosion, precludeaccumulation of gas pressures, and accommodatesettling and subsidence.b. Elements of the cover system. Designfeatures and criteria recommended for final cover in theEPA guidance documents are shown in figure 6-10. Therecommended three-layered final cover includes:* A soil layer for vegetation* A drainage layer* A low permeability layer(1) The upper soil layer is to sustain vegetationand minimize erosion of the cover; the middle drainagelayer is to carry infiltrating water from sustainedprecipitation to the sides of the cover for discharge; thelow-permeability layer is to prevent fluid inflow andensure that infiltrating water is carried by the drainagelayer.(2) An overview of procedures for evaluating clo-Table 6-6. Requirements for Surface Water Run-on and Run-off Control SystemsSection of 40 CFR 264 Describing RequirementsK L M NDesign Requirements Surface Impoundments Waste Pile Land Treatment LandfillCover the unit with a final cover designed andconstructed to: ’ 264.2282(iii) May apply NA 264.310(a)Provide long-term minimization of themigration of liquids through the closed unit.Function with minimum maintenance Promotedrainage and minimize erosion or abrasion ofthe final cover Accommodate settling andsubsidence so that the cover’s integrity ismaintained; and Have a permeability less thanor equal to the permeability of any bottom linersystem or natural subsoils present.Maintain the integrity and effectiveness of the finalcover, including making repairs to the cap asnecessary to correct the effects of settling,subsidence, erosion, or other events. 264.228(bXl) May apply* NA 264.310(bXl)Prevent run-on and run-off from eroding orotherwise damaging the final cover. 264.228(bX4) May apply’ NA 264.310(bX5)*If not all contaminated subsoils can be practicably removed or decontaminated, the unit must be closed in accordancewith requirements that apply to landfills.CANCELLEDAdapted from 40 CFR 2646-22
Page 2 and 3: ARMY TM 5-814-7HAZARDOUS WASTE LAND
Page 5 and 6: TM 5-814-7LIST OF FIGURESPageFigure
Page 7 and 8: CHAPTER 2TM 5-814-72-1. Federal reg
Page 10 and 11: Table 3-1. Composition and Quantity
Page 12 and 13: ial. All facilities must be designe
Page 14 and 15: Table 3-2. Design/Operational Requi
Page 16 and 17: (Identification and Listing of Haza
Page 18 and 19: TM 5-814-7Figure 5-1. Illustrative
Page 20 and 21: 5-4The structure should be designed
Page 22 and 23: c. Procedures. Impoundment of hazar
Page 24 and 25: particular soil, the compatibility
Page 26 and 27: d. Design elements. Design requirem
Page 28: (3) Basic equipment for subsurface
Page 33 and 34: TM 5-814-7of preventing migration o
Page 35 and 36: priate coatings would be a suitable
Page 37 and 38: TM 5-814-7Figure 6-3. Base liner de
Page 39 and 40: Table 6-2-Summary of Liner Types-Co
Page 41 and 42: TM 5-814-7Figure 6-4. Typical clay
Page 43 and 44: Table 6-4. Requirements for Leachat
Page 45 and 46: conductivity of the drainage layer
Page 47 and 48: TM 5-814-7Figure 6-6. Typical run-o
Page 49 and 50: TM 5-814-7Figure 6-8. Typical run-o
Page 51: TM 5-814-7Figure 6-9. Run-on sedime
Page 55 and 56: 6-24sure covers is provided in EPA
Page 57 and 58: Table 6- 7. Requirements for Specia
Page 59 and 60: CHAPTER 7OPERATIONS AND CONTINGENCY
Page 61 and 62: TM 5-814-7tending into the area of
Page 63 and 64: ing hydrogeologic conditions are de
Page 65 and 66: TM 5-814-7CANCELLEDFigure 8-2. Moni
Page 67 and 68: CHAPTER 9TM 5-814-79-1. Introductio
Page 69 and 70: 10-1. Cost Elementsa. Cost elements
Page 71 and 72: APPENDIX ATM 5-814-7Government Publ
Page 73 and 74: TM 5-814-7Table B-I. Summary of RCR
Page 75 and 76: APPENDIX CTM 5-814-7C-1. Purpose an
Page 77 and 78: TM 5-814-7CANCELLEDC-3
Page 79 and 80: (c) Based upon these calculations,
Page 81 and 82: The proponent agency of this public
Page 83 and 84: CANCELLEDPIN: 057162
Page 85: UFC 3-280-02A16 January 2004FOREWOR

UFC 3-280-02A Hazardous Waste Land Disposal/Land Treatment ...

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