CORRESPONDENCE_1982-1983 - Laserfiche WebLink

Home Browse Search

�,z i r t' caustics may react with it." Jones's concern is not limited to the A► word of caution effects of caustics. "We can predict that ®iseussics with a number of certain other chemicals that are highly D. Earl Jones is Chief of Architec- waste fill operators indicate active will cause changes in the clays,"he ture and Engineering for the Federal that disposal of chemical says. "We know many things will affect Housing Administration and an ac- wastes into such pits otten them but we just don't know everything. Live member. of ASCE's Expansive Occurs directly, without There's a vast range of unpredictable Soils Research Council. He is con- special effort to-assure that i. organic compounds, and no one has ex- cerned that information about the the wastes will not adversely plored their behavior with clay." effects of chemicals on clay that may Jf p affect clay it linings. I Solvents display significant effects on. be common knowledge among soil permeability of clay and for that reason researchers is apparently unknown to are banned from dump sites in many the hazardous waste disposal com- states; as of November they will be pro- munity. The pressing need for this Most clay soils whose shrink-swell hibited nationally under RCRA, the fed- technology transfer prompted him to characteristics are damaging to con eral Resource Conservation and Recov- write the following for CIVIL ENGt- struction have a significant montmo- ery Act. Nevertheless, says Peter Skin- NEERING: rillonite content. About $9 billion is , ner,barrels of mixed lab wastes routinely About 25%of the U.S.has what are the current best estimate of annual i landfilled at New York sites can contain commonly termed expansive clay damage in the U.S.caused by shrink up to 25 gal(95 L)of solvents and liquids soils, soils that shrink as they dry out age or swelling of such soils as they despite the state's-pcnhibition— and swell as they become wet. The change in moisture content. Why has there been so little research worst ol`t�iese soi'is contain a high per- Considerable engineering attention on the effects of aggressive chemicals on centage of sodium or calcium mont- has been directed recently toward im- the barriers landfillers use to contain morillonite, both clay minerals. Many proved quantification of the potential them? Says Earl Jones: "These things engineers are familiar with a clay shrinking and—swefilittg behavior of ous waste landfills) have grown material called bentonite, a nearly these expansive clay soils. One ap- (hazard1 (hfrom city dumps, and the operators pure natural form of montmorillonite. proach explored as a means for avoid- just don't have the money." The old city Bentonite can swell with the addition ing such behavior is chemical soil StA dump mentality of "out of SI-9177—Out OT of water by as much as 1500 as mots- bilization,which has ren success u y mm "has been carried over,he says,into ture contends varied om 6 ow the used for many years by a Denver firm: tear more comp ex e o toxic waste Shrinkage Limit moisture content to This firm has demon*tsated that ispasa. full saturation.Bentonite is often used strong caustics can be used to effect a Earl Jones's concerns about clay liner as a moisture barrier. permanent base exchange in clay soils. integrity are echoed by G. Fred Lee of SECURE LANDFILL PERFORMANCE CONSIDERATIONS Colorado State University's Department IntnaeNem cause in wi l hdeme®iate failure Resources Activities Resultant of Civil Engineering. Working with the I., I failure conditions a rcanned le,"M EPA Groundwater Research Branch in I... cgdiNont eenswnaAda, Oklahoma, Lee and his associates . Advense.abttmr (hie&heave/tea.cyclo) Cap seepage tested the effects Of various solvents On i Earthquake Real packed clay columns designed to simulate Suboptimal nyarogeotogy DesiccationInfiNrahon estate tax Perpetual liners used at chemical waste disposal cracks at to,S wre coos sites. Solvents were chosen for the test Failure m maintain sortation E c block access at Ps Vegetative because they are showing up in drinking Bad msign cnamelx marogmmre water at many places in the country. Lim,soil and SrUxi Three kinds of mixed, inter-layer type Berms.cap,N= Above Tell-tale lacer gnouM 1, clay were tested,two of which were main' silo 1 kaolinite; the third was about equal Leawte collection/ Perpetual case surveilbnce I y ,. eRhaction system plan DifferentialEinencing pparts kaolinite, illite, and montmoril on- selttemmt in place Inedawete constructba cracks ite. (Montmorillonites are the most ex- Moisture content, Monitoring pansive kind of expansive clay. In one onaoli(atrm Cap&Clan El"areo ttoi�on leachate Long-taro nearly pure form it is identical to benton- Minnolov we costs e els MBebrane iMe6;lY (time period rte, which IS sometimes mixed with CC- 1, Illicit i"°'m"m' lRce.tWV811m - mens and used in the construction of slur- Bred ) Bad operstiam j ry trenches.) The solvents tested were Banal of liquids Burial of soWents benzene, xylene, carbon tetrachloride, Barrel of incompatible vgsteFacility trichloroethylene, acetone, and glycerol, Inadequate Cordell idatim Beam repair with water as a control. r' Breach of round Yes "Our studies," Lee reports, "showed t Onplea gUrnal activity linens ' Dillerential consolidation Is aniney Leachale and that certain solvents could cause packed available gas extraction, off-site Barrel decay migration clay columns to shrink, crack, and allow, Slope Stip ton activities i S heatmeM or _ Gas production remedia4iont incineration of waste rapid transport Of eQntained materials lute dissolution LeachaU deeateling Meek No through them.Some clay liners in contact luteleacDdm wasting with these solvents may not contain the materials they were designed to." Lee i' cautions that the lab results don't neces- Flg.2.Flow diagram illustrates the potential causesand effects of breeches of security at a"secure" sarily mean that the chemicals tested hazardous waste landfill Causes include design flaws.operating errors,and acts of God.effects should be barred from every dump site. include perpetual site monitoring,maintenance and financing,or else oA'-site migration of wastes. That's just the point:the on-site effects of (Diagram courtesy Peter N.Skinner.) 62 Civil Engineering-ASCE July 198`