Abstract:
A method of chemically and physically treating unconsolidated soils, over burden, fill and certain waste materials (the “ground”), or partly consolidated materials that can be excavated and broken up by normal earth moving and soil mixing equipment. This treatment results in the reduction of permeability in the ground, and as a result permits the prevention or control of contaminant migration from a site containing ground wastes of various types, thereby isolating these wastes.

Description:
FIELD OF THE INVENTION 
     This invention pertains to a system for the reduction of permeability in unconsolidated soils, over burden, fill and certain waste materials (the “ground”), or partly consolidated materials that can be excavated and broken up by normal earth moving and soil mixing equipment. The system permits the prevention or control of contaminant migration via groundwater flow or surface water (precipitation) infiltration from a site containing ground wastes (other than garbage) of various types, thereby isolating these wastes. In some applications the system may also increase the cohesion and mechanical strength of unconsolidated ground. 
     BACKGROUND OF THE INVENTION 
     In nature, the lithification of unconsolidated materials commonly occurs by the infilling of intergranular void space with interstitial material deposited from solution as mineral overgrowths and cements. This loss of void space progressively decreases the primary permeability and could reduce it to insignificance. A close natural analog of the Natural Analog System (NAS) is the formation of “caliche” soils in the southwestern United States desert regions. Such regions are typically characterized by dry lake beds that are progressively cemented by salts precipitated from the occasional run-off precipitation which reaches the lake basin and then evaporates. 
     Another example of a natural analog of the NAS is the formation of low permeability “hard pan” soil zones caused by precipitation of cement via ground water evaporation at the sub-surface water table interface. The most common precipitate cement in these examples are calcium carbonate (CaCO 3 ) and various forms of silica (SiO 2  or SiO x (H 2 O) y ) as compatible in ambient alkaline or acid environments, respectively. Most ground waters, however, are neutral to alkaline (pH&gt;7.0). NAS is primarily designed for this situation. 
     The NAS process follows the same principle of reducing void space to reduce permeability by artificially stimulating or inducing void space filling via interstitial precipitation, crystallization, and addition of particulates plus or minus cementation to duplicate that natural process, but much faster. 
     Related methods of treatment of ground strata include U.S. Pat. No. 4,869,621, issued on Sep. 26, 1989 to McLaren et al. for METHOD OF SEALING PERMEABLE EARTH SURFACE OR SUBSURFACE MATERIALS HAVING ALKALINE CONDITIONS BY INDUCED PRECIPITATION OF CARBONATES. McLaren et al. propose a method of artificially sealing voids in earth strata under alkaline conditions by inducing precipitation, via pumped slurries of aqueous solutions which may include finely divided solids, for example, of calcium carbonate, usually in the form of calcite. 
     U.S. Pat. No. 4,981,394, issued on Jan. 1, 1991 to McLaren et al. for METHOD OF SEALING PERMEABLE UNCONSOLIDATED MATERIALS. McLaren et al. propose a method for forming solid layers or local zones of material upon or below the earth&#39;s surface and above the water table to inhibit the flow of ground waters through such layers of materials. 
     The NAS process is a method of precipitating calcium carbonate cement in the ground that duplicates natural geologic cementing mechanisms. Calcium carbonate, the artificially produced product of the process, is analogous to the naturally produced calcium carbonate cements of sedimentary rock. A significant potential use, among several, of the NAS process is to reduce or eliminate ground water flow-though in contaminated soils and rocks, and thereby immobilize and isolate such sources of contamination in the natural environment. A principal advantage of the NAS process in environmental remediation and engineering applications is that the cement (calcite) is a natural analog, the permanence of which can be established by comparison with similar naturally calcite-cemented geologic materials. The NAS process introduces the concept of using such natural analog materials in environmental remediation and restoration projects rather than using artificial materials. Such artificial materials can not be assessed in terms of very long-term performance of the projects in various geologic settings. 
     The principal advantage of the NAS process when used in environmental remediations and restorations is that it can be applied by fluid injection in situ, that is, without excavation and processing of the contaminated-site soil or rock. A contaminated site can be isolated from the ambient ground water and immobilized as a source of hydrologically transported chemical species, without disturbance of surrounding terrain or structures. Further, the subsequent long-term performance of the remediated site can be determined by comparison with naturally occurring carbonate-cemented sites. Where appropriate, the NAS process can be applied by physically mixing NAS process components in contaminated soil and waste material to achieve remediation. 
     An important aspect of the NAS process is the induced precipitation of ancillary compounds that bind or capture hazardous chemical species from ground water or directly from the waste associated with a contaminated site. Such compounds are analogs of minerals known to be stable (insoluble) in such hydrogeologic conditions. The result is the immobilization of various hazardous chemical species (e.g., lead) into artificial minerals, the subsequent long-term environmental permanence of which can be documented by comparison with the equivalent naturally occurring minerals. 
     It is an object of this invention to reduce and/or eliminate soil/rock permeability and achieve isolation from ground water flow/pathways in land-fill, hazardous and toxic waste-site, and radioactive waste-site remediation. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided a method of using the Natural Analog System (NAS) to reduce the permeability of ground. A waste zone is impregnated with a composition to produce a precipitate that fills pore space. The aforementioned composition can include solutions, solid-phase fillers, ancillary reactants (solutions and gases), and specific contaminant remediation agents (e.g., agents for petroleum products that are compatible with neutral to alkaline ambient conditions such as alkali silicate hydrocarbon degradation agents). This waste zone impregnating step is repeated until refusal occurs. The aqueous composition is selected from the group of:
 
CaCl 2 (solution)+Na 2 CO 3 (solution),
 
CaCl 2 (solution)+Na 2 SO 4 (solution),
 
CaCl 2 (solution)+Na 2 HPO 4 (solution),
 
CaCl 2 (solution)+2NaOH(solution), and
 
FeCl 3 (solution)+3NaOH(solution)=3NaCl+Fe(OH) 3  
 
     The composition can also be a solution and a gas phase. In one embodiment of the preceding group, the solution is 2NaOH+CaCl 2 , and the gas phase is CO 2 . 
     First, to achieve long term stability (i.e., as a natural analog (calcite)) the treatment is stable indefinitely in the present geological or physiochemical environment. After application, because of resulting “self healing” properties within the ambient system, the treated soil/rock will not fail because of rupture or stress fracturing such as occurs in concrete, degradation or flocculation (concrete, clay caps, and slurry walls), or external changes in the state of oxidation/reduction (specific metal compound precipitates). NAS process products are stable, non-toxic analogs of naturally occurring minerals. 
     Second, to achieve self-healing, additional buffering and latent reactive capacity can be built into a specific application in anticipation of an unpredictable future activation, as an added protection. The treated site-system can be designed to be self-healing on a long term basis, or it can be designed to be gradually or continually implemented over time. Treatment additions or repairs to ground missed during initial application are easily performed. 
     Third, to provide a solution to permeability reduction that is commercially viable, the NAS process uses chemicals/preparations that are readily available in bulk commercial lots; cost-per-ton for materials is much less than cement. Waste zone permeation is proportional to void space (L+water), not to the volume dilution (3:1 and greater) required to make concrete. It is likely that application and engineering costs would dominate over the cost of materials in any commercial scale project, in terms of cost of treated material, except for projects where ground surface dispersal of the process treatment materials or constituents that utilize meteoric water infiltration are appropriate (dry-mix, least expensive application). 
     Fourth, to provide a solution to permeability reduction that may be implemented in otherwise untreatable waste sites, (i.e., in combination with directed drilling techniques such as navigational drilling, and geophysical methods of monitoring underground injection), it is possible to apply the NAS process to otherwise untreatable waste sites, such as where surface access is restricted, sealing beneath an existing landfill or dump, diverting groundwater flow, or treatments beneath bodies of water or in marine environments. 
     In addition, a further objective of this invention is to provide solutions to problems other than waste-site remediation. For example, the process can be used to stiffen or increase the cohesion of soils subject to liquefaction such as in permafrost regions (e.g., road beds, building foundations) and seismic zones; as a slurry wall substitute in areas of salt water incursion where clay walls degrade; as a cementations fill in salt water environments wherein the product hardens and is stable indefinitely; as an admixture with coal/fly/incinerator ash for disposal of the ash and/or its use to fill abandoned coal mines or other cavities or workings that are subject to collapse, or the use of the ash as a cementations slurry; as an advanced preparation of sub-soils in construction sites to mitigate the effects of future waste spills or storage (anticipatory remediation); as an injectable low-viscosity slurry in construction applications using sand or other admixtures; and various other applications wherein the natural analog advantage of the process is beneficial. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A complete understanding of the present invention may be obtained by reference to the accompanying drawings, when considered in conjunction with the subsequent detailed description, in which: 
         FIG. 1  is a graph of test results on a first sample in accordance with the method of the invention; 
         FIG. 2  is a graph of test results on a second sample in accordance with the method of the invention; and 
         FIG. 3  is a moisture-density (i.e., Proctor) curve showing the relationship between the dry unit weight (density) and the water content of the waste material for a given compactive effort. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     This technology emphasizes compatibility with ambient natural conditions, and is a natural analog process; the results and predicted durability of a treatment can be evaluated by comparison with natural geologic examples. The technology stiffens or solidifies soil/rock masses in a way that is analogous to the natural formation of sedimentary rock (lithification). 
     By using this technology, hazardous sites can be remediated in situ, by the introduction of finely divided solids or slurries, or liquid chemicals, by injection with drilled pathways and installed pipes, by use of seepage trenches, and/or by admixture of solid remediation components, and/or by direct admixture of various components as by commercial soil-mixing technologies. This avoids removal and off-site treatment and disposal of the waste/soil. The products of the remediation process are artificially produced analogs of naturally occurring substances or reaction breakdown products that are not hazardous. 
     Moreover, natural analog minerals can be caused to form during or after remediation. Those minerals are insoluble in the ambient system and chemically bind toxic components such as Pb and Cr ions from the waste. Additionally, in this sense chemicals and elements can be introduced into the waste during treatment that react in the waste zone and adsorb toxic chemical species. For example, iron in solution can be introduced into the waste zone and will then oxidize to produce Fe(OH) 2 , a natural analog of the mineral limonite, that then adsorbs and chemically binds a toxic element such as chromium into this resultant insoluble mineral (limonite). These resultant minerals are called “designer minerals” in that specific reactions and mineral products can be produced, during and after application that bind, or “lock-up” specific toxic components that are in the contaminated soil/waste. 
     This technology can also be used to treat sites in anticipation of future events, for example, before they might become contaminated. Subsurface soil/rock of a site can be treated, for example, upon which a chemical plant, petroleum refinery, factory, etc., is to be built. This is “anticipatory remediation” in that specific treatments to reduce or eliminate the permeability of a specific site can be introduced in anticipation of future use of the site. Anticipatory remediation would be a general civil engineering/construction practice, usually involving non-hazardous soil/rock that is intended to protect the subsurface environment in anticipation of contamination. Such contamination would include, but not be limited to, future spills of hazardous materials on the treated site, accidental or otherwise. 
     Further use of this technology in the sense of anticipating future events involves the strengthening or solidification of soils/rocks by application of the process through admixture or injection of the chemical components that precipitate the carbonates or other products. For example, the technology can improve the stability of sites that are susceptible to changes or damage caused by erosion, flooding, subsurface water-flow or human activities. Soil/rock slumping and mass wasting of natural and artificial slopes can be reduced or eliminated by the stiffening or solidification of the soil/rock. Such solidification of soil/rock in regions of permafrost or seasonal freezing that reduces or eliminates permeability of sub-surface water, would remediate the effects of frost-heaving wherein water within soil bedrock freezes, expands, and causes subsurface and surface disturbance. 
     Examples of such applications are constructions of road-beds, building foundations, and aircraft landing strips. Yet another use of the process is to reduce or eliminate the permeability of soils that are susceptible to soil liquefaction, induced by human or natural events. Examples include soils that are susceptible to liquefaction during construction, or during use of constructions, such as roads and railways, and general construction in fresh water, marine and shore-line environments that involve saturated soils. In seismically active regions, or regions that are otherwise susceptible to seismic energy, soils that are prone to liquefaction could be treated to reduce or eliminate permeability to subsurface water and reduce or eliminate susceptibility to soil liquefaction. 
     The chemical remediation or treatment of waste sites operates by inducing chemical reactions or combinations of the waste components with materials that are added to, or impregnate, the waste in its host soil or matrix. The remediation effect also includes accompanying physical changes in the waste/host mass that act to support or enhance the chemically induced changes. In some applications the physical changes alone may be the primary remediation. The objective of chemical remediation in any case, however, is to isolate, or prevent migration of waste components from the disposal site. Inasmuch as transportation in ground or surface waters is the most common contaminant pathway for inorganic and many organic wastes, chemical remediation acts by a) altering waste components to insoluble or immobile forms that are stable under natural ambient conditions, and b) reducing the permeability of the waste site, or sealing it in respect to the transmission of ground or soil water. This technique of remediation is applied on a site-specific basis that is tailored to the site conditions and waste composition. Both the materials used in chemical remediation and the application methods are specific adaptations of this general concept. 
     Chemical Effects 
     Chemical effects that are invoked in this new remediation technology include: 
     precipitation from solution. For example:
 
Ca ++ +CO 3   −− =CaCO 3 (precipitate) as calcite cement.
 
     Reactions between waste and added solutions yielding insoluble products. For example:
 
Pb ++ +CO 3   −− =PbCO 3 ;
 
Ba ++ +Cr 2 O 7   −− =BaCr 2 O 7 ;
 
2Hg ++ +Na 2 S 2 =2HgS+2Na + .
 
     Adsorption of ions is effected by added adsorptants. For example: Pb ++  adsorbed and chemically bound into Fe(OH) 2  or other basic iron hydroxy-oxides. Such adsorptants can be created by the use of FeCl 3  solution in addition to the calcium ion solution, wherein exposure to alkaline pH will cause the precipitation of ferric hydroxide solid, a phase well known to adsorb heavy metals and effectively remove them from further dispersal or migration, which subsequently flocculates to particulate form (limonite or goethite, etc.). No oxidation reduction step is needed, although ferrous iron solution could certainly be used in a specific case. For example:
 
FeCl 3 =Fe(OH) 3 (sol or gel).
 
     In some cases oxidation-reduction couples can yield a more insoluble or less toxic product. For example:
 
As 5+ +2HOH+3Fe 0 =As 3+ +Fe ++ (FeOH) 2  
 
6Fe ++ +Cr 2 O 7   −− =Cr 2 O 4   −− +6Fe 3+ .
 
     Reactions can produce components known to occur as stable phases in nature under the same ambient conditions. For example:
 
Ca(OH) 2 +CO 2 =CaCO 3 +HOH;
 
Ca ++ +SO 4   −− =CaSO 4 ;
 
2Mg ++ +HOH+CO 2 =Mg 2 (OH) 2 CO 3 (basic magnesium carbonate).
 
     Buffering capacity provided at the site helps complete reactions and provides continued reaction capacity, and helps control pH. 
     Physical Effects 
     Physical changes that are intended to accompany a chemical remediation application include a reduction of soil/waste permeability and an increase in soil/waste cohesion or consolidation as a result of pore-filling and cementation/crystal growth enhancements. These changes are desired in order to restrict or inhibit the long-term access of ground/soil water to the waste, and any resultant leaching effects. An example of this is the NAS process which introduces a calcium carbonate matrix into the waste zone via application techniques that include: 
     a) Admixture of solid reactants with the waste, which subsequently react in the presence of water (e.g., CaCl 2  and Na 2 CO 3 ). 
     b) Admixture of finely particulate solid components that subsequently crystallize, react, or bond with the waste/soil (e.g., CaCO 3  as calcite or aragonite, Ca(OH) 2 —hydrated lime, CaO—lime, and others). A variation of this technique with added matrix materials (e.g., fly ash, incinerator ash, cement kiln slag and ash, etc.) can be used to fill larger void spaces of coarse ground/waste materials such as gravels, coarse sands, waste debris, etc., found in abandoned mine workings. 
     c) Introduction or impregnation of the waste zone, which is waste and admixed soil or overburden, with sequential solutions that react to produce a precipitate that fills pore-space (e.g., CaCl 2  (solution)+Na 2 CO 3  (solution)=CaCO 3  (precipitate)+2NaCl (solution loss to external soil/groundwater). This application of the solutions can be repeated until refusal occurs. Other examples of these solutions include CaCl 2 +Na 2 SO 4 =CaSO 4  (precipitate)+NaCl (solution); CaCl 2 +Na 2 HPO 4 =Ca 3 (PO 4 ) 2  (precipitate)+NaCl (solution). 
     d) Sequential solution-gas phase impregnation of the waste zone to produce a calcium carbonate precipitate and cementing action, or result, as the reaction proceeds. For example:
 
2NaOH+CaCl 2 =Ca(OH) 2 (precipitate)+2NaCl(solution);
 
Ca(OH) 2 +CO 2 (introduced)=CaCO 3 +2(OH − ).
 
     Another embodiment of this application is the admixture of solid hydrated lime or the introduction of slaked lime into the waste zone prior to the introduction of CO 2 . Yet another embodiment of the above remediation applications is the introduction of silica gel into the waste zone as the pore-filling agent. This can be accomplished via infiltration or impregnation of an aqueous alkali-silicate solution to which a suitable gelling agent (e.g., brine salts) has been added at the point of solution introduction so that gelation occurs after emplacement. However, to prevent dehydration of the gel, this embodiment is restricted mostly to wastes of acid pH at and within the saturated zone. 
     Example I 
     A specific example including the results of a field trial of this invention is shown below. 
     Sample and In-Situ Measurement Collection 
     Samples of “Solvay” waste (waste material produced by Solvay Process Corporation primarily from the production of soda ash) were collected from the surface (upper 24 inches) of Honeywell waste bed #14 in Syracuse, N.Y. Honeywell International is currently the owner of the former Solvay waste beds. The samples were hand collected and transported in polyethylene-lined, five gallon pails that were sealed. At the time of collection in-situ measurements for moisture, wet density and dry density were measured with a Troxler nuclear gauge (Troxler, 349 1-B Series, Surface Moisture-Density Gauge) at the sampling site. Additional measurements were made at approximately 20 meters from the sampling site along N-S, and E-W axes. Samples were collected Jun. 7, 2000. The GPS coordinates for the sampling site and field measurement sites, moisture and density measurements are given in Table 1. 
                                                                 TABLE 1                   Honeywell waste bed sampling            SITE   SAMPLE       WET   DRY       LOCATION   LOCATION   MOISTURE 1     DENSITY 2     DENSITY 2                      43°03′95N   43°03′96N   118.6   76.7   35.1       76°15′70W   76°15′70W       43°03′95N       91.0   77.9   40.8       76°15′71W       43°03′95N       101.2   73.1   35.3       76°15′70W       43°03′95N       85.8   74.0   39.8       76°15′68W       43°03′95N       85.1   79.7   43.1       76°15′69N                 1 Moisture by Dry Weight;         2 lbs/Ft 3              
Standardized Testing
 
     The NAS chemical process was tested for its ability to reduce the hydraulic conductivity of Honeywell waste bed material. The following testing methods and protocols were used in conducting the testing: 
     Laboratory Services:
         Parrott-Wolff, Inc.   East Syracuse, N.Y. 13057   (Hydraulic Conductivity, Proctor Tests)   Life Science Laboratory   East Syracuse, N.Y. 13057   (process solution preparation)       

     Analytical Methods:
         ASTM D 5084-90: Standard Test Method for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter   ASTM D 89$: Test Method for Laboratory Compaction Characteristics of Snits Using Standard Effort (12.400 ft. lbs/ft 3 )   ASTM D 2922: Standard Test Method for Density of Soil and Soil-Aggregate in Place by Nuclear Methods (Shallow Depth)   ASTM D 3017: Standard Test Method for Water Content of Soils and Rock in Place by Nuclear Methods (Shallow Depth)       

     Equipment:
         Troxler 3411-B Series Surface Moisture-Density Gauge   Brainard-Kilman E-4flO Digital Transducer integrated with a Trautwein Flexible-Wall Permeameter and Bladder Accumulator       

     Process Fluids:
         The specific chemical composition of the process fluids used in the testing of the Natural Analog System are proprietary. Process fluid “A” is a carbonate source delivered at −85% saturation and Process fluid “B” is a calcium ion source delivered at 100% saturation.       

     
       
         
               
             
               
               
             
           
               
                   
               
               
                 Procedure Application 
               
               
                 Sample #14207C 
               
             
          
           
               
                 DATE 
                 PROCEDURES 
               
               
                   
               
               
                 Sep. 5, 2000 
                 The sample material was 
               
               
                   
                 compacted in accordance with 
               
               
                   
                 ASTM D698 (Standard Compaction). 
               
               
                   
                 The water content, at the time 
               
               
                   
                 of compaction was 93.8 as a 
               
               
                   
                 percent of dry weight. The dry 
               
               
                   
                 density, after compaction, was 
               
               
                   
                 determined to be 44.3 pcf. 
               
               
                 Sep. 6, 2000 
                 The sample was placed into the 
               
               
                   
                 trixial confinement cell. A #200 
               
               
                   
                 (0.074 mm) size stainless steel 
               
               
                   
                 mesh screen was used in place of 
               
               
                   
                 the typical filter paper and 
               
               
                   
                 porous stone, in order to avoid 
               
               
                   
                 any false positive reduction in 
               
               
                   
                 permeability due to clogging in 
               
               
                   
                 the paper and/or stone. 
               
               
                   
                 The sample saturation process 
               
               
                   
                 began as backpressure was 
               
               
                   
                 applied by simultaneously 
               
               
                   
                 increasing the cell pressure and 
               
               
                   
                 the influent and effluent 
               
               
                   
                 pressures in 5 psi increments. 
               
               
                   
                 During this incremental 
               
               
                   
                 procedure, the influent and 
               
               
                   
                 effluent pressures are kept 
               
               
                   
                 equal while the cell pressure is 
               
               
                   
                 maintained at 5 psi greater than 
               
               
                   
                 the influent and effluent 
               
               
                   
                 pressures. 
               
               
                   
                 During this procedure, regulated 
               
               
                   
                 air pressure is applied to a 
               
               
                   
                 column of desired water. In 
               
               
                   
                 turn, the deaired water 
               
               
                   
                 transfers the applied pressure 
               
               
                   
                 to deaired process fluid 
               
               
                   
                 (previously diluted to 85.0 
               
               
                   
                 percent saturation) across an 
               
               
                   
                 impermeable flexible membrane. 
               
               
                   
                 Ultimately the deaired process 
               
               
                   
                 fluid applies the regulated 
               
               
                   
                 pressure to and into both ends 
               
               
                   
                 of the confined sample. This 
               
               
                   
                 replaces any air in the influent 
               
               
                   
                 and effluent lines, as well as 
               
               
                   
                 any air filled pores in the 
               
               
                   
                 sample, with the desired deaired 
               
               
                   
                 fluid. 
               
               
                 Sep. 8, 2000 5:27PM until 
                 Saturation continued using the 
               
               
                 Sep. 12, 2000 2:45PM 
                 deaired process fluid “A” 
               
               
                   
                 solution until a B coefficient 
               
               
                   
                 (saturation) of 98% was obtained 
               
               
                   
                 in the sample (a minimum of 95% 
               
               
                   
                 saturation is normally 
               
               
                   
                 required). 
               
               
                 Sep. 12, 2000 3:01PM to 
                 An initial gradient of 30 was 
               
               
                 3:42PM 
                 then applied to the sample to 
               
               
                   
                 begin the test run using the 
               
               
                   
                 process fluid as the influent. 
               
               
                   
                 Forty-one minutes after the test 
               
               
                   
                 was begun, the first preliminary 
               
               
                   
                 hydraulic conductivity was 
               
               
                   
                 obtained and determined to be 
               
               
                   
                 1.8 × 10 −5  cm/sec. The hydraulic 
               
               
                   
                 gradient was then reduced back 
               
               
                   
                 to zero in order to temporarily 
               
               
                   
                 halt the test. 
               
               
                 Sep. 13, 2000 7:00PM to 
                 The initial gradient of 30 was 
               
               
                 8:31PM 
                 reapplied and a minimum of one 
               
               
                   
                 void volume of process fluid 
               
               
                   
                 (approximately 670 milliliters) 
               
               
                   
                 was put through the sample. The 
               
               
                   
                 hydraulic gradient was then 
               
               
                   
                 reduced back to zero in order to 
               
               
                   
                 temporarily halt the test. A 
               
               
                   
                 hydraulic conductivity was not 
               
               
                   
                 obtained after an additional 96 
               
               
                   
                 minutes of run time. 
               
               
                 Sep. 14, 2000 8:36AM to 
                 The initial gradient of 30 was 
               
               
                 4:11PM 
                 reapplied. A second test run was 
               
               
                   
                 begun and continued for 455 
               
               
                   
                 minutes. The second preliminary 
               
               
                   
                 hydraulic conductivity was 
               
               
                   
                 obtained and determined to be 
               
               
                   
                 5.1 × 1 −6  cm/sec. The hydraulic 
               
               
                   
                 gradient was then reduced back 
               
               
                   
                 to zero in order to temporarily 
               
               
                   
                 halt the test. 
               
               
                 Sep. 20, 2000 8:00AM to 
                 The initial gradient of 30 was 
               
               
                 9:50AM 
                 reapplied. The test run was 
               
               
                   
                 begun and continued for 110 
               
               
                   
                 minutes. A third preliminary 
               
               
                   
                 hydraulic conductivity was 
               
               
                   
                 obtained and determined to be 
               
               
                   
                 3.4 × 10 −6  cm/sec. The hydraulic 
               
               
                   
                 gradient was reduced back to 
               
               
                   
                 zero in order to temporarily 
               
               
                   
                 halt the test. 
               
               
                 Sep. 22, 2000 8:13AM to 
                 The initial gradient of 30 was 
               
               
                 8:43AM 
                 reapplied and deaired process 
               
               
                   
                 fluid “B” solution was 
               
               
                   
                 introduced into the sample. The 
               
               
                   
                 test run was begun and continued 
               
               
                   
                 for 30 minutes. A fourth 
               
               
                   
                 preliminary hydraulic 
               
               
                   
                 conductivity was obtained and 
               
               
                   
                 determined to be 1.2 × 10 −6  cm/sec. 
               
               
                 Sep. 22, 2000 8:43AM to 
                 The test continued to run an 
               
               
                 4:18PM 
                 additional 455 minutes. A fifth 
               
               
                   
                 preliminary hydraulic 
               
               
                   
                 conductivity was obtained and 
               
               
                   
                 determined to be 8.3 × 10 −7  cm/sec. 
               
               
                   
                 The hydraulic gradient was 
               
               
                   
                 reduced back to zero in order to 
               
               
                   
                 temporarily halt the test and to 
               
               
                   
                 let the sample “cure”. 
               
               
                 Sep. 25, 2000 9:47AM to 
                 The initial gradient of 30 was 
               
               
                 4:59PM 
                 reapplied. The test run was 
               
               
                   
                 begun and continued for 432 
               
               
                   
                 minutes. A sixth preliminary 
               
               
                   
                 hydraulic conductivity was 
               
               
                   
                 obtained and determined to be 
               
               
                   
                 9.9 × 10 −7  cm/sec. The hydraulic 
               
               
                   
                 gradient was reduced back to 
               
               
                   
                 zero in order to temporarily 
               
               
                   
                 halt the test. 
               
               
                 Sep. 27, 2000 8:42PM to 
                 The initial gradient of 30 was 
               
               
                 5:59PM 
                 reapplied and the process fluid 
               
               
                   
                 “B” solution was introduced into 
               
               
                   
                 the sample a second time. The 
               
               
                   
                 test run was begun and continued 
               
               
                   
                 for 557 minutes. A seventh 
               
               
                   
                 preliminary hydraulic 
               
               
                   
                 conductivity was obtained and 
               
               
                   
                 determined to be 3.9 × 10 −7  cm/sec. 
               
               
                   
                 The hydraulic gradient was 
               
               
                   
                 reduced back to zero in order to 
               
               
                   
                 temporarily halt the test. 
               
               
                 Oct. 2, 2000 11:19AM to 
                 The initial gradient of 30 was 
               
               
                 5:20PM 
                 reapplied. The test run was 
               
               
                   
                 begun and continued for 361 
               
               
                   
                 minutes. An eighth preliminary 
               
               
                   
                 hydraulic conductivity was 
               
               
                   
                 obtained and determined to be 
               
               
                   
                 1.6 × 10 −7  cm/sec. The hydraulic 
               
               
                   
                 gradient was reduced back to 
               
               
                   
                 zero in order to temporarily 
               
               
                   
                 halt the test. 
               
               
                 Oct. 4, 2000 8:00AM to 
                 The initial gradient of 30 was 
               
               
                 10:30AM 
                 reapplied and the test run was 
               
               
                   
                 begun and continued for 150 
               
               
                   
                 minutes. A ninth hydraulic 
               
               
                   
                 conductivity was obtained and 
               
               
                   
                 determined to be 2.1 × 10 −7  cm/sec. 
               
               
                   
                 The hydraulic gradient was 
               
               
                   
                 reduced back to zero in order to 
               
               
                   
                 temporarily halt the test. 
               
               
                 Oct. 5, 2000 8:05AM to 
                 The initial gradient of 30 was 
               
               
                 12:35PM 
                 reapplied and the test run begun 
               
               
                   
                 and continued for four 
               
               
                   
                 consecutive constant readings 
               
               
                   
                 were obtained. An end of test 
               
               
                   
                 percent saturation of 98.0% was 
               
               
                   
                 obtained. The average final 
               
               
                   
                 hydraulic conductivity was 
               
               
                   
                 obtained and determined to be 
               
               
                   
                 2.65 × 10 −7  cm/sec. 
               
               
                 Oct. 6, 2000 
                 The sample was removed from the 
               
               
                   
                 cell and photographed. 
               
               
                   
               
             
          
         
       
     
     The results of the test on sample #14707C are graphically illustrated in  FIG. 1 , and shown in Table 2 in the Test Results Summary, below. A final hydraulic conductivity value of 2.65×10 −7  cm/sec was achieved with the “Solvay” waste sample #14207C. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Sample #14207D 
               
             
          
           
               
                   
                 DATE 
                 PROCEDURES 
               
               
                   
                   
               
               
                   
                 Sep. 5, 2000 
                 The sample material was 
               
               
                   
                   
                 compacted in accordance with 
               
               
                   
                   
                 ASTM D698 (Standard Compaction). 
               
               
                   
                   
                 The water content at the time of 
               
               
                   
                   
                 compaction was 99.5 as a percent 
               
               
                   
                   
                 of dry weight. The dry density 
               
               
                   
                   
                 after compaction was determined 
               
               
                   
                   
                 to be 41.8 pcf. 
               
               
                   
                 Sep. 6, 2000 
                 The sample was placed into the 
               
               
                   
                   
                 trixial confinement cell. A #200 
               
               
                   
                   
                 (0.074 mm) size stainless steel 
               
               
                   
                   
                 mesh screen was used in place of 
               
               
                   
                   
                 the typical filter paper and 
               
               
                   
                   
                 porous stone in order to avoid 
               
               
                   
                   
                 any false positive reduction in 
               
               
                   
                   
                 permeability due to clogging in 
               
               
                   
                   
                 the paper and/or stone. 
               
               
                   
                   
                 The sample saturation process 
               
               
                   
                   
                 began as backpressure was 
               
               
                   
                   
                 applied by simultaneously 
               
               
                   
                   
                 increasing the cell pressure and 
               
               
                   
                   
                 the influent and effluent 
               
               
                   
                   
                 pressures in 5 psi increments. 
               
               
                   
                   
                 During the incremental 
               
               
                   
                   
                 procedure, the influent and 
               
               
                   
                   
                 effluent pressures are kept 
               
               
                   
                   
                 equal while the cell pressure is 
               
               
                   
                   
                 maintained at 5 psi greater than 
               
               
                   
                   
                 the influent and effluent 
               
               
                   
                   
                 pressures. 
               
               
                   
                   
                 During this procedure, regulated 
               
               
                   
                   
                 air pressure is applied to a 
               
               
                   
                   
                 column of deaired water. In 
               
               
                   
                   
                 turn, the deaired water 
               
               
                   
                   
                 transfers the applied pressure 
               
               
                   
                   
                 to of test percent saturation of 
               
               
                   
                   
                 98.0% was obtained. The average 
               
               
                   
                   
                 final hydraulic conductivity was 
               
               
                   
                   
                 obtained and determined to be 
               
               
                   
                   
                 2.12 × 10 −5  cm/sec. 
               
               
                   
                 Oct. 6, 2000 
                 The sample was removed from the 
               
               
                   
                   
                 cell and photographed. 
               
               
                   
                   
               
             
          
         
       
     
     The results of the test on sample #14207D are graphically illustrated in  FIG. 2 , and shown in Table 2 in the Test Results Summary, below. A final hydraulic conductivity value of 2.12×10 −8  cm/sec was achieved with “Solvay” waste sample #14207D. 
     Test Results Summary 
     The Natural Analog System process was tested on “Solvay” waste collected from a Honeywell wastebed in Central New York. Two samples were prepared and tested at the Parrott-Wolff Laboratories using standard ASTM testing procedures. The goal of the testing was to determine the utility of the NAS process to effectively reduce permeability of ground, and reduce or eliminate leachate from waste beds and to remediate subsurface contamination plumes of chemical contaminants resulting from former Honeywell chemical operations. Cementation of the host material was achieved in a relatively short time. The results show a strong capacity for the process to reduce permeability in the host material, effectively reducing water flow through and thus isolating the material from the environment. 
     Key Results 
     Test results show that the NAS process significantly reduced the hydraulic conductivity of the host material from 1.8×10 −5  cm/second to 2.65×10 −7  cm/second in approximately 550 hours for sample #14207C which represents a 98.53% reduction. The values for sample #14207D were from 1.8×10 −5  cm/second to 2.12×10 −8  cm/second in approximately 548 hours which represents a 99.88% reduction. It is noteworthy that both tests were terminated after hydraulic conductivities were reached that met or exceeded required values for remedial isolation technologies. It is expected that hydraulic conductivities would continue to decrease and reach final values typical for the crystalline structure of the cementing compound, a natural analog of calcite.  FIG. 3  shows the moisture-density curve (Proctor curve) with the relationship between the dry unit weight (density) and the water content of the waste material for a given compactive effort. 
     
       
         
               
             
               
               
             
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Hydraulic Conductivity (k) Study Test Results 
               
               
                 And Timeline for Testing of Allied Waste Material 
               
             
          
           
               
                 Lab I.D. #14207C 
                 Lab I.D. #14207D 
               
             
          
           
               
                   
                 Hydraulic 
                   
                 Hydraulic 
               
               
                 Cumulative 
                 Conductivity (k) 
                 Cumulative 
                 Conductivity (k) 
               
               
                 Elapsed Time 
                 (cm/sec) 
                 Elapsed Time 
                 (cm/sec) 
               
               
                   
               
               
                  0 Hours 
                 1.8 × 10 −5   
                  0 Hours 
                 1.8 × 10 −5   
               
               
                  41 Minutes 
                   
                  41 Minutes 
               
               
                  48 Hours 
                 5.1 × 10 −6   
                  47 Hours 
                 9.9 × 10 −6   
               
               
                  24 Minutes 
                   
                  24 Minutes 
               
               
                 185 Hours 
                 3.4 × 10 −6   
                 185 Hours 
                 7.2 × 10 −6   
               
               
                  16 Minutes 
                   
                  15 Minutes 
               
               
                 233 Hours 
                 1.2 × 10 −6   
                 233 Hours 
                 5.7 × 10 −6   
               
               
                  41 Minutes 
                   
                  38 Minutes 
               
               
                 239 Hours 
                 8.3 × 10 −7   
                 239 Hours 
                 5.5 × 10 −6   
               
               
                  41 Minutes 
                   
                  9 Minutes 
               
               
                 312 Hours 
                 9.9 × 10 −7   
                 312 Hours 
                 2.2 × 10 −6   
               
               
                  41 Minutes 
                   
                  48 Minutes 
               
               
                 362 Hours 
                 3.8 × 10 −7   
                 361 Hours 
                 1.6 × 10 −6   
               
               
                  41 Minutes 
                   
                  26 Minutes 
               
               
                 481 Hours 
                 1.68 × 10 −7   
                 481 Hours 
                 2.71 × 10 −8   
               
               
                  41 Minutes 
                   
                  4 Minutes 
               
               
                 523 Hours 
                 2.07 × 10 −7   
                 482 Hours 
                 5.7 × 10 −8   
               
               
                  41 Minutes 
                   
                  19 Minutes 
               
               
                 549 Hours 
                 2.65 × 10 −7   
                 548 Hours 
                 2.12 × 10 −8   
               
               
                  41 Minutes 
                   
                  19 Minutes 
               
               
                   
               
             
          
         
       
     
     Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the examples chosen for purposes of disclosure and covers all changes and modifications which do not constitute departures from the true spirit and scope of the invention. 
     Having thus described the invention, what is desired to be protected by Letters Patent is presented in the subsequently appended claims.