CDM Federal Programs Corporation · CDM Federal Programs Corporation July 29, 1988 ... It has been previously estimated by CDM that approximately 4 million gallons per day ... (Cohansey

CDM Federal Programs Corporation

July 29, 1988

Rose Harvell Project Officer U.S. Environmental Protection Agency 401 M Street, Room 2834 Washington, D.C. 20460

PROJECT:

DOCUMENT NO.

SUBJECT:

EPA CONTRACT NO.: 68-01-7331

T1057-C02-EP-CFXX-1

Pinal Report for EPA Work Assignment C02036 Technical Responses to Public Comments Ciba-Geigy Chemical Company Site Toms River, New Jersey Document Control No.: T1057-C02-RT-CFXV-1

Dear Ms. Harvell:

Please find enclosed the Final Report entitled, "Technical Responses to Public Comments, Ciba-Geigy Chemical Company Site, Toms River, New Jersey", as partial fulfillment of the reporting requirements for this work assignment.

I f you have any comments regarding this submittal, please contact Robert Hyde of Camp Dresser and McKee Inc. at (201) 225-7000 within two weeks from the date of this letter.

Sincerely,

CDM Federal Programs Corporation

Robert D. Goltz, P.E. TES I I I Regional Manager

JB:jb

cc: Pat Wells, EPA Primary Contact, CERCLA Region I I Cathy Moyik, EPA Regional Contact, CERCLA Region I I Glenn Hardcastle, EPA HO Coordinator, CERCLA Region I I Harry Butler, CDM Federal Programs Corporation, Deputy Program Manager

(letter and cover only) Barbara Kuberski, EPA Contracting Officer (letter only) Robert Hyde, Camp Dresser and McKee Inc. Document Control, CDM Federal Programs Corporation (2 copies)

(JB4/40) • 2 3 6405

59 John Screw, Eighth Floor New York, NY 10036 21239W634 CIB ee>9 l e 2 6

FINAL REPORT TECHNICAL RESPONSES TO PUBLIC COMMENTS

CIBA-GEIGY CHEMICAL COMPANY SITE TOMS RIVER, NEW JERSEY

Prepared for

U.S. ENVIRONMENTAL PROTECTION AGENCY Office of Waste Programs Enforcement

Washington, D.C. 20460

EPA Work Assignment No. EPA Region Contract No. CDM Federal Programs Corporation Document No. Prepared By Work Assignment Project Manager Telephone Number Primary Contact Telephone Number Date Prepared

: C02036 : I I : 68-01-7331

: T1057-C02-RT-CFXV-1 : Camp Dresser and McKee Inc. : Robert Hyde : (201) 225-7000 : Pat Wells : (212) 264-3774 : July 29, 1988

(JB4/40)

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IBT10DDCTI0*

The purpose of this work assignment (CDM Federal Programs Corp. WA 1057) is to provide technical assistance to the U.S. Environmental Protection Agency (EPA) concerning a series of questions previously posed to the EPA by the community potentially affected by the Ciba-Geigy Chemical Company site in Toms River, New Jersey.

In accordance with direction received from the EPA at a coordination meeting on July 12, 1988, Camp Dresser and McKee Inc. has evaluated each specific question from the perspective of technical feasibility, regulatory and environmental advantages/disadvantages, cost, and the ability to protect public health and the environment.

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Ciba-Geigy Technical Enforcement Support Document Contract No.: 68-01-7331

Subject: Feasibility of Treated Groundwater Recharge via Reinjection Wells or Infiltration Basins

Background:

It has been previously estimated by CDM that approximately 4 million gallons per day (MGD) of contaminated groundwater will require extraction from the water table aquifer (Cohansey Formation) which underlies the Ciba-Geigy site. Pumping 4 MGD will effectively prevent or minimize off-site migration of groundwater contamination at the property borders and remediate contamination in the Cardinal Drive Area. After extraction, the contaminated groundwater will undergo neutralization (pH adjustment), metals precipitation, and biological treatment utilizing a patented powdered activated carbon process (PACT). This effluent has been proposed for reinjection back into the Cohansey Formation.

Question:

Evaluate whether or not reinjection wells or infiltration basins will work for discharging all treated groundwater from the Ciba-Geigy site.

Technical Feasibility:

Groundwater recharge is not a new technology. In Long Island, New Yak, New Jersey, Arkansas, Idaho. Texas, New Mexico, Washington, Oregon and Southern California, the collection of rainwater in infiltration or recharge basins has successfully been used to increase the amount of recharge introduced into unconfined aquifer systems (similar to that underlying the Ciba-Geigy site) as a means to augment public water supplies. In New Jersey and Florida, groundwater is injected into aquifers, through wells, for storage to be used during dry seasons. Injection well systems have also been used successfully for the remediation for subsurface contamination at hazardous waste sites in New Hampshire (at the Gilson Rd. site) and Colorado (at the Rocky Mountain Arsenal). Additionally, during fiscal year 1987. the U.S. Environmental Protection Agency signed Records and Decisions at 6 sites where reinjection was selected for the disposal of treated groundwater and at 7 sites where surface water discharge of treated groundwater was selected.

The key factors influencing the successful reinjection of water through wells or infiltration basins are as follows:

• hydrogeotogic factors such as hydraulic conductivity, porosity, saturated thickness, and areal extent of the receiving formations, quality of the receiving waters, depth to the groundwater, and extent of groundwater fluctuations, especially from tidal influences if near the shoreline;

• well or basin construction;

• Injection water quality, especially suspended solids, biological oxygen demand (BOD), residual chlorine, and oil and grease:

• injection schedule; and

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• maintenance and rehabilitation practices.

Each of these factors is discussed below as they pertain to the Ciba-Geigy site:

The hydrogeotogic factors at the Ciba-Geigy site and in the immediate vicinity, in general, are conducive for the reinjection or infiltration of water into the groundwater flow system. The Cohansey Formation should allow ample quantities of water to percolate into the water table since it is characterized as very transmissive (i.e. is characterized by a high hydraulic conductivity, and large saturated thickness), is fairly porous (characteristic of medium to find grained sand), has a large unsaturated zone (i.e. 20-40 feet from groundsurface to the water table), and is areally extensive in the vicinity of the plant (extending beyond all the major surface water features such as Pine Lake, Toms River, and Wrangle Brook and Sunken Branch). There are no significant groundwater level fluctuations in the shallow flow system, in that tidal influences are non-existent and variations due to rainfall are on the order of at most a couple of feet.

The water in the upper-most water bearing zone upgradient of the Ciba-Geigy Rant is of fairly high quality, with concentrations of very few constituents exceeding safe drinking water standards or criteria (e.g., iron, manganese, lead, cadmium). The existence of these metals in their soluble form is typically indicative of the mineral content of the native soils and essentially represent background conditions. However, the presence of these constituents at background levels (especially iron) in exceedance of the drinking water standards indicates that iron bacteria and other sessile bacteria may become active in the well screen, develop into a biofilm, and clog the screen. It should be noted that reinjection wells are much more suseptible to clogging than infiltration basins.

Injection well and recovery well construction are essentially the same; the only difference may be in the size of the well casing used. Injection wells are generally constructed of 4-inch plastic or PVC casing; however larger diameter casings are also used. It is important that the injection well be large enough to accommodate a pump during development and a pump and surge block or wire brush during restoration and maintenance. For the Ciba-Geigy site it is recommended that at least 6-inch diameter wells be used (assuming 15-20 injection wells will be operating at any one time) to insure that ample injection capacity is available. Additionally, duplicate (if not triplicate) wells should be installed at each station to insure that proper maintenance and redevelopment practices do not interfere with operation of the reinjection procedures.

Proper infiltration basin operation and maintenance requires the construction of a series of basins (called cells) which are used on a rotating basis where at least one (and preferably two) cell is offline for maintenance (i.e. raking and grading). For the Ciba-Geigy site, a series of six to eight cells are recommended with two cells off-line continuously for maintenance. Therefore, at least 10 acres of active cells are required given the drainage characteristics of the native soils, such that 15 to 20 acres of land must be allocated for siting the infiltration basins.

Recharged water quality should be free of all substances and constituents which hinder the free flow of water into the subsurface. Suspended solids, and oil and grease can physically clog the well screen or basin thereby significantly reducing the efficiency of the recharge process. Waters with a high biological oxygen demand (BOO) can induce the growth of bbfilms and/or mats also causing clogging of the wells. Infiltration basins are also affected by waters with high BOD, but the most significant problem becomes one of odor rather than clogging. Chlorine, which is used effectively as a disinfectant, can be beneficial in low concentrations, by controlling enzymes essential to the metabolic processes of bacterial cells. In high concentrations, however, the chlorine simply oxidizes the microbial cell walls and creates a suspended solids problem, which contributes to blocking of the well screen and water bearing zone. Chlorination is only recommended for reinjection well groundwater recharge scenarios.

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Clogging of the well screen and formation can also include processes associated with precipitate formation, and temperature and pressure changes which alter the chemical equilibria causing expansion of clays or reduction of formation porosity and permeability. Additionally, dissolved gas concentrations in the injected waters can become entrained in the pore spaces of the receiving formation causing a reduction in well efficiency. Infiltration basins are not significantly impacted by precipitate formation, temperature and pressure changes, or dissolved gas concentrations, and as such are not nearly as susceptible to clogging as are reinjection wells.

The injection schedule can impact successful reinjection of water in that unused wells are more susceptible to clogging and sedimentation. Therefore, continuous well use. and regular maintenance and rehabilitation practices are necessary to insure successful application of this technology. Infiltration basin performance is not significantly impacted by application schedule. This is supported by the sucessful use of such basins in recharging rainfall runoff in various locations thoughout the country.

The most significant possible hydrogeotogic hindrance to successful recharge of effluent into the Cohansey at the Ciba-Geigy site are the occasionally extensive clay layers in the unsaturated zone. Proper siting of the injection wells or infiltration basins to insure that extensive clays do not impact the steady flow of recharge downward into the groundwater system should alleviate this problem. It should be noted that the clays found in the unsaturated zone extended over approximately 20 percent of the site.

The high iron and manganese mineral content of the native soils can potentially induce the growth of certain bacteria on the injection well screen. In order to effectively overcome the mineral problem, a cooperative effort involving a proper treatment train (i.e. treatment to remove oil and grease. BOD. suspended solids, and minerals of concern) to handle the contaminated groundwater plus a rigorous maintenance and rehabilitation program is required for both reinjection wells and infiltration basins. The treatment train is very important to the success of an artificial recharge program. Chlorine may be added to the extracted groundwater after treatment in order to reduce the amount of microbial activity which will occur as the effluent interacts with the formation at the well screen. Also, the treatment process should remove the solids (especially minerals) contained in the extracted groundwater in order to minimize the effect of clogging at the wells screen or in the infiltration basin.

Regardless of how effective the treatment process is, regular maintenance of the recharge system, be it wells or basins or both, is paramount to successful application of this technology. For wells, regular maintenance involves the use of chemical treatment of the casing and screen with an acid such as hydrochloric or sulfuric acid together with inhibition to reduce corrosion, followed by a disinfectant such as chlorine to destroy the biomass which will probably form. In addition, mechanical agitation with wire brushes or surge blocks is desirable to help facilitate dislodging and removal of unwanted substances from the well screen. Strong oxidizers such as sodium hypochlorite or potassium permanganate are also commonly used in well rehabilitation. Such oxidizers and acids would be pumped out of the rehabilitated wells and treated prior to their ultimate reinjection in conjunction with other treated groundwater.

Since maintenance is required regularly on the operating injection wells, duplicates if not triplicates should be installed such that clogging or a general reduction of injection capacity does not shut down the operation, instead a well is simply removed from service for maintenance, and a nearby injection point is brought on line. For basins, a rotating application operation, as discussed previously, is recommended to afford proper preparation of the cell bottoms fa percolating the effluent. This preparation generally pertains to removing caked solids from the underlying soils and raking the native material to enhance its ability to infiltrate effluent.

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Advantages and Disadvantages* (in strict comparison with surface water discharge)

Technical:

The following is a list of technical advantages associated with groundwater disposal of the treatment plant effluent in comparison to surface water discharge:

• groundwater recharge scenarios require that the treatment plant effluent be of higher quality than the surface water discharge scenarios therefore, more of the contamination is removed from the environment under the former.

• groundwater recharge at the plant site will result in an increased flow of water beneath the plant. This increased flow will help to flush water soluble contamination from any underground source areas and may result in a decrease in clean-up time for on-site remediation.

The following is a list of technical advantages comparing infiltration basins with reinjection wells:

• infiltration basins are technically advantageous over reinjection wells because they are less susceptible to clogging due to their larger surface area available fa recharge. Also, the maintenance program associated with reinjection wells is much more labor and capital intensive then infiltration basin requirements.

• injection wells afford the option of either disposing of the treatment plant effluent in deep sand zones other than the water table aquifer or piping the effluent offsite and injecting in a less sensitive area without a significant land requirement.

• infiltration basins do not require chlorination of the effluent.

The following is a list of technical disadvantages associated with groundwater disposal of the treatment plant effluent in comparison to surface water discharge:

• the groundwater recharge system (i.e. wells a basins) is much more difficult to maintain than a surface water discharge system (pipelines).

• groundwater recharge onsite results in either a hydraulic barrier being famed resulting in a change in the direction of naturally occurring flow from the west (including contaminated groundwater detected beneath the residential area of Pine Lake Park) or increased vertical migration of suspected a known contaminatiai downward into drinking water aquifers.

• recharging the water table on site by either reinjection wells or infiltration basins could cause a generalized rise in the saturated zone of up to 10 feet which could potentially inun date contaminant sources not presently contributing pollutants to the groundwater flow system. This may increase the amount of soluble components which are likely to migrate into the groundwater flow system. It should be noted, however, that rainfall percolating downward through the unsaturated also comes into contact with such a 'source" causing some solubilization of contamination.

• groundwater discharge is more susceptible to upsets than surface water discharge in that clogging, sedimentation, a microbial infestations can significantly reduce the efficiency of the system potentially causing shutdowns.

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The following is a Hst of technical disadvantages comparing infiltration basins and reinjection wells:

• infiltration basins are more susceptible to weather conditions such as freezing than reinjection wells. Freezing would not be a concern, however, except in very harsh weather since the groundwater temperature will generally be elevated about freezing conditions.

• infiltration basins can attract pests such as mosquitos and are suseptibte to odor problems.

• reinjection wells require significantly more maintenance and a more sophisticated treatment system (to remove fines) than do infiltration basins.

Regulatory:

The following is a list of regulatory advantages associated with groundwater disposal of the treatment plant effluent in comparison to surface water discharge:

• assuming that the treatment train is effective, the groundwater recharge practice can augment the public water supply, and if properly placed can increase the hydraulic barrier between the Ciba-Geigy plant and the public water supply wells.

The following is a list of regulatory disadvantages associated with groundwater disposal of the treatment plant effluent in comparison to surface water discharge:

• chlorination of the treatment effluent specifically for recharge via reinjection wells could potentially cause the formation of trihalomethanes (e.g.. chloroform) which could adversely impact the public water supply. It should be noted, however, that trihalomethanes are generally formed as a result of chlorine coming in contact with humic and fulvic acids in the waste stream. It is very unlikly that either of these organic acids would persist through the treatment processes. Therefore, the formation of trihalomethanes is very unlikely.

• the groundwater recharge scenarios keep the treatment plant effluent closer to the potentially impacted citizenry than does the surface water discharge scenario.

Environmental:

The following is a list of environmental advantages associated with groundwater disposal of the wastewater treatment plant effluent in comparison to surface water discharge:

• groundwater discharge quality criteria are more stringent than surface water quality criteria, therefore, more of the mass of contaminants must be removed from the local environment under a groundwater recharge scenario.

• recharging the groundwater flow system on the Ciba-Geigy property, west of the production area, will help to increase flushing of water-transportable contaminants from any underground sources and may potentially accelerate on-site clean-up.

The following is a list of environmental advantages comparing infiltration basins and reinjection wells:

• infiltration basins have tower maintenance requirements than reinjection wells

• infiltration basins do not require chemical treatment prior to recharge

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• reinjection wells can discharge the treatment plant effluent at depth into aquifers with non-potable water.

The following is a list of environmental disadvantages associated with groundwater disposal of the wastewater treatment plant effluent in comparison to surface water discharge:

• the groundwater recharge practice is more difficult to maintain than the surface water discharge route.

• groundwater discharge is more susceptible to upsets than surface water discharge in that clogging, sedimentation, or microbial infestations can significantly reduce the efficiency of the system potentially causing shutdowns.

• if the treatment plant does not maintain compliance with water quality criteria standards. NUS (1988) determined that a groundwater discharge places the public at a greater risk than does a surface water discharge.

• chlorination of the effluent required under the reinjection scenarios could potentially form trichalomethanes which impact native groundwater quality. Again, however, it is unlikely that trihalomethanes will be formed because the necessary precursors (humic and fulvic acid) are not expected to be persistant in the treatment train.

Cost:

There are no cost advantages to the groundwater recharge scenarios over the surface water discharge scenarios. The following compares costs for infiltration basins versus reinjection wells:

• infiltration basins are less expensive to construct, and maintain than injection wells (wells 5 million; basins 3 million, NUS (1988)).

• reinjection wells do not require much land to construct therefore offsite reinjection scenarios are more favorable than off-site infiltration basins.

The following is a list of cost disadvantages associated with groundwater disposal of the wastewater treatment plant effluent in comparison to surface water discharge:

• the groundwater recharge practice is slightly more expensive than the surface water discharge scenarios for two reasons: (1) the additional treatment required to meet groundwater discharge standards (surface water discharge treatment is 73 million, groundwater discharge treatment is 75.3 million; NUS (1988)) and (2) the recharge system installation and maintenance required (surface water discharge is 8 million; groundwater discharge through wells is 14 million, and through basins is 12 million; NUS (1988).

• for off-site recharge, infiltration basins require more land, and therefore, may be more expensive to use than injection wells.

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Ability to Protect Public Health and tha Environment:

The use of reinjection wells or infiltration basins to dispose of the treatment plant effluent creates two specific concerns regarding impacts on public health and the environment These concerns are as follows:

• horizontal and vertical migration of existing contamination into a regional water supply aquifer caused by mounding due to recharging the groundwater flow system; and

• generation of a hydraulic barrier along the western and northern Ciba-Geigy property Mnes causing a significant shift in the prevailing hydraulic gradient under existing condi ttons. This shift potentially impacts the migration of contamination from an unkown source in the vicinity of the Pine Lake Park area and may cause pollutants to move in other directions.

Regardless of the application method used to recharge the groundwater flow system, vertical gradients downward are induced. These downward gradients are insignificant except in areas where known and suspected contamination exists. Such areas sensitive to the induced downward gradients are generally east of the plant proper, beneath the Cardinal Drive residential area, and near well RI-9. At these locations contamination has been detected in the sand units of the upper most water bearing aquifer, and are suspected to exist at depth where no monitoring wells presently exist.

Since the recharged treatment plant effluent would be applied mainly to the water table, and the existing vertical hydraulic gradient in the area of concern is either very slight or upward, inducing downward gradients is a concern. This problem can be avoided, however, by applying recharge at locations on the plant site where subsurface contamination neither exists nor is expected to exist. This leaves the majority of the Ciba-Geigy property west of the production area as available for the placement of reinjection/infiltration facilities. Placement of reinjection/infiltration facilities west of the production area, however, impacts the second concern listed above in that applying 4 mgd of recharge in this location creates a hydraulic barrier influencing the existing gradient in the vicinity of the upgradient private supply wells. Therefore, no location on the plant will allow 100% recharge ofjhe treatment plant effluent A possible exception to this situation is the reinjection of the effluent into a deep aquifer. ' ~

Reinjection into a deeper water bearing zone would eliminate concerns associated with both the vertical and horizontal gradients, however, it would remove the groundwater resource from the shallow acquifer system. Additionally, deeper injection would be more maintenance intensive and difficult to monitor and recover (if needed).

Another possible choice for locating recharge facilities (wells or basins) would be either west of the Asphalt Pits or east of Toms River. In both locations, available land is scarce thereby making reinjection wells more attractive, however, infiltration basins cannot be ruled out completely. An advantage that both of these two possible siting strategies have is that the influence of the recharged water on the extraction well system is minimized, therefore, cleanup times can be optimized. Additionally, injecting the water east of Toms River can help to augment the capacity of the existing water supply wells. This benefit could backfire if the treatment plant fails, however, and ample groundwater monitoring would be required to insure the safety of the public water supply. Additionally, the impact of reinjection well operation and maintenance program on groundwater quality could weigh the decision against such a proposal.

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Subject: Mixing Zone Regulation* Regarding Discharge of Treated Groundwater to Surface Waters

Question:

Provide information regarding the health risks and regulatory requirements involved in the alternative to discharge treated groundwater to the Toms River and the Ocean via pipelines. Of particular concern is the area within the mixing zone.

Technical Feasibility: Not applicable

Advantages and Disadvantages: Not applicable

Ability to Protect Public Health and the Environment:

The "mixing zone" in a stream is a term which refers to the area within which a discharge is initially mixed with and diluted by the receiving water. By the time the discharge reaches the edge of the mixing zone, it must be sufficiently dilute so as to meet all applicable water quality criteria. The area within the mixing zone is a "free" area in which criteria need not be met while dilution is taking place. The dimensions of the mixing zone can be very large or very small and are generally established by the regulatory agency. The mixing zone can pertain to either the ocean outfall or the stream discharge.

For the proposed situation wherein treated groundwater will be discharged into the Atlantic Ocean or Toms River, it is assumed in the NUS Feasibility Study (1988) that the treatment facility will be designed so that the effluent will meet all health and aquatic criteria at the time it leaves the plant accounting for dilution from the 7 day-10 year low flow in accordance with NJPDES Regulations procedures (N.J.A.C. 7:14A-3:14). Since the discharge will already meet receiving water quality criteria when it enters the ocean or stream, with dilution assumed instantaneous and one dimensional, the "mixing zone" becomes an irrelevant term. All applicable state and federal water quality criteria will be met at the discharge point, therefore further dilution of the effluent in the stream will not affect compliance with the regulations.

One the other hand, the term "mixing length" is a term which refers to the distance from the discharge point at which the discharge will be completely mixed with the stream water throughout the width and depth of the receiving waters. It does not involve regulations or criteria limits and is not a characteristic associated with outfalls. In streams it is uniquely defined by the physical characteristics of the receiving waters.

Using stream depth data obtained by NUS from a nearby U.S. Geological Survey monitoring station for Toms River, the mixing length is calculated at approximately 1000 to 2000 feet. It should be reiterated, however, than the effluent discharge does not violate any state or federal surface water quality criteria.

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Subject: Evaluation of Alternatives for Infiltrating Treatment Plant Effluent Into the Shallow Qroundwater Flow System

Question:

What is the feasibility of using seepage basins to allow treated effluent to slowly discharge into Toms River? The size, location, and ability of these basins to "polish" the treated effluent should be evaluated.


The seepage basin concept involves percolating treatment plant effluent through a rapid sand infiltration basin, collecting it with an underdrain system, and discharging it to Toms River. Such a basin could be constructed most anywhere on the plant site with the discharge pipes emptying into the cooling water effluent channel which ultimately discharges into Toms River. The discharge pipes could be either submerged or above the average water level in the receiving waters.

This system is differentiated from the ground water recharge scenarios in that no mounding of the water table occurs due to the underdrain configuration. This system is also differentiated from the direct surface water discharge scenario because the seepage basin retains the treatment plant effluent for a period of time before discharging it to the receiving waters.

The rapid sand infiltration basin bottom would consist of a medium to fine grained well sorted sand, or gravel pack, which would be used as a final filter to remove fines from the effluent before discharge to the river. The rapid sand infiltration basin does not however "polish" the effluent, in the sense that volatile organic constituents are not removed. Either mixed bed filters, requiring all together different bedding materials, or mechanical aeration of the water as it enters the basin, would be necessary to provide some degree of polishing. It should be noted that the proposed ground water treatment train employing PACT or GAC will reduce the concentration of many volatile organic constituents to below detection limits, therefore the used of mixed bed filters may be an unnecessary redundancy.

It should also be noted that the use of agricultural techniques, such as having water hyacinths in the basins, would not result in any sizable reduction of VOCs. The treatment plant effluent would most probably require added nutrients in the form of phosphorus and nitrogen to support a flourishing plant population. Additionally, the plants would not survive the winter unless the basins were enclosed.

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Advantages and Disadvantages:

Technical:

The following is a list of technical advantages associated with the use of seepage basins:

• Discharges from seepage basins may be stopped immediately by closing a valve whereas discharges from infiltration basins require a considerably longer period of time to cease.

• Seepage basins do not impact the water table via a mounding effect, therefore, vertical gradients in areas of concern are not created nor are hydraulic barriers. Seepage basins would not be expected to adversely impact the ground water system.

• Seepage basins require less maintenance than reinjection wells.

• Seepage basins are more flexible in terms of siting requirements in that they could be located over the yellow clay which constitutes approximately 20% of the Ciba-Geigy site whereas infiltration basins could not.

The following is a list of disadvantages associated with seepage basins:

• Seepage basins, unlike reinjection wells or infiltration basins located on the plant site, do not afford any additional flushing of any underground sources of contamination.

• Seepage basins may be susceptible to freezing although it would require particularly harsh weather since the ground water would be expected to enter the basin at a temperature of between 40 and 60° F.

• Seepage basins can be susceptible to odors and pests.

Regulatory:

The following is a list of regulatory advantages associated with seepage basins:

• Seepage basins delay the discharge of the effluent to the receiving waters allowing the recall of treated groundwater if not in compliance.

The following is a list of regulatory disadvantages associated with seepage basins:

• No regulatory disadvantages are apparent.

Environmental

The following is a list of environmental advantages associated with seepage basins:

• Seepage basins do not adversely impact the ground water flow system.

• Discharges from seepage basins may be stopped immediately by closing a valve if the contents of the basins are not in compliance with discharge permits.

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The following is a list of environmental disadvantages associated with seepage basins:

• The potential for accelerated flushing of contaminants from the site is not realized with the use of seepage basins.

• The total mass of contaminants released to the local environment is greater if a surface water discharge technology like a seepage basin is utilized as opposed to a ground water discharge device such as an infiltration basin. This is because ground water discharge standards are stricter than standards governing the discharge to surface waters.

Costs

Estimates of costs are not available for seepage basin construction at this time, however, it is understood that infiltration basins are less expensive to construct. Infiltration basins would be more expensive to maintain.

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Ciba-Geigy Technical Enforcement Support Document Contract No.: €8-01-7331

Subject: Evaporation Basins

Question:

What is the feasibility of using evaporation basins to discharge the treated effluent?


The use of evaporation basins as a method of discharging the treatment plant effluent to the air is technically feasible only if the evaporation rate exceeds the precipitation rate plus the rate of infiltration to the pond. In the Toms River area, precipitation averages about 48* per year. Evaporation rates have been reported to be approximately 34" per year. Thus evaporation alone could not be expected to be a feasible method unless there were some method to prevent precipitation from reaching the pond.

For evaporation alone to handle the 4 MGD estimated flow volume, assuming no precipitation reached the ponds, basins would have to be constructed with a surface area of approximately 1600 acres. The entire Ciba-Geigy site is only 1275 acres, of which 320 acres are developed, with the remaining acreage wooded. Therefore, a significant amount of acreage would need to be purchased to affect construction of such a pond system. It should also be noted that the figure of 34' per year assumes that during the winter months evaporation continues at the same rate; this would not

- happen unless the pond was heated to above freezing. In addition, storage would be necessary— either greater depth or greater surface area—to temporarily store the winter flow.

In conclusion, the use of evaporation basins at the Ciba-Geigy site does not appear to be feasible without procuring large amounts of land and utilizing a significant heat source requiring over 1 million KW hours/day (which corresponds to over $25 million/year in operating costs).


Technical:

Technical advantages would include the simple operation of the system, the low maintenance required for this type of operation, and the ease with which the treated effluent could be monitored.

The main disadvantage of this method would be the very large land area required and the necessity of diverting all the precipitation from the pond. The area needed for evaporation is not readily available in the vicinity of Toms River.

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Regulatory:

There are no regulatory advantages or disadvantages.

Environmental:

An environmental advantage of this option would be the creation of a large water body that could support plant and wildlife. An apparent disadvantage would be the upset to the surrounding area due to removal of runoff from 1600 acres.

Cost:

Capital costs would likely be extremely high due to the cost of real estate in the Toms River vicinity. Operation and maintenance costs would be low unless a heat source is used as described above at a yearly cost in excess of $25 million.


The use of evaporation ponds would not be expected to significantly effect public health and the environment assuming that the pond bottoms were lined. If not, the ponds would partially act as infiltration basins and consequently have the same impacts.

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Subject: Feasibility of Transporting Untreated Groundwater to off-site Disposal

Question:

What is the feasibility and what are the risks associated with transporting the wastes to DuPont Environmental Services?


While transportation of the untreated groundwater for off-site treatment is technically possible, it is not a practical alternative for the Ciba-Geigy site. The volume of the groundwater, at 4 MGD. is so large that togistically the groundwater could not be moved from the site.

Three methods of transportation have been proposed for moving the groundwater: truck; railroad car; or barge. Tanker trucks have a weight road limitation of approximately 6000 gallons. A flow rate of 4 MGD would, therefore, require a truck every two minutes around the clock. The truck route to DuPont Chamber-Works plant in Deepwater, N J is about 80 miles. Access to Route 37 from the Ciba-Geigy site is direct, and the DuPont Chamber-Works plant is at the foot of the Delaware Memorial bridge and is easily accessed by the New Jersey Turnpike.

Railroad tanker cars typically have a capacity of about 20,000 gallons, 3.5 times as large as trucks. The flow rate would require filling a railroad car every 7 minutes throughout the day and night. Therefore even though the Ciba-Geigy site has a railroad spur on-site, this option does not appear feasible without dual tracks running to and from the DuPont Chamber-Works Rant.

Barges can hold 250,000 to 1,000.000 gallons, with 500.000 an average. This mode of transportation would require that eight barges be filled at Ciba-Geigy and discharged to the DuPont plant daily. According to DuPont. this could not be done at the present time. Furthermore, the fact that the Toms River is shallow (about 2 feet deep) and narrow (about 25 feet wide) at the Ciba-Geigy plant site effectively precludes the use of barges.


Technical:

A technical advantage of this option would be that it obviates the need for the construction of a treatment plant at the Ciba-Geigy site.

The technical disadvantages of this option include the unreasonable number of truck, rail, or barge trips that would be required to transport the daily capacity of the Ciba-Geigy site and the large distance between the site and the DuPont treatment plant in Deepwater.

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Regulatory:

There seem to be no regulatory advantages.

Requlatory disadvantages include the strict regulatory protocol of the N.J. Department of Transportation which would need to be followed, and any permits that would be required by the NJDEP or EPA governing the disposal of wastewater from Superfund sites in off-site treatment works.

Environmental:

There are no environmental advantages of this option.

A disadvantage of this option would be the spilling of untreated groundwater in case of a truck accident. Other disadvantages would be truck, rail, or barge noise, fumes, damage to roads, and increased traffic.

Cost:

DuPont charges for its treatment services in three ways. It measures the acidity of the waste and assesses a charge of $0.30 per pound of calcium carbonate equivalent in the waste. It also charges $0.31 per pound of solids , after filtering and drying. This cost includes the disposal in DuPont's hazardous waste landfill. Last, the influent level of dissolved organic carbon (DOC) is analyzed, and the client is charged $1.75 per pound of DOC equivalent. This cost covers the cost of the carbon in the PACT process. For example, 6000 gallons of waste (50,000 pounds) with a DOC concentration of 10,000 mg/l would contribute $875 toward the cost of treatment. The three components of the cost are then added to arrive at a final figure. The cost is subject to an overriding minimum of $1000 for the first truck (5000 gallons) and $550 thereafter. A DuPont spokeperson said a typical waste costs $0.20 per gallon.

Transportation costs would also be significant. Figures from a 1984 feasibility study prepared for EPA reported trucking costs of $0.62/100 pounds, with a 45000pound minimum, for a trip of 22 miles. Using these figures, four years out of date and applicable to a trip about one-fourth as long, still result in an average trucking cost of about $200,000 per day. The total cost would be roughly $1,000,000 per day.


A main drawback of this method of disposal is the potential for an accidental release of contaminated groundwater anywhere that human health or the environment could be adversely affected. Particularly, the chance of a release during the transport from Toms River to Deepwater would be cause for concern. Using figures derived from the Final Draft of the Lipari On-Site FS (1985) for the increase in the number of accidents, injuries, and deaths associated with transporting leachate to a treatment works. the anticipated increased number of daily accidents would be on the order of 0.48, the increase in the number of daily injuries would be 0.40. and the anticipated increased number of daily deaths would be 0.05 or one death every 20 days. These figures assume 160 miles per round trip and 667 trips per day for tanker trucks of 6000 gallon capacity.

CIB 009 1 8 4 3


Subject: Incinerating Treated Groundwater

Question:

What is the feasibility of and the risks associated with incinerating treated groundwater?

Background:

Incineration of the treated groundwater at the Ciba-Geigy site has been proposed as a potentially viable option for disposal. By incinerating (evaporating) the treated groundwater, it has been postulated that there will be no need to discharge any water to either nearby surface waters nor to the Cohansey aquifer.


Incinerating the groundwater is not a viable option. The cost associated with this option would be prohibitive, and the available incineration capacity would not be sufficient to treat the entire daily flow rate. Attempts to site a new, off-site permanent incinerator would very likely meet with strenuous opposition, causing long delays with no guarantee of future incineration capacity. Furthermore, off-site incineration would require one tanker truck every two minutes around the clock, and would bring with it additional risks from transport of the hazardous wastes. Accordingly, on-site incineration at the Ciba-Geigy site would be the more likely of the two scenarios if incineration were chosen.


Technical:

A technical advantage of incineration is that, when properly undertaken, the wastes are destroyed rather than just concentrated or dispersed.

The biggest technical disadvantage of incinerating groundwater is the lack of incineration capacity in the United States and Canada. The entire annual U.S. incineration capacity is much less than 4 MGD. Since the estimated volume of groundwater requiring trealment at the Ciba-Geigy site is about 4 MGD. it would not be possible to incinerate the daily wastewater production. Incineration on-site, in addition to siting difficulties and institutional constraints, may require the use of air pollution controls, with attendant problems such as scrubber sludge disposal.

Because the groundwater would be of high quality following tertiary treatment, incinerating the water would likely require large amounts of supplemental fuel. This fuel requirement is unknown but would be significant in order to bum 4 MGD.

CIB 999 1B44

Regulatory:

Incineration of hazardous waste is one of the most heavily regulated disposal options. If this option were employed it would be necessary to site and construct additional capacity. Public opposition to incinerators is usually quite high, and it would likely be very difficult to accomplish siting such an incinerator in a useful time horizon.

Environmental:

The biggest advantage of incineration, when done correctly, is the complete destruction of the wastes.

Although it is not expected to be a problem at this site, a disadvantage of incineration is the potential creation of products of incomplete combustion (PICs) which may be as hazardous or more hazardous than the original wastes.

Cost:

Incineration is generally a very costly disposal option. CDM estimates the marginal cost of mobile incineration of soil is $175 per cubic yard. Converting this to costs for water is difficult. However, if we assume the prices are equivalent, the cost would be about $0.80 per gallon for incineration alone, exclusive of transportation costs and any pollution control costs. For a flow of 4 MGD. the daily cost would approach $3 million just for incineration.


Although unlikely considering the high degree of groundwater treatment envisioned for this site, this option may impact public health through the emission of pollutants through the stack, through the disposition of the scrubber sludge, and through risks associated with transporting the water off-site for incineration.

CIB 009 1849


Subject: Potential for Salt Water Intrusion Due to Groundwater Pumpage

Question:

Evaluate whether or not salt water intrusion is a concern with regard to the groundwater pumping scenarios.

Technical Feasibility: Not applicable

Advantages and Disadvantages: Not applicable


Given the existing database characterizing the groundwater quality beneath the site and adjacent residential communities, salt water intrusion has not historically been a problem in the upper 300 feet of subsurface water bearing zones. Under the various groundwater pumpage scenarios presented in the NUS Feasibility Study, salt water intrusion would not be induced. This is due to the following factors:

• salt water surface water bodies are not adjacent to the areas being pumped;

• changes to the saline line in the Toms River estuary are not expected to be significant enough to bring salt water into the groundwater extraction system (in the form of stream water exfiltrate) in that the estuary is estimated to be 1 to 2 miles downstream of the southern most extraction well, and the change in flow in Toms River due to groundwater pumpage will have an influence only on the order of hundreds of feet.

CIB 009 I S 4 6


Subject: Effect of Groundwater Pumpage on the Salt/Freeh Water interface

Question:

Evaluate whether or not the salVfresh water interface in the Toms River is affected by any of the groundwater pumping scenarios.

Technical Feasibility Not applicable

Advantages and Disadvantages Not applicable

Ability to Protect Public Health and the Environment

The mitigation scenarios all involve reducing the flow of Toms River on an average of 3-5 percent (except where the treatment plant effluent is discharged into the stream), and such reductions can be expected to change the location of the salt/fresh water interface and impact the local marsh ecosystem. Given the data available, the impacts can only be described qualitatively.

The Toms River is a freshwater stream that flows, without any barriers, into a salty estuary. At some point the fresh and salt waters mix creating a zone where the salinity is intermediate between the river and the bay. This mixing zone between fresh and salt water is dynamic and moves with the tide and with the amount of freshwater coming down the river. It represents a balance between flow generated by the stream gradient and by those generated by the tides. In general, a reduction in the freshwater flow of the Toms River will cause the mixing zone to move upstream, and introduce salt water into areas previously only subject to freshwater. Since the freshwater flows and tides vary from day to day, the existing mixing zone will probably overlap the new one some of the time. The critical environmental factor, however, is the average location of the mixing zone.

A quantitative estimate of the distance of such a shift cannot be predicted since it depends on a number of parameters including:

a. The present location of the mixing zone, and the size of the channel. b. Estimates of the reduction of flow resulting from pumping during the dry season. c. The tidal range at the mixing zone, and the salinity of the salt water at the mixing zone.

Given the uncertainty which exists in identifying the distance a saline line may move in the estuary, it is estimated that the migration would be on the order of hundreds of feet.

CIB »®9 1 8 4 7

The environmental impacts of this salt water intrusion include possible changes in the marsh vegetation. The local marshes have adapted to the present salinity regime, and the patterns of vegetation distribution reflect this. Marshes where the bay waters are little diluted by the freshwater are dominated by the usual saltmarsh vegetation common the area. Marshes along the upstream portion are all freshwater. The marshes adjacent to the mixing zone contain plant ife tolerant of intermediate salinities, and form a distinct zone centered around the average location of the mixing zone. Should the area of mixing change as a result of changes in river flow, the vegetation zones, and all the other organisms associated with them, can be expected to move upstream. Thus, the size of the salt marshes would be increased at the expense of the freshwater marshes.

The exact extent of such a change cannot be determined without additional data including:

a. The location of the mixing zone. If the mixing zone is below the confluence of Wrangell and Sunken Ranch Brooks with the Toms River then the reduction of flow in the last will be a smaller proportion of the total freshwater flow.

b. The composition of the dominant plants and animals that inhabit the marshes. Some species are more tolerant to changes in salinity than others. If the present populations located near the mixing zone are among those known to be very tolerant to salinity changes, then a smaller displacement of vegetation zones may be expected.

C I B 009 I ® * 8

Clba-Gelgy Technical Enforcement Support Document Contract No.: 68-01-7331

Subject: Potential for Subsidence Due to Groundwater Pumpage

Question:

Evaluate whether or not settling of foundations is a concern with regard to the groundwater pumping scenarios.

Response:

Given the existing database characterizing the lithofogy beneath the site and adjacent residential communities, subsidence caused by the consolidation of soils dewatered under the various groundwater pumpage scenarios presented in the NUS Feasibility Study (1988) is very unlikely. This is due mainly to the following facts:

• Most of the sediments beneath the site are fine-to medium-grain or coarse-grain sand which will not subside when dewatered.

• In the sand, approximately 20-45 feet below the surface, lies a band of over-consolidated yellow clay with an average saturated thickness of 3-5 feet. This layer has a potential for subsidence when dewatered.

• Given a conservative estimate of a 10 feet of drawdown of the groundwater due to pumping, the maximum subsidence expected, given all worst-case scenarios, is 0.055 ft (about 2/3 in.). The actual occurrence of this maximum level is very unlikely. More typical estimates of subsidence range from 0.0085 to 0.035 ft. (about 0.1 in. to 0.4 in.)

• The estimated subsidence will take place gradually over many years.

• The expected subsidence is not expected to cause significant settling of foundations.

C I B 009 1849


Subject: Impact of Groundwater Reinjection on Water Table Levels Which May Potentially Flood Baaementa

Question:

Is flooding a concern in any of the reinjection scenarios?

Response:

The discharge of the treatment plant effluent into the groundwater flow system whether by reinjection wells or infiltration basins will raise the water table elevation locally. For this reason it is important to determine the impact of the higher water table on existing structures in the area.

Of all the remediation scenarios evaluated, only the 100% reinjection scenarios cause an increase in the water table. These increases were only identified in the vicinity of Irving Place. The Cardinal Drive area did not experience any increase in the water table elevation. On average, the amount of the water table increase was only a foot or two. This increase does not influence existing structures in the vicinity of Irving Place. The depth to water in this locale is generally between 30 to 40 feet. Therefore, flooding of basements in this area is not a concern.

CIB 009 1850


Subject: Clba-Gelgy Pipeline Integrity

Question:

Review existing information on the integrity of the Ciba-Geigy pipeline and provide a summary of the tests performed to date.

Response:

According to NJDEP, the outfall pipe at Ciba-Geigy is in very good condition. During it's original construction, the pipe exterior was lined with cathodic protection. The lifetime of this lining was expected to be 20 years. It was replaced within the last two years.

Pressure tests are conducted on the outfall pipe twice per year. No leaks have ever been detected during these tests. The most recent of available inspection reports, from November 1987. stated that the 'test was successful and showed the pipeline to be sound and not leaking". During March 1987. a diving survey was conducted of the Ciba-Geigy outfall pipe. The finding was that the overall condition of the pipe was very good. Several recommendations were made for minor repairs. It is not known whether Ciba-Geigy has followed up on these.

In July 1987, an investigation of the cathodic protection on the Ciba-Geigy outfall pipe was conducted by PCA Engineering. They stated that "At the time of this survey the cathodic protection rectifier unit was completely checked out and found to be operating satisfactorily." However, PCA recommended that an ineffective isolating flange at the plant pump station be repaired, bolt sleeves and fiber washers be installed, and upon the satisfactory completion of the above, all cathodic protection test stations and questionable locations be re-tested. PCA also recommended that additional cathodic protection test monitoring stations be installed along the pipeline route. It is not known whether this report was prepared before or after the cathodic protection was replaced or whether Ciba-Geigy has complied with the recommendations of this report.

Ground water monitoring wells have been installed by Ciba-Geigy along the length of the outfall pipe. Sample results for volatile organics and conventional water quality parameters were presented by Northeastern Analytical Corp. on April 13. 1988. Essentially no contaminants of concern were

•i detected.

Ciba-Geigy's 28" diameter outfall pipeline is constructed of welded steel and is approximately 10 miles long. Its origin is at the processing plant and travels approximately 34.000 feet to Barnegat Bay. The Bay crossing is approximately10.000 feet. The Ortley Bay crossing is another 1,500 feet and the Atlantic Ocean outfall section is about a half mile. The last 3,500 feet of the outfall pipe is under water and extends perpendicularly from the shoreline. Fifty discharge ports are located alternatively on either side of the last 1.000 feet of the pipe which is at a depth of40-45 feet below mean water level.

CIB 999 1B51

Waste generated at the Ciba-Geigy plant includes dye processing wastes, landfill ieachate. sanitary wastes, ground water, and laboratory wastes. Wastes are passed through a treatment plant at an average daily rate of about 4 million gallons per day before entering the outfall pipe. Organic compounds have not been detected during testing of the effluent. The effluent averages 5 mg/l BOD, 10 mg/l TSS. and 25 mg/l TOC. Also, approximately 200 ppb heavy metals are in the effluent. A diagram of the treatment train and a copy of effluent sample results are also attached to this document.

CIB 009 1852

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Approximately forty sites worldwide use the PACT process, which is available from Zimpro/ Passavant This process uses powdered activated carbon in a modified activated sludge process and achieves contaminant reduction through both adsorption (onto the PAC) and biodegradation. These systems are typically used as a means of tertiary treatment of wastewater. Sites where PACT is used range in size from 5000 gpd to 50 MGD. The closest PACT facility to the Tom's River. New Jersey Ciba-Geigy plant is the Dupont Chambers Works Plant in Deepwater. NJ.


Technical:

Activated carbon is a relatively well understood technology. It has been used for many years for a broad range of applications, and experience with the PACT process and with GAC give insight into the feasibility of using carbon at Ciba-Geigy. Carbon is effective for a wide range of contaminants, including the organic compounds found at Ciba-Geigy. A major advantage of carbon is that contaminants can be removed to extremely low levels. The low levels of contaminants that would be expected following secondary treatment would allow extended use of the carbon. A disadvantage of the PACT process when compared to GAC is that the PACT process produces a sludge which would require treatment and disposal. Furthermore, the effluent from the PACT unit can be expected to include fines which would impact attempts to recharge this water unless filtration was employed to remove the fines.

Regulatory:

Activated carbon is well accepted by the regulatory community, and this option is less burdened by regulations than other alternatives. One disadvantage of carbon is the disposal or regeneration of the saturated carbon. Disposal may be impeded by the possible classification of the spent carbon as a hazardous waste. Regeneration on-site may necessitate the need for air emission regulation. Major suppliers, such a Calgon. typically will pick up spent carbon and regenerate it at their own facility and provide fresh carbon to the user.

Environmental:

There are no advantages or disadvantages.

Cost:

Granular activated carbon costs up to $1.00 per pound for virgin GAC. GAC may be reactivated and used again, cutting costs to about $0.60 per pound. The capacity of the carbon and thus the carbon usage rate, is highly dependent on not only the toxic loading but also the total organic carbon of the wastewater.

The PACT process may be cheaper than GAC for tertiary treatment. According to Zimpro. treatment by PACT may cost $0.50 to $2.00 per 1000 gallons for a wastewater with roughly 20 mg/l COD. This cost is exclusive of sludge handling costs. Additionally, if effluent fron the PACT unit was to be recharged to the groundwater, flltrarion of the effluent to remove fines would be necessary thus further increasing the cost per gallon for treatment.


Both GAC and PACT could produce an effluent that meets all relevant discharge standards and thus would be expected to be protective of human health and the environment.

CIB N 9 1855


ubject: Feasibility of Slurry Walla

Question:

What is the feasibility of installing a slurry wall around the Ciba-Geigy site to contain all reinjected groundwater and decrease the amount of groundwater pumped?


Slurry walls have been sucessfully employed at a number of Superfund sites including the Upari Landfill in Pitman, New Jersey and the Gilson Road site in Nashua. New Hampshire.The installation of a slurry wall at the Ciba-Geigy site is technically feasible, however, no configuration would effectively decrease the required amount of groundwater pumpage. Two configurations of the slurry wall were investigated for the purpose of this analysis. The first is circular which serves to envelop the area of known and suspected subsurface contamination. The second is a line which would be placed between the extraction wells and Toms River. A slurry wall of this configuration and placed in this locale would make the extraction wells more efficient. Both configurations were evaluated for cost, the ability to protect the environment and the feasibility for decreasing the amount of groundwater pumped.

The circular slurry wall would need to envelop approximately 800 acres. With the isolation afforded by a soil bentonite slurry wall, the only water which would effect pumping would be the 1 billion plus

•allons of groundwater within the system and approximately 1 million gallons a day introduced by ainfall recharge. Therefore, only one million gallons a day would need to be pumped to maintain

existing groundwater levels within the system, however, this water would need to be discharged outside the slurry wall. This balance illustrates that regardless of the circular configuration of the slurry wall, without a cap impermeable to rainfall recharge covering the entire containment system it is not feasible to reinject all the effluent. It should be noted, however, that a circular slurry wall could potentially reduce the total amount of pumpage. It is difficult to define the exact amount of savings in total extraction rate without a more thorough investigation because the 1 MGD extraction rate estimated for interior to the containment system would need to be augmented by pumpage in the RI-9 area and immediately adjacent to Toms River (where is is not feasible to construct a slurry wall).

In light of this analysis, a second scenario was investigated which looked at a line-type slurry wall. This configuration would not be feasible for containing all reinjected groundwater, however, it potentially reduces the extraction rate by limiting the impact of reinjection on the extraction well system. Additionally, it serves to make the extraction well pumpage more efficient and reduces the amount of clean water to be pumped.


Subject: OAC and PACT ma Tertiary Treatment Option*

Question:

Provide a brief description and evaluation of other locations where either PACT or GAC is being used as tertiary treatment.

Response:

Many examples exist of successful application of GAC and PACT systems in treatment facilities. Facilities report cost and higher efficiency in the removal of organic compounds as significant advantages of these systems.

GAC's used for drinking water treatment is well established. It has traditionally been used for taste and odor removal in surface water treatment plants. More recently GAC has been used for removal of contaminants of health concern. The following is a list of ground and surface water purveyors who use GAC in New Jersey:

• Atlantic City • Boonton • Hackettstown • New Jersey Water Supply Co. (Delaware and Washington Districts) • Park Ridge • Rockaway Borough • Rockaway Township • South Brunswick Water Department

A survey of several up-and running treatment plants that utilize GAC or PACT follows:

One of the first transportable treatment systems of it's size and type for aquifer restoration was installed at the McClellanAir Force Base in Sacramento, California. The facility is designed to treat 1,000 gallons per minute of groundwater contaminated by volatile and nonvolatile organig chemical concentrations from as high as 50 ppm to below analytical detection limits. C)ontamInants removed include cbiomjum. nickel, selenium, lead, cadmium, dichloroethylene. trichloroethane, trichtoroeth-ylene, methylene chloride, vinyl chloride, benzene, chlorinated benzene, and ketones. Groundwater extraction wells deliver contaminated groundwater to a high-temperature air-stripper system to remove volatile organics. followed by a fixed media biological reactor for reduction of ketones and other solvents. The water then passes through a granular activated carbon filter to remove nonvolatile organics. The incineration system destroys volatile organics removed from the groundwater in the air-stripper process.

In Kalamazoo, Michigan, the public wastewater treatment plant uses the PACT wastewater treatment system to handle a concentrated mixture of industrial and domestic wastewater. The plant receives two flows: one from paper mills, the other from domestic, commercial, and industrial users. After separate primary treatment, the two flows come together in the PACT system where the combination of powdered activated carbon and biological treatment perform the bulk of the organic removal. Treated wastewater is clarified and the overflow goes to a 10-celled pulsed bed fine sand filter where

CIB 999 1697

remaining suspended solids are removed. Then, the effluent is chlorinated and re-aerated before discharge to the river. Spent carbon and btomass are wasted to a Zimpro wet air regeneration system for carbon regeneration and solids destruction. The unit operates autothermally at around 450° F. The plant came on line in 1985. Performance has been well within discharge Hmits. During one month, when BOD averaged 333mg/l into the PACTsystem. removal was 98 percent, producing an effluent with 7 mg/l. Effluent suspended solids removal averaged 96 percent. The system has also been effective in removing phosphorous and odor.

According to the plant superintendent. Kalamazoo is "getting results (pollutant removal and odor control) we could never have achieved when the plant was a straight activated sludge facility".

At the Bridgeport Rental and OO Services Superfund Site in Bridgeport, New Jersey, GAC is used to treat contaminated water at an on-site lagoon. Aqueous waste is pumped from a lagoon via a floating intake system. The intake penetrates the floating oil layer and provides a minimum depth of intake to maintain pumping without cavitation. Wastewater is pumped to an oil/solid/water phase separation unit to be collected and disposed of off-site. Wastewater is pretreated in a flash mixer, and then sent to a flocculation unit. From there, wastewater goes to the multi-media filter system] where residual suspended solids in the effluent are captured on the filter media. Following filtration, the wastewater is pumped into a granular activated carbon system to remove dissolved organic compounds in the wastewater. An air stripper is used to remove volatile organic compounds prior to feeding the granular activated carbon system. Approximately 200 gpm are treated in the Bridgeport system. Effluent quality averages about 50 mg/l TOC.

At the Hill Air Force Base in Ogden, Utah, a GAC unit is used to treat effluent from industrial wastewater to remove chlorinated aliphatic and aromatic solvents. The wastewater treatment facility consists of chromium precipitation, primary and secondary clarifiers. oil removal (granular media), air stripper, and GAC adsorption. The plant treats 800 gpm to effluent concentrations of less than 0.2 mg/l VOCs and less than 0.2 mg/l total phenols.

At the Chanute Air Force Base wastewater treatment plant in Rantoul, Illinois, an original wastewa-tertreatment system was upgraded with a GAC system tomeetmore stringent effluent requirements. Chanute's original system consisted of primary treatment including a clarifier and an Imhoff tank which were operated in parallel. Secondary biological treatment was provided by an intermediate rate trickling filter and two final clarifiers where were operated in series. A granular activated carbon system was installed in 1980. Approximately 2 MGD of wastewater pass through the carbon system, which includes four free standing back washable absorbers, each holding 20.000pounds of carbon] and a transfer vessel. The absorbers operate in a downflow parallel configuration. Dissolved organic chemicals in the wastewater are removed during passage through the carbon system at a superficial contact time of five minutes per column.


Activated carbon, in both granular or powdered form, is widely used as a method to purify water. It has been applied most extensively in drinking water treatment, especially as a method to remove taste and odor. Granular Activated Carbon (GAC) has also been widely employed as a remediation technique for the cleanup of contaminated groundwater from Superfund sites, underground storage tank sites, and spills. Activated carbon has also been applied, although less often, in the treatment of wastewater. The ability to remove a wide range of contaminants to very tow levels make carbon a popular, effective and flexible treatment alternative.

CIB 999 1858

Approximately forty sites worldwide use the PACT process, which is available from Zimpro/ Passavant This process uses powdered activated carbon in a modified activated sludge process and achieves contaminant reduction through both adsorption (onto the PAC) and biodegradation. These systems are typically used as a means of tertiary treatment of wastewater. Sites where PACT is used range in size from 5000 gpd to 50 MGD. The closest PACT facility to the Tom's River. New Jersey Ciba-Geigy plant is the Dupont Chambers Works Plant in Deepwater, NJ.


Technical:

Activated carbon is a relatively well understood technology. It has been used for many years for a broad range of applications, and experience with the PACT process and with GAC give insight into the feasibility of using carbon at Ciba-Geigy. Carbon is effective for a wide range of contaminants, including the organic compounds found at Ciba-Geigy. A major advantage of carbon is that contaminants can be removed to extremely low levels. The tow levels of contaminants that would be expected following secondary treatment would allow extended use of the carbon. A disadvantage of the PACT process when compared to GAC is that the PACT process produces a sludge which would require treatment and disposal. Furthermore, the effluent from the PACT unit can be expected to include fines which would impact attempts to recharge this water unless filtration was employed to remove the fines.

Regulatory:

Activated carbon is well accepted by the regulatory community, and this option is less burdened by regulations than other alternatives. One disadvantage of carbon is the disposal or regeneration of the saturated carbon. Disposal may be impeded by the possible classification of the spent carbon as a hazardous waste. Regeneration on-site may necessitate the need for air emission regulation. Major suppliers, such a Calgon. typically will pick up spent carbon and regenerate it at their own facility and provide fresh carbon to the user.

Environmental:

There are no advantages or disadvantages.

Cost:

Granular activated carbon costs up to $1.00 per pound tor virgin GAC. GAC may be reactivated and used again, cutting costs to about $0.60 per pound. The capacity of the carbon and thus the carbon usage rate, is highly dependent on not only the toxic loading but also the total organic carbon of the wastewater.

The PACT process may be cheaper than GAC for tertiary treatment. According to Zimpro. treatment by PACT may cost $0.50 to $2.00 per 1000 gallons for a wastewater with roughly 20 mg/l COD. This cost is exclusive of sludge handling costs. Additionally, if effluent fron the PACT unit was to be recharged to the groundwater, filtrarton of the effluent to remove fines would be necessary thus further increasing the cost per gallon for treatment.


Both GAC and PACT could produce an effluent that meets all relevant discharge standards and thus would be expected to be protective of human health and the environment.

CIB 8*9 1859


Subject: Sole Source Aquifer

Question:

Does the Impending 'sole source aquifer" designation for the Cohansey Formation beneath the Ciba-Geigy site affect the use of any of the reinjection scenarios?

Response:

An aquifer or aquifer system may be designated by the Administrator of the EPA pursuant to section 1424(e) of the Safe Drinking Water Act as a sole source aquifer if it is the sole or principal drinking water source for an area and which, if contaminated, would create a significant hazard to public health.

On July 7.1988 (pursuant to section 1424(e) of the Safe Drinking Water Act) the Administrator of the U.S. Environmental Protection Agency determined that the New Jersey Coastal Plain Aquifer System, underlying the New Jersey Coastal Plain Area, is the sole a principal drinking water source for the Counties of Monmouth, Burlington, Ocean, Camden, Gloucester. Atlantic. Salem. Cumberland, Cape May and portions of Mercer and Middlesex Counties, New Jersey. The determination will become effective on August 8, 1988. As a result of this action, the EPA will review projects requesting Federal financial assistance for implementation whose area includes a portion of the New Jersey Coastal Plain Aquifer System. EPA's review will also ensure that the project is designed and constructed so that it does not create a significant hazard to public health. (Federal Register Vol 53. No. 122. 6-24-88).

At present, the NJDEP does not have any regulations specifically concerning a federally designated sole source aquifer. It does, however, regulate extraction of contaminated waters and. after above ground treatment, the injection of these waters into any aquifer.

Extraction of any contaminated subsurface waters in excess of 100.000 gallons per day per site is regulated by the NJDEP. At the Ciba-Geigy site, each remedial action pumping scenario would extract over 3,000,000 gallons per day for the site. Thus, it would be necessary to obtain a permit from the NJDEP prior to implementation of a water extraction plan.

Injection of waters into an aquifer is regulated by the Underground Injection Control Program (UIC) in accordance with the New Jersey Water Pollution Control Act. The UIC program has classified all injection wells within the State. Wells which inject treated water into the subsurface for the purpose of aquifer remediation are classified as Class V wells. Regulations for Class V injection wells include:

• any underground injection is prohibited, except as excluded under NJAC 5.1. authorized by permit or by rule. In addition, the construction of any well required to have a permit (including, where applicable, a well drilling permit) is also prohibited until the permit has been issued.

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• no UIC authorization by permit or by mle shall be aJlowed where a Class V well causes or allows movement of fluid containing any contaminant into underground sources of drinking water, and the presence of that water may cause a violation of any primary drinking water regulation (NJAC 7:10-5), any ground water quality standards (NJAC 7:9-6). or which adversely affects the public health.

The regulations above are those of the NJDEP. There is a question of applicability of some of these regulations to a Superfund clean-up site such as Ciba-Geigy.

Table 4-3 of the Ciba-Geigy Feasibility Study denotes assumed discharge levels should the contaminated ground water at the site be treated in Ciba-Geig/s existing wastewater treatment facility. A comparison of assumed effluent quality from the existing plant to the National Primary Drinking Water Regulations and New Jersey Ground Water Quality Criteria (NJGWQC) appear on table A which accompanies this document so as to determine whether a violation of these standards would occur as a result of injection into the sole source aquifer.

Upon a review of this table, it is apparent that some modifications to the existing Ciba-Geigy plant would be necessary due to violations of the criteria for ammonia, nitrates, sulfate and total dissolved soilds (TDS). Of these components, only nitrates presents a direct health-related concern. The other components are related to aesthetics. Technologies do exist to reduce all of the components to comply with the NJGWQC. For example, reverse osmosis can be used to remove inorganic tons and some of the trace organics in the water; ion exchange would reduce the amount of the TDS prior to discharge; and the ammonia can be reduced further by a modification to the PACT process which would increase the level of nitrification.

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TABLE A Ground Water Discharge Evaluation

National Primary New Jersey dba-Gelgy Discharge Drinking Water Regulations Ground Water Quality Criteria Levels

Component (40CFRPart141)<»> (NJAC 7:9 - 6.6) (Table 4-3 of FS)

Arsenic 0.05 mg/l Barium 1 mg/l Cadmium 0.010 mg/l Chromium 0.05 mg/l Lead 0.05 mg/l Mercury 0.002 mg/l Nitrate (as N) 10 mg/l Selenium 0.01 mg/l Silver 0.05 mg/l Turbidity 1-5 TU Fecal Conform 4 per 100 ml Ammonia

4 per 100 ml

Chloride Cyanide Phenol Color Copper Iron Manganese Odor and Taste Oil and Grease PH Sodium Sulfate TDS Zinc

0.05 mg/l ND 1.0 mg/l ND 0.01 mg/l ND 0.05 mg/l ND 0.05 mg/l 0.005 mg/l 0.002 mg/l ND 10 mg/l 12.6 mg/l 0.01 mg/l ND 0.05 mg/l

4 per 100 ml 0.5 mg/l 3.4 mg/l 250 mg/l

3.4 mg/l

0.2 mg/l 0.3 mg/l 0.01 mg/l None

0.01 mg/l

1.0 mg/l 0.016 mg/l 0.3 mg/l 0.05 mg/l None None 0 . 64 mg/l 5-9 std. units 6-8 std. units 50 mg/l 250 mg/l 323 mg/l 500mg/l 1,400 mg/l 5 mg/l ND

«•» The National Primary Drinking Water Regulations have been adopted by the State of New Jersey (NJAC 7:10-5.1)

NO - Not Delected.


Subject: Impact of Groundwater Pumpage on Public Water Supply

Question:

How much will the water table drop in each of the pumping scenarios? Could this significantly affect water availability for public use?

Response:

A drop in the groundwater levels due to pumpage is important at three separate locations: the public water supply wells, and at private wells located on and near the south end of Cardinal Drive and along Irving Place. The following table summarizes the effect of the various remediation schemes on the water table level and the yield of groundwater pumping at each of the locations:

Remediation Effect on Groundwater Availability

Location Irving Place scenario 1 scenario 2 scenario 3 scenario 4

South End of Cardinal Drive scenario 1 scenario 2 scenario 3 scenario 4

Toms River Water Company Well No. 20 scenario 1 scenario 2 scenario 3 scenario 4

Average Water Table Changf?

-1.2 ft -1.3 ft + 1.5 ft +0.7 ft

-3.5 ft -3.7 ft -3.1 ft -3.2 ft

-0.5 ft -0.5 ft -0.4 ft -0.4 ft

Average Change in Pumninn Yield

-4.2 gpm -4.5 gpm +5.3 gpm +2.5 gpm

-12.3 gpm -13.0 gpm -10.9 gpm -11.2 gpm

-6.1 gpm -6.1 gpm -5.1 gpm -5.1 gpm

Percent Change in

Pumping Fiftlrt

(-3%)* (-3%)* (+4%)* (+2%)*

(-9%)* (-9%)* (-8%)* (-8%)*

(-1%)" (-1%)** (-1%)"

(-1%)"

estimated for average well screened 40 feet into the saturated zone, based on an average daily flow rate for past 20 years of record.

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Under the most extreme pumping scenario, the average drawdown along the line of extraction wells located along the bluff east of the residential area is approximately 6 feet. This drawdown which lessens beneath the residences as denoted In the table above, does not significantly impactthe area public water supply in that the average decrease in pumped groundwater at Toms River Water Company well #20 is at most 9.000 gpd (approximately 1% of average daily pumpage). where as Ihe decreased yield due to variations in annual recharge at the same location can be on the order of 16.000 gpd or more.

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Subject: Discussion of Real Time Sampling and Analysis Equipment for Monitoring

Question:

What state-of-the-art monitoring methods exist to help insure that treatment plant effluent would not go out of compliance and be discharged without the public's knowledge?


The treatment plant effluent must be sampled continuously to insure the public that slugs with unacceptable water quality are not discharged into the receiving waters. In order to perform this task, some sampling and analysis device must be installed online which can determine and record the quantity of a particular constituent within moments of sampling (i.e.. real time). The constituent of interest must be organic-based due to the nature of the hazardous substances present in the contaminated groundwater.

Continuous recording TOC (total organic carbon) analyzers are available for such a process. The TOC analyzer is able to detect low levels of organic contamination (below 10 ppb) which is in the range of the treated groundwater effluent quality. The cost of such an item is approximately $15,000. This analyzer could be equipped with an alarm fuction and could further be installed to send a signal to a valve on the treatment plant discharge line, effectively shutting off the discharge should the effluent exceed a pre-set TOC level.

A relatively inexpensive and sensitive real time monitoring device which is also available is a catylitic system conductivity meter. However, it is uncertain how effective a monitoring device this system would be for detecting small quantities of volatile organic contamination.

In response to the question of whether a bioassay has been developed for continuous monitoring of treatment plant effluent, the NJDEP Department of Science and Research reported that the accepted methods for btomonitoring are the acute toxicity tests and a newly developed test using the Japanese Medeka. The latter test is dependent on the reproductive cycle of the Medeka and requires 11 days for completion. The acute toxicity biomonitoring tests are mandated for use by the National Pollutant Discharge Elimination System (NPDES). These tests include an 8 to 24 hour range-finding (screening) bioassay, a 24 to 96 hour static bioassay, a 96 hour flow-through bioassay, and a 24 hour QA bioassay with a reference toxicant. The intent of these tests is to determine an LC-50 orEC-50.

The purpose of any continuous biomonitoring at Ciba-Geigy, however, would be to monitor any deterioration of effluent quality. According to the NJDEP, no continuous biomonitoring test has been developed or documented, and the acute toxicity tests were not developed for this purpose. (Source: Roy Meyer, NJDEP, Trenton. NJ (609) 984-5311)

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Advantages and Disadvantages: Not Applicable


Real time analysis of the waste stream will help to determine whether or not the groundwater treatment plant is operating at specifications, although it is not specifically making determinations of particular constituent concentrations. Therefore, as an aid to protecting the environment from treatment plant upsets, it is beneficial. However, additional regular monitoring and laboratory analyses must be performed to fully determine the effectiveness of the contaminant removal process.

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Subject: Description of other Ciba-Geigy Facilities

Question:

Provide a brief history or description of other Ciba-Geigy plants and their environmental compliance (or noncompliance) history. Of particular interest is the recent closing of the Cranston, Rhode Island and Glen Falls. New York plants.

Response:

Glen Falls, New York-This plant site has been in existence since the 1800 s. Ciba-Geigy purchased the site in 1979 from Hercules. Inc. and undertook the manufacture of organic and inorganic pigments. Ciba-Geigy made a business decision to close the plant down when the line of products produced at the plant proved to be unprofitable. Ciba is currently in the process of shutting down the plant. Such activities are planned to be completed by the end of 1989.

A RCRA site investigation was recently conducted by the New York State Department of Environmental Conservation (NYSDEC). Waste disposal was identified in burial sites, lagoons, and surface piles on the property. The soil and groundwater were found to be contaminated onsite with both organic and inorganic contaminants. Ciba-Geigy is under a Consent Order with the State to conduct additional onsite and offsite investigations and institute corrective actions. The NYSDEC believes that offsite migration of contaminated groundwater has probably occured. (Source: George Stahler, NYSDEC. Albany. NY. (518)-891-1370).

Cranston, Rhode Island -This site began operations in 1949. The primary products produced at this facility since its inception included: dyestuffs, agricultural products, plastics, plastic additives, and pharmaceutical products. In 1986, Ciba-Geigy announced its intentions to close this facility. Reportedly, this decision was based on the ability of other Ciba-Geigy plants to produce the same products in a more cost-effective manner. Shut-down of the facility was completed in 1987. During1987. EPA issued an order to Ciba-Geigy to perform a facility investigation under RCRA. Sampling and analysis results from the site revealed the presence of organic contamination in the soil and groundwater. The soil contaminants detected in the highest concentrations were fluoranthene. pyrene. chrysene, phenanthrene. benzo-b-fluoranthene. and benzo-a-pyrene. Xylenes, chlorobenzene, ethylbenzene, phenol, and acetones were the primary contaminants in the groundwater. The concentrations of the soil and groundwater samples ranged from 200 ug/l to 2000 ug/l. (It should be noted that the groundwater samples were collected from piezometers and the results were not validated). The waste generated by the plant was stored in above ground tanks and drums, and the wastewater treatment plant was subject to overflows resulting in releases onto the ground. The property is presently surrounded by a fence and all buildings have been leveled. EPA-Region I plans to issue another order to Ciba-Geigy in about 3 months requiring further investigative activities be conducted at the site. If this follow-up investigation confirms the presence of soil and groundwater contamination. EPA will order Ciba-Geigy to undertake a cleanup program at the site (Source: Frank Battaglia. USEPA-Region I. Boston. MA) (617) 573-9640

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Subject: Discharge to OCUA

Question:

Does the Ocean County Utilities Authority (OCUA) Central Plant, nearest Ciba-Geigy, have the hydraulic capacity to handle an additional 4 MGD of contaminated ground water expected to be generated by the proposed ground water extraction program? If such capacity is available, what would be the approximate cost of constructing a pumping station and force main to deliver 4 MGD to OCUA?

Response:

The hydraulic capacity of the Central Plant is currently 24 MGD. The average daily flow at the plant is 23 MGD. Accordingly. OCUA would not be able to handle an additional 4 MGD from the Ciba-Geigy site. OCUA is considering expanding the capacity of the Central Plant to either 30 or 36 MGD. Such expansion would not expect to enter the design phase until the completion of a feasibility study scheduled to commence at the end of this year.

If. after expansion, 4 MGD were to be pumped to this plant from Ciba-Geigy via an underground force main, a distance of approximately 35.000 linear feet would need to be traversed. A pipe diameter of 14 inches would be required to carry such a flow at a hydraulically acceptable rate of 6 feet per second. Applying this information to a series of engineering curves based on compiled historical data concerning the cost to construct and operate a pumping station and force main, the following information may be discerned:

• The capital cost of the force main can be estimated at $173 per linear foot for a total cost of approximately $6 million.

• The capital cost of a 4 MGD pump station would be approximately $1 million.

• The operations and maintenance cost of the pump station would be on the order of $45,000 per year.

• On a present worth basis, assuming a life cycle of 30 years and an interest rate of 10 percent, the cost for such a pumping station and force main would be:

e $6 million + $1 million + $45,000 (present worth facta)

«= $7 million + $45,000 (9.427)

B $7 million + 0.4 million

s $7.4 million

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Subject: Carbon Flnea In PACT Effluent

Question:

Does the PACT process put carbon fines into the effluent stream such that difficulties in recharging the effluent either via infiltration basins or reinjection wells will occur?

Response:

The PACT process operates similarly to the activated sludge process. The main differences are the addition of powdered carbon to the aeration tank and the increased concentration of mixed liquor suspended solids to an approximate range of 10.000 to 15.000 milligrams per liter. At the existing Ciba-Geigy wastewater treatment plant, the biological solids and the added powdered carbon are captured in the secondary clarifiers. This process is assisted by the addition of polymers prior to the secondary clarifiers. While the effluent from the clarifiers is presently suitable for ocean discharge, it would be expected to contain sufficient fines such that attempts to recharge this effluent to the ground water via injection wells or infiltration basins would be adversely impacted.

The fines can be removed by filtration. Sand filters with an effective size of 0.45 millimeters and a 1.6 uniformity coefficient should be effective in removing the fine solids present in the secondary clarifier effluent. Subsequent to filtration, the effluent would be suitable for recharge.

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Subject: Feasibility of the PACT Process for On-Slte Treatment

Question:

Is the ground water to be extracted from the Ciba-Gergy site too dilute to be effectively treated by the PACT process?

Response:

The PACT process treats waste streams through two basic mechanisms: biological oxidation (biodegradation) and carbon adsorption. If the ground water has a BOD of greater than 40 to 50 milligrams per liter, then both mechanisms will be active in the treatment of ground water. As the BOD decreases, carbon adsorption becomes the dominant mechanism. Thus, for low BOD concentrations, the use of granular activated carbon (GAC) may be more cost-effective than the PACT process.

The PACT process can be used to treat waste streams with BOD's less than 10 milligrams per liter. The powdered carbon in effect concentrates the organics on its surface which subsequently supports biological activity. In such cases there may be a need to add to the ground water the basic nutrients phosphorous and nitrogen along with some micro-nutrients (i.e. metals) to promote biological activity. It should be recognized that in the absence of biodegradable organics, the PACT process acts as an adsorption process.

When contacted, NUS could not provide any original data regarding the levels of BOD in the ground water at the Ciba-Geigy site. They did cite, however, data from prior reports produced by Ciba-Geigy which gave values for BOD of between 40 and 52 milligrams per liter. Given this information, it is apparent that the ground water is not too dilute to be treated by the PACT process.

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Subject: Feasibility of the DuPont Chamber Works PACT Process

Question:

Is the ground water from the Ciba-Geigy site too dilute for proper treatment by PACT at DuPont Chamber Works? Does DuPont have a problem with carbon fines in the effluent?

Response:

The DuPont plant treats approximately 35-40 MGD of wastewater, including a wide variety of wastes trucked to the plant from over 1,000 different sources. The impact of any one source on plant operations is minimal.

The waste strength is watched closely by the plant operator, however. During the day shift (8 A.M. - 4 P.M), the plant typically receives a large amount of waste from off-site, giving the mixed liquor a high organic loading. In fact, at one point DuPont informed off-site generators that their waste would only be accepted during an off-shift due to the high level of loading. During the two other shifts (4-12 P.M.and 12-8 A.M.) the loading is typically lower in strength. DuPont keeps on-site a tank full of very high strength waste to mix into the influent during these hours as necessary in order to maintain a somewhat steady feed rate.

Based on this description of the DuPont operation, delivering a tow strength waste (such as Ciba-Geigy's) during the 8 A.M.-4 P.M. shift would actually be favorable to plant operations.

At the Chamber Works the PACT process is followed by filters that remove the powdered activated carbon. The water is then discharged to clarifiers where any remaining solids are allowed to settle out.

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Subject: Sprinkler Application of Treated Wastewater

Question:

What is the feasibility of applying treated ground water to the ground surface utilizing a system similar to that of spray irrigation?


The application of the treated ground water to the ground surface with a spray irrigation-type system is technically feasible. Such systems have been used successfully for the application of municipal wastewater to land at other locales.

The amount of land required for application of 4 MGD is estimated to be 10 acres. This figure assumes that the system will be delivering the water to the land surface 24 hours/day, and that the evaporation and infiltration rates are 52% and 0.6 inches/hour, respectively. Whether the treatment plant effluent could be applied 24 hours/day would depend on the treatment plant schedule and storage facilities. If the 4 MG were to be applied in less time a proportionately greater amount of land and more extensive spray irrigation system would be required.

Several potential problems are associated with the use of such a system. During cold weather a frozen water layer on the surface of the ground could form. This layer would prevent further infiltration of the wastewater leading to pooling of the water or its runoff into surface water bodies. Because the spray system would function as a stripping device, volatilization of organic compounds would also be a concern if volatiles were not appropriately removed in the treatment plant. Volatilization would be particularly great during the summer when the temperature and evaporation rate are elevated. Wind-induced migration of these volatiles or the spray itself also present a potential problem since residential areas are nearby. Lastly, any fines present in the treatment plant effluent would need to be removed as they could cause plugging of the spray nozzles.


Technical:

Technical advantages would include the simple operation of the sprinkler system and the low maintenance required for this type of operation. Some benefits of flushing water-transportable contaminants from the soil might also be realized. The main technical disadvantage would be the potential operational problems during the winter months or if fines were not removed.

Regulatory:

There are no known regulatory advantages or disadvantages.

C I B 009 1872

An environmental advantage of this option would be the introduction of water to the ground water system which meets the stringent ground water discharge criteria.

An environmental disadvantage might be caused if the infiltration rate were slower than the application rate leading to runoff (particularly during the winter months) or creation of a large area of stagnant water.

Cost:

There is a cost advantage associated with the minimal construction required, and the low operation and maintenance costs associated with this system. Specific costs for the sprinkler system are not available at this time.


The major area of concern is:

Miigration of air-borne contaminants to residential areas during strong wind conditions if the treatment plant is out of compliance.

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Documents

CDM Federal Programs Corporation · CDM Federal Programs Corporation July 29, 1988 ... It has been previously estimated by CDM that approximately 4 million gallons per day ... (Cohansey