Performance Evaluation Report No.19 (January 2004

DICO

Performance Evaluation Report No. 19(January 2004 Through December 2004)

Groundwater ExtractionAnd Treatment SystemDes Moines TCE Site

Des Moines, Iowa

July 2005

40263139

SUPERFUND RECORDS

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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY&

REGION VII901 NORTH 5TH STREET

KANSAS CITY, KANSAS 66101

0 7 DEC 2005Mr. Brian MillsDico, Inc.P.O. Box 161 6Des Moines, Iowa 50306-1616

Dear Mr. Mills:

RE: Comments on the Performance Evaluation Report No. 19 for the GroundwaterExtraction and Treatment System, Des Moines TCE Site, Des Moines, Iowa

The U.S. Environmental Protection Agency (EPA) has reviewed the subject reportand is providing this letter in response to the conclusions and recommendations in thereport.

As you know, Performance Evaluation Report No. 19 (PER 1 9) evaluates the firstfull year of operation of the groundwater extraction and treatment system under modifiedconditions. System modifications approved in 2003 included shutting down extractionwells 3, 4, and 8 as well as reducing the monitoring frequency. These modifications wereapproved for a one-year period to be followed by an evaluation of the capture zoneachieved under the modified pumping scheme.

Since the first full year of operation under modified conditions has been evaluatedin PER 19, it is time to determine whether the modifications could become permanent,additional modifications may be appropriate, or the prior pumping regime restored. If wewere to make these changes permanent, we would have to modify the Operable Unit 1(OU 1) Record of Decision (ROD) as provided in the National Contingency Plan (NCP),40 CFR Part 300. The nature of the changes we are considering would appear to requireeither an Explanation of Significant Differences or a ROD Amendment, depending uponthe full extent of the changes. A ROD Amendment could only be made after providingthe public with an opportunity to review and comment on the proposed changes in theremedy. So any changes EPA indicates a willingness to make in this letter should beconsidered as being conditioned upon being subject to reconsideration based upon anycomments from the public.

Furthermore, these types of permanent remedy changes cannot be implementedsimply by EPA sending Dico an approval letter. The changes would need to be reflectedin either a revised administrative order or a consent decree. A consent decree would alsorequire providing an opportunity for the public to review and comment on the proposedsettlement. Therefore, the responses provided in this letter represent the things EPA

RECYCLED

might be willing to agree to, subject to the possible need for public review and comment,but this letter does not provide Dico with authority to implement them.

We would like to begin a dialogue with you to gauge your level of interest inmaking these modifications permanent through a new or modified order or consentdecree. After reviewing the responses below, please respond to this letter to indicate yourpreference regarding how to proceed.

The modified pumping scheme using only extraction wells 5, 6, and 7 appears tobe providing adequate capture of the contaminant plume under current site conditions.Given that the volatile organic compound (VOC) concentrations in extraction well 5 aregenerally less than 100 micrograms per liter (ug/1), significantly lower than the VOCconcentrations of extraction wells 6 and 7, which remain greater than 500 ug/1, EPA mayalso be willing to agree to shut down well 5, or at least agree to a schedule for evaluatingthe possible shut down of well 5. The reduced pumping scheme would need to be re-evaluated if site conditions were to change, such as if the Des Moines Water Worksresumed using the north gallery.

In order to better assess the mass removal rate of each extraction well and to makedecisions regarding future operation of the system, it would be helpful to gather andreport the following information for each extraction well in future PER reports:

• Average pumping rate• Average concentration of trichloroethene (TCE), cis-l,2-dichJoroethene (DCE),

and total VOCs• Total VOC volume removed

PER 19 suggests that a thorough examination be made of the need for thecontinued operation of the pump and treat system and that other remedial alternatives beconsidered. The EPA would be willing to consider evaluating other remedial measures.Any such proposal would be evaluated in accordance with the remedy modificationprovisions of the NCP. However, until such time as a revised remedy is approved andimplemented, continued operation of the pump and treat system is necessary to preventcontaminant migration to the west side of the Raccoon River.

The EPA does not believe that natural attenuation alone could replace the currentpump and treat system. Historical data suggest that natural attenuation is quite slowwhile plume migration is relatively fast, without the containment system in place. In-situtreatment methods, such as reductive dechlorination, may be feasible, but thoroughevaluation of such methods would be needed using the nine evaluation criteria in theNCP.

PER 19 suggests that the natural hydraulics of the system alone may be capable ofproviding migration control. This seems to be based on the author's conclusion that theriver presents a barrier to ground water flow. The EPA does not agree with thisassessment. Data from recent PERs clearly show that the extraction system causes

drawdown in wells on the west side of the river. The data confirm the hydraulicconnection between the east and west sides of the river, and refute the notion that theriver is a hydraulic barrier, at least for lower portions of the aquifer. If the extractionsystem were shut down entirely, the plume would likely migrate south-southwestward,under the Raccoon River, and into the south gallery or other areas of uncontaminatedgroundwater.

In closing, EPA is willing to consider making the temporary modificationspermanent and possibly exploring additional modifications or remedial measures underthe conditions discussed above. Please respond as soon as possible regarding yourinterest in negotiating an agreement under which these modifications can be permanentlyimplemented. If you have any questions regarding this letter, please call me at (913) 551-7882.

Sincerely,

M/Mary P. PetersonProject ManagerIowa/Nebraska Remedial BranchSuperfund Division

Cc: Quintin Macdonald, EME

EMEI ENVIRONMENTAL SOLUTIONS

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28 Middleton Street • Nashville, Tennessee 37210615.742.0875 • 615.742.0873 (facsimile)

June 30, 2005

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Ms. Mary PetersonProject ManagerIowa/Nebraska Branch, Superrund DivisionUSEPA Region VII901 North 5th Street, Kansas City, Kansas 66101-2907

Dear Ms. Peterson:

Enclosed are three copies of the 2004 Performance Evaluation Report for thegroundwatsr extraction system at the Des Moines TCE site (DICO). An Adobe PDFversion of the report is provide on the CD-ROM that is attached to the inside cover of thebinder. The laboratory data (Appendix E) from 2004 is provided only in the PDF versionof the report.

If you have any questions regarding the contents of this report please do not hesitate tocontact me at (615) 742-0875 or [email protected].

Sincerely,Environmental Management and Engineering, Inc.

mtin G. Macdonald, PGProject Manager

cc:

Cheri Holly

DICO

Performance Evaluation Report No. 19(January 2004 Through December 2004)

Groundwater ExtractionAnd Treatment SystemDes Moines TCE Site

Des Moines, Iowa

July 2005

Performance Evaluation Report No. 19 (January 2004 Through December 2004)

Groundwater Extraction And Treatment System Des Moines TCE Site

Des Moines, Iowa

July 2005

PERFORMANCE EVALUATION REPORT NO. 19 (JANUARY 2004 THROUGH DECEMBER 2004)

GROUNDWATER EXTRACTION AND TREATMENT SYSTEM DES MOINES TCE SITE

DES MOINES, IOWA

Prepared for:

Iowa/Nebraska Branch Superfund Division USEPA Region VII 901 North 5th Street

Kansas City, Kansas 66101-2907

Prepared by:

DICO 2345 East Market Street Des Moines, Iowa 50317

July 1, 2005

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TABLE OF CONTENTS

Page No. 1.0 INTRODUCTION........ ................................................................................................................. 1 2.0 SYSTEM PERFORMANCE ......................................................................................................... 3 2.1 Introduction......... ................................................................................................................. 3 2.2 Extraction Well Operation .................................................................................................. 3 2.3 Air Stripper Operation ......................................................................................................... 4 2.4 Extraction System Capture Zone ....................................................................................... 7 2.5 Gallery Operation ................................................................................................................. 9 2.6 Groundwater Quality ........................................................................................................... 9 2.7 Surface Water Quality ........................................................................................................10 3.0 CONCLUSIONS AND RECOMMENDATIONS ................................................................11

LIST OF TABLES

Table No.

Title

2-1 Summary of Air Stripper Efficiency Calculations (2004) 2-2 Summary of Air Stripper Influent and Effluent pH and Iron Data (2004)

2-3 Summary October 2004 Groundwater and Surface Water Quality Data

LIST OF FIGURES

Figure No.

Title

2-1 Hydrograph of Northern Extraction Wells (1987 – 2004) 2-2A Hydrograph of Southern Extraction Wells (1987 – 2004) 2-2B Hydrograph of Southern Extraction Wells and the Raccoon River (2004) 2-3A VOC Air Stripper Influent Concentration (1987 – 2004) 2-3B VOC Air Stripper Influent Concentration (2004)

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LIST OF FIGURES (Cont.’d) Figure No.

Title

2-4 pH and Iron Concentrations Air Stripper Influent 2-5 pH and Iron Concentrations Air Stripper Effluent 2-6 Air Stripper Efficiency (1987 – 2004) 2-7 Static Pressure Stripping Tower (1987 – 2004) 2-8 Air Flow at Air Stripping Tower (1987 – 2004) 2-9A Cumulative Mass Removed (1987 – 2004) 2-9B Cumulative Mass Removed (2004) 2-10A Potentiometric Map: February 27, 2004 2-10B Potentiometric Map: April 22, 2004 2-10C Potentiometric Map: July 23, 2004 2-10D Potentiometric Map: October 27, 2004 2-11A Hydrograph of Elevations in Galleries (1987 – 2004) 2-11B Hydrograph of Elevations in Galleries and the Raccoon River (2004) 2-12 Trichloroethene Concentrations in Groundwater - October 2004 2-13 Total 1,2-Dichloroethene Concentration in Groundwater - October 2004

APPENDICES Appendix A - Groundwater Level Measurements and Elevations Appendix B - Hydrographs of Selected Wells Appendix C - Summary of Groundwater and Surface Water Quality Data Appendix D - Water Quality Plots for Selected Wells Appendix E - Volatile Analysis Data Package

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1.0 INTRODUCTION

A groundwater extraction and treatment system was installed in 1987 at the Des Moines TCE Superfund Site. The purpose of that system was to prevent groundwater contaminated with chlorinated volatile organic compounds (VOCs) from migrating toward an infiltration gallery system (north gallery) that supplied drinking water to the City of Des Moines, Iowa. Operation of the northern infiltration gallery stopped around 1988. As a result, natural groundwater flow patterns have returned to the north gallery and the surrounding area. Over the past 17 years, a groundwater monitoring program has been conducted to evaluate the performance of the extraction and treatment system. The monitoring program was revised in January 1993, and again in July 2003. The 2003 modifications were completed between March – November 2003. Some of the 2003 modifications are considered temporary, until the United States Environmental Protection Agency (USEPA) reviews this annual report (2004), in order to evaluate the effects of operating under those modifications for at least a full year. The monitoring program presently includes the following elements:

• The collection of water level measurements in operating extraction wells, selected monitoring wells and in the Des Moines Water Works (DMWW) gallery system and corresponding surface water elevation data from the Iowa District United States Geologic Survey’s (USGS) and the City of Des Moines gage at Fleur Drive Bridge in the Raccoon River;

• The collection of samples from the gallery, groundwater and surface water for

chemical analysis;

• The collection of stripping tower influent and effluent samples for chemical analysis; and

• The collection of groundwater flow and air-flow measurements through the

stripping tower. The surface water, influent and effluent samples are collected in accordance with the requirements of DICO's National Pollutant Discharge Elimination System (NPDES) Permit (No. 77-27-1-27).

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This report describes the operation and performance of the extraction system during the past 17 years of operation, with a special emphasis on the system's performance in 2004. Analysis of the data from 2004 indicates that the system continues to meet its containment objective.

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2.0 SYSTEM PERFORMANCE

2.1 INTRODUCTION The following sections present data that were collected over the past 17 years to evaluate the groundwater extraction and treatment system, with an emphasis on data collected in 2004. 2.2 EXTRACTION WELL OPERATION The extraction system originally consisted of seven extraction wells (ERW-3 through ERW-9), which were installed at the Des Moines TCE site in the fall of 1987. Those wells began to operate on December 17, 1987. As discussed in previous performance evaluation reports, extraction well ERW-9 has not operated since late 1988 when the well became inoperable due to excessive iron deposits. ERW-3 and ERW-4 were shut down in March 2003 and ERW-8 was shut down in November 2003. The USEPA approved discontinuing operation of those three wells because the 2003 system evaluation indicated that they were providing negligible recovery of groundwater contaminants and that the system could operate equal well using only wells ERW-5, ERW-6 and ERW-7. The operation of recovery wells ERW-5, ERW-6 and ERW-7 has continued after the three previously mentioned wells were removed from service in 2003. Between January 2004 and December 2004, those three wells pumped at an average cumulative rate of approximately 297 gallons per minute (gpm). As detailed in the following sections, the 2004 operation data indicates that the system, as a whole, has achieved its containment objective. Water level measurements have been collected from the extraction wells on a regular basis since December 1987. The water level measurements from 2004 are provided in Appendix A. Two hydrographs (Figures 2-1 and 2-2A) were prepared to show changes in the water levels in the extraction wells over the last 17 years. Figure 2-1 depicts the northern extraction wells, and Figure 2-2A shows the southern extraction wells. Well ERW-6 is included in both Figures because it is centrally located between all of the extraction wells. Figure 2-2B shows 2004 groundwater elevation trends in extraction wells ERW-5, ERW-6 and ERW-7 and the elevation of the Raccoon River (i.e., surface water). The surface elevation data from the Raccoon River was obtained from the United States Geologic Survey’s (USGS) gage at Fleur Drive Bridge. The surface water gage is located approximately 465 feet from the right edge of the SW 18th Street Bridge in Des Moines.

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These data confirm the direct hydraulic relationship between the Raccoon River and the watertable aquifer. Specifically, the seasonal elevation fluctuations observed in the Raccoon River are identical to those observed in these extraction wells. These data indicate that the Raccoon River is a losing stream (i.e., it is a significant source of recharge for the aquifer). As such, groundwater near the Raccoon River’s east bank (i.e., the DICO site side) flows away from the River to the east. The hydraulic influence of the Raccoon River controls the elevation and local groundwater flow patterns observed in the DICO monitoring and extraction wells. The elevation of the portion of the Raccoon River that fronts the DICO site is controlled, in part, by the spillway that it to the south of ERW-8. According to the Des Moines Water Works (DMWW), the elevation of the spillway with its flashboards down is 780.34 feet. The DMWW can raise the flashboards on the spillway when needed to control drainage rates to 783.34 feet. A comparison of elevation data from the northern and southern infiltration galleries and the Raccoon River (see Figure 2-11B) supports these conclusion. These data also suggest that the existing extraction system, despite aggressively pumping of the aquifer for more than 18 years, has little overall influence of groundwater elevations. Further, that the extraction wells are probably receiving significant quantities of groundwater directly from the Raccoon River as it loses water to the formation. 2.3 AIR STRIPPER OPERATION Groundwater collected by the extraction system is treated by removing volatile organic compounds (VOCs) at the air stripping tower located on the site. To evaluate the effectiveness of the air stripper, influent and effluent samples were collected monthly in accordance with DICO's National Pollution Discharge Elimination System (NPDES) Permit (No. 77-27-1-27). The samples were analyzed for pH, iron and seven target chlorinated VOCs: vinyl chloride, 1,1-dichloroethene (1,1-DCE), total 1,2-dichloroethene (total 1,2-DCE), trichloroethene (TCE), chloroform, 1,1,1-trichloroethane (1,1,1-TCA) and 1,2-dichloroethane (1,2-DCA). Those results are summarized in Table 2-1. Figure 2-3A illustrates VOC influent concentrations since 1987. Figure 2-3B illustrates VOC influent concentrations over the last 10 years of operation. The results of pH and iron analyses conducted in 2004 are presented in Table 2-2. The pH and iron concentrations in influent samples for 2004 are plotted in Figure 2-4, and the pH and iron concentrations in effluent samples from the same period are plotted in Figure 2-5.

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Figure 2-3A illustrates the dramatic reduction in the treatment system’s influent concentration of TCE, total 1,2-DCE and vinyl chloride after only four years of operation (i.e., from part per million to part per billion concentrations). Figure 2-3A shows that the concentration of TCE being removed from the aquifer has been relatively stable since 1991. Figure 2-3B illustrates the influent VOC concentrations since 1994. This graph shows that apart from increasing trend at the end of 2003 (see discussion below) and other erratic spikes that the concentration of the target VOCs has been relatively stable. The efficiency of the stripper in 2004 for removing vinyl chloride, 1,1-DCA, total 1,2-DCE and TCE is shown in Table 2-1. The efficiency of the stripping tower in removing TCE from groundwater since December 1987 is plotted in Figure 2-6. That graph shows that the stripping tower has regularly achieved a removal efficiency for TCE above the NPDES permit limit of 95 percent, and the OU1 limit of 96%. In 2004, the removal efficiency briefly dropped to 94.8% in December; however, that drop is still statistically within the SD range and is insignificant. The static pressure of the stripping tower is graphed in Figure 2-7. That figure, compared with Figure 2-6, shows that the decline in the efficiency of the air stripping tower for TCE removal generally corresponds to increases in the static pressure of the tower. An increase in the static pressure indicates an increase in resistance to air flow within the tower, which causes the efficiency of the stripper to decrease. That occurrence was attributed to the accumulation of ferric oxide (i.e., a reddish rust brown precipitant) within the stripper system. In January and February 2005, corrective measures were implemented to restore the efficiency of the treatment system. Those measures appear to have been successful as the early 2005 influent and effluent iron results (not included as part of this report) indicate that the high iron content of the groundwater is now remaining solubilized as it moves through the system. Continued monitoring will be performed to ensure that the implemented remedy is working. Air flow measurements have been made in the stripping tower weekly since June 1988. The measurements from June 1988 to December 2004 are shown in Figure 2-8. Except for the period when the iron incrustation of the system occurred, the airflow rate was generally at 5,000 cubic feet per minute (cfm), which is an acceptable operating range. The groundwater withdrawal rates discussed in Section 2.2 have been used in conjunction with the analytical data from the stripping tower to calculate the mass of contaminants recovered from groundwater during the last 17 years. The results are shown in Figure 2-9A and indicate that approximately 3,198 gallons of TCE have been removed from the

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groundwater since operation began in 1987. The total VOCs removed during the operating period time is estimated to be approximately 3,640 gallons. Figure 2-9B shows the mass removal rates for total VOCs, TCE and Total 1,2-DCE in 2004. In the first year of operation (1987 – 1988) the system removed approximately 926 gallons of VOCs, the majority of which was TCE. Whereas, in the last two years (2003 and 2004), the system’s total VOC removal rate was measured at only 42 and 100 gallons, respectively. For 2004, that equals a 90% drop (a 95% drop for 2003) in the system’s annual total VOC removal rate from its high in 1987. The average pumping rate in 2004 was 297 gpm, which equates to approximately 1.56 x 108 (156,000,000) gallons of groundwater being removed from the aquifer. The monthly average removal rate for total VOCs was 8.4 gallons per month or only 6.4 x 10-7 (0.00000064) gallons of total VOCs in each gallon of groundwater recovered. TCE remains the most prevalent VOC. Finally, a comparison of volume of total VOCs removed from the aquifer over the last four years (i.e., 2001 94 gallons; 2002 77 gallons; 2003 42 gallons; and, 2004 100 gallons) indicates that shutting down extraction wells ERW-3 and ERW-4 in March 2003 and ERW-8 in November 2003 has not had an adverse effect. As previously mentioned, the effluent TCE results from the stripping tower in January 2005 suggested a lower than normal TCE removal rate. That finding immediately lead to an inspection of the stripper tower and the discovery that the tower media were encrusted with ferric oxide. The tower was shut down on January 18, 2005 to inspect the degree of encrustation and to determine what corrective measures were warranted. In an effort to minimize the downtime of the system, and to meet the efficiency limits of the OU1 and NPDES permit, new replacement media was ordered on January 21, 2005 and installed on February 2, 2005. After installation, the system was returned to full operation. The removed media was sent to a subtitle D landfill for disposal in accordance with applicable state and federal regulations. The 2004 total iron concentrations in the influent were significantly higher than the levels reported in 2003. Based on that observation, it was determined that the existing pre-treatment additive for iron was not functioning properly. Accordingly, DICO immediately notified USEPA and proposed the use of 38% sodium bisulfite solution (NaHSO3) as the pre-treatment chemical to effectively counter the iron scale buildup. The purpose of adding sodium bisulfite was to prevent the iron from precipitating within the treatment system. Sodium bisulfite is a safe food-grade additive that is used in many different food processing applications to control bacteria, yeasts and fungi. Accordingly, the effectiveness of the pre-

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treatment of the groundwater with sodium bisulfite can be measured by comparing the influent and effluent iron concentrations. If the concentrations of the two remain similar, then pre-treatment is effective and the iron is remaining solubilized and is safely passing through the system. USEPA approved this Modification, DICO is closely monitoring the efficiency of iron removal and will notify USEPA of the study results. Attached to this report is a proposed addendum to the July 2003 Work Plan that includes the practices to prevent the tower from accumulating iron or other deposits in the media. 2.4 EXTRACTION SYSTEM CAPTURE ZONE

The success of any extraction system is directly related to its ability to capture and remove the targeted contaminants. To evaluate the size of the capture zone created by the extraction system, periodic depth-to-water level measurements were made in 2004 in most of the monitoring and recovery wells (Appendix A). Figures 2-10A through 2-10D are potentiometric maps of the watertable aquifer in 2004. To include the hydraulic influence of the Raccoon River on groundwater flow patterns in the area, surface water data from the Fleur Drive gage was also used. The Fleur Drive gage (Long. -93.6427330/Lat. 41.5816660, Gage Zero: 780.70 ft) is cooperatively managed by the Iowa District, United States Geologic Survey (USGS) and the City of Des Moines. Daily surface water elevation data can be obtained from http://waterdata.usgs.gov/ia/nwis. Figures 2-10A through 2-10D show the estimated groundwater capture zones from the DICO extraction wells as well as the hydraulic influence of the Raccoon River. Specifically, those Figures illustrate the seasonal changes in groundwater flow patterns and the considerable influence that the elevation of the Raccoon River has on local groundwater flow directions. The Raccoon River is a constant head boundary. The elevation of the River in the vicinity of the DICO site is controlled by the spillway to the south of the site. As such, under natural conditions, the Raccoon River is in direct hydraulic communication with the groundwater watertable aquifer and functions as a barrier to the easterly migration of groundwater from the DICO site. As the pumping of the northern infiltration gallery has ceased, the natural hydraulics of the Raccoon River have been re-established and, based on the apparent groundwater flow patterns shown in the referenced Figures, the migration of groundwater from the Des Moines TCE site to the west beneath the River is unlikely. Based on the 2004 water level data, the elevation of the Raccoon River at the Fleur Drive Bridge gage (i.e., SW 18th Street) is typically higher than the elevation of surrounding the groundwater (as observed in the DICO monitoring wells). Groundwater within the northern infiltration gallery (west side of

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the river) and beneath the DICO site (east side of the river) flows toward the Raccoon River, where it converges on both sides with groundwater leaking from the Raccoon River into the formation. At certain locations along the River and at certain times, the Raccoon River appears to provide significant recharge to the aquifer (i.e., it is losing water to the aquifer). That is an important natural characteristic of groundwater flow in the area because it likely plays an important role in preventing the migration of groundwater contaminants from the east beneath the Raccoon River. As shown on Figures 2-10A through 2-10D, the extraction system is maintaining some onsite hydraulic control of the plume (i.e., it maintains capture zones around the extraction wells). Coupled with the natural constant head boundary of the Raccoon River, they prevent the migration of groundwater contaminants beneath the Raccoon River toward the infiltration gallery. Based on the comparison of extraction well groundwater elevations and surface water elevations in the Raccoon River, it is also likely that the DICO extraction system is pulling water from the Raccoon River toward the site. All of these interpretations of the water level data and groundwater flow is supported by the continued absence of TCE associated contaminants in the northern infiltration gallery wells. Water level elevations in selected wells have been plotted on the hydrographs in Appendix B. Water level measurements have been made monthly on each side of the packers in Manhole No. 1 at MH-1N and MH-1S. MH-1N measure the elevation of groundwater within the DWMM’s infiltration system and the north gallery and MH-1S measures the elevation of groundwater within the south gallery (Figure 2-11A). Figure 2-11B illustrates the hydraulic connection between the Raccoon River (i.e., Fleur Drive gage) and the north gallery and to a lesser extent the south gallery. Similar to the extraction well data, the data shows that the elevation trend in the north infiltration gallery/aquifer is identical to the trend observed in the neighboring surface water body. However, of particular importance is the trend exhibited by the south gallery relative to the Raccoon River. The south gallery is different indicating that it is under different hydraulic conditions and probably receives its recharge from a different area. This is important because it may indicate that the south gallery is not directly hydraulically connected to the watertable aquifer in the vicinity of the DICO site. In 2004, the water level was generally 5 feet higher on the north side of the packers. Figure 2-11A indicates that groundwater in the north gallery is consistently higher than in the south gallery. The difference in elevation is probably related to the influence of the Raccoon River and its elevation above (i.e., up stream) and below (i.e., down stream) the spillway. Although

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a head difference south to north might be preferred, there been no indication of an adverse impact to the water quality of the gallery as a result of a higher head on the north side. 2.5 GALLERY OPERATION

In 2004, water samples were collected from both sides of the packers in manhole MH-1. The samples were analyzed for the target VOCs (see Appendix E). Except for a single detection of total 1,2-DCE in April 2004 at both locations, none of the seven compounds were detected. The concentration of total 1,2-DCE detected in April 2004 in MH-1N was 1.2 ug/L and in MH-1S it was 0.8 ug/L. Both detections are well below the MCL for cis 1,2-DCE and trans 1,2-DCE of 70 and 100 ug/L. Acetone was also detected with an estimated concentrations of 5 J ug/L at both locations in October 2004. The USEPA has not established an MCL for acetone. Further, acetone is a common laboratory artifact and the estimated low concentration detected is probably due to an exogenous source at the laboratory and not representative of groundwater quality within the manhole. 2.6 GROUNDWATER QUALITY

Approximately 77 groundwater sampling events have been completed since the extraction system was installed. Analytical results of groundwater samples collected in 2004 have been tabulated by well number and sampling event and are provided in Appendix C. The concentrations of TCE, total 1,2-DCE and vinyl chloride during the period from December 1987 to 2004 have been plotted for selected wells (Appendix D). Since 1993, groundwater samples have been collected from selected wells for analysis by the University Hygienic Laboratory (UHL) at the University of Iowa. In 2003, the analysis for the Seven Target VOC’s (7 VOC’s) changed from quarterly to semi-annually (April and October) and the analysis of the Hazardous Substance List VOC’s (HSLVOC’s) changed from semi-annually to annually (October). That change will become permanent after the USEPA reviews this report and completes its analysis of the systems operation. The results for 2004 are provided in Appendix E. TCE and total 1,2-DCE concentration isopleths from the October 2004 sampling event have been plotted on Figures 2-12 and 2-13, respectively. Table 2-3 provides a summary of the October 2004 groundwater and surface water quality data. A comparison of those data with the results from 2003, indicates that the concentrations of TCE have remained

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relatively stable over the total area except for a slight increase at ERW-6 and ERW-7. There was an erratic spike in the TCE and total DCE concentrations in January 2004. Such spikes are to expected. The exact cause for concentration spikes can vary. A review of the systems operational data does not point to any one issue relative to the operation of the system. However, it could be a precursor to the pending iron fouling of the extraction system or it could be related to seasonal fluctuations in groundwater elevations. In 2004, no groundwater monitoring wells on the west side of the Raccoon River (in the vicinity of the northern infiltration gallery) reported the detection of any VOCs above the laboratory’s Practical Quantitation Limits (PQL). The absence of VOCs in all of the west side wells supports the finding that the recovery system along with the natural hydraulics of the Raccoon River (see Figures 2-10A through 2-10D) is preventing the offsite migration of VOCs beneath the river. In 1987 and 1988 and before the extraction system was operating, the highest concentration of TCE and total 1,2-DCE detected on the west side of the Raccoon River was in well MW-25 at 93 ug/L and 7 ug/L, respectively. 2.7 SURFACE WATER QUALITY Surface water samples were collected twice in 2004 from both the Raccoon River (Sampling location S-2) and the Des Moines River (Sampling location S-3). The samples were analyzed for the 7 VOC’s in April, and for the 33 HSLVOC’s in October. Except for an estimated detection of acetone (5 J ug/L) at both locations in October 2004, no VOCs were detected at either location1. Acetone is a common laboratory artifact. The detection of acetone at a concentration below the detectable limit is likely the result of an exogenous source at the laboratory.

1 The laboratory reported a total of fifteen samples in October 2004 with estimated detections of acetone.

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3.0 CONCLUSIONS AND RECOMMENDATIONS

In 2003, The USEPA approved the July 2, 2003, Work Plan. That plan proposed the following changes to the operation of the OU1 remediation and monitoring program: 1. Weekly sampling for VOC’s, pH and iron in the influent and effluent of the air

stripping tower was reduced to monthly; 2. Recovery wells ERW-3, ERW-4 and ERW-8 were taken out of service for one year

pending the USEPA’s final review and approval to permanently remove them from service following the submittal of this 2004 Performance Evaluation Report;

3. Twenty-two groundwater monitoring wells were abandoned in October 2003, and; 4. The sampling frequency of target monitoring wells was reduced from quarterly to

semi-annually. All of those changes were implemented as proposed. The various components of the monitoring program have been effective in providing the necessary data to evaluate the performance of the groundwater recovery and treatment system. Based on the 2004 data, the extraction and treatment system is working efficiently with the three current operating recovery wells. Currently, there is no evidence of VOC migration beneath the Raccoon River or impact to groundwater in wells near the northern infiltration gallery. Further, there is no evidence of elevated levels of VOCs in the surface waters of the Raccoon and Des Moines Rivers or near the southern infiltration gallery. As a result, the limits of the VOC plume appear to be confined onsite on the east side of the Raccoon River. The operation of the system was maintained in 2004, despite severe iron fouling and incrustation problems that were immediately addressed in early 2005. A simple and prompt modification to the pre-treatment process appears to have abated the iron issue within the treatment system. However, it is currently not know whether iron encrustation has affected well efficiency or piping. Those determinations can only be made over time and if problems persist. Currently, the three operating recovery wells are providing adequate plume capture and contaminant recovery rates from the aquifer and VOC mass recovery rates as a whole, are approaching or have become asymptotic. Resuming operation of recovery wells ERW-3, ERW-4 and ERW-8 is not necessary as their operation will not alter the life cycle of this

12

treatment system. Based on research by Battelle and others, the life cycle of most pump and treat systems is relatively short because the dramatic contaminant recovery rates occur in their early stages of operation. At this site, the majority of the mass removal occurred within the first four years of operation. Typically, as the operation of the extraction system matures, the mass removal rate per volume of water drops significantly and diminishing returns can be expected as the system continues to operate. The operating cost per gallon of contaminant recovered is inversely proportional to the mass concentration per gallon of groundwater recovered. As the mass concentration per gallon of groundwater recovered drops, the cost per gallon of contaminant recovered increases. In 2004, the total gallons of VOCs removed from the aquifer was 90% lower than the volume removed in 1987. Figure 2-9A shows the TCE removal rates over time at this site. It clearly indicates that this type of mass removal rate phenomena is occurring and that this system is incapable of removing larger volumes of mass per gallon of water recovered. As the data shows in Figure 2-9B, erratic concentration spikes should be expected. However, based on the overall operational and mass removal history of this system, it can be predicted with relative confidence that the annual recovery rates presently observed will continue to decline. Finally, the hydraulic relationship between the Raccoon River and the aquifer has been confirmed by comparing groundwater elevation trends measured in the aquifer to those measured by the USGS at their Fleur Drive gage. These data indicate that the Raccoon River is a source of recharge (i.e., the Raccoon River is losing water to the aquifer) for the aquifer and that fluctuations within the aquifer are controlled mainly by the River’s elevation. Furthermore, despite the aggressive removal of groundwater through the operation of the DICO remediation system over the last 17 years, groundwater elevations within the extraction wells are ultimately controlled by the seasonal fluctuations in surface water elevations of the adjacent Raccoon River and the extraction pump system. In addition, based on the groundwater equipotential lines generated using both groundwater and surface water elevation data, the Raccoon River is probably contributing significant volumes of groundwater to the extraction system. Because the Raccoon River is a dominant constant head boundary within this hydrogeologic system, under natural hydraulic conditions, the River should limit plume growth. At some point in the near future, a thorough examination of the need for the continued operation of this pump and treat system should be considered as there may be more effective and less expensive in-situ technologies such as source-area treatment or natural attenuation processes that can be used to “polish-off’ the remaining mobile component of

13

the groundwater plume. Or, perhaps even newer risk-based decision criteria may be used to review the overall threat the current contaminants may pose to human health and environment in the area. Fortunately, this site is underlain by a shale unit that acts like an aquitard and has limited the vertical penetration of the VOCs, the saturated zone is relatively thin (i.e., approximately 25 feet thick) and the Raccoon River is providing some level of hydraulic influence over groundwater movement. Because of those hydrogeologic constraints, and with the re-emergence of natural hydraulic conditions in the north gallery, the natural hydraulics alone may be capable of providing adequate groundwater plume migration protection and prevent the offsite migration of a plume. With those considerations in mind, and based on the determined current adequacy of the current three well recovery system, it is recommended that the system continue to operate as is for the remainder of 2005. Extraction wells ERW-3, ERW-4 and ERW-8 should be permanently removed from service as proposed in the July 2, 2003 Work Plan. After 2005, further review and analysis should be performed to determine the fate of the current remediation system and/or the need for any additional measures.

TABLES

TABLE 2-1

SUMMARY OF AIR STRIPPER EFFICIENCY CALCULATIONS (2004)DES MOINES TCE SITE

Stripper Inffluent (ug/L) Stripper Effluent (ug/L) Stripper Efficien

1,1 Total-1,2- 1,1- Total 1,2- 1,1- Total 1,2-Date Vinyl Dichloro- Dichloro- Trichloro- Vinyl Dichloro- Dichloro- Trichloro- Vinyl Dichloro- Dichloro-Collected chloride ethene ethene ethene Total chloride ethene ethene ethene Total chloride ethene ethene

01/05/04 ND ND 180 1400 1580 ND ND 1.1 2.7 3.8 100.0 100.0 99.402/02/04 ND ND 73 450 523 ND ND 0.8 1.4 2.2 100.0 100.0 98.903/01/04 ND ND 63 410 473 ND ND 1.4 2.9 4.3 100.0 100.0 97.804/05/04 ND ND 70 460 530 ND ND 1.6 4.1 5.7 100.0 100.0 97.705/03/04 ND ND 69 470 539 ND ND 1.9 4.4 6.3 100.0 100.0 97.206/01/04 ND ND 87 610 697 ND ND 1.7 3.6 5.3 100.0 100.0 98.008/02/04 ND ND 62 470 532 ND ND 1.5 3.8 5.3 100.0 100.0 97.608/30/04 ND ND 67 460 527 ND ND 1.4 3.2 4.6 100.0 100.0 97.909/13/04 ND ND 72 490 562 ND ND 2.2 5.3 7.5 100.0 100.0 96.910/04/04 ND ND 72 480 552 ND ND 4.2 13.0 17.2 100.0 100.0 94.211/01/04 ND ND 62 470 532 ND ND 3.8 14.0 17.8 100.0 100.0 93.912/07/04 ND ND 77 780 857 ND ND 7.8 37.0 44.8 100.0 100.0 89.9Average 79.5 579.2 658.7 2.5 8.0 10.4 100.0 100.0 96.6Max. 180.0 1400.0 1580 7.8 37.0 44.8 100.0 100.0 99.4Min. 62.0 410.0 473.0 0.8 1.4 2.2 100.0 100.0 89.9

NA indicates data not available.ND indicates not detected.

Page 1 of 1 Tables 2-1_2-2_2-3 6/17/2005

TABLE 2-2

SUMMARY OF AIR STRIPPERINFLUENT AND EFFLUENTpH AND IRON DATA (2004)

DES MOINES TCE SITE

Influent EffluentpH Iron pH Iron

DATE (Units) (ug/L) (Units) (ug/L)

1/5/04 7.0 650 8.4 3002/2/04 7.1 370 8.3 903/1/04 7.4 250 8.4 804/5/04 7.6 1400 8.4 1305/3/04 7.4 1200 8.3 1306/1/04 7.0 230 8.2 1407/6/04 7.4 2000 8.4 1708/2/04 7.2 340 8.3 1608/30/04 7.0 370 8.2 1209/13/04 7.0 360 8.2 10010/4/04 7.0 1600 8.2 10011/1/04 6.9 920 8.2 8012/7/04 7.0 360 8.1 50Average 7.2 773.1 8.3 126.9Max. 7.6 2000.0 8.4 300.0Min. 6.9 230.0 8.1 50.0

ug/L = micrograms per Liter or parts per billion (ppb)

Page 1 of 1 Tables 2-1_2-2_2-3 6/17/2005

TABLE 2-3

SUMMARY GROUNDWATER AND SURFACE WATER QUALITY DATA (OCTOBER 2004)DES MOINES TCE SITE

Well Sampling TCE 1,2-DCE VC 1,2-DCA 1,1,1-TCA 1,1-DCE Chloroform PCE Acetone Toluene CD 1,2 DCP CT MC BenzeneNumber Date Lab. (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L)

ERW- 5 10/29/04 UHL 20 21 ND ND ND ND ND 1 5J ND ND ND ND ND NDERW- 6 10/29/04 UHL 680 110 1 ND ND ND ND 2 ND ND ND ND ND ND NDERW- 7 10/29/04 UHL 540 72 1 ND ND ND ND 2 ND ND ND ND ND ND NDEW- 5 10/29/04 UHL 1 1 ND ND ND ND ND ND 5J ND ND ND ND ND NDEW- 6 10/29/04 UHL 4 13 1J ND ND ND ND ND ND ND ND ND ND ND NDEW-19 10/29/04 UHL 1 2 ND ND ND ND ND ND 5J ND ND ND ND ND NDMH-1N 10/28/04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND ND NDMH-1S 10/28/04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND ND NDNW- 1 10/28/04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND ND NDNW- 2 10/28/04 UHL 1 24 ND ND ND ND ND ND ND ND ND ND ND ND NDNW-4 10/29/04 UHL 18 11 ND ND ND ND ND ND 5J ND ND ND ND ND NDNW- 6 10/29/04 UHL ND 4 ND ND ND ND ND ND 5 ND ND ND ND ND NDNW- 7 10/29/04 UHL 230 140 ND ND ND ND ND 5 5J ND ND ND ND ND NDNW- 8 10/29/04 UHL ND 31 7 ND ND ND ND ND 5J ND ND ND ND ND NDNW- 9 10/28/04 UHL NS NS NS NS NS NS NS NS NS NS NS NS NS NS NSNW-10 10/28/04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND ND NDNW-12 10/29/04 UHL 210 160 ND ND ND ND ND ND ND ND ND ND ND ND NDNW-14 10/28/04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND ND NDNW-15 10/28/04 UHL NS NS NS NS NS NS NS NS NS NS NS NS NS NS NSNW-20 10/29/04 UHL 6 25 2 1J ND ND ND ND ND ND ND ND ND ND NDNW-22 10/29/04 UHL 10 17 2 ND ND ND ND 1J ND ND ND ND ND ND NDNW-23 10/29/04 UHL ND 1J ND ND ND ND ND ND ND ND ND ND ND ND NDNW-24 10/28/04 UHL NS NS NS NS NS NS NS NS NS NS NS NS NS NS NSNW-27 10/28/04 UHL 4 110 2 ND ND ND ND 1 ND ND ND ND ND ND ND

P- 1 10/28/04 UHL ND 6 ND ND ND ND ND ND 5J ND ND ND ND ND NDP- 9 10/29/04 UHL 3 69 ND ND ND ND ND ND ND ND ND ND ND ND NDP-13 10/28/04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND ND NDP-18 10/29/04 UHL 4 4 ND ND ND ND ND ND 5J ND ND ND ND ND NDS-2 10/29/04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND ND NDS-3 10/29/04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND ND ND

Notes:All concentrations are reported in micrograms per Liter (ug/L) or parts per billion (ppb)ND = not detected TCE = Trichloroethene PCE = TetrachloroetheneNS = not sampled 1,2-DCE = Total 1,2-Dichloroethene CD = Carbon DisulfideJ = estimated concentration VC = Vinyl Chloride 1,2 DCP = 1,2 DichloropropaneB = compound also detected in associated blank 1,2-DCA = 1,2-Dichloroethane CT = Carbon TetrachlorideD = sample diluted 1,1,1-TCA = 1,1,1-Trichloroethane MC = Methylene Chloride

1,1-DCE = 1,1-Dichloroethene

Page 1 of 1 Tables 2-1_2-2_2-3 6/17/2005

FIGURES

HYDROGRAPH OF NORTHERNEXTRACTION WELLS (1987-2004)

FIGURE 2-1

DICO

DES MOINES TCE SITEDES MOINES, IOWA

760

765

770

775

780

785

790

795

Dec-8

7

Jun-8

8

Dec-8

8

Jun-8

9

Dec-8

9

Jun-9

0

Dec-9

0

Jun-9

1

Dec-9

1

Jun-9

2

Dec-9

2

Jun-9

3

Dec-9

3

Jun-9

4

Dec-9

4

Jun-9

5

Dec-9

5

Jun-9

6

Dec-9

6

Jun-9

7

Dec-9

7

Jun-9

8

Dec-9

8

Jun-9

9

Dec-9

9

Jun-0

0

Dec-0

0

Jun-0

1

Dec-0

1

Jun-0

2

Dec-0

2

Jun-0

3

Dec-0

3

Jun-0

4

Dec-0

4

ERW-3

ERW-4

ERW-5

ERW-3 ERW-4 ERW-5

Ele

vati

on

(ft.

)

Date

Extraction Well Elevations

HYDROGRAPH OF SOUTHERNEXTRACTION WELLS (1987-2004)

FIGURE 2-2A

DICO


760

765

770

775

780

785

790

795

Dec-8

7

Jun-8

8

Dec-8

8

Jun-8

9

Dec-8

9

Jun-9

0

Dec-9

0

Jun-9

1

Dec-9

1

Jun-9

2

Dec-9

2

Jun-9

3

Dec-9

3

Jun-9

4

Dec-9

4

Jun-9

5

Dec-9

5

Jun-9

6

Dec-9

6

Jun-9

7

Dec-9

7

Jun-9

8

Dec-9

8

Jun-9

9

Dec-9

9

Jun-0

0

Dec-0

0

Jun-0

1

Dec-0

1

Jun-0

2

Dec-0

2

Jun-0

3

Dec-0

3

Jun-0

4

Dec-0

4

Ele

vati

on

(ft.

)

ERW-6 ERW-7 ERW-8

Date

ERW-6

ERW-7

ERW-8

Extraction Well Elevations

HYDROGRAPH OF SOUTHERNEXTRACTION WELLS ANDRACCOON RIVER (2004)

FIGURE 2-2B

DICO


770

775

780

785

790

1/3

1/2

004

2/2

7/2

004

3/1

8/2

004

4/2

2/2

004

5/1

8/2

004

6/1

8/2

004

7/2

3/2

004

8/2

2/2

004

9/2

4/2

004

10/2

7/2

004

11/3

0/2

004

12/1

6/2

004

Ele

vati

on

(ft.

)

ERW-5 ERW-6 ERW-7

Date

ERW-5

ERW-7

RACCOON RIVERERW-6

RACCOON RIVER

Elevations of the Southern Extraction Wellsand the Raccoon River

Notes:(1) No surface water measurements were collected from the Raccoon River on July 23, 2004. Data

from July 22, 2004 was used for this graph.

(2) Surface water elevation data for October 27, 2004 was obtained from the Raccoon River gage at

Fleur Drive (SW 18th St.) bridge in Des Moines attached to the handrail 465 ft from the right edge of the

bridge (long. -93.64273330/ lat. 41.5816660. This gage is cooperatively operated by the Iowa District

USGS and the city of Des Moines, Iowa.

VOC AIR STRIPPER INFLUENTCONCENTRATIONS (1987-2004)

FIGURE 2-3A

DICO


0

500

1000

1500

2000

2500

3000

Dec-8

7

Dec-8

8

Dec-8

9

Dec-9

0

Dec-9

1

Dec-9

2

Dec-9

3

Dec-9

4

Dec-9

5

Dec-9

6

Dec-9

7

Dec-9

8

Dec-9

9

Dec-0

0

Dec-0

1

Dec-0

2

Dec-0

3

Dec-0

4

Co

ncen

trati

on

(ug

/L)

TCE

Total 1,2-DCE

Date

VINYL CHLORIDE (VC)

TCE

VC

Total 1,2-DCE

INFLUENT

VOC AIR STRIPPER INFLUENTCONCENTRATIONS (2004)

FIGURE 2-3B

INFLUENT

DICO


0

500

1000

1500

Dec-9

4

Dec-9

5

Dec-9

6

Dec-9

7

Dec-9

8

Dec-9

9

Dec-0

0

Dec-0

1

Dec-0

2

Dec-0

3

Dec-0

4

Co

ncen

trati

on

(ug

/L)

TCE

Total 1,2-DCE

Date

VINYL CHLORIDE (VC)

TCE

VC

Total 1,2-DCE

pH and IRON CONCENTRATIONSAIR STRIPPER INFLUENT

FIGURE 2-4

INFLUENT

DICO


6.70

6.80

6.90

7.00

7.10

7.20

7.30

7.40

7.50

7.60

7.70

Ja

n-0

4

Fe

b-0

4

Ma

r-0

4

Ap

r-0

4

Ma

y-0

4

Ju

n-0

4

Ju

l-0

4

Au

g-0

4

Au

g-0

4

Se

p-0

4

Oct-

04

No

v-0

4

De

c-0

4

0

500

1000

1500

2000

2500

Ja

n-0

4

Fe

b-0

4

Ma

r-0

4

Ap

r-0

4

Ma

y-0

4

Ju

n-0

4

Ju

l-0

4

Au

g-0

4

Au

g-0

4

Se

p-0

4

Oct-

04

No

v-0

4

De

c-0

4

pH

(Sta

nd

ard

Un

its)

pH Avg. pH

Co

ncen

trati

on

(ug

/L)

Date

Date

Iron Avg. Iron

pH and IRON CONCENTRATIONSAIR STRIPPER EFFLUENT

FIGURE 2-5

EFFLUENT

DICO


8.0

8.1

8.2

8.3

8.4

8.5

Jan-0

4

Feb-0

4

Mar-

04

Apr-

04

May-0

4

Jun-0

4

Jul-04

Aug-0

4

Aug-0

4

Sep-0

4

Oct-

04

Nov-0

4

Dec-0

40

50

100

150

200

250

300

350

Jan-0

4

Feb-0

4

Mar-

04

Apr-

04

May-0

4

Jun-0

4

Jul-04

Aug-0

4

Aug-0

4

Sep-0

4

Oct-

04

Nov-0

4

Dec-0

4

pH

(Sta

nd

ard

Un

its)

pH Avg. pH

Co

ncen

trati

on

(ug

/L)

Date

Date

Iron Avg. Iron

AIR STRIPPER EFFICIENCY(1987-2004)

FIGURE 2-6

DICO


30

40

50

60

70

80

90

100

Dec-8

7

Dec-8

8

Dec-8

9

Dec-9

0

Dec-9

1

Dec-9

2

Dec-9

3

Dec-9

4

Dec-9

5

Dec-9

6

Dec-9

7

Dec-9

8

Dec-9

9

Dec-0

0

Dec-0

1

Dec-0

2

Dec-0

3

Dec-0

4

Perc

en

tE

ffic

ien

cy

(%)

TCE

Date

NPDES Limit (95%) Ou1 Limit (96%)

STATIC PRESSURESTRIPPING TOWER (1987-2004)

FIGURE 2-7

DICO


1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

Jun-8

8

Dec-8

8

Jun-8

9

Dec-8

9

Jun-9

0

Dec-9

0

Jun-9

1

Dec-9

1

Jun-9

2

Dec-9

2

Jun-9

3

Dec-9

3

Jun-9

4

Dec-9

4

Jun-9

5

Dec-9

5

Jun-9

6

Dec-9

6

Jun-9

7

Dec-9

7

Jun-9

8

Dec-9

8

Jun-9

9

Dec-9

9

Jun-0

0

Dec-0

0

Jun-0

1

Dec-0

1

Jun-0

2

Dec-0

2

Jun-0

3

Dec-0

3

Jun-0

4

Dec-0

4

Inch

es

of

Wate

r

Date

Static Pressure

AIR FLOW AT STRIPPINGTOWER (1987-2004)

FIGURE 2-8

DICO


0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

Dec-8

8

Dec-8

9

Dec-9

0

Dec-9

1

Dec-9

2

Dec-9

3

Dec-9

4

Dec-9

5

Dec-9

6

Dec-9

7

Dec-9

8

Dec-9

9

Dec-0

0

Dec-0

1

Dec-0

2

Dec-0

3

Dec-0

4

Cu

bic

Feet

per

Min

ute

Date

Air Flow

CUMMULATIVE MASSREMOVED (1987-2004)

FIGURE 2-9A

DICO


0

500

1000

1500

2000

2500

3000

3500

4000D

ec-8

7

Dec-8

8

Dec-8

9

Dec-9

0

Dec-9

1

Dec-9

2

Dec-9

3

Dec-9

4

Dec-9

5

Dec-9

6

Dec-9

7

Dec-9

8

Dec-9

9

Dec-0

0

Dec-0

1

Dec-0

2

Dec-0

3

Dec-0

4

To

talG

allo

ns

Rem

oved

(1987-2

004)

Date

TOTAL VOCS TOTAL 1,2-DCETCE

TOTAL VOCS

TCE

TOTAL 1,2-DCE

CUMMULATIVE MASSREMOVED (2004)

FIGURE 2-9B

DICO


0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

Jan-0

4

Feb-0

4

Mar-

04

Apr-

04

May-0

4

Jun-0

4

Jul-04

Aug-0

4

Sep-0

4

Oct-

04

Nov-0

4

Dec-0

4

Total TCE 1,2-DCE

Jan-04 5.3 4.7 0.6

Feb-04 7.8 6.7 1.1

Mar-04 6.7 5.8 0.9

Apr-04 9.6 8.4 1.3

May-04 8.1 7.1 1.0

Jun-04 10.1 8.9 1.2

Aug-04 15.3 13.5 1.8

Aug-04 5.9 5.2 0.7

Sep-04 4.1 3.6 0.5

Oct-04 5.8 5.1 0.7

Nov-04 7.3 6.5 0.8

Dec-04 14.7 13.4 1.2

Min 4.1 3.6 0.5

Max 15.3 13.5 1.8

Total 100.6 88.7 11.9

Avg 8.4 7.4 1.0

Ga

llo

ns

Re

mo

ve

d(2

00

4)

Date

TOTAL VOCS TOTAL 1,2-DCETCE

TOTAL VOCS

TCE

TOTAL 1,2-DCE

Summary of 2004 ContaminantMass Recovery Rates (gal.)

POTENTIOMETRIC MAP:FEBRUARY 27, 2004

FIGURE 2-10A

February 2004

DICO


RECOVERY WELL

MONITORING WELL

PIEZOMETER

LEGEND:

Notes:

ERW-3

EW-3,NW-18

P-1

WALN

UT

ST

DMWWBLDG

SOUTH GALLERY

SPILLWAY

MANHOLE

No.1

X

X

X

STOCKPILE

X

X X

AREA

X

FORMER

SOIL

X X

GRANDAVENUE

NORTH GALLERY

RACCOON

RIV

ER

PRODUCTION

BLDG.

LOC

UST

STR

EET

DESMOIN

ES

TECH\CENTRAL

CAMPUSBLDG

MER

ED

ITH

BLD

G

x

x

x

No.3

x

BLDG. No.5

MAINT.

BLDG. No.4

BLDG.

OFFICE

x

BLDG.

BLDG.

No.2

BLDG.

No.1

x

x

x

x

SUBSTATIO

N

x

x

x

x

x

x

x

x

x

x

x

x

SPILLWAY

780.73 (min.)

SPILLWAY

780.73 (min.)

780

780

781

782

782

783.11779

783

783

781

778

778

781

779

778

777

776

780

(780.37)

(780.29)

(780.70)

(780.07)

(780.15)

(780.00)

(780.40)

(779.32)

(777.60)

(780.14)

(780.11)

(773.76)

(780.98)

(779.99)

(774.70)

(778.70)

(776.86)

(779.08)

(776.18)

(780.39)

(780.83)

(780.70)

(781.00)

(779.79)

(780.45)

NR

(779.62)

NR

NR

NR

NR

(780.37)

NW-8

NW-20

P-9

EW-6

NW-23

EW-19

NW-22

NW-6

ERW-9

EW-5

P-18

ERW-8

NW-4

ERW-7

NW-7

ERW-6

P-13

NW-10

P-4

NW-15

P-2

P-1

NW-14

NW-24

NW-12

ERW-5

NW-29

ERW-4

ERW-3

NW-2

NW-27

NW-1

MH-1N

MH-1S

SPILLWAY DAM ELEVATION IS 780.73 FEET WITH THE FLASHBOARDS DOWN AND

783.73 FEET WITH THE FLASHBOARDS UP (DMWW). THE ELEVTION AT THE SPILLWAY

ASASSUMED TO BE 780.73 FEET FOR THIS POTENTIOMETRIC MAP.

2.

1. SURFACE WATER ELEVATION DATA FOR OCTOBER 27, 2004 WAS OBTAINED FROM

THE RACCOON RIVER GAGE AT FLEUR DRIVE (SW 18th St) BRIDGE IN DES MOINES

ATTACHED TO THE HANDRAIL 465 FT FROM THE RIGHT EDGE OF THE BRIDGE (LONG. -

93.64273330/LAT. 41.5816660. THIS GAGE IS COOPERATIVELY OPERATED BY THE

IOWADISTRICT USGSAND THE CITY OF DES MOINES, IOWA.

POTENTIOMETRIC MAP DEVELOPED BASED ON THE HYDRAULIC RELATIONSHIP

SHOWN BETWEEN THE RACCOON RIVER AND THE MONITORING AND EXTRACTION

WELLS AT THE DICO SITE. SURFACE WATER AND GROUNDWATER ELEVATION

TRENDS INDICATE THAT THE RACCOON RIVER AND LOCAL GROUNDWATER ARE IN

DIRECT HYDRAULIC COMMUNICATION. ELEVATION DATA INDICATES THAT THE

RACCOON RIVER ISALOSING STREAMAND ISASIGNIFICANT SOURCE OF RECHARGE

TO THE WATERTABLEAQUIFER NEAR TH THE DICO SITE.

3.

CONTOUR INTERVAL: 1 FOOT

EQUIPOTENTIAL LINE

(DASHED WHERE INFERRED)

GROUNDWATER ELEVATION

GROUNDWATER DIVIDE

SURFACE WATER ELEVATION GAGE

780

(781.19)

APPROXIMATE EXTENT OF

CAPTURE ZONE

APPROXIMATE DIRECTION OF

GROUNDWATER AND SURFACE WATER

FLOW

POTENTIOMETRIC MAP:APRIL 22, 2004

FIGURE 2-10B

April 2004

DICO


RECOVERY WELL

MONITORING WELL

PIEZOMETER

LEGEND:

Notes:

ERW-3

EW-3,NW-18

P-1

WALN

UT

ST

DMWWBLDG

SOUTH GALLERY

SPILLWAY

MANHOLE

No.1

X

X

X

STOCKPILE

X

X X

AREA

X

FORMER

SOIL

X X

GRANDAVENUE

NORTH GALLERY

RACCOON

RIV

ER

PRODUCTION

BLDG.

LOC

UST

STR

EET

DESMOIN

ES

TECH\CENTRAL

CAMPUSBLDG

MER

ED

ITH

BLD

G

x

x

x

No.3

x

BLDG. No.5

MAINT.

BLDG. No.4

BLDG.

OFFICE

x

BLDG.

BLDG.

No.2

BLDG.

No.1

x

x

x

x

SUBSTATIO

N

x

x

x

x

x

x

x

x

x

x

x

x

SPILLWAY

780.73 (min.)

SPILLWAY

780.73 (min.)

780

782

780

779

778

779

780781782

782

780

781

782

781

783.74

779

779

783

783

778

782

(781.17)

(781.59)

(782.10)

(781.37)

(781.75)

(781.60)

(781.90)

(780.72)

(779.90)

(781.34)

(783.31)

(776.16)

(780.38)

(779.89)

(776.30)

(779.80)

(777.56)

(779.88)

(776.98)

(780.79)

(780.03)

(778.30)

(781.40)

(781.19)

(781.55)

NR

NR

NR

NR

NR

NR

NR

NR

NR

NW-8

NW-20

P-9

EW-6

NW-23

EW-19

NW-22

NW-6

ERW-9

EW-5

P-18

ERW-8

NW-4

ERW-7

NW-7

ERW-6

P-13

NW-10

P-4

NW-15

P-2

P-1

NW-14

NW-24

NW-12

ERW-5

NW-29

ERW-4

ERW-3

NW-2

NW-27

NW-1

MH-1N

MH-1S




2.




93.64273330/LAT. 41.5816660. THIS GAGE IS COPPERATIVELY OPERATED BY THE









3.


EQUIPOTENTIAL LINE



GROUNDWATER DIVIDE


780

(781.19)


CAPTURE ZONE



FLOW

POTENTIOMETRIC MAP:JULY 23, 2004

FIGURE 2-10C

July 2004

DICO


RECOVERY WELL

MONITORING WELL

PIEZOMETER

LEGEND:

Notes:

ERW-3

EW-3,NW-18

P-1

WALN

UT

ST

DMWWBLDG

SOUTH GALLERY

SPILLWAY

MANHOLE

No.1

X

X

X

STOCKPILE

X

X X

AREA

X

FORMER

SOIL

X X

GRANDAVENUE

NORTH GALLERY

RACCOON

RIV

ER

PRODUCTION

BLDG.

LOC

UST

STR

EET

DESMOIN

ES

TECH\CENTRAL

CAMPUSBLDG

MER

ED

ITH

BLD

G

x

x

x

No.3

x

BLDG. No.5

MAINT.

BLDG. No.4

BLDG.

OFFICE

x

BLDG.

BLDG.

No.2

BLDG.

No.1

x

x

x

x

SUBSTATIO

N

x

x

x

x

x

x

x

x

x

x

x

x

SPILLWAY

780.73 (min.)

SPILLWAY

780.73 (min.)

783.29

*

782

782

783

783

782

781

780

780

781

784

782

781

782 781

784

781782

(783.97)

(782.09)

(782.80)

(782.47)

(783.15)

(783.20)

(783.10)

(782.72)

(781.80)

(783.14)

(782.81)

(776.06)

(781.58)

(781.99)

(779.00)

(782.50)

(780.26)

(782.48)

(778.88)

(783.49)

(782.83)

(782.90)

(783.60)

(783.39)

(783.65)

(779.98)

NR

NR

NR

NR

NR

NR

NR

NR

NW-8

NW-20

P-9

EW-6

NW-23

EW-19

NW-22

NW-6

ERW-9

EW-5

P-18

ERW-8

NW-4

ERW-7

NW-7

ERW-6

P-13

NW-10

P-4

NW-15

P-2

P-1

NW-14

NW-24

NW-12

ERW-5

NW-29

ERW-4

ERW-3

NW-2

NW-27

NW-1

MH-1N

MH-1S

*4. ELEVATION DATA FROM MW-27 WAS RECORDED AS 788.97. ALL OTHER

NEIGHBORING WELLS HAD CHANGED ONLY 2 FEET IN ELEVATION FROM THE PRIOR

MEASUREMENT. THIS MEASUREMENT IS SUSPECTED TO HAVE BEEN MIS-WRITTEN

BYTHE FIELD CREW. THE CORRECT MEASUREMENT IS THOUGHTTO BE 753.97.

NO SURFACE WATER ELEVATION DATA WAS COLLECTED BETWEEN 7/23/04 AND

7.27.04. DATA FROM 7/22/04 IS BEING USED. THE ELEVATION ON 7/22/04 WAS 783.29

AND ON 7/28/04 IT WAS 782.34.

1.

3.

SURFACE WATER ELEVATION DATA FOR OCTOBER 27, 2004 WAS OBTAINED FROM












5.




2.


EQUIPOTENTIAL LINE



GROUNDWATER DIVIDE


780

(781.19)


CAPTURE ZONE



FLOW

POTENTIOMETRIC MAP:OCTOBER 27, 2004

FIGURE 2-10D

October 2004

DICO


RECOVERY WELL

MONITORING WELL

PIEZOMETER

LEGEND:

Notes:

ERW-3

EW-3,NW-18

P-1

WALN

UT

ST

DMWWBLDG

SOUTH GALLERY

SPILLWAY

MANHOLE

No.1

X

X

X

STOCKPILE

X

X X

AREA

X

FORMER

SOIL

X X

GRANDAVENUE

NORTH GALLERY

RACCOON

RIV

ER

PRODUCTION

BLDG.

LOC

UST

STR

EET

DESMOIN

ES

TECH\CENTRAL

CAMPUSBLDG

MER

ED

ITH

BLD

G

x

x

x

No.3

x

BLDG. No.5

MAINT.

BLDG. No.4

BLDG.

OFFICE

x

BLDG.

BLDG.

No.2

BLDG.

No.1

x

x

x

x

SUBSTATIO

N

x

x

x

x

x

x

x

x

x

x

x

x

SPILLWAY

780.73 (min.)

SPILLWAY

780.73 (min.)

781.31

780

781

781

780

780

779

778

777

779

779

779

781

780

(780.57)

(779.69)

(780.80)

(780.47)

(780.65)

(780.70)

(780.20)

(780.22)

(779.10)

(780.34)

(780.11)

(773.76)

(779.28)

(779.59)

(776.90)

(780.00)

(778.16)

(780.28)

(777.28)

(781.29)

(780.76)

(780.70)

(781.30)

(780.99)

(781.25)

(777.68)

NR

NR

NR

NR

NR

NR

NR

NR

NW-8

NW-20

P-9

EW-6

NW-23

EW-19

NW-22

NW-6

ERW-9

EW-5

P-18

ERW-8

NW-4

ERW-7

NW-7

ERW-6

P-13

NW-10

P-4

NW-15

P-2

P-1

NW-14

NW-24

NW-12

ERW-5

NW-29

ERW-4

ERW-3

NW-2

NW-27

NW-1

MH-1N

MH-1S













3.




2.


EQUIPOTENTIAL LINE



GROUNDWATER DIVIDE


780

(781.19)


CAPTURE ZONE



FLOW

HYDROGRAPH OF ELEVATIONSIN GALLERIES (1987-2004)

FIGURE 2-11A

DICO


770

775

780

785

790

795

800

Dec-8

7

Dec-8

8

Dec-8

9

Dec-9

0

Dec-9

1

Dec-9

2

Dec-9

3

Dec-9

4

Dec-9

5

Dec-9

6

Dec-9

7

Dec-9

8

Dec-9

9

Dec-0

0

Dec-0

1

Dec-0

2

Dec-0

3

Dec-0

4

MH1N MH1S

MH1S

MH1N

Ele

vati

on

(ft.

)

Date

Comparison of North and South Gallery Head ElevationMeasured in Manhole 1N and 1S (1987-2004)

HYDROGRAPH OF ELEVATIONSIN THE GALLERIES ANDTHE RACCOON RIVER

FIGURE 2-11B

DICO


RACCOON RIVER

770

775

780

785

790

01/3

1/0

4

02/2

7/0

4

03/1

8/0

4

04/2

2/0

4

05/1

8/0

4

06/1

8/0

4

07/2

3/0

4

08/2

2/0

4

09/2

4/0

4

10/2

7/0

4

11/3

0/0

4

12/1

6/0

4

Elevation of Groundwater in the North and SouthInfiltration Galleries and the Raccoon River

MH1N MH1S

Southern Infiltration Gallery (MH1S)

Northern Infiltration Gallery (MH1N)

Ele

vati

on

(ft.

)

Date

Raccoon River

Notes:(1) No surface water measurements were collected from the Raccoon River on July 23, 2004. Data

from July 22, 2004 was used for this graph.

(2) Surface water elevation data for October 27, 2004 was obtained from the Raccoon River gage at

Fleur Drive (SW 18th St.) bridge in Des Moines attached to the handrail 465 ft from the right edge of the

bridge (long. -93.64273330/ lat. 41.5816660. This gage is cooperatively operated by the Iowa District

USGS and the city of Des Moines, Iowa.

TCE CONCENTRATIONS INGROUNDWATER (OCT 2004)

FIGURE 2-12

DICO


RECOVERY WELL

MONITORING WELL

PIEZOMETER

LEGEND:

Notes:

ERW-3

EW-3,NW-18

P-1

WALN

UT

ST

DMWWBLDG

SOUTH GALLERY

SPILLWAY

MANHOLE

No.1

X

X

X

STOCKPILE

X

X X

AREA

X

FORMER

SOIL

X X

GRANDAVENUE

NORTH GALLERY

RACCOON

RIV

ER

PRODUCTION

BLDG.

LOC

UST

STR

EET

DESMOIN

ES

TECH\CENTRAL

CAMPUSBLDG

MER

ED

ITH

BLD

G

x

x

x

No.3

x

BLDG. No.5

MAINT.

BLDG. No.4

BLDG.

OFFICE

x

BLDG.

BLDG.

No.2

BLDG.

No.1

x

x

x

x

SUBSTATIO

N

x

x

x

x

x

x

x

x

x

x

x

x

SPILLWAY

780.73 (min.)

SPILLWAY

780.73 (min.)

4

ND

6

3

4

ND

ND

1

18

4

1

ND

ND

ND

540

230

680

210

20

1

NS

ND

ND

ND

ND

NS

NR

NS

NS

NS

NS

NS

NS

10

NW-8

NW-20

P-9

EW-6

NW-23

EW-19

NW-22

NW-6

ERW-9

EW-5

P-18

ERW-8

NW-4

ERW-7

NW-7

ERW-6

P-13

NW-10

P-4

NW-15

P-2

P-1

NW-14

NW-24

NW-12

ERW-5

NW-29

ERW-4

ERW-3

NW-2

NW-27

NW-1

MH-1N

MH-1S

1. ALL CONCENTRATIONS REPORTED IN MICROGRAMS PER LITER (UG/l) OR PARTS PER

BILLION (PPB). ALLSAMPLES WERE COLLECTED ON OCTOBER 28THAND 29TH, 2004.

2. GROUNDWATER RESULTS SHOWNARE FOR TRICHLOROETHENE (TCE).

500

600

250

<1

<1

<10

100

<10

<1

?

?

?

500 ug/L

600 ug/L

100 ug/L

250 ug/L

<1 ug/L

<10 ug/L

DCE CONCENTRATIONS INGROUNDWATER (OCT 2004)

FIGURE 2-13

DICO


RECOVERY WELL

MONITORING WELL

PIEZOMETER

LEGEND:

Notes:

ERW-3

EW-3,NW-18

P-1

WALN

UT

ST

DMWWBLDG

SOUTH GALLERY

SPILLWAY

MANHOLE

No.1

X

X

X

STOCKPILE

X

X X

AREA

X

FORMER

SOIL

X X

GRANDAVENUE

NORTH GALLERY

RACCOON

RIV

ER

PRODUCTION

BLDG.

LOC

UST

STR

EET

DESMOIN

ES

TECH\CENTRAL

CAMPUSBLDG

MER

ED

ITH

BLD

G

x

x

x

No.3

x

BLDG. No.5

MAINT.

BLDG. No.4

BLDG.

OFFICE

x

BLDG.

BLDG.

No.2

BLDG.

No.1

x

x

x

x

SUBSTATIO

N

x

x

x

x

x

x

x

x

x

x

x

x

SPILLWAY

780.73 (min.)

SPILLWAY

780.73 (min.)

110

31.0

25

69

13

1 J1 J

4

2

11

4

1

ND

ND

ND

72

140

110

160

21

24

NS

ND

6

ND

ND

NS

NR

NS

NS

NS

NS

NS

NS

17

NW-8

NW-20

P-9

EW-6

NW-23

EW-19

NW-22

NW-6

ERW-9

EW-5

P-18

ERW-8

NW-4

ERW-7

NW-7

ERW-6

P-13

NW-10

P-4

NW-15

P-2

P-1

NW-14

NW-24

NW-12

ERW-5

NW-29

ERW-4

ERW-3

NW-2

NW-27

NW-1

MH-1N

MH-1S

1. ALL CONCENTRATIONS REPORTED IN MICROGRAMS PER LITER (UG/l) OR PARTS PER

BILLION (PPB). ALLSAMPLES WERE COLLECTED ON OCTOBER 28THAND 29TH, 2004.

2. GROUNDWATER RESULTS SHOWNARE FOR TOTAL1,2-DICHLOROETHENE (1,2-DCE)

100 ug/L

200 ug/L

<1 ug/L

<10 ug/L

6

3

100?

?

?

200

100

<10

100

<10

<10

<10

<1

<1

<1

?

?

?

APPENDIX A

DEPTH TO GROUNDWATER MEASUREMENTS ELEVATION DATA

APPENDIX ADEPTH TO GROUNDWATER MEASUREMENTS

(2004)

31-Jan-04 27-Feb-04 18-Mar-04 22-Apr-04 18-May-04 18-Jun-04 23-Jul-04 22-Aug-04 24-Sep-04 27-Oct-04 30-Nov-04 16-Dec-04

TOC DTW DTW DTW DTW DTW DTW DTW DTW DTW DTW DTW DTWWELL ELEV. (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft)

ERW- 5 806.18 NR 30.00 29.10 29.20 27.30 26.70 27.3 27.9 28.2 28.9 27.9 28.10ERW- 6 804.56 NR 27.70 26.70 27.00 25.40 23.00 24.3 25.7 26.2 26.4 26.3 26.50ERW- 7 801.40 NR 26.70 25.00 25.10 23.40 20.70 22.4 23.7 24.2 24.5 24.3 24.30EW- 5 803.41 NR 23.30 NR 22.10 NR NR 20.6 NR NR 23.3 NR NREW- 6 799.55 NR 19.40 NR 17.80 NR NR 16.4 NR NR 18.9 NR NREW-19 800.42 NR 21.10 NR 19.70 NR NR 17.7 NR NR 20.2 NR NRMH-1N 796.58 NR 15.60 16.60 16.20 15.70 13.4 15 16.5 17.1 17.3 16.9 17.50MH-1S 796.56 NR 22.80 22.20 20.40 19.60 20.7 20.5 20.7 21.4 22.8 21.5 23.70NW- 1 803.55 NR 23.10 NR 22.00 NR NR 19.9 NR NR 22.3 NR NRNW- 2 806.69 NR 26.30 NR 25.90 NR NR 23.2 NR NR 25.4 NR NRNW- 4 803.30 NR 25.70 NR 23.40 NR NR 21.5 NR NR 24.2 NR NRNW- 6 803.20 NR 22.80 NR 21.30 NR NR 20.1 NR NR 23 NR NRNW- 7 800.80 NR 22.10 20.80 21.00 19.30 19.7 18.3 19.7 20.5 20.8 NR 22.90NW- 8 793.89 NR 13.60 NR 12.30 NR NR 11.8 NR NR 14.2 NR NRNW-10 793.09 NR 13.10 13.10 13.20 11.10 8.8 11.1 12.7 13.2 13.5 13.2 13.70NW-12 805.08 NR 26.00 NR 25.20 NR NR 22.6 NR NR 24.8 NR NRNW-14 794.50 NR 13.80 NR 16.20 NR NR 11.6 NR NR 13.8 NR NRNW-15 795.46 NR NR NR NR NR NR NR NR NR NR NR NRNW-20 797.00 NR 16.30 NR 14.90 NR NR 14.2 NR NR 16.2 NR NRNW-22 799.89 NR 20.10 18.40 18.70 17.50 15.50 16.5 17.8 18.5 18.9 19 19.10NW-23 802.20 NR 22.20 NR 20.60 NR NR 19 NR NR 21.5 NR NRNW-24 797.63 NR 16.80 NR 17.60 NR NR 14.8 NR NR 16.87 NR NRNW-25 796.40 NR NR NR NR NR NR NR NR NR NR NR NRNW-27 802.57 NR 22.20 NR 21.40 NR NR 13.6 NR NR 22 NR NRNW-29 800.52 NR 20.90 NR NR NR NR NR NR NR NR NR NRP- 1 804.10 NR 23.10 NR 22.70 NR NR 20.5 NR NR 22.8 NR NRP- 2 798.79 NR NR NR NR NR NR NR NR NR NR NR NRP- 4 795.17 NR 14.80 NR NR NR NR NR NR NR NR NR NRP- 9 792.17 NR 12.10 NR 10.80 NR NR 9.7 NR NR 11.7 NR NRP-13 793.08 NR NR NR NR NR NR 13.1 NR 14.9 15.4 NR NRP-18 802.64 NR 22.50 NR 21.30 NR NR 19.5 NR NR 22.3 NR NR

NR = no measurement taken1 of 2 WATERLEVELS.xls6/17/2005

APPENDIX AGROUNDWATER ELEVATIONS

(2004) 31-Jan-04 27-Feb-04 18-Mar-04 22-Apr-04 18-May-04 18-Jun-04 23-Jul-04 22-Aug-04 24-Sep-04 27-Oct-04 30-Nov-04 16-Dec-04

TOC Elevation Elevation Elevation Elevation Elevation Elevation Elevation Elevation Elevation Elevation Elevation ElevationWELL ELEV. (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft)

ERW- 5 806.18 NR 776.18 777.08 776.98 778.88 779.48 778.88 778.28 777.98 777.28 778.28 778.08ERW- 6 804.56 NR 776.86 777.86 777.56 779.16 781.56 780.26 778.86 778.36 778.16 778.26 778.06ERW- 7 801.40 NR 774.70 776.40 776.30 778.00 780.70 779.00 777.70 777.20 776.90 777.10 777.10EW- 5 803.41 NR 780.11 NR 781.31 NR NR 782.81 NR NR 780.11 NR NREW- 6 799.55 NR 780.15 NR 781.75 NR NR 783.15 NR NR 780.65 NR NREW-19 800.42 NR 779.32 NR 780.72 NR NR 782.72 NR NR 780.22 NR NRMH-1N 796.58 NR 780.98 779.98 780.38 780.88 783.18 781.58 780.08 779.48 779.28 779.68 779.08MH-1S 796.56 NR 773.76 774.36 776.16 776.96 775.86 776.06 775.86 775.16 773.76 775.06 772.86NW- 1 803.55 NR 780.45 NR 781.55 NR NR 783.65 NR NR 781.25 NR NRNW- 2 806.69 NR 780.39 NR 780.79 NR NR 783.49 NR NR 781.29 NR NRNW- 4 803.30 NR 777.60 NR 779.90 NR NR 781.80 NR NR 779.10 NR NRNW- 6 803.20 NR 780.40 NR 781.90 NR NR 783.10 NR NR 780.20 NR NRNW- 7 800.80 NR 778.70 780.00 779.80 781.50 781.10 782.50 781.10 780.30 780.00 NR 777.90NW- 8 793.89 NR 780.29 NR 781.59 NR NR 782.09 NR NR 779.69 NR NRNW-10 793.09 NR 779.99 779.99 779.89 781.99 784.29 781.99 780.39 779.89 779.59 779.89 779.39NW-12 805.08 NR 779.08 NR 779.88 NR NR 782.48 NR NR 780.28 NR NRNW-14 794.50 NR 780.70 NR 778.30 NR NR 782.90 NR NR 780.70 NR NRNW-15 795.46 NR NR NR NR NR NR NR NR NR NR NR NRNW-20 797.00 NR 780.70 NR 782.10 NR NR 782.80 NR NR 780.80 NR NRNW-22 799.89 NR 779.79 781.49 781.19 782.39 784.39 783.39 782.09 781.39 780.99 780.89 780.79NW-23 802.20 NR 780.00 NR 781.60 NR NR 783.20 NR NR 780.70 NR NRNW-24 797.63 NR 780.83 NR 780.03 NR NR 782.83 NR NR 780.76 NR NRNW-25 796.40 NR NR NR NR NR NR NR NR NR NR NR NRNW-27 802.57 NR 780.37 NR 781.17 NR NR 788.97 NR NR 780.57 NR NRNW-29 800.52 NR 779.62 NR NR NR NR NR NR NR NR NR NRP- 1 804.10 NR 781.00 NR 781.40 NR NR 783.60 NR NR 781.30 NR NRP- 2 798.79 NR NR NR NR NR NR NR NR NR NR NR NRP- 4 795.17 NR 780.37 NR NR NR NR NR NR NR NR NR NRP- 9 792.17 NR 780.07 NR 781.37 NR NR 782.47 NR NR 780.47 NR NRP-13 793.08 NR NR NR NR NR NR 779.98 NR 778.18 777.68 NR NRP-18 802.64 NR 780.14 NR 781.34 NR NR 783.14 NR NR 780.34 NR NR

NR = no measurement taken 1 of 1 WATERLEVELS.xls6/17/2005

APPENDIX B

HYDROGRAPHS OF SELECTED WELLS

HYDROGRAPH OF NORTHERNWELLS (1987 - 2004)

APPENDIX B - 1

DICO


774

776

778

780

782

784

786

788

790

792

794

Dec-8

7

Dec-8

8

Dec-8

9

Dec-9

0

Dec-9

1

Dec-9

2

Dec-9

3

Dec-9

4

Dec-9

5

Dec-9

6

Dec-9

7

Dec-9

8

Dec-9

9

Dec-0

0

Dec-0

1

Dec-0

2

Dec-0

3

Dec-0

4

NW-1 NW-2

Ele

vati

on

(ft.

)

Date

Nothern Wells NW-1 and NW-2

NW-1

NW-2

HYDROGRAPH OF WESTERNWELLS (1987 - 2004)

APPENDIX B - 2

DICO


772

777

782

787

792

Dec-8

7

Dec-8

8

Dec-8

9

Dec-9

0

Dec-9

1

Dec-9

2

Dec-9

3

Dec-9

4

Dec-9

5

Dec-9

6

Dec-9

7

Dec-9

8

Dec-9

9

Dec-0

0

Dec-0

1

Dec-0

2

Dec-0

3

Dec-0

4

EW-19 NW-15 NW-25

Ele

vati

on

(ft.

)

Date

West (North Gallery) Monitoring Wells

EW-19

NW-15

NW-25

HYDROGRAPH OF EASTERNWELLS (1987 - 2004)

APPENDIX B - 3

DICO


772

777

782

787

792D

ec-8

7

Dec-8

8

Dec-8

9

Dec-9

0

Dec-9

1

Dec-9

2

Dec-9

3

Dec-9

4

Dec-9

5

Dec-9

6

Dec-9

7

Dec-9

8

Dec-9

9

Dec-0

0

Dec-0

1

Dec-0

2

Dec-0

3

Dec-0

4

EW-19 NW-23

Ele

vati

on

(ft.

)

Date

Eastern Wells EW-19 and NW-23

EW-19

NW-23

APPENDIX C

SUMMARY OF GROUNDWATER AND SURFACE WATER QUALITY DATA

APPENDIX C

SUMMARY OF 2004 GROUNDWATER AND SURFACE WATER QUALITYDES MOINES TCE SITE

Well Sampling TCE 1,2-DCE VC 1,2-DCA 1,1,1-TCA 1,1-DCE Chloroform PCE Acetone Toluene CD 1,2 DCP CT MCNumber Date Laboratory (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/

ERW- 5 23-Apr-04 UHL 23.0 25.0 ND ND ND ND ND ERW- 6 23-Apr-04 UHL 600D 120D 5.0 ND ND ND ND ERW- 7 23-Apr-04 UHL 620D 78.0 1.2 ND ND ND ND EW-19 23-Apr-04 UHL 1.2 2.1 ND ND ND ND ND EW-5 23-Apr-04 UHL 5.1 33.0 ND 0.7 ND ND ND EW-6 23-Apr-04 UHL 3.0 26.0 0.8 ND ND ND ND

MH-1N 23-Apr-04 UHL ND 1.2 ND ND ND ND ND MH-1S 23-Apr-04 UHL ND 0.8 ND ND ND ND ND NW- 1 23-Apr-04 UHL ND ND ND ND ND ND ND NW- 10 23-Apr-04 UHL ND ND ND ND ND ND ND NW-12 23-Apr-04 UHL 390D 330D 0.6 1.1 ND 0.8 ND NW-14 23-Apr-04 UHL ND ND ND ND ND ND ND NW-2 23-Apr-04 UHL 1.4 18.0 ND ND ND ND ND NW-20 23-Apr-04 UHL 2.8 35.0 1.9 0.8 ND ND ND NW-22 23-Apr-04 UHL 11.0 32.0 4.4 0.6 ND ND ND NW-23 23-Apr-04 UHL ND 2.5 0.6 ND ND ND ND NW-24 23-Apr-04 UHL ND ND ND ND ND ND ND NW-27 23-Apr-04 UHL 3.1 150D 1.2 ND ND ND ND NW-4 23-Apr-04 UHL 36.0 16.0 ND ND ND ND ND NW-6 23-Apr-04 UHL 0.6 3.6 ND ND ND ND ND NW-7 23-Apr-04 UHL 180D 170D 2.4 ND ND 0.7 0.5 NW-8 23-Apr-04 UHL ND 34.0 5.5 0.7 ND ND ND P-1 23-Apr-04 UHL ND ND ND ND ND ND ND P-18 23-Apr-04 UHL 8.9 9.9 ND ND ND ND ND P-9 23-Apr-04 UHL 4.0 40.0 ND ND ND ND ND S-2 27-Apr-04 UHL ND ND ND ND ND ND ND S-3 27-Apr-04 UHL ND ND ND ND ND ND ND

ERW- 5 29-Oct-04 UHL 20 21 ND ND ND ND ND 1 5J ND ND ND ND NDERW- 6 29-Oct-04 UHL 680 110 1 ND ND ND ND 2 ND ND ND ND ND NDERW- 7 29-Oct-04 UHL 540 72 1 ND ND ND ND 2 ND ND ND ND ND NDEW- 5 29-Oct-04 UHL 1 1 ND ND ND ND ND ND 5J ND ND ND ND NDEW- 6 29-Oct-04 UHL 4 13 1J ND ND ND ND ND ND ND ND ND ND NDEW-19 29-Oct-04 UHL 1 2 ND ND ND ND ND ND 5J ND ND ND ND NDMH-1N 28-Oct-04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND NDMH-1S 28-Oct-04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND NDNW- 1 28-Oct-04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND NDNW- 2 28-Oct-04 UHL 1 24 ND ND ND ND ND ND ND ND ND ND ND NDNW-4 29-Oct-04 UHL 18 11 ND ND ND ND ND ND 5J ND ND ND ND NDNW- 6 29-Oct-04 UHL ND 4 ND ND ND ND ND ND 5 ND ND ND ND NDNW- 7 29-Oct-04 UHL 230 140 ND ND ND ND ND 5 5J ND ND ND ND NDNW- 8 29-Oct-04 UHL ND 31 7 ND ND ND ND ND 5J ND ND ND ND NDNW- 9 28-Oct-04 UHL NS NS NS NS NS NS NS NS NS NS NS NS NS NSNW-10 28-Oct-04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND ND

Page 1 of 2 WQAL041 6/17/2005

APPENDIX C

SUMMARY OF 2004 GROUNDWATER AND SURFACE WATER QUALITYDES MOINES TCE SITE

Well Sampling TCE 1,2-DCE VC 1,2-DCA 1,1,1-TCA 1,1-DCE Chloroform PCE Acetone Toluene CD 1,2 DCP CT MCNumber Date Laboratory (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/

NW-12 29-Oct-04 UHL 210 160 ND ND ND ND ND ND ND ND ND ND ND NDNW-14 28-Oct-04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND NDNW-15 28-Oct-04 UHL NS NS NS NS NS NS NS NS NS NS NS NS NS NSNW-20 29-Oct-04 UHL 6 25 2 1J ND ND ND ND ND ND ND ND ND NDNW-22 29-Oct-04 UHL 10 17 2 ND ND ND ND 1J ND ND ND ND ND NDNW-23 29-Oct-04 UHL ND 1J ND ND ND ND ND ND ND ND ND ND ND NDNW-24 28-Oct-04 UHL NS NS NS NS NS NS NS NS NS NS NS NS NS NSNW-27 28-Oct-04 UHL 4 110 2 ND ND ND ND 1 ND ND ND ND ND ND

P- 1 28-Oct-04 UHL ND 6 ND ND ND ND ND ND 5J ND ND ND ND NDP- 9 29-Oct-04 UHL 3 69 ND ND ND ND ND ND ND ND ND ND ND NDP-13 28-Oct-04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND NDP-18 29-Oct-04 UHL 4 4 ND ND ND ND ND ND 5J ND ND ND ND NDS-2 29-Oct-04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND NDS-3 29-Oct-04 UHL ND ND ND ND ND ND ND ND 5J ND ND ND ND ND

Notes:All concentrations are reported in micrograms per Liter (ug/L) or parts per billion (ppb)ND = not detected TCE = Trichloroethene PCE = TetrachloroetheneNS = not sampled 1,2-DCE = Total 1,2-Dichloroethene CD = Carbon DisulfideJ = estimated concentration VC = Vinyl Chloride 1,2 DCP = 1,2 DichloropropaneB = compound also detected in associated blank 1,2-DCA = 1,2-Dichloroethane CT = Carbon TetrachlorideD = sample diluted 1,1,1-TCA = 1,1,1-Trichloroethane MC = Methylene Chloride = parameter not reported by the laboratory. 1,1-DCE = 1,1-Dichloroethene

Page 2 of 2 WQAL041 6/17/2005

APPENDIX D

WATER QUALITY PLOTS FOR SELECTED WELLS

TCE AND TOTAL 1,2-DCECONCENTRATIONS ERW-5,

ERW-6 & ERW-7 (1987 - 2004)

APPENDIX D - 1

DICO


0

1000

2000

3000

4000

5000

6000

7000

8000

0

200

400

600

800

1000

1200

1400

ERW-5

ERW-6

ERW-7

ERW-6

ERW-6

ERW-7

ERW-7

ERW-5

ERW-5

TCE CONCENTRATIONS

Total 1,2-DCE CONCENTRATIONS

TC

EC

oncentr

ation

(ug/L

)Tota

l1,2

-DC

EC

oncentr

ation

(ug/L

)

1998

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1999

2000

2001

2002

2003

2004

1998

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1999

2000

2001

2002

2003

2004

17 yrs of Operation

TCE AND TOTAL 1,2-DCECONCENTRATIONS ERW-5,

ERW-6 & ERW-7 (1994 - 2004)

APPENDIX D - 2

DICO


0

20

40

60

80

100

120

140

160

Nov-1

994

Sep-1

995

Jul-

1996

May-1

997

Mar-

1998

Jan-1

999

Nov-1

999

Sep-2

000

Jul-

2001

May-2

002

Mar-

2003

Jan-2

004

0

500

1000

1500

2000

2500

3000

Nov-1

994

Sep-1

995

Jul-

1996

May-1

997

Mar-

1998

Jan-1

999

Nov-1

999

Sep-2

000

Jul-

2001

May-2

002

Mar-

2003

Jan-2

004

ERW-5

ERW-6

ERW-7

ERW-6

ERW-6

ERW-7

ERW-7ERW-5

ERW-5

TCE CONCENTRATIONS

Total 1,2-DCE CONCENTRATIONS

TC

EC

oncentr

ation

(ug/L

)Tota

l1,2

-DC

EC

oncentr

ation

(ug/L

)

Last 10 yrs of Operation

APPENDIX E

VOLATILE ANALYSIS DATA PACKAGE

Documents

Performance Evaluation Report No.19 (January 2004