Contents:

Chapter Highlights

One potential pathway for exposure (primarily to workers) to contaminants released from the Idaho National Engineering and Environmental Laboratory (INEEL) is through surface water, drinking water, and groundwater. The Management and Operating contractor monitors liquid effluents, drinking water, groundwater, and storm water runoff at the INEEL to comply with applicable laws and regulations, U.S. Department of Energy (DOE) orders, and other requirements (e.g., Wastewater Land Application Permit [WLAP] requirements). Argonne National Laboratory-West (ANL-W) and the Naval Reactors Facility (NRF) conduct their own WLAP and drinking water monitoring. The U.S. Geological Survey (USGS) INEEL Project Office performs groundwater monitoring, analyses, and studies of the Snake River Plain Aquifer under and adjacent to the INEEL. The Environmental Surveillance, Education and Research (ESER) program contractor monitors drinking water and surface water at offsite locations.

During 2002, liquid effluent and groundwater monitoring was conducted in support of WLAP requirements for INEEL facilities that generate liquid waste streams covered under WLAP rules. The WLAPs generally require compliance with the state of Idaho groundwater quality primary and secondary constituent standards in specified groundwater monitoring wells. The permits specify annual discharge volume and application rates and effluent quality limits. As required, an annual report was prepared and submitted to the Idaho Department of Environmental Quality (DEQ). Additional parameters are also monitored in the effluent in support of surveillance activities. Most wastewater and groundwater regulatory and surveillance results were below applicable limits in 2002.

Samples from public water systems and wells continue to show measurable quantities of carbon tetrachloride at the Radioactive Waste Management Complex production well. The annual average of 4.3 µg/L was below the U.S. Environmental Protection Agency (EPA) established maximum contaminant level (MCL) of 5 µg/L. Trichloroethylene concentrations in samples from the Test Area North (TAN) drinking water Well #2 during 2002 also remained below the MCL. ANL-W and NRF systems were sampled as required by regulations and found to be below all limits during 2002.

As required by the General Permit for storm water discharges from industrial activity, visual examinations were made and samples were collected from selected locations. Visual examinations showed no deficiencies. Total suspended solids, iron, magnesium, and chemical oxygen demand all exceeded benchmark levels in collected samples. All of these parameters have occurred above benchmark levels in the past. Examination of storm water flow paths showed no deficiencies in storm water protection.

Tritium and strontium-90 continue to be measured in the groundwater under the INEEL. Neither of these radionuclides has been detected off the INEEL since the mid-1980s. A maximum effective dose equivalent of 0.98 mrem/yr (9.8 µSv/yr), less than the 4 mrem/yr EPA standard for public drinking water systems, was calculated for workers at the Central Facilities Area (CFA) on the INEEL in 2002.

Results from a number of special studies conducted by the U.S. Geological Survey of the properties of the aquifer and the water within it were published during 2002. Several purgeable organic compounds continue to be found in monitoring wells, including drinking water wells at the INEEL. Concentrations of organic compounds were below the EPA MCLs for these compounds except for two wells at the Radioactive Waste Management Complex, where concentrations of carbon tetrachloride slightly exceeded the MCL during certain months.
Drinking water samples were collected from 14 locations off the INEEL and around the Snake River Plain in 2002. One sample had measurable gross alpha activity, three had measurable tritium, and all samples had measurable gross beta activity. None of the samples exceeded the EPA MCL for these constituents.

Offsite surface water was collected from five locations along the Snake River. Nine of 12 samples had measurable gross beta activity, while only two samples had measurable tritium. None of these constituents were above regulatory limits. Onsite sampling of surface water runoff for waste management purposes showed no values above regulatory limits.

Back to top

5. ENVIRONMENTAL MONITORING PROGRAMS - WATER

Operations at facilities located on the INEEL release radioactive and nonradioactive constituents into the environment. This chapter presents results from radiological and nonradiological analyses of liquid effluent, drinking water, groundwater, surface water, and storm water samples taken at both onsite and offsite locations. Results from sampling conducted by the Management and Operating (M&O) contractor; ANL-W, the USGS; and the ESER contractor are all presented here. Results are compared to the EPA health-based MCL for drinking water and/or the DOE Derived Concentration Guide (DCG) for ingestion of water.

This chapter begins with a general overview of the various organizations responsible for monitoring of water at the INEEL in Section 5.1. Sections 5.2 and 5.3 describe liquid effluent and groundwater monitoring as required by permits and that are done for surveillance activities only, respectively. The INEEL drinking water programs are discussed in Section 5.4. Sections

5.5 and 5.6 describe groundwater monitoring and aquifer studies. Radiological and nonradiological monitoring of groundwater at the INEEL is discussed in Section 5.7. Section 5.8 describes storm water and surface water monitoring. Section 5.9 summarizes onsite waste management water surveillance activities.

5.1 Organization of Monitoring Programs

The M&O contractor monitors liquid effluents, drinking water, groundwater, and storm water runoff at the INEEL to comply with applicable laws and regulations, DOE orders, and other requirements (e.g., Wastewater Land Application Permit requirements).

The ESER contractor monitors drinking water and surface water at offsite locations and collected a total of 93 water samples for analyses in 2002.

The USGS INEEL Project Office performs groundwater monitoring, analyses, and studies of the Snake River Plain Aquifer (SRPA) under and adjacent to the INEEL. This is done through an extensive network of strategically placed observation wells on the INEEL (Figures 5-1 and 5-2) and at locations throughout the Eastern Snake River Plain. Chapter 3 summarizes the USGS routine groundwater surveillance program. In 2002, USGS personnel collected 1915 samples for radionuclides and inorganic constituents including trace elements and 51 samples for purgeable organic compounds.

In addition, through an interagency agreement, the USGS performs groundwater monitoring activities for the NRF. As part of the 2002 NRF sampling program, the USGS performed quarterly sampling from nine NRF wells and four USGS wells, collecting a total of 60 samples. Samples were analyzed for radionuclides, inorganic constituents, and purgeable organic compounds.

ANL-W performs semiannual groundwater monitoring at one upgradient monitoring well, three down gradient monitoring wells and one production well. Samples are analyzed for gross activity (alpha and beta), uranium isotopes, tritium, inorganics and water quality parameters.

ANL-W performs semiannual groundwater monitoring at one upgradient monitoring well, three down gradient monitoring wells and one production well. Samples are analyzed for gross activity (alpha and beta), uranium isotopes, tritium, inorganics and water quality parameters.

Table 5-1 presents the various water-related monitoring activities performed on and around the INEEL.

Back to top

5.2 Liquid Effluent and Related Groundwater Compliance Monitoring

The Liquid Effluent and Groundwater Monitoring Programs conducted by the M&O contractor monitor for nonradioactive and radioactive parameters in liquid waste effluent and groundwater. Wastewater is typically discharged to the ground surface and evaporation ponds. Discharges to the ground surface are through infiltration ponds, trenches, drainfields, or a sprinkler irrigation system at the following areas:

  • Infiltration ponds at the Idaho Nuclear Technology and Engineering Center (INTEC) Existing and New Percolation Ponds, Test Area North/Technical Support Facility (TAN/TSF) Sewage Treatment Plant Disposal Pond, Test Reactor Area (TRA) Cold Waste Pond, ANL-W Industrial Waste ditch and pond, ANL-W Sanitary Lagoons, and NRF Industrial Waste Ditch;

  • INTEC Sewage Treatment Plant infiltration trenches;
  • Septic tank drainfields at various locations on the INEEL; and
  • A sprinkler irrigation system at the Central Facilities Area (CFA) used during the summer months to land-apply industrial and treated sanitary wastewater.

Discharge of wastewater to the land surface is regulated under Idaho Wastewater Land Application Permit (WLAP) rules (IDAPA 58.01.17). An approved WLAP will normally require monitoring of nonradioactive parameters in the influent waste, effluent waste, and groundwater, as applicable. These monitoring programs also support WLAP requirements for INEEL facilities that generate liquid waste streams covered under WLAP rules. Table 5-2 lists the six facilities operated by the M&O contractor that require WLAPs and the current permit status of each facility.

Table 5-2.  Current M&O Contractor Wastewater Land Application Permits.

The WLAPs generally require compliance with the Idaho groundwater quality primary constituent standards (PCS) and secondary constituent standards (SCS) in specified groundwater monitoring wells (IDAPA 58.01.11). The permits specify annual discharge volume and application rates and effluent quality limits. As required, an annual report is prepared and submitted to the DEQ.

During 2002, the M&O contractor conducted monitoring as required by the permits for each of the first five facilities listed in Table 5-2. The Test Reactor Area (TRA) Cold Waste Pond has not been issued a permit; however, quarterly samples for total nitrogen and total suspended solids are collected to show compliance with the regulatory effluent limits for rapid infiltration systems. The following subsections present results of wastewater and groundwater monitoring for individual facilities conducted for compliance purposes.

Additional parameters are also monitored in the effluent. Section 5.3 discusses the results of liquid effluent surveillance monitoring for individual facilities.

Back to top

Idaho Falls Facilities

Description -The City of Idaho Falls is authorized by the Clean Water Act, National Pollutant Discharge Elimination System (NPDES) to set pretreatment standards for nondomestic discharges to publicly owned treatment works. The M&O contractor facilities in Idaho Falls are required to comply with the applicable regulations in Chapter 1, Section 8, of the Municipal Code of the City of Idaho Falls.

Industrial Wastewater Acceptance Forms were obtained for facilities that discharge process wastewater through the City of Idaho Falls sewer system. Twelve M&O contractor Idaho Falls facilities have associated Industrial Wastewater Acceptance Forms for discharges to the city sewer system. The Industrial Wastewater Acceptance Forms for these facilities contain special conditions and compliance schedules, prohibited discharge standards, reporting requirements, monitoring requirements, and effluent concentration limits for specific parameters; however, only the INEEL Research Center has specific monitoring requirements.

Wastewater Monitoring Results -Semiannual monitoring was conducted at the INEEL Research Center in April and October of 2002. Table 5-3 summarizes the 2002 semiannual monitoring results.

Back to top

Central Facilities Area Sewage Treatment Plant

Description - The CFA Sewage Treatment Plant serves all major facilities at CFA. It is southeast of CFA, approximately 671 m (2200 ft) downgradient of the nearest drinking water well.

A 1500-L/min (400-gal/min) pump applies wastewater from a 0.2-ha (0.5-acre) lined, polishing pond to approximately 30 ha (74 acres) of desert rangeland through a computerized center pivot irrigation system. The permit limits wastewater application to 25 acre in./acre/yr from March 15 through November 15 and limits leaching losses to 8 cm/yr (3 in./yr).

WLAP Wastewater Monitoring Results -The permit requires influent and effluent monitoring, as well as soil sampling in the application area (see Chapter 6 for results pertaining to soils). Influent samples were collected monthly from the lift station at CFA (prior to Lagoon No. 1) during 2002. Effluent samples were collected from the pump pit starting in June 2002 and continued through September 2002 (the period of pivot operation for 2002). An additional effluent sample was collected on October 1, 2002, for the same parameters (excluding fecal and total coliform). All samples collected were 24-hour composites, except pH and coliform samples, which were collected as grab samples. Tables 5-4 and 5-5 summarize the results.

Table 5-4.  CFA Sewage Treatment Plant influent monitoring results (2002). a,b

Table 5-5.  CFA Sewage Treatment Plant effluent monitoring results (2002). a,b

Daily influent flows averaged less than 398,000 L/d (105,000 gal/d). Total influent flow volume was approximately 144 million L (38 million gal) for the 2002 calendar year. Discharge to the pivot averaged 652,754 L/d (172,458 gal/d) when it operated. A total of 54.8 million L (14.49 million gal) was discharged through the pivot in 2002.

Removal efficiencies for biochemical oxygen demand, chemical oxygen demand, total suspended solids, and total nitrogen were calculated to estimate treatment in the lagoons. During the 2002 calendar year, all average removal efficiencies were higher than the previous year, and treatment in the lagoons was sufficient to produce a good quality effluent for land application.

Soil and weather conditions, combined with the relatively low volume of wastewater applied, resulted in no leaching loss for the year, compared to the permit limit of 8 cm/yr (3 in./yr). As a result, land application of wastewater had a negligible impact on soils and groundwater.

WLAP Groundwater Monitoring Results -The WLAP does not require groundwater monitoring at the CFA Sewage Treatment Plant.

Back to top

Idaho Nuclear Technology and Engineering Center Existing Percolation Ponds

Description - The INTEC generates an average of 3.8 to 7.6 million L/d (1 to 2 million gal/d) of nonhazardous process wastewater during normal operations. This wastewater, commonly called service waste, was discharged to the Existing Percolation Ponds via the service waste system. Wastewater was discharged to the INTEC Existing Percolation Ponds from January 1, 2002, through August 25, 2002. Beginning August 26, 2002, the wastewater was routed to the INTEC New Percolation Ponds.

The Percolation Ponds receive only nonhazardous wastewater. Wastewater with the potential to contain hazardous constituents is disposed of in accordance with the applicable Resource Conservation and Recovery Act requirements. Sanitary wastes from restrooms and the INTEC cafeteria are either discharged to the INTEC Sewage Treatment Plant or directed to onsite septic tank systems.

The service waste system serves all major facilities at INTEC. This process-related wastewater from INTEC operations consists primarily of steam condensates, noncontact cooling water, reverse osmosis products, water softener and demineralizer regenerate, and boiler blowdown wastewater.

All service waste enters building CPP-797, the final sampling and monitoring station, before discharge to the Percolation Ponds. In CPP-797, the combined effluent is measured for flow rate and monitored for radioactivity, and samples are collected for analyses. No radioactivity is expected; however, if radioactivity is detected above a specified level, contaminated waters are directed to a diversion tank rather than discharged to the Percolation Ponds. Two sets of two pumps transfer the wastewater from CPP-797 to the Percolation Ponds.

WLAP Wastewater Monitoring Results -The WLAP for the Existing Percolation Ponds requires effluent monitoring as well as groundwater sampling. A 24-hour flow-proportional composite sample is collected monthly from the sample point located in CPP-797 and analyzed. Table 5-6 summarizes the effluent results from the INTEC Existing Percolation Ponds.


Based upon analytical results, the quality of wastewater discharged to the Existing Percolation Ponds in 2002 is consistent with previous years. The permit does not specify concentration limits for effluent to the ponds; however, concentrations were compared to the applicable state of Idaho groundwater PCS and SCS. Yearly average effluent concentrations for all constituents, except total dissolved solids, met these standards. The SCS for total dissolved solids is 500 mg/L. During the 2002 application year, the SCS for total dissolved solids was exceeded four times, and the yearly average concentration was 523 mg/L.

The flow volumes to the Existing Percolation Ponds were recorded daily from the flow meter located in CPP-797. Total flow discharged in 2002 to the Exiting Percolation Ponds was
1.52 × 109 L (401.9 × 106 gal). Total flow during the 2002 permit year was well below the permit limit of 3.45 × 109 L/yr (912 × 106 gal/yr).

WLAP Groundwater Monitoring Results - To measure potential percolation pond impacts to groundwater, the WLAP requires that groundwater samples be collected semiannually from four monitoring wells:

  • One background aquifer well (USGS-121) up gradient of INTEC;

  • One aquifer well (USGS-048) immediately up gradient of the Percolation Ponds; and
  • Two aquifer wells (USGS-112 and -113) down gradient of the Percolation Ponds, which serve as points of compliance.

Analytical results for 2002 were very similar to those of previous years with the exception of iron in well USGS-112 and total Kjeldahl nitrogen (TKN) in well USGS-048. Table 5-7 shows the parameter concentrations as well as the groundwater quality PCS and SCS for the April and September/October WLAP groundwater sampling.

The iron concentration in well USGS-112 exceeded the SCS of 0.3 mg/L in both the April and September samples. The April iron concentration was 1.4 mg/L, and the September iron concentration was 1.7 mg/L. These concentrations were significantly higher than those from the previous year's sampling events (0.12 mg/L for April 2001 and 0.093 mg/L for October 2001). It is expected that corrosion of the carbon steel casing and the galvanized riser pipe and not the discharge of effluent to the Existing Percolation Ponds may be contributing to the elevated iron concentrations. Subsequent to the September 2002 sampling event, a 6.1-m (20-ft) section of the old riser pipe was replaced with new galvanized pipe.

The October 2002 concentration for TKN in well USGS-048 was 3.9 mg/L and is significantly higher than expected when compared to previous sampling events. The April 2002 TKN concentration was undetected at 1 mg/L. From 1997 through 2001, the highest detected TKN concentration in well USGS-048 was 0.34 mg/L. During 2002, only one effluent sample had detectable levels (0.21 mg/L) of TKN. Because of the low effluent TKN concentration and the fact that well USGS-048 is upgradient of the Existing Percolation Ponds, it is highly unlikely that the effluent would be the cause of the elevated TKN in the well. The TKN result is not representative of historical TKN concentrations in USGS-048 or in the effluent and may have been an anomaly.

Back to top

Idaho Nuclear Technology and Engineering Center New Percolation Ponds

Description - The above description of the INTEC Existing Percolation Ponds applies to the INTEC New Percolation Ponds. The only major difference is that as of August 26, 2002, the wastewater was discharged to the New Percolation Ponds instead of the Existing Percolation Ponds.

The INTEC New Percolation Ponds are designed to function similarly to the Existing Percolation Ponds south of INTEC. The new pond complex is a rapid infiltration system and is comprised of two ponds excavated into the surficial alluvium and surrounded by bermed alluvial material. Each pond is approximately 93 x 93 m (305 × 305 ft) at the top of the berm and is about 3-m (10-ft) deep. Each pond is designed to accommodate a continuous wastewater discharge rate of approximately 11 million L/d (three million gal/d).

During normal operation, wastewater is discharged to only one pond at a time. Periodically, the pond receiving the wastewater will be alternated to minimize algae growth and maintain good percolation rates. Ponds are routinely inspected, and the depth is recorded via permanently mounted staff gauges.

WLAP Wastewater Monitoring Results -The WLAP for the New Percolation Ponds requires effluent monitoring, as well as groundwater sampling. As with the existing percolation ponds, a 24-hour flow-proportional composite sample is collected monthly from the sample point in CPP-797 for all parameters except pH, which is taken as a grab sample as required by the permit. Table 5-8 summarizes the effluent results from the INTEC New Percolation Ponds.

Sample collection for the New Percolation Ponds began in September 2002, after the wastewater was rerouted from the Existing Percolation Ponds to the New Percolation Ponds on August 26, 2002.

The permit does not specify concentration limits for effluent to the ponds; however, concentrations were compared to the applicable state of Idaho groundwater PCS and SCS. Yearly average effluent concentrations for all constituents, except total dissolved solids (TDS), met these standards. The SCS for TDS is 500 mg/L. During the 2002 calendar year, the SCS for TDS was exceeded in the December sample. The yearly average TDS concentration was 558 mg/L.

The flow volumes to the New Percolation Ponds were recorded daily from the flow meter located in CPP-797. Total flow discharged to the New Percolation Ponds in 2002 (from August 26, 2002, through December 31, 2002) was approximately 7.45 × 108 L (1.97 × 108 gal). Total flow during the 2002 permit year was well below the permit limit of 4.145 × 109 L/yr (1.095 × 109 gal/yr).

WLAP Groundwater Monitoring Results -To measure potential impacts to groundwater from the New Percolation Ponds, the permit requires that groundwater samples be collected semiannually from six monitoring wells:

  • One background aquifer well (ICPP-MON-A-167) upgradient of the New Percolation Ponds;

  • One background perched water well (ICPP-MON-V-191) north of the New Percolation Ponds and just south of the Big Lost River;

  • Two aquifer wells (ICPP-MON-A-165 and -166) downgradient of the New Percolation Ponds; and
  • Two perched water wells (ICPP-MON-V-200 and ICPP-MON-V-212) adjacent to the New Percolation Ponds. Well ICPP-MON-V-200 is north of the New Percolation Ponds and well ICPP MON-V-212 is between the two ponds.

The New Percolation Ponds were placed into service on August 26, 2002. Therefore, samples were only collected in October of the 2002 permit year. The permit provides a specified list of parameters to be analyzed for in the groundwater samples. Aquifer wells ICPP MON-A-165 and ICPP-MON-A-166 and perched water wells ICPP-MON-V-200 and ICPP MON V 212 are the permit compliance points. Aquifer well ICPP-MON-A-167 and perched water well ICPP-MON-V-191 are listed in the permit as upgradient, noncompliance points. Contaminant concentrations in the compliance wells are limited by the groundwater PCS and SCS.

Table 5-9 shows water levels (recorded before purging and sampling) and analytical results for all parameters specified by the permit. The concentrations for aluminum, iron, and manganese in aquifer wells ICPP-MON-A-166 and ICPP-MON-A-167 were above the SCS levels. As stated previously, well ICPP-MON-A-166 is a compliance well and is regulated by the permit not to exceed the PCS and SCS levels. Well ICPP-MON-A-167 is the background aquifer monitoring well and is not regulated to these levels by the permit.

The data from the October 2002 sample from perched water well ICPP-MON-V-200 indicate that no PCS or SCS levels were exceeded.

Concentrations of aluminum, iron, and manganese in well ICPP-MON-A-166 from the October sample (Table 5-9) are similar to the pre-operational baseline concentrations for this well. The aluminum, iron, and manganese concentrations in the October sample from well ICPP-MON-A-167 were lower than those in the pre-operational baseline samples. The concentrations of these constituents in well ICPP-MON-A-167 appear to be decreasing over time.

No other PCS or SCS levels were exceeded in any of the permit wells. However, TKN levels in ICPP-MON-A-166 and ICPP-MON-A-167 were higher than expected and significantly higher than in the preoperational baseline samples. There is no PCS or SCS limit for TKN.

It is unlikely that the elevated levels of TKN, aluminum, iron, and manganese in the aquifer wells could be the result of the disposal of wastewater to the new ponds for the following reasons:

  • Well ICPP-MON-A-167 was selected as the upgradient (background) monitoring well and should not be affected by discharges to the new ponds;

  • The concentrations of TKN, aluminum, iron, and manganese in the effluent since August 26, 2002, are considerably lower than the concentrations in the aquifer wells in October 2002; and
  • The wastewater discharged to the New Percolation Ponds is the same wastewater that had been discharged to the Existing Percolation Ponds since 1995, and the concentrations of TKN, aluminum, iron, and manganese in the aquifer wells associated with the Existing Percolation Ponds have not exceeded the SCS levels in the past.

With the exception of TKN, the aluminum, iron, and manganese had been detected in the pre-operational samples at approximately equal or higher concentrations.

One possible explanation for the elevated levels of aluminum, iron, and manganese may be that both wells were insufficiently developed during construction activities. Another possible explanation is that the annular seals were placed incorrectly, thus, allowing bentonite slurry to affect the water quality. The sampling logbook entry for October 2002 described the purge water from ICPP-MON-A-167 as murky and the color of bentonite for the entire purge. Before the next sampling event, additional purging will be performed on wells ICPP-MON-A-166 and ICPP-MON-A-167 to try to remove any residual contaminants that may be in the wells as a result of the well construction activities.

The reason for the higher than expected TKN concentrations in the October 2002 samples from wells ICPP-MON-A-166 and ICPP-MON-A-167 is unknown. However, TKN concentrations, as well as the other permit-required parameter concentrations in the six WLAP monitoring wells, will continue to be evaluated as more data become available.

Back to top

Idaho Nuclear Technology and Engineering Center Sewage Treatment Plant

Description - The INTEC Sewage Treatment Plant treats and disposes of sanitary and other related nonprocess wastes (cafeteria and building water softeners) using natural biological and physical processes (digestion, oxidation, photosynthesis, respiration, aeration, and evaporation). The INTEC Sewage Treatment Plant consists of

  • Two aerated lagoons (Cell Nos. 1 and 2);

  • Two quiescent, facultative stabilization lagoons (Cell Nos. 3 and 4);
  • Six control stations; and
  • Four rapid infiltration trenches.

The six control stations direct the wastewater flow to the proper sequence of lagoons and infiltration trenches. Automatic flow-proportional composite samplers are located at control stations CPP-769 (influent) and CPP-773 (wastewater from the Sewage Treatment Plant to the rapid infiltration trenches). The composite samplers are connected to flow meters, thus, allowing collection of flow-proportional samples.

WLAP Wastewater Monitoring Results -The WLAP requires monthly sampling and analysis of the influent and effluent. Influent samples were collected from control station CPP-769 and effluent samples were collected from control station CPP-773. The WLAP sets effluent limits at CPP-773 for total nitrogen (TKN plus nitrite/nitrate nitrogen) and total suspended solids. Permit-required influent and effluent monitoring results are summarized in Tables 5-10 and 5-11, respectively.

Except for the monthly total coliform grab sample, all samples were collected as 24-hour flow proportional composites. Monthly average effluent total suspended solids concentrations remained below the permit limit of 100 mg/L, with an annual average of 34 mg/L. During 2002, the average monthly total nitrogen exceeded the monthly average limit of 20 mg/L during January, February, and March. Typically, the highest nitrogen concentrations occur during the colder months.

Total annual effluent flow to the trenches (measured by the flow meters) was 46.3 million L (12.24 million gal) during 2002, which is well below the permit limit of 78 million L/yr (30 million gal/yr). Although there were several periods throughout the year when the accuracy of the effluent flow meters was suspect, 46.3 million L (12.24 million gal) is considered a conservative value.

WLAP Groundwater Monitoring Results - To measure potential INTEC Sewage Treatment Plant impacts to groundwater, the WLAP requires collecting groundwater samples semiannually from three monitoring wells:

  • One background aquifer well (USGS-121) upgradient of INTEC;

  • One perched water well (ICPP-MON-PW-024) immediately adjacent to the Sewage Treatment Plant; and
  • One aquifer well (USGS-052) downgradient of the Sewage Treatment Plant, which serves as the point of compliance.

Contaminant concentrations in USGS-052 are limited by primary and secondary groundwater standards specified in Idaho regulations. Table 5-12 presents the monitoring results for 2002.

Groundwater samples collected from USGS-052 were in compliance with all permit limits during 2002. Chloride and nitrate concentrations in USGS-052 were elevated compared to USGS-121, as in previous years.

Monitoring well ICPP-MON-PW-024 was completed in the perched water zone approximately 21 m (70 ft) below the surface of the infiltration trenches. Similar to previous years, TDS and chloride concentrations in ICPP-MON-PW-024 approximated those of the effluent. Total coliform was detected in the October 2002 sample from this well and was present also in the effluent. The species of bacteria detected was identified as Enterobacter cloacae at a concentration of 30 colonies/100 mL.

Background aquifer well USGS-121 exceeded the PCS level for total coliform in the April sample. The sample result was 38 colonies/100 mL total coliform (Table 5-12). The laboratory identified the coliform species as Citrobacter fruendii. Because this is the upgradient (background) well, contamination from the INTEC Sewage Treatment Plant is not expected. Total coliform was absent in the October sample, and fecal coliform was absent in both April and October samples.

Back to top

Test Area North/Technical Support Facility Sewage Treatment Plant

Description - The TAN/TSF Sewage Treatment Plant (TAN 623) was constructed in 1956. It was designed to treat raw wastewater by biologically digesting the majority of the organic waste and other major contaminants, then applying it to the land surface for infiltration and evaporation. The Sewage Treatment Plant consists of

  • A wastewater-collection manhole;

  • An Imhoff tank;
  • Sludge drying beds;
  • A trickle filter and settling tank;
  • A contact basin; and
  • An infiltration disposal pond.

The TAN/TSF Disposal Pond was constructed in 1971. It consists of a primary disposal area and an overflow section, both of which are located within an unlined, fenced 14.2-ha (35-acre) area. The overflow pond is used only when wastewater is diverted to it for brief periods of cleanup and maintenance of the primary pond. In addition to receiving treated sewage wastewater, the TAN/TSF Disposal Pond also receives process wastewater, which enters the facility at the TAN-655 lift station.

The TSF sewage primarily consists of spent water containing wastes from restrooms, sinks, and showers. The sanitary wastewater goes to the TAN 623 Sewage Treatment Plant, and then to the TAN 655 lift station, which pumps to the TAN/TSF Disposal Pond.

The process drain system collects wastewater from process drains and building sources originating from various TAN facilities. The process wastewater consists of liquid effluent, such as steam condensate; water softener and demineralizer discharges; cooling water; heating, ventilating, and air conditioning; and air scrubber discharges. The process wastewater is transported directly to the TAN-655 lift station, where it is mixed with sanitary wastewater before being pumped to the TAN/TSF Disposal Pond.

WLAP Wastewater Monitoring Results -The permit flow limit is 129 million L/yr (34 million gal/yr) discharged to the TAN/TSF Disposal Pond. Total effluent to the TAN/TSF Disposal Pond for calendar year 2002 was approximately 30 million L (7.8 million gal). The permit for the TAN/TSF Sewage Treatment Plant also sets concentration limits for total suspended solids and total nitrogen measured in the effluent to the TAN/TSF Disposal Pond and requires that the effluent be sampled and analyzed monthly for several parameters. During 2002, 24-hour composite samples (except fecal and total coliform, which were grab samples) were collected from the TAN-655 lift station effluent monthly.

Table 5-13 summarizes the effluent monitoring results for calendar year 2002. Monthly concentrations of total suspended solids were well below the permit limit (100 mg/L) throughout the entire year, with an annual average of 4.1 mg/L. All monthly total nitrogen (TKN + nitrite/nitrate nitrogen) concentrations were well below the permit limit of 20 mg/L, with the maximum monthly concentration of 7.4 mg/L reported in November.

WLAP Groundwater Monitoring Results -To measure potential TAN/TSF Disposal Pond impacts to groundwater, the WLAP for the TAN/TSF Sewage Treatment Plant requires collecting groundwater samples semiannually from four monitoring wells:

  • One background aquifer well (TANT-MON-A-001) upgradient of the TAN/TSF Disposal Pond; and

  • Three aquifer wells (TAN-10A, TAN-13A, and TANT-MON-A-002) that serve as permit points of compliance.

The permit limits contaminant concentrations in TAN-10A, TAN-13A, and TANT-MON-A-002 to the Idaho primary and secondary groundwater standards. Table 5-14 presents the monitoring results for 2002.

Iron concentrations exceeded the permit standard of 0.3 mg/L in TANT-MON-A-001 (the background well) and TAN-13A in April and in TAN-10A in April and October. These concentrations are consistent with results of the past few years; elevated iron concentrations historically have been detected in the TAN WLAP monitoring wells.

The older galvanized steel riser pipes were replaced with stainless steel riser pipes in all four TAN WLAP monitoring wells during August 2001. Video log information gathered during the well maintenance showed that the stainless steel well casings in wells TAN-13A, TANT-MON-A-001, and TAN-MON-A-002 appeared relatively free of rust to the water table. Iron concentrations have decreased in all three of these wells when compared to samples collected before the maintenance (April 2001) and those collected after the maintenance. The iron concentrations in these three wells continued to decrease between the April and October 2002 sampling events.

Video log information gathered on TAN-10A showed that the carbon steel well casing appeared to be rusted most of the way to the water table. During 2001, the iron concentrations in TAN-10A increased after maintenance, and iron concentrations for TAN-10A were the highest of the four wells. The condition of the well casing, coupled with the residual effects relating to the replacement of the galvanized riser pipe, may have resulted in the increased iron concentrations in TAN-10A in 2002.

All samples and duplicate samples collected from well TAN-10A in April and October exceeded the permit limit (SCS) for TDS of 500 mg/L (Table 5-14). The TDS increased from 509 and 540 mg/L in the April samples to 568 and 627 mg/L in the October samples. The condition of the well casing and the residual effects from replacing the riser pipe may also be contributing to the increase of the TDS in well TAN-10A.

Fecal coliform was absent in all samples and wells during the 2002 permit year. However, total coliform was present in TANT-MON-A-001 (background well) and TANT-MON-A-002 (compliance well) in the October samples. The PCS for total coliform is 1 colony/100 mL. The total coliform in wells TANT-MON-A-001 and TANT-MON-A-002 was 1 colony/100 mL and 700 colonies/100 mL, respectively. The coliform species identified by the laboratory was Enterobacter agglomerans in well TANT-MON-A-001 and Enterobacter sakazakii in well TANT-MON-A-002. The TAN/TSF Disposal Pond effluent contains total coliform bacteria; however, it is unlikely the coliform detected in these two wells was the result of the Disposal Pond effluent. TANT-MON-A-001 is the background well and is not influenced by the Disposal Pond. TANT-MON-A-002 is northwest of the Disposal Pond, and groundwater flows at TAN are primarily to the south or southeast; therefore, it is unlikely that bacteria could be transported into the well without significant transverse dispersivity in the vadose zone. A possible source of the bacteria in TANT-MON-A-002 could be the formation of a biofilm due to long periods of inactivity.

No other parameters exceeded groundwater quality standards during calendar year 2002.

Back to top

Test Reactor Area Cold Waste Pond

Description -The TRA Cold Waste Pond was constructed in 1982. The majority of wastewater received by the Cold Waste Pond is secondary cooling water from the Advanced Test Reactor when it is in operation. Chemicals used in the cooling water are primarily commercial corrosion inhibitors and sulfuric acid to control pH. Other wastewater discharges to the Cold Waste Pond are nonhazardous and nonradioactive and include, but are not limited to, maintenance cleaning waste, floor drains, and yard drains

The cold waste effluents collect at the cold well sump and sampling station (TRA-764) before being pumped to the Cold Waste Pond. The cooling tower system has a radiation monitor with an alarm that prevents accidental discharges of radiologically contaminated cooling water.

WLAP Wastewater Monitoring Results -A letter from the Idaho DEQ issued in 2001, authorized the continued operation of the Cold Waste Pond under the terms and conditions of the WLAP regulations (Johnston 2001). As a result, total nitrogen (TKN + nitrite/nitrate nitrogen) and total suspended solids analyses were added in August 2001 to the list of parameters analyzed quarterly at the Cold Waste Pond. These are the only parameters required for compliance. Other parameters are sampled for surveillance purposes.

Automated samplers are used to collect quarterly 24-hour time-proportional composite samples from TRA-764. Total suspended solids and total nitrogen results are summarized in Table 5-15. Additional monitoring for surveillance parameters is discussed in the next section. Total suspended solids were undetected in all samples collected during 2002. The detection level of 4.0 mg/L is well below the regulatory limit of 100 mg/L. The maximum total nitrogen concentration during 2002 was 3.3 mg/L, and it was also significantly less then the regulatory limit of 20 mg/L.

WLAP Groundwater Monitoring Results -Currently, there are no groundwater monitoring requirements associated with the TRA Cold Waste Pond. However, groundwater monitoring is expected to be required when a permit is issued.

Back to top

5.3 Liquid Effluent Surveillance Monitoring

As stated in Section 5.2, additional parameters specified in the Idaho groundwater quality standards are also monitored. The results of this additional monitoring are discussed by individual facility in the following sections. This additional monitoring is performed in support of surveillance activities.

Argonne National Laboratory-West

During 2002, the Industrial Waste Pond and Secondary Sanitary Lagoon at ANL-W were monitored monthly for iron, sodium, chloride, fluoride, sulfate, pH, conductivity, total dissolved solids, turbidity, biological oxygen demand, gross alpha, gross beta, gamma spectrometry, and tritium. Additionally, the Secondary Sanitary Lagoon was also monitored monthly for total coliform. All parameters for both ponds were well below applicable Idaho groundwater standards (Table 5-16).

Central Facilities Area

The influent and effluent to the CFA Sewage Treatment Plant are both monitored according to the WLAP issued for the plant. The results of the permit-related monitoring are discussed in detail in Section 5.2. Table 5-17 summarizes the additional monitoring conducted during 2002 at the CFA Sewage Treatment Plant and shows those parameters with at least one detected result during the year. Additional monitoring is performed quarterly from the floor drains and vehicle maintenance areas of the Transportation Complex at CFA 696. During 2002, no corresponding limits were exceeded for any of the additional parameters monitored, and all additional parameters were within historical concentration levels.

Back to top

Idaho Nuclear Technology and Engineering Center

Wastewater Land Application permits exists for the Sewage Treatment Plant and the New and Existing Percolation Ponds at the INTEC. The results of permit-related monitoring are discussed in detail in Section 5.2. Table 5-18 summarizes the additional monitoring conducted during 2002 at INTEC and shows those parameters with at least one detected result during the year.

For the INTEC Existing Percolation Ponds, all results were well within the applicable limits and historical concentration levels. For the INTEC Sewage Treatment Plant, none of the additional parameters exceeded applicable limits. Although the pH level exceeded the historical high concentration limit at both the influent to and effluent from the INTEC Sewage Treatment Plant, it did not exceed applicable limits.

Naval Reactors Facility

Liquid effluent monitoring confirmed all discharges to the industrial waste ditch in 2002 were controlled in accordance with applicable federal and State laws. No detections above these limits were seen. Specifics regarding this monitoring are published in the 2002 Environmental Monitoring Report for the Naval Reactors Facility (Bechtel Bettis 2002).

Test Area North

The effluent to the TAN/TSF Disposal Pond receives a combination of process water from various TAN facilities and treated sewage waste. The effluent is monitored monthly, and the results are discussed in Section 5.2. Additional monitoring for surveillance purposes is conducted monthly for metal parameters and quarterly for radiological parameters. Table 5-19 summarizes the results of this additional monitoring for those parameters with at least one detected result. During 2002, the concentrations of the additional parameters were within historical levels and applicable limits.

Test Reactor Area

The effluent to the Cold Waste Pond receives a combination of process water from various TRA facilities. The effluent is monitored quarterly, with the results of monitoring discussed in Section 5.2. Additional monitoring for surveillance purposes is conducted quarterly for metal parameters and for radiological parameters. Table 5-20 summarizes the results of this additional monitoring for those parameters with at least one detected result. During 2002, the concentrations of the additional parameters were within historical levels and applicable limits. Both the sulfate and TDS levels were above the historical high concentration limits.

The largest volume of wastewater received by the TRA Cold Waste Pond is secondary cooling water from the Advanced Test Reactor when it is in operation. During 2002, concentrations of sulfate and TDS were elevated in samples collected during reactor operation. These differences are due to the normal raw water hardness, as well as corrosion inhibitors and sulfuric acid added to control the cooling water pH. Concentrations of sulfate and TDS exceeded the risk-based release levels specific for the TRA Cold Waste Pond during reactor operation but not during reactor outages. The annual average was also slightly above the risk-based release limit, which is the concentration predicted to degrade groundwater quality to above drinking water standards.

Back to top

5.4 Drinking Water Monitoring

In 1988, a centralized drinking water program was established for most INEEL facilities. ANL-W and the NRF are the only two facilities that are not included in the M&O contractor Drinking Water Program. ANL-W is managed by DOE Chicago, and the NRF is operated for the DOE-Pittsburgh Naval reactors, Idaho Branch Office by Bechtel Bettis, Inc.

The Drinking Water Program was established to monitor drinking water and production wells, which are multiple use wells for industrial use, fire safety, and drinking water. According to the "Idaho Regulations for Public Drinking Water Systems" (IDAPA 58.01.08), INEEL drinking water systems are classified as either nontransient or transient, noncommunity water systems. The M&O contractor transient, noncommunity water systems are at the Experimental Breeder Reactor No. 1 (EBR-I), the Gun Range, and the Main Gate. The rest of the M&O contractor water systems are classified as nontransient, noncommunity water systems, which have more stringent requirements than transient, noncommunity water systems.

The Drinking Water Program monitors drinking water to ensure it is safe for consumption and to demonstrate that it meets federal and State regulations (that MCLs are not exceeded). The Safe Drinking Water Act establishes the overall requirements for the Drinking Water Program.

Because groundwater supplies the drinking water at the INEEL, information on groundwater quality was used to help develop the Drinking Water Program. The USGS and the M&O contractor monitor and characterize groundwater quality at the INEEL. Three groundwater contaminants have impacted M&O contractor drinking water systems: tritium at CFA, carbon tetrachloride at the Radioactive Waste Management Complex (RWMC), and trichloroethylene at TAN/TSF.

As required by the state of Idaho, the Drinking Water Program uses U.S. EPA-approved (or equivalent) analytical methods to analyze drinking water in compliance with IDAPA 58.01.08 and 40 Code of Federal Regulations (CFR) 141-143 (2002).

Currently, the Drinking Water Program monitors ten water systems, which include 17 wells. Drinking water parameters are regulated by the state of Idaho under authority of the Safe Drinking Water Act. Parameters with primary maximum contaminant levels must be monitored at least once during every three-year compliance period. Parameters with secondary maximum contaminant levels are monitored every three years based on a recommendation by the EPA. The three-year compliance periods for the Drinking Water Program are 1999-2001, 2002-2004, and so on. Many parameters require more frequent sampling during an initial period to establish a baseline, and subsequent monitoring frequency is determined from the baseline.

Because of known contaminants, the Drinking Water Program monitors certain parameters more frequently than required. For example, the program monitors for bacteriological analyses more frequently because of historical problems with bacteriological contaminants. These detections were possibly caused by biofilm on older water lines and stagnant water, and resampling results were normally in compliance with the MCL.

Back to top

Onsite Drinking Water Monitoring Results

During 2002, 254 routine samples and 24 quality control samples were collected and analyzed from CFA, EBR-I, Gun Range, INTEC, Main Gate, Power Burst Facility (PBF), RWMC, TAN/Contained Test Facility (CTF) and TAN/TSF, and TRA. In addition to the routine sampling, the Drinking Water Program also collects nonroutine samples. For example, a nonroutine sample is one collected after a water main breaks and is repaired to determine if the water is acceptable for use before the main is put back into service. The Drinking Water Program received 23 requests for nonroutine sampling during 2002.

Analytical results of interest, exceedances, nitrate (required to be monitored annually) results, and lead/copper results in 2002 are presented in Tables 5-21 through 5-24, respectively, and are discussed in the following subsections. EBR-I, Gun Range, INTEC, Main Gate, PBF, TAN/CTF, and TRA were well below drinking water limits for all regulatory parameters and are, therefore, not discussed further in this report.

In addition to the listed parameters monitored in 2002, the M&O contractor also sampled for arsenic, lead, and copper. The MCL for arsenic is 10 µg/L. All M&O contractor water systems monitored were less than the reporting limit of 5 µg/L.

Lead and copper is required to be monitored once every three years for all INEEL water systems, except for the transient noncommunity water systems at the Gun Range, Main Gate, and EBR-I. The MCL is calculated by taking the two highest concentrations and averaging the results. All samples were below the MCL for lead (15 µg/L) and copper (1300 µg/L).

Central Facilities Area -The CFA water system serves approximately 850 people daily. Since the early 1950s, wastewater containing tritium was disposed to the SRPA at TRA and INTEC through injection wells and infiltration ponds. These wastewaters migrated south southwest and are the suspected source of tritium contamination in the CFA water supply wells. The practice of disposing of wastewater through injection wells has been discontinued for many years.

In 2002, water samples were collected quarterly from CFA #1 Well (at CFA-651), CFA #2 Well (at CFA-642), and CFA-1603 (point of entry to the distribution system) for compliance purposes. Since December 1991, the mean tritium concentration has been below the MCL at all three locations. In general, tritium concentrations in groundwater have been decreasing (Figure 5-3) because of changes in disposal rates, disposal techniques, recharge conditions, and radioactive decay.


Figure 5-3.  Tritium concentrations in two wells and two distribution systems at the INEEL (1992-2002).

 

CFA Worker Dose -Because of the potential impacts to downgradient workers at CFA from radionuclides in the SRPA, the potential effective dose equivalent from radioactivity in water was calculated. CFA was selected because tritium concentrations found in these wells were the highest of any drinking water wells. The 2002 calculation was based on

  • Mean tritium concentration for the CFA distribution system in 2002;

  • Water usage information for 2002 showing CFA #1 was used for approximately 50 percent of the drinking water and CFA #2 for 50 percent of the drinking water; and
  • Data from a 1990-1991 USGS study for iodine-129 (129) using the accelerator mass spectrographic analytical technique that indicated water from both CFA #1 and CFA #2 had measurable concentrations of 129. The average (four samples) concentration for 129 for the CFA distribution system was 0.28 ± 0.03 pCi/L for 2002. For perspective, the proposed EPA drinking water standard for 129 is 1 pCi/L.

For the 2002 dose calculation, the assumption was made that each worker's total water intake came from the CFA drinking water distribution system. This assumption overestimates the dose because workers typically consume only about half their total intake during working hours and typically work only 240 days rather than 365 days per year. The estimated effective dose equivalent to a worker from consuming all their drinking water at CFA during 2002 was 0.98 mrem (9.8 µSv), below the EPA standard of 4 mrem/yr for public drinking water systems.

Radioactive Waste Management Complex -Various solid and liquid radioactive and chemical wastes, including transuranic wastes, have been disposed at the RWMC. The RWMC contains pits, trenches, and vaults where radioactive and organic wastes were disposed below grade, as well as placed above grade on a large pad and covered. During an INEEL-wide characterization program conducted by USGS, carbon tetrachloride and other volatile organic compounds were detected in groundwater samples taken at the RWMC (Lewis and Jensen 1984). Review of waste disposal records indicated an estimated 334,630 L (88,400 gal) of organic chemical wastes (including carbon tetrachloride, trichloroethylene, tetrachloroethylene, toluene, benzene, 1,1,1 trichloroethane, and lubricating oil) were disposed at the RWMC before 1970. High vapor-phase concentrations (up to 2700 parts per million vapor phase) of volatile organic compounds were measured in the zone above the water table. Groundwater models predict that volatile organic compound concentrations will continue to increase in the groundwater at the RWMC.

The RWMC production well is located in WMF-603 and supplies all of the drinking water for over 300 people at the RWMC. The well was put into service in 1974. Water samples were collected at the wellhead and from the point of entry to the distribution system, which is the point of compliance, at WMF-604.

Since monitoring began at RWMC in 1988, there had been an upward trend in carbon tetrachloride concentrations until 1999 (Figure 5-4). Since 1999, carbon tetrachloride concentrations have remained fairly constant. In October 1995, the carbon tetrachloride concentrations increased to 5.48 µg/L at the well. This was the first time the concentrations exceeded the maximum contaminant level of 5.0 µg/L. However, the maximum contaminant level for carbon tetrachloride is based on a four-quarter average and applies to the distribution system. The distribution system is the point from which water is first consumed at RWMC and is the compliance point. Table 5-25 summarizes the carbon tetrachloride concentrations at the RWMC drinking water well and distribution system for 2002. The mean concentration at the well for 2002 was 4.3 µg/L, and the maximum concentration was 4.8 µg/L. The mean concentration at the distribution system was 2.88 µg/L, and the maximum concentration was 2.9 µg/L.


Figure 5-4.  Carbon Tetrachloride concentrations in the RWMC drinking water well and distribution system.
 

Table 5-25. Carbon tetrachloride concentrations in the RWMC drinking water well and distribution system (2002).

In addition to the carbon tetrachloride detections, total coliform bacteria were detected in the RWMC water system for the months of August and September. Through an onsite investigation, resampling, and inspection of the water system, it was determined that the coliform bacteria detection was caused by older water lines and stagnant water. Since that time, a temporary chlorination system has been installed, and no coliform bacteria have been detected. When funding is provided, a permanent chlorination system will be installed.

Test Area North/Technical Support Facility -In 1987, trichloroethylene was detected at both TSF #1 and #2 Wells, which supply drinking water to approximately 100 employees at Technical Support Facility (TSF) daily. The inactive TSF injection well (TSF-05) is believed to be the principal source of trichloroethylene contamination at the TSF. Bottled water was provided until 1988 when a sparger system (air stripping process) was installed in the water storage tank to volatilize the trichloroethylene to levels below the MCL.

During the third quarter of 1997, TSF #1 Well was taken offline, and TSF #2 Well was put online as the main supply well because the trichloroethylene concentration of TSF #2 had fallen below the MCL of 5.0 µg/L. Therefore, by using TSF #2 Well, no treatment (sparger air stripping system) is currently required. TSF #1 Well is used as a backup to TSF #2 Well. If TSF #1 Well must be used, the sparger system must be activated to treat the water.

Figure 5-5 illustrates the concentrations of trichloroethylene in both TSF wells and the distribution system from 1993 through 2002. Past distribution system sample exceedances are attributed to preventive maintenance activities interrupting operation of the sparger system.


Figure 5-5.  Trichloroethylene concentrations in TSF drinking water wells and distribution system (during 2002, sampling of Well #1 was not required).

Table 5-26 summarizes the trichloroethylene concentrations at TSF #2 Well and the distribution system. Regulations do not require sampling of TSF #2 Well; however, samples were collected to monitor trichloroethylene concentrations. The distribution system is the compliance point. TSF #1 Well was not sampled during 2002 because it was not required by the regulations. The mean concentration of trichloroethylene at the distribution system for 2002 was 1.30 µg/L, which is well below the MCL.

Table 5-26. Trichloroethylene concentrations at TSF #2 Well and distribution system (2002)

Back to top

Argonne National Laboratory-West

During 2002, ANL-W analyzed quarterly samples for gross alpha, gross beta, and tritium from the entrance to the drinking water distribution system in accordance with the Safe Drinking Water Act. Values for both gross alpha concentration and gross beta concentration were well below MCLs. No detectable concentrations of tritium were reported.

ANL-W collected a nitrate sample as required by regulation. Results were below the EPA MCL (Table 5-23). A single sample was also collected for all primary and secondary drinking water organic and inorganic contaminants, including arsenic, in preparation for the next nine-year cycle of monitoring. No constituents were above their respective MCLs. ANL-W also collected 20 samples for lead and copper analysis again as part of the next cycle of testing required under Idaho drinking water regulations. The average of the two highest copper concentrations was below the MCL. However, as in the past, the average of the two highest concentrations (51 µg/L) for lead were well above the MCL of 15 µg/L (Table 5-24). ANL-W also tested their system quarterly for coliform bacteria with no positive results for the year.

Naval Reactors Facility

Drinking water samples were collected at a point before entering the distribution system. The samples were drawn from a sampling port immediately downstream from the NRF water softening treatment system. The water was monitored for volatile organic compounds, inorganic constituents, and water quality parameters. Radionuclides were sampled at each wellhead.

Drinking water monitoring at NRF did not detect any volatile organic compounds above minimum detection levels. No gross alpha, gross beta, programmatic gamma-emitters, or strontium-90 (Sr) were measured in excess of natural background concentrations in 2002.

Tritium values were generally comparable to background concentrations and showed no increase over levels reported in 2001. For more information see the 2002 Environmental Report for the Naval Reactors Facility (Bechtel Bettis 2002).

Offsite Drinking Water Sampling

As part of the offsite monitoring performed by the ESER contractor, radiological analyses are performed on drinking water samples taken at offsite locations. In 2002, the ESER contractor collected a total of 30 drinking water samples from 14 offsite locations.

One drinking water sample collected in the fourth quarter of 2002 in Minidoka contained detectable levels of gross alpha activity (Table 5-27). The value (2.47 ± 0.76 pCi/L) is much lower than the EPA MCL of 15 pCi/L for drinking water.

As in years past, measurable gross beta activity was present in most offsite drinking water samples (26 of the 30 samples). Detectable concentrations ranged from 1.98 ± 0.94 to 8.74 ± 1.26 pCi/L (Table 5-27). The upper value of this range is below the EPA screening level for drinking water of 50 pCi/L. Concentrations in this range are normal and cannot be differentiated from the natural decay products of thorium and uranium that dissolve into water as the water passes through the basalt terrain of the Snake River Plain.

Tritium was measured in eight drinking water samples during 2002. Tritium concentrations ranged from 66.7 ± 30.1 to 349.9 ± 71.5 pCi/L, with the high result coming from Aberdeen (Table 5-27). The maximum level is still well below the DOE's DCG of 2.0 x 106 pCi/L and the EPA MC of 20,000 pCi/L for tritium in water.  Again, these levels can be explained by natural variability.

Back to top

5.5 Aquifer Studies

The SRPA, which underlies the Eastern Snake River Plain and the INEEL, serves as the primary source for drinking water and crop irrigation in the Upper Snake River Basin. A brief description of the hydrogeology of the INEEL and the movement of water in the SRPA is given in Chapter 1. Further information may be found in numerous publications of the USGS. Copies of these publications can be requested from the USGS INEEL Project Office at 208-526-2438. During 2002, the USGS published eight documents covering hydrogeologic conditions at the INEEL or on the Eastern Snake River Plain. The abstracts to each of these reports are presented in Appendix C.

Back to top

5.6 Radiological Groundwater Monitoring

Historic waste disposal practices have produced localized areas of radiochemical contamination in the SRPA beneath the INEEL. The INTEC facility used direct injection as a disposal method up to 1984. This wastewater contained high concentrations of both tritium and 90Sr. Injection at the INTEC was discontinued in 1984 and the injection well sealed in 1990. When direct injection ceased wastewater from INTEC was directed to a pair of shallow percolation ponds, where the water infiltrates into the subsurface. Disposal of low- and intermediate-level radioactive waste solutions to the percolation ponds ceased in 1993 with the installation of the Liquid Effluent Treatment and Disposal Facility (LET&D). TRA also discharged contaminated wastewater, but to a shallow percolation pond. The TRA pond was replaced in 1993 by a flexible plastic (hypalon) lined evaporative pond, which stopped the input of tritium to groundwater, and the new INTEC percolation ponds went into operation in August 2002.

The average combined rate of tritium wastewater disposal at the TRA and INTEC during 1952-1983 was 910 Ci/yr; during 1984-1991, 280 Ci/yr; and during 1992-1995, 107 Ci/yr. From 1952-1998, the INEEL disposed about 93 Ci of 90Sr at TRA and about 57 Ci at INTEC. Wastewater containing 90Sr was never directly discharged to the SRPA at TRA, but at INTEC a portion of the 90 was injected directly to the SRPA. From 1996 to 1998, the INEEL disposed about 0.03 Ci of 90 Sr to the INTEC infiltration ponds (Bartholomay et al. 2000).

Presently only 90Sr continues to be detected by the M&O contractor and the USGS at levels above the MCL value in some wells between INTEC and CFA.

U.S. Geological Survey

Tritium - Because tritium is equivalent in chemical behavior to hydrogen, a key component of water, it has formed the largest plume of any of the radiochemical pollutants. The configuration and extent of the tritium contamination area, based on the 1998 data, are shown in Figure 5-6 (Bartholomay et al. 2000). The area of contamination within the 0.5-pCi/L contour line decreased from about 103 km2 (40 mi 2) in 1991 to about 52 km2 (~20 mi2) in 1998.

Concentrations of tritium in the area of contamination have continued to decrease. The area of elevated concentrations near CFA likely represents water originating at INTEC some years earlier when larger amounts of tritium were disposed. This is further supported by the fact that there are no known sources of tritium contamination to groundwater at CFA.

Two monitoring wells downgradient of TRA (Well 65) and INTEC (Well 77) (see Figure 5-2) have continually shown the highest tritium concentrations in the aquifer over time. For this reason, these two wells are considered representative of maximum concentration trends in the rest of the aquifer. The average tritium concentration in Well 65 near TRA decreased from (1.30 ± 0.18) x 104 pCi/L in 2001 to (0.96 ±  0.11) x 104 pCi/L in 2002; the tritium concentration in Well 77 south of INTEC decreased from (1.38 ± 0.16) x 104 pCi/L in 2001 to (1.35 ± 0.14) x 104 pCi/L in 2002.

The EPA MCL for tritium in drinking water is 20,000 pCi/L. The values in both Well 65 and Well 77 have remained below this limit in recent years as a result of radioactive decay (tritium has a half-life of 12.3 years), a decrease in tritium disposal rates, and dilution within the SRPA.

Strontium-90 - The configuration and extent of 90Sr in groundwater, based on the latest published data, are shown in Figure 5-7 (Bartholomay et al. 2000). The contamination originates from INTEC as a remnant of the earlier injection of wastewater. No 90Sr in groundwater has been detected in the vicinity of TRA. All 90Sr at TRA was disposed to infiltration ponds in contrast to the direct injection that occurred at the INTEC. At TRA, 90Sr is retained in surficial sedimentary deposits, interbeds, and in the perched groundwater zones. The area of the 90Sr contamination from INTEC is approximately the same as it was in 1991.

Concentrations of 90Sr in wells have remained relatively constant since 1989. The concentration in Well 65 remained essentially unchanged between 2001 (0.95 ± 2.39 pCi/L) and 2002 (0.96 ± 0.11 pCi/L). Concentrations in Well 77 decreased from 2.00 ± 1.98 pCi/L in 2001 to1.35 ± 0.14 pCi/L in 2002. The MCL for 90Sr in drinking water is 8 pCi/L.

Before 1989, 90Sr concentrations had been decreasing because of changes in waste disposal practices, radioactive decay, diffusion, dispersion, and dilution from natural groundwater recharge. The relatively constant 90Sr concentrations in the wells sampled from 1992 to 1998 are thought to be due, in part, to a lack of recharge from the Big Lost River that would act to dilute the 90Sr. Also, an increase in the disposal of other chemicals into the INTEC percolation ponds may have changed the affinity of 90Sr on soil and rock surfaces, causing it to become more mobile (Bartholomay et al. 2000).