EPA Testing of Groundwater And Initial Results
Near 1-25 and Logan Street                                                         Denver, Colorado
Volume I, Issue I                                                                        January 2005
What Is EPA Doing?

The U.S. Environmental Protection Agency (EPA) began an environmental investigation in the area around Interstate 25 and Logan Street in Denver in the Fall of 2004. The primary purpose of the investigation is to determine if there is groundwater contamination under residential or commercial buildings and if it might pose any potential health risk to nearby residents. The contaminant of most interest is trichloroethylene (TCE), used mainly as a solvent to remove grease from metal parts. TCE can move from groundwater through soil and as a vapor, enter buildings, usually through cracks or openings in the foundation slab or a crawl space.

What Did EPA Find?

Initially, EPA sampled groundwater at locations along Mississippi at Lincoln, Sherman, and Grants Streets. TCE was not detected at these locations. In addition, EPA obtained information from the Colorado Department of Transportation (CD 01) regarding the location of de-watering wells in which ICE was detected during I-Rex construction. The wells were located east of Buchtel Street in what is now the lightrail corridor along 1-25.

Consequently, EPA did more groundwater sampling in that area. Sampling from 15 of 16 locations did not detect ICE. Sampling from one location (north of 1-25 and on the east side of Logan Street) detected ICE at a level of 910 micrograms per liter, which is above the established federal and State of Colorado drinking water standard of 5. EPA sampled again in this location at a more shallow depth and found no ICE contamination.

What Will EPA Do Next?

EPA will do additional sampling. We will sample at deeper depths at the location where the TCE was detected, and we will sample existing wells located on the U.S. Postal Service facility at Logan and Kentucky Streets.

All well locations and elevations will be surveyed to determine the direction of the groundwater flow. This information is needed to better under-stand the movement of the groundwater and will help us to track any contamination. Groundwater flow in this area is complicated. The retaining wall put in by CDOT, as part of its T-Rex construction, further complicates flow.

If we find contaminated groundwater at shallow depths under residential areas, we will conduct sampling in the home, as appropriate, to deter-mine if there are vapors directly underneath the foundation and if indoor air sampling is warranted.

Give Us A Call!

Steve Way                                                                                             Diane Sanelli
EPA Project Manager                                                                             EPA Community Involvement Coordinator
999 18th Street, Suite 300                                                                       999 18th Street, Suite 300 (80C)
Denver, Colorado 80202                                                                          Denver, Colorado 80202
303-312-6723                                                                                         303-312-7822
                                                                                                            Email: sanelli.diane@epa.gov
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EPA’s Ongoing Investigation of Groundwater: Second Round of Sampling Results
Volume I Issue 2
                                                                                                          March 2005
What Is EPA Doing?
The U.S. Environmental Protection Agency (EPA) began an environ-mental investigation in the area around Interstate 25 and Logan Street in Denver during the Fall of 2004. The specific area lies between Kentucky and Mississippi and a few blocks to the east and west of Logan Street.

The primary purpose of the investigation is to determine if there is ground-water contamination under residential or commercial buildings and if it might pose any potential health risk to nearby residents. The contaminant of most interest is trichloroethylene (TCE), used mainly as a solvent to re-move grease from metal parts. TCE can move from groundwater through soil and as a vapor enter buildings, usually through cracks or openings in the foundation slab or a crawl space.

What Did EPA Find?
Initially, EPA found that groundwater sampling from 15 of 16 locations did not detect TCE in the shallow water at approximately 33 feet. Subsequent sampling from deeper groundwater below a clay layer from one location (north of 1-25 and on the east side of Logan Street) detected TCE at a level of 910 micrograms per liter or parts per billion (ppb). EPA collected additional samples in that area in deeper wells at approximately 45 feet. Results show a high level of TCE (approximately 500 ppb) in one well. Al-though the groundwater is not used for drinking water, these levels are well above the established federal and State of Colorado drinking water standard of 5 ppb.

EPA then installed more deep wells both north and south of 1-25 to deter-mine the extent of the contamination and determine if any threat to residents may exist. A total of 27 wells, both shallow and deep, have been in-stalled, Of those, 3 deeper wells on Logan Street between Buchtel and Kentucky have shown TCE levels ranging from about 500 ppb to 1,000 ppb. The deeper wells east and west of Logan Street have shown only low levels from 3 ppb to 20 ppb.

What Did EPA Find? No Health Threat to Residents
In addition, a clay layer that exists in this area has been observed in all EPA wells. It separates the shallow from the deeper groundwater and appears to be acting as a barrier, keeping the contamination from migrating to the shallow groundwater. No significant groundwater contamination was found at more shallow depths.

Based on these sampling results, we do not believe that homeowners’ health and indoor air is being impacted by the groundwater contamina-tion present in this area.

What Will EPA Do Next?
EPA will continue to investigate the extent of the higher levels of TCE found along Logan Street. If we find contaminated groundwater at shallow depths under residential areas, we will conduct sampling in the home, as appropriate, to determine if there are vapors directly underneath the foundation and if indoor air sampling is warranted.


Give Us A Call!
Steve Way                                                                   Peggy Linn
EPA Project Manager                                                   EPA Community Involvement Coordinator
999 18th Street, Suite 300
Denver, Colorado 80202                                                999 18th Street, Suite 300 (80C)
303-312-6723                                                               Denver, Colorado 80202
                                                                                  303-312-6622
                                                                                  Email: linn.peggy@epa.gov
 

Colorado Department of Public Health and Environment


Trichloroethylene (TCE) Health Effects Fact Sheet       January 2005
 

Reducing Exposure to Trichloroethylene
Trichloroethylene (TCE) is one of a group of chemicals known as volatile organic compounds, which readily evaporate at room temperature. It is a chlorinated solvent that is of concern as an air pollutant, a water pollutant, and as a substance frequently present in ground water as the result of industrial operations. TCE is a non-flammable, colorless manufactured liquid with a somewhat sweet odor and a sweet, burning taste. It is used as an industrial cleaner in the automotive and metals industries. It also is found in many common consumer and household products. Prior to 1977, TCE was used as a surgical anesthetic, so the medical community has a substantial body of knowledge regarding the health effects of TCE exposure in adults.

How Could TCE Get Into My Home?
The presence of TCE in the home may be the result of historic disposal practices of industrial wastes, or it may come from other sources, such as household products that contain the chemical. TCE can enter a building when it has been discharged into the environment through spills and leaks that contaminate surface water, soil or ground water. It’s vapors quickly evaporate from surface water or surface soils in outdoor air, posing no danger. TCE vapors can move through the soil and into buildings, migrating through cracks in foundations, crawl spaces or air space around pipes. Indoor air tests conducted by specialists can determine whether occupants are being exposed to air-born TCE.

TCE is found in products including typewriter correction fluid, paint removers, paint strippers, gun cleaning fluid, cleaners for electronic equipment, rust removers, adhesive glues, spot removers, and other types of fluids. These products can emit TCE into the air during their use and even during common household storage. Exposure to TCE can be avoided by checking labels before purchasing products and determining whether a solvent-free alternative is available, or removing products that contain TCE from the home. The requirements for product labeling are not as stringent as those for food and drugs, so you may not find TCE as a listed chemical. Try to use products that might contain solvents out of doors when possible, or at least in a well ventilated area. Additional information on chemicals in household products can be found at the National Institute of Health’s Web site http://householdproducts.nlm.nih.gov/products.htm.

The primary ways people are exposed to TCE are through breathing or ingesting. However, if you are exposed to TCE, many factors will determine whether you will be harmed. These factors include the dose (how much), the duration of exposure (how long), and the pathway of exposure to TCE (breathing, ingestion, skin absorption). In addition, other factors that must be considered include exposure to other chemicals, age. gender, diet, lifestyle, general state of health, and sensitive populations.

Draft TCE Health Risk Assessment (EPA 2001)
EPA has recently completed a draft assessment of the health risks posed by TCE after reviewing the available data since 1989(EPA 2001 at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=23249).This health risk assessment is intended to replace a previous TCE health risk assessment conducted in the 1980s. The draft assessment has been formally reviewed by the EPA’s Science Advisory Board and had a public comment period. The EPA, with support from the National Academy of Sciences, will prepare a response to the Science Advisory Board comments. The draft health risk assessment indicates TCE poses a higher risk for sensitive populations than previously understood. In particular, the cancer toxicity values that define protective levels of exposure to TCE over a lifetime are significantly more conservative than the previous numbers. As a result, the Colorado Department Public Health and Environment has lowered its health screening and clean-up action guidelines for TCE.

Major Findings of EPA’s Draft Health Risk Assessment (EPA 2001)
• Cancer effects - EPA concludes that TCE is "highly likely” to cause cancer in humans. This cancer classification is supported by increased risks seen in TCE-exposed workers to various cancers, including cancer of the kidney, liver, lymphatic system, prostate and cervix. Additional support is provided by notable similarity between tumors in lab animals and in workers exposed to high levels of TCE.
• Noncancer effects - While noncancer effects of TCE exposure are unlikely, TCE can have a significant impact under certain conditions. It can affect the central nervous system, immune system, secretion system, organs such as the liver and kidney and fetus development. EPA has derived a reference concentration (RfC) of 40 micrograms per cubic meter of air (parts per billion per cubic meter), based on the critical effects in the central nervous system. liver and secretion system. A reference concentration is the concentration in air below which non-cancerous harmful effects are unlikely applied to lifetime (30 year) human environmental exposures, including to sensitive populations.
• Sensitive individuals - EPA predicts that sensitive individuals or populations may be more at risk to TCE exposures than an average individual. Sensitive individuals include infants and children, and those with certain diseases (e.g., diabetes), lifestyle factors (alcohol consumption), and higher exposures from other sources.
• Impacts of other exposures - Exposure to certain chemicals other than TCE were found to increase TCE toxicity, and vice-versa.
• Measuring cancer risks - While the link between long-term exposure to TCE and cancer appears strong, there are many uncertainties in the current ability to measure cancer risks to humans. EPA included a range of cancer probability in its draft assessment. At this time, using the most protective end of EPA’s cancer factor range is a reasonable choice to protect sensitive populations.

New Interim Policy for TCE Screening and Cleanup
Federal regulatory standards, called Maximum Contaminant Levels, have been established for TCE in water. Because there is no established national standard for TCE in air, the Colorado Department of Public Health and Environment in August 2004 established a new interim policy revising screening and clean-up levels for TCE. The state of Colorado uses a calculated risk-based level to determine when action may be taken to prevent residential exposure to TCE. The most protective end of the cancer factor range is based upon a residential exposure scenario in which a person theoretically is exposed to TCE for 24 hours-a-day, 350 days a year for 30 years (including 6 years of exposure as a child and 24 years as an adult).

The Colorado Department of Public Health and Environment’s interim policy is intended to provide guidance for risk management decisions at Colorado sites subject to the Department’s regulatory authority. Under the new interim policy, risk screening will use the most protective level of 0.016 micrograms/parts per billion per cubic meter of air and may involve indoor air testing. This screening level is based on a risk level of one additional cancer in 1,000,000 people. If TCE levels in a home range from 0.8 to 1.6 micrograms/parts per billion per cubic meter of air, the Colorado Department of Public Health and Environment intends to conduct further study to determine the source(s) of contamination and whether remediation will be required. Sources could include groundwater or emissions from household products. Due to the uncertainty associated with ongoing evaluation of TCE health risk assessment, the Colorado Department of Public Health and Environment will continue to use the standard of one additional cancer in 10,000 people as the maximum acceptable risk.

Remediation of TCE
If TCE levels meet or exceed 1.6 micrograms per cubic meter of air, and the levels are attributable to an environmental source, the party responsible for the contamination may be required to provide a ventilation system for the home. This involves the use of relatively simple fan and vent systems that draw air from beneath the building and prevent vapors from ever entering the structure. This is the same method used to effectively remove radon from buildings.


For More In formation About TCE:
Colorado Department of Public Health and Environment
Hazardous Materials and Waste Management Division
4300 Cherry Creek Drive South
Denver, CO 80246

Marion Galant                                                                   Cathy Schuster
Community Involvement Manager                                        Community Involvement Specialist
303-692-3304                                                                    303-692-3308
marion.galant@state.co.us                                                cathy.schuster@state.co.us
Redfield Site                                                                     Cherokee/Gates and Gates Sites

Walter Avramenko
Unit Leader
303-692-3362
walter.avramenko@state.co.us
 

   Methods of TCE cleanup being used at the Cherokee and Gates sites.
       1. Air Spurge & Vapor Extraction=bubble air into the bedrock and extract the vapor.
           Cherokee has extracted 700 pounds or 55 gallons of TCE using this method on their site.
       2. Molasses=supplies food for the biomass in the ground resulting in breakdown of TCE into "daughter products"
           which includes ethane and various chloride compounds (one being vinyl chloride)
           Cherokee is using this method offsite  to decontaminate the TCE plume extending  into the West Washington Park
           neighborhood via the ground water.
       3. Carbon Molecules infused with Iron Molecules=They fuse with the TCE and cause them the breakdown into "daughter
           products" (chloride compounds)
           Gates East is using this compound in 3 wells to test its effectiveness.
               Results: Well #MW7 which initially had 52,000 micrograms per liter TCE, now shows 100 micrograms per liter (as
                                 of March1)
                            Well #PZ02 which initially had 15,000 micrograms per liter TCE, now shows 20 micrograms per liter
                            Well #PZ01 which initially had 45,000 micrograms per liter TCE, now shows 15 micrograms per liter
                             The results look promising. This method will be used in more wells onsite if tests reveal that it is working.
       4. Potassium Permanganate=is an oxidation chemical used on the Cherokee site.
For more complete and authoritative information on the cleanup methods please see: Remediation Techniques

TCE was discovered by the Colorado Department of Transportation (CDOT) at Logan & Mississippi when they installed the tunnel under Mississippi to drain I-25 during storms. The latest tests show no TCE. There is speculation that because CDOT pumped  a million gallons of ground water each day during construction, that the TCE was sucked backward temporarily from the Gates East site.

Test wells drilled:  See maps below
   Cherokee has drilled 89 wells on and off the site.
   Gates East has drilled 23 wells and 50 "grab samples"...Well MW7 had 52,000 micrograms per liter TCE (5 micrograms per
      liter is the EPA liter is the EPA standard). Gates entered the Voluntary Cleanup Program on March 2nd.
   EPA drilled wells along Mississippi and on the postal property=TCE was non-detectable.
       A deep well at Kentucky and Pennsylvania showed TCE but at a depth that prevents vapor intrusion.
       An off site well to the East of Gates (in the area where I-25 and Logan meet) showed TCE.

We will post more complete information as we get it. If anyone has more comprehensive details or corrections, please share them with PPRC and we will share them with everyone.