Aspen Park Solvents

All POL/SITREP's for this site Aspen Park Solvents
Conifer, CO - EPA Region VIII
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Aspen Park Solvents - Removal Polrep

EPA Emergency Response

Region VIII

Subject: POLREP #11
Aspen Park Solvents
Conifer, CO
Latitude: 39.5414000 Longitude: -105.2936000

From: Pete Stevenson, OSC
Date: 1/7/2014
Reporting Period:

1. Introduction
  1.1 Background
Site Number: 08-6D    Contract Number:  
D.O. Number:      Action Memo Date: 8/22/1995
Response Authority: CERCLA    Response Type: Time-Critical
Response Lead:    Incident Category: Removal Action
NPL Status: Non NPL    Operable Unit:
Mobilization Date:      Start Date: 10/25/1994
Demob Date:      Completion Date:  
ERNS No.:    State Notification:
FPN#:    Reimbursable Account #:

1.1.1 Incident Category

Removal Action

1.1.2 Site Description Location

The Site is in a residential area called Aspen Park, which is in Jefferson County, Colorado, in the foothills of the Rocky Mountains. Description of Threat

In October of 1994 EPA found carbon tetrachloride (CCl4) at levels as high as 120,000 parts per billion (ppb) in residential wells.

1.1.3 Preliminary Removal Assessment/Removal Site Inspection Results

2. Current Activities
  2.1 Operations Section
    2.1.1 Narrative

On October 25, 1994, EPA initiated the Removal Action and began supplying bottled water to 33 residents.  A Treatability Study was conducted by EPA’s Emergency Response Team (ERT) to determine the best method of removing the CCl4, which ranged from 6 to 99,000 ppb.  Four air strippers and 29 carbon filters were installed on 33 homes.  A thorough investigation was conducted by EPA and contractors (TAT and REAC) in 1995 and 1996.  A source removal system was installed in March of 1997; it consisted of 4 pumping wells, 6 reinfiltration wells, a shallow tray air stripper system, and carbon polishing tanks.  The current system has 2 pumping wells feeding the air stripper and has treated over 22.2 million gallons of water as of July 18, 2012.  There are currently 29 residential carbon systems installed- 7 original systems were removed and 3 new systems were added, including 1 installed on a newly built house.  All 4 air stripper systems have been converted to carbon-only systems.

The carbon tet plume has diminished greatly in both size and concentration.  There are currently only three hot spots and the source area that show carbon tet concentrations > 5 ug/l. Plume maps for carbon tet over time have been prepared and are available on the website.

2.1.2 Response Actions to Date

The source area around Cornelius and Vosler Streets, where we are pumping and treating groundwater, continues to clean up slowly. We have pumped, treated and reinjected over 22.2 million gallons of contaminated water as of July 18, 2012.

The carbon absorption systems continue to work well. We found only three systems this year experiencing breakthrough of contaminant between the primary system and secondary carbon tank.

Compared to data from 2012, the average carbon tet concentration of all residential well samples decreased to 13.4 ug/L from 16.3 ug/L. After 18 years of treatment by individual home systems and 16 years of pumping and treating in the source area, the residential sampling results for carbon tet can be summarized as follows:

    4 homes at non-detect
    11 homes between 0 and 5 ug/L;
    7 homes between 5 and 11 ug/L;
    2 homes between 11 and 20 ug/L;
    3 homes between 21 and 49 ug/L;
    0 homes between 51 and 100 ug/L; and
    1 home greater than 100 ug/L, with the highest at 315 ug/L.

The three contaminant hot spots outside the source area are undergoing additional treatment with automatic sprinklers set up on tri-pods. These five systems are set to run daily for two to five hours during the heat of the day to see if additional contaminant reduction can be achieved. 

The air stripper developed a leak, and has gotten worse. It needs to be torn down and rebuilt. This is planned for January 2014.

2.1.3 Enforcement Activities, Identity of Potentially Responsible Parties (PRPs)

2.1.4 Progress Metrics

Waste Stream Medium Quantity Manifest # Treatment Disposal

  2.2 Planning Section
    2.2.1 Anticipated Activities Planned Response Activities Next Steps

Rebuild the air stripper due to water leaks.

Continue running system until the last well is below 100ug/l. Monitoring of the removal system and the affected homes should continue..

2.2.2 Issues

Carbon systems need monitoring, as they can slug contaminant at much higher concentrations into the homes once they saturate.  Homeowners may also disconnect the systems.  There is no one else willing to do this and pay for it.

Yearly sampling for plume monitoring should continue to verify continued downward trends in contaminant concentration.

  2.3 Logistics Section
    No information available at this time.

  2.4 Finance Section
    No information available at this time.

  2.5 Other Command Staff
    No information available at this time.

3. Participating Entities
  No information available at this time.

4. Personnel On Site
  One OSC.  Two ERRs as needed.  ERT assists with yearly sampling.

5. Definition of Terms
  No information available at this time.

6. Additional sources of information
  No information available at this time.

7. Situational Reference Materials
  No information available at this time.