Rider 1 Well by Trail Ridge Middle School


The Rider 1 well is a single head gas well located 360 ft. north of Trail Ridge Middle School. In 2006, the property owner, Engle Homes, in the course of testing the property for home development, found that the ground water around the well was contaminated with toxic chemicals, among them benzene.

Benzene is a known carcinogen.The state water quality standard for safety for benzene in ground water is 5 micrograms per liter (μg/l). The standard was exceeded at two locations near the Rider 1 Well which measured 491 μg/l and 34.3 μg/l.

In 2009, nearly 2 years after the contamination was reported, TOP Operating, the well’s operator, erected a fence around the well because children had been playing on the equipment. At this point, despite being asked several times to clean up the site, nothing had been done. After eventually being found in violation and fined, they eventually performed a planned remediation. The remediation as of 2009 had not successfully brought the levels down to required standards. The latest testing of the site was in 2009, the levels of benzene in the ground water at two test locations were at 43 μg/l and 190 μg/l, still well above the standard allowed.

Below is a complete timeline of the correspondence between Engle Homes, TOP Operating and the COGCC.

Rider 1 Well Contamination Timeline

How it took TOP Operating Company and the Colorado Oil and Gas Conservation Commission two years to do anything about it, what was done, how (un)successful it was.

Information gathered from Colorado Oil and Gas Conservation Commission’s website http://cogcc.state.co.us

July 17, 2006
Engle Homes, the residential developer of the surface, submitted to the COGCC a complaint and a Phase II environmental report, which indicated contamination of soil and ground water by TOP Operating Company’s oil and gas operations. The state water quality standard for benzene in ground water is 5 micrograms per liter (μg/l).  The standard was exceeded at two locations near the Well (MW-2 and MW-3) which measured 491 μg/l and 34.3 μg/l, respectively.

July 21, 2006
COGCC sent a letter to TOP, requiring submittal of a Site Investigation and Remediation Work Plan.

August 17, 2006
TOP submitted an initial work plan which was not acceptable. (Click here to view pdf). Basically, it offers absolutely no remediation plan, merely explains how the contamination might have happened.

December 7, 2006
COGCC issued Notice of Alleged Violation (“NOAV") #200100371 (Click here to view pdf), to TOP for violation of the following Rules:

  • Failing to take precautions to prevent the unauthorized discharge or disposal of E&P waste
  • Conducting oil and gas operations that constitute a violation of water quality standards or classifications established by the Water Quality Control Commission (“WQCC") for waters of the state
  • Failing to investigate and clean up spills/releases as soon as practicable
  • Failing to remediate spills/releases to meet the allowable concentrations in Table 910-1 (Water Quality Control Commission standards for organics in ground water)
  •  Failing to manage E&P waste in accordance with Rule 907 (which requires operators to ensure that E&P waste is properly stored, handled, transported, treated, recycled or disposed to prevent threatened or actual significant adverse environmental impacts  or to the extent necessary to ensure compliance with the allowable concentrations and levels in Table 910-1, with consideration to WQCC ground water standards and classifications)
  • Failing to submit a Site Investigation and Remediation Workplan, Form 27

The NOAV required TOP to submit a Site Investigation and Remediation Work Plan  by December 22, 2006, to address the nature and extent and remediation of the E&P waste contamination in the vicinity of the Well.

December 10, 2006
TOP submitted a Remediation Work Plan which was satisfactory to COGCC. (Click here to view pdf).

December 15, 2006
COGCC approved the plan.

January 30, 2007
TOP submitted a letter to COGCC, indicating that weather conditions were causing a delay in the work and that TOP would commence work as soon as weather permitted.

December 2007 to early January 2008
Engle Homes began the process of selling the property and sought information from COGCC about the status of TOP’s remediation.  Engle Homes determined that TOP had not performed remediation work in 2007.

January 17, 2008
Engle Homes sent TOP a letter demanding immediate performance of the remediation work.  TOP replied on January 22, 2008 that it was reassessing the site to determine how to proceed.

January 28, 2008
Engle Homes complained to COGCC about TOP’s lack of responsiveness, lack of remediation of the site, and demanded that an enforcement action proceed.  On the same day, COGCC sent a letter to TOP demanding that it perform remediation within 45 days.

February 4, 2008
TOP responded, stating it would perform testing at one of the monitoring well sites (MW-2) and trenching at the other site.  (TOP was unable to sample MW-3, which could not be found, presumably due to destruction by mowing activities.)  TOP also committed to weekly updates on remediation activities.

February 20, 2008
TOP submitted water quality data from the sampled monitoring well (MW-2).  The water sample showed benzene at a concentration of 170 μg/l, still significantly higher than the 5 μg/l state standard.

February 22, 2008, and in March and April 2008
Engle Homes demanded that COGCC undertake enforcement against TOP for failure to comply with its remediation obligations.

March 7, 2008
TOP sent a letter to COGCC, seeking approval of a delay in performing the work until the end of the school year because of the proximity of the site to a school.  COGCC responded on March 21, 2008, agreeing to the delay if the work could not be done safely at the site. The letter also states that they put a fence up around the well because “children were coming over and playing on the tanks, etc.” Presumably, up until this point, there was no fence around the contaminated well site. (Click here to view pdf of letter.)

April 23, 2008
Engle Homes sent a demand letter to TOP to perform the remediation work within 30 days.  According to Engle Homes, TOP did not respond.

May 6, 2008
COGCC sent a letter to TOP demanding a written schedule for remediation activities and an update on the status of work.  TOP responded to COGCC on May 8, 2008, reporting that it had commenced trenching work at the site on April 25, 2008.  To this date, TOP had failed in its commitment to provide weekly updates or the written schedule for work required by COGCC (These are the COGCC words)

June 13, 2008
Engle Homes visited the site and determined that no active remediation activities were being performed and advised COGCC of TOP’s inactivity.

July 30, 2008
Cordilleran Compliance Services on behalf of TOP, conducted soil and groundwater sampling at the site.  On August 14, 2008, Cordilleran submitted a report to TOP, indicating that benzene concentration in the ground water at MW-2 monitoring well was 53 μg/l, still significantly higher than the 5 μg/l state standard but declining from the February 20, 2008 measurement of 170 μg/l.

September 22, 2008
COGCC finds that TOP failed to perform timely remediation and as a result, benzene continued to exceed allowable concentrations. COGCC fines top $10,000 for failure to remediate.

TOP retains Cordilleran Compliance Services to perform a subsurface investigation and install additional groundwater monitoring wells. Cordilleran recommends “conducting quarterly groundwater monitoring at the site to obtain data and assess remediation options for the groundwater at the site.” (Click here to view the Cordillaran report letter.)

Mar 30, 2009
The ground water monitoring wells were tested. Concentrations of benzene exceeding the maximum
allowable concentration were identified in a groundwater sample from two of the groundwater
monitoring wells (MW-2, 27μg/l and MW-4, 150μg/l), one of which also contained concentrations of toluene
exceeding the maximum allowable concentration (MW-4, 1,300 μg/l). (Click here to view the Top Operating Rider 1 2009 1st Quarter Report.)

July 1, 2009
The ground water monitoring wells were tested. The concentrations had gone up since the March report. Concentrations of benzene exceeding the maximum allowable concentration were identified in a groundwater sample from two of the groundwater monitoring wells (MW-2, 43 μg/l and MW-4, 190), one of which also contained concentrations of toluene exceeding the maximum allowable concentration (MW-4, 1,800 μg/l). Click here to view the Top Operating Rider 1 2009 July GW Report)

Additional reporting and testing have been done. Longmont ROAR will update this page soon.