2.0 METHODOLOGY

On October 18, 2005, Stewart Environmental met with local utility companies to identify existing onsite utilities. Identification of such locations is required prior to drilling.

On October 27 and 28, 2005, Stewart Environmental, with drilling assistance from Aspen
Environmental, advanced three soil borings (3-5, 3-6, and 3-7) and installed six monitoring wells
(MW-I through MW-6) in the vicinity of the previously identified contaminated B-I borehole.

Boring and well locations are shown on Figure 2.

Boring and well locations were established using a modified version of the 45-Degree “Step Out” Technique for sampling, allowing for the building adjacent to B-l. The six monitoring wells consisted of these nested pairs (MW-I and 2, MW-3 and 4, and MW-S and 6). Wells MW-I, MW- 3, and MW-S were installed to a depth of 6 feet below ground surface (bgs) and wells MW-2, MW-4, and MW-6 were installed to a depth of 16 feet bgs, the depth at which weathered bedrock was encountered. Drilling refusal occurred at approximately 19 feet bgs; solid bedrock appeared to be at 18.5 to 19 feet bgs.

The rationale for installing nested wells and at the previously referenced depths is as follows. Onsite groundwater is very shallow, approximately 3 feet bgs. The 6-foot deep monitoring wells were slotted from 2 feet to 5 feet bgs to collect potential contaminants with specific gravities less than that of water (floaters). The 16-foot wells were slotted from 14 feet to 16 feet bgs to collect potential contaminants with specific gravities greater than that of water (sinkers). Well logs indicate that a confining layer does not exist between groundwater surface and top of bedrock; soils consisted of clayey sands, sandy clays, and sand with gravel. Therefore, it is thought that a continuous water column   exists between approximately 3 feet bgs and bedrock depth and that more than one discreet aquifer does not exist at the site.

The three boreholes (3-5, B-6, and 13-7) were installed to delineate horizontal and vertical soil contamination as well as groundwater contamination. Drilling was completed with a Geoprobe rig, using standard U.S. Environmental Protection Agency (EPA) sampling and decontamination protocol. The three borings were advanced to approximately 19 feet bgs, the depth at which drill refusal occurred. Continuous soil cores were collected from the borings. The core samples were screened in the field for volatile vapors with a photoionization detector (PID). At Borings B-S and B-6, soil cores appeared clean; therefore, one soil sample was selected from each core at the approximate groundwater/soil interface depth. Boring B-7 was advanced near the known contaminated B-I Boring. B-7 soil samples were collected at two depths, one in the area of what appeared to be maximum contamination based on field screening and one at a depth below that where soils appeared clean. The purpose of collecting the lower sample was to delineate the vertical extent of contamination. One groundwater sample was collected from each boring. Samples were stored in an ice-filled cooler and delivered to Stewart Environmental’s laboratory under standard chain-of-custody protocol. Borehole soil and groundwater samples were collected on October 27, 2005, the day the boreholes were advanced.
The six monitoring wells were installed to delineate aerial extent of groundwater contamination. Groundwater samples were collected from the six monitoring wells on October 28, 2005, the day after the wells were installed. Standard EPA sampling and decontamination protocol were observed. Samples were stored in an ice-filled cooler and delivered to Stewart Environmental’s laboratory under standard chain-of-custody protocol.

3554-001(2) Site Characterization Investigation Page 2 of 8

Community Airpark Association, Inc.
Fort Collins, Colorado
Stewart Environmental Consultants Inc.