1 - the Envirostor

On Tuesday, October 6, 1987, the excavation activities started. The OVA
was calibrated using zero hydrocarbon air and methane at 6.7 ppm. Back-
ground was established outside the exclusion area and upwind of the site.
Background level was 1.0 ppm. During the majority of the day, the OVA did
not register any significant levels above background in the area of excava-
tion or the general yard. When the excavation started along the building
foundation, the employee providing dust suppression to the excavation
reported a strong odor. Excavation activities were stopped while OVA and
Draeger tube readings could be obtained.
OVA Vinyl Chloride
Concentration Imml Concentration (~oml
Foundation 2 5 6.0
Top of excavation pit None detected None detected
Based on the positive detector tube reading, it was determined that further
excavation would be continued with continuous reading being taken at the
top of the excavation pit near the backhoe operator. Due to the moist
soil, it was determined that dust suppression during excavation would be
discontinued. For the remainder of the day, the OVA reading at the top of
the excavation pit did not indicate any sustained levels above the
background level of 1.0 ppm. Instantaneous levels up to 1.4 ppm were
noted. The level of protection utilized was Level D with boots, tyveks,
gloves, and hard hats.
On Wednesday, October 7, 1987, the excavation activities continued. The
OVA was calibrated using zero hydrocarbon air and methane at 6.7 ppm.
Background was established outside the exclusion area and upwind of the
site. Background level was 1.5 ppm. Continuous OVA readings were taken at
the top of the excavation pit. The initial protection level for the back-
hoe operator was Level D with boots, tyveks, gloves, and hard hats. When
the OVA registered sustained levels of 1 ppm above background, in this
instance 2.5 ppm, a Draeger tube reading for vinyl chloride was taken. The