Petroleum Sciences, Inc.
Report on field Inspection

October 19, 2001

Project # 4016-A

Re: Las Vegas Field Inspection, Test Strip for 405 Beltway Project

Introduction

The purpose of this field inspection was to check for the presence of Hydrogen Sulfide during the production of hot mix asphalt using SEAM.  A Drager MicroPac "Personal Gas Alarm" was used as the monitoring device.  This monitor has two pre-set alarms at 10 ppm and 20 ppm H2S.  The readings are given in units of 1, therefore the presence of Hydrogen Sulfide at less than 1 ppm would not be recorded.

Observations

On Wednesday, October 18, 2001 continuous monitoring of Hydrogen Sulfide gas was performed at both the plant and the job site but none was detected.  The Drager monitor was positioned on four occasions for about 30 seconds over the discharge chute within 1 - 2 inches of the hot mix flow and the display remained at 0 ppm.  At the onset of production a pile of hot mix was discharged for visual inspection by the plant operator.  The Drager monitor was placed with 1 inch of this hot mix and no reading above 0 ppm was obtained.  The monitor was also placed with 1 - 2 inches of mix sitting in the screed hopper on six occasions and the reading remained at 0 ppm.  The Drager monitor was held at a slight angle in contact with freshly laid hot mix on four occasions and no Hydrogen Sulfide was detected.  The Drager monitor was also placed in the downwind air stream, about one foot from the back of the paver, on several occasions and no Hydrogen Sulfide was detected.

In all there were at least twenty specific attempts to record the presence of Hydrogen Sulfide over a three hour period on this jobsite and the Drager monitor remained at 0 ppm during all attempts.

Respectfully submitted,

Kent Henderson, Manager HMA Lab Services