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' Report-Pilot Remedial System Test Page 25 Former Manna Pro Site Protect No 207 3 July 31,2000 ' located about 20 feet from the monitoring well, and it is assumed that the influence from the ORC has not yet migrated a sufficient distance to be observed in the well, MW-6 ' To calculate the total amount of oxygen available for removal, it is necessary to calculate the amount present in the ORC installed in ORC-1 According to information provided by Regenesis, ORC Technical Bulletin #21 2 Oxygen Releasing Compound, ORC Source Treatment Applications - Tank Excavations, it can be assumed that 1 pound of ORC will produce 0 1 pounds of free oxygen Therefore, it can be expected that a total of 30 pounds of oxygen (from 300 pounds of ORC) would be produced over the course of the life of the ORC material inserted into ORC-1 Another technical paper (ORC Technical Bulletin #11 1 Ox en Releasin Co+m and ORC Source Treatment .plications - Tank ExcavationJ, suggests that when there is a large percentage of contaminants or contaminant flux relative to the amount of ORC, the ORC will be released at a constant rate from the date installed to approximately 120 days after installation Therefore, at the time of the last oxygen reading during the pilot test (on June, 1, 2000), 32 days after the installation of the ORC, approximately 6 pounds (20%) of the oxygen from the installed ORC should have been released The most recent ' sampling event occurred on July 20, 2000, but to date, no measurable effect has been witnessed in MW-6 relative to the oxygen released from ORC-1 Assuming that the approximate beginning of the gasoline release was in the early- to mid- 1980's and that the greatest extent of groundwater contamination was measured in the early 1990's from MW-9, groundwater contamination has migrated an estimated 300 feet in approximately 10 years (approximate distance from tank pit to MW-9) This is most likely a conservative estimate in that some natural attenuation must have occurred and the ' earliest groundwater samples collected from the well (in 1993) had measurable levels of contamination This being the case, and discounting lateral dispersion, groundwater velocity(v) based upon this simple model of groundwater flow would be GW Velocity (v)(ft/day)= (distance from tank pit to MW-9)/(years x days/year) (v) = 300/10(365) (v)=0.08 feet/day Given this velocity, and assuming that ORC-1 is generally up-gradient from MW-6, it would be expected in a simple isotropic system, with no oxygen loss to oxygen sinks (such as hydrocarbons and dissolved iron in the groundwater), as well as no lateral dispersion, it can be expected that positive changes in oxygen levels can be measured in ' MW-6 in approximately 225 days from the installation of the ORC Clearly, however, this is a very crude and uncertain estimate ' 2937 Veneman Ave , #B240 Geo-Phase Environmental Inc Phone(209)569-0293 Modesto,CA 95356 Fax(209) 569-0295