Evaluation and Reporting on Contaminant Hydrogeological

12-12-01

Conditions at the Tajiguas Landfill

Page 18 of 24

(97 Correspondence.tif, Image 17)

A July 21, 1997, semi-annual, winter/spring 1997, MONITORING AND

REPORTING PROGRAM NO. 93-69 report identified the following chemicals in the

GLCRS on March 18, 1997.

(1) cis-1,2--dichloroethylene @ 1.0 ug/1,

(2) 1,4-dichlorobenzene @ 1.3 ppb

and the following chemicals were identified in the GLCRS on June 23, 1997.

(1) cis-1,2-dichloroethylene @ 1.6 ppb

(2) 1,2-dichlorobenzene @ 0.64 ppb

(3) 1,4-dichlorobenzene @ 2.6 ppb

(4) chlorobenzene @ 1.0 ppb

(5) benzene @ 0.61 ppb

(6) MTBE @ 40 ppb

(7) trimethylsilanol @ 23 ppb

No verification as to what point sources of aforementioned contamination in

groundwater has been provided.

(97 Correspondence.tif, Image 18)

An October 8, 1997 County letter to the Regional board reports that the

September 15 & 16, 1997, third quarter sampling event, had the following

compounds identified in groundwater monitoring wells:

1)fluorotrimethylsilane in MW#3 @ 12 ppb, MW#14 @ 5.3 ppb and MW#15 @ 65

ppb

2) trimethylsilanol in MW#3 @ 17 ppb, MW#10 @ 150 ppb, MW#13@ 58 ppb and

MW#14@ 16 ppb

3) methoxytrimethylsilane in MW#l0 @ 9.1 ppb, MW#12 @ 5.1 ppb and MW#13 @