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From: Jim Sisler
Date: 1/25/2002
Time: 11:18:24 AM
Remote Name: 129.82.108.32

Hi Frank, We found that coarse mass could usually be substituted, fine soil frequently substituted (but almost never missing), nitrate could be substituted on certain years, and carbons could occasionally be substituted. It is sulfate that can never be substituted across the board.

The exact story varies from site to site but the above is based on a detailed study of the sites in operation since 1988. We will shortly start examining the other sites to give specific guidance on those issues. Snoqualmie Pass will one of those sites. Until then to get the specific answer on when you could substitute you will have to follow the 10 set procedure in chapter 2 of the "Draft Guidance for Tracking Progress Under the Regional Haze Rule."

In the interim I recommend that you try substituting for coarse mass to see if that makes a difference. The next logical steps would be to test for nitrate substitution, and a combo with coarse mass and nitrate. The problem with the carbons is that when one is missing (EC or OC), then usually the other is missing then both have to be substituted which causes them to jointly fail the substitution requirements for dual substitution spelled out in the Draft Guidance