South Coast Air Quality Management District

REPORT: 

Report of Changes to Risk Assessment Procedures for Rules 1401 -New Source Review for Toxic Air Contaminants, and 212 - Standards for Approving Permits

SYNOPSIS: 

Risk Assessment Procedures for Rules 1401 and 212 is a dynamic document updated as risk values or procedures are revised pertaining to permitting under Rule 1401 and Rule 212. Recent sampling and analysis efforts associated with the rulemaking process for Proposed Amended Rule 1421 – Control of Perchloroethylene Emissions from Dry Cleaning Systems, has resulted in changes to screening values for risk associated with perc dry cleaning equipment. Staff presents this report to inform the Board of the implications associated with these changes.

COMMITTEE: 

Stationary Source, September 27, 2002, Discussed

RECOMMENDED ACTION:

Receive and file.

Barry R. Wallerstein, D.Env.
Executive Officer

Purpose

New information has become available during recent rule development efforts for Proposed Amended Rule 1421 – Control of Perchloroethylene Emissions from Dry Cleaning Systems, that will affect permitting under Rule 1401 regardless of the outcome of PAR 1421. The objective of this Board letter is to inform the Board and the public of changes to be made to the "Risk Assessment Procedures for Rules 1401 and 212." During the rule development process for PAR 1421, sampling and analysis of perc dry cleaning equipment was conducted. The results indicated that the perc emissions used in the risk assessment procedures are significantly understated. Changes are being made to the Risk Assessment Procedures to incorporate the new information independent of Rule 1421 proposed amendments. While the changes will affect permitting of Rule 1421 equipment, the extent of the impacts depends on the Board’s action regarding PAR 1421.

The Risk Assessment Procedures document has always been a dynamic document created by the Executive Officer for permitting purposes. It has historically not been part of a rulemaking procedure, but rather has been presented to the Board for notification purposes only, as is being done at this time.

If proposed amendments to Rule 1421 are approved by the Board, after January 1, 2003 new dry cleaning establishments and facilities adding machines would be required to install non-perc machines. If Rule 1421 is not amended, permit applications for such action are not likely, given the very low quantities of perc that would be allowed. Regardless of the outcome of PAR1421, cleaners operating without a permit would be affected by the technical update to the "Risk Assessment Procedures for Rules 1401 and 212."

Background

The "Risk Assessment Procedures for Rules 1401 and 212" is a dynamic document which assists permit applicants and engineers in evaluating Rule 1401 compliance for permitting. Rule 1401 – New Source Review for Toxic Air Contaminants applies to new, modified, and relocated sources and sets a risk limit of 10-in-one million for equipment with TBACT. The document provides explanations, sample calculations and the methodology to conduct basic risk assessments. Also contained in the document are screening values in look-up tables, which provide an applicant with an indication of Rule 1401 requirements and whether or not emissions from the equipment subject to permitting will need to be reduced. The look-up tables for dry cleaning tell a dry cleaner what amount of perc may be used without exceeding a risk of 10-in-one-million. These values are dependent on emissions, as well as a cleaner’s geographical location and the distance to the nearest commercial or residential receptor. Permit applicants can choose to perform site-specific modeling in lieu of screening analysis. However, Rule 1421 sources mostly use Table 1B screening levels.

Current permitting of perc dry cleaning equipment has been based on an estimate of 85% perc recycled and 15% emitted. This was based on limited data from a field test study (2 machines) contracted by the AQMD in May 2000. Staff recently conducted sampling and analysis on liquid sludge of twenty perc dry cleaning equipment to determine the percent of perc emitted to the atmosphere and that which is recycled. The results indicate the amount of perc emitted by equipment with primary and secondary controls averages 50% (currently used value is 15%). Thus, the screening levels established in the "Risk Assessment Procedures for Rules 1401 and 212" need to be adjusted to reflect the amount of perc being emitted.

Update of Risk Assessment Procedures for Rule 1401 and 212

Staff will revise the screening levels for perc dry cleaning equipment in the "Risk Assessment Procedures for Rule 1401 and 212" for dry cleaning equipment based on the assumption that 50% of perc used is emitted. This table will indicate the allowable perc usage depending on geographical location and the distance from the nearest commercial or residential receptors. The new allowable perc usage will be approximately 34% less than the existing allowable usage limits. The new revised allowable usage limits will be applicable to new, modified, or relocated perc dry cleaners with applications for permits to construct or permits to operate on or after January 1, 2003.

These numbers do not yet take into account additional changes that will be necessary. OEHHA has recently revised their methodology used in calculating cancer and non-cancer risks. According to OEHHA staff, the final documents may be released by the end of the year. Revised breathing rates may further reduce the numbers in the table by approximately 30%. However, other factors in the calculation are also under review and may offset this change. Nonetheless, based on staff’s review of the revised changes, it is likely that the screening levels will make it more difficult to permit new, modified, and relocated perc dry cleaning equipment.

Attachment

Table - 1B of Risk Assessment Procedures for Rule 1401 and 212 (Draft)

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