April 26 2012 email from Tuyet-le Pham (SCAQMD) to LaWeeda Ward (EPA)

Nancy Levin to: Nancy Levin 01/03/2013 02:56 PM

----- Forwarded by Nancy Levin/R9/USEPA/US on 01/03/2013 02:54 PM -----

----- Forwarded by LaWeeda Ward/R9/USEPA/US on 11/26/2012 02:56 PM -----

From: Tuyet-le Pham <TPham@aqmd.gov>

To: LaWeeda Ward/R9/USEPA/US@EPA

Cc: Tracy Goss <TGoss@aqmd.gov>

Date: 04/26/2012 08:49 AM

Subject: Rule 1127 - Previous Inventory Methodology

LaWeeda:

We included VOC, ammonia, and PM10 in our original Rule 1127 baseline inventory; however, we did 

not claim PM10 emissions reduction in the SIP submittal as it was not a commitment in the 2003 AQMP. 

The main reason, I believe, was because VOC and ammonia emission factors were based on manure 

production and their emissions reductions were based on manure removal while it was not the case for 

PM10.

The assumptions and methodology for Rule 1127 emissions inventory and reductions can be found in 

the attached file (which is an excerpt from the 2004 Staff Report), but here is a summary:

Activity

· Actual headcounts from 1993 through 2002 (514,000 in 1993 and 394,000 in 2002)

· Assumption of 2% decrease in cows per year from 2002 through 2010 (based on data 

provided by the Milk Producer’s Council, which indicated the decline resulting from farm sales to 

residential developers)

Ammonia

Emission factor of 51 lbs/head/yr was used. This factor was converted to 0.005 ton NH3/ton manure 

(assuming 5.25 tons of manure per year for each milking cow). The conversion was necessary to 

estimate the emissions reduction that was based on the fate of manure. Please note that the 

conversions were different for heifers and calves (assuming 1.5 tons and 0.6 tons of manure per year 

for each heifer and calf, respectively)

VOC

Emission factor of 12.8 lbs/head/yr was used. This factor was converted to 0.002 ton VOC/ton manure 

for milking cow (assuming 5.25 tons of manure per year) and differently for heifers and calves

PM10

Emission factor of 1.78 lbs/head/yr was used and only milking cows were accounted (per ARB’s 

methodology)

Control Efficiency

Type of Disposal Practice % Control Removal Factor [0 Total % Control Effectiv
Effectiveness -1]

Land Application 23% 0.5 11.5%

Composting (open windrow) 75% 0.5 38.5%

Composting(enclosed) 95% 0.5 47.5%

Digester (plug and complete mix) 99% 1.0 100%

Manure: Sent out of Basin 100% 0.5 50%

The frequency of manure removal (required by Rule 1127) is an important factor of the control 

efficiency.

In October 2011, we revised the inventory by using the most recent headcounts provided by the 

waterboards and the most recent emission factors that accounted for enteric emissions. The summary 

of the emission estimates, as well as the assumptions, growth factors, control factors, and emission 

factors can be found from Appendix I of the following Technology Assessment:

http://www.aqmd.gov/hb/attachments/2011-2015/2011Oct/2011-Oct7-022.pdf

Please note that with recent research, particularly by UC Davis, emissions are now based on headcount, 

not tons of manure.

I hope this information is helpful. Please let me know if you have further questions.

Best,

Le

Temp - R1127 Emissions Inventory.doc