MCPB TASK FORCE

C.M. Schofield, EPA Liaison

8325 Old Deer Trail

Raleigh, North Carolina  27615

Phone:  573-446-6451 Fax:  573 446-2960

Email:   HYPERLINK "mailto:dgminc@bellsouth.net"  dgminc@bellsouth.net 

February 6. 2009

Mr. James Parker

Special Review & Reregistration Division (7504P)

U.S. Environmental Protection Agency

Room S-4900, One Potomac Yard

2777 South Crystal Drive

Arlington, VA  22202-4501

 RE:	MCPB Data Call-In Response

	Terrestrial Field Dissipation Study

Data Requirement 835.6100

Dear Mr. Parker:

This letter is to request a change in the location of the MCPB
Terrestrial Field Dissipation study (guideline 835.6100) agreed to in a
12 March 2008 conference call with EPA.1  During that conference call
the counties of  either Renville, Brown or Olmsted, Minnesota were
identified as acceptable sites for the dissipation study.  While there
were no qualified research facilities in those counties capable of
conducting GLP studies, arrangements were made with a Paynesville, MN
based researcher to travel off-site to conduct the study in Renville
County.  These arrangements were not acceptable and as identified in a
24 September 2008 letter to you the study was terminated due to
contamination observed in samples collected at Day 0.  Subsequent to
this letter, a one-year extension to submit the data was granted until
March 6, 2010 as noted in a letter from EPA dated 14 October 2008.

In an attempt to avoid similar problems with the repeat study the MCPB
Task Force asked Grayson Research, LLC to identify appropriate
facilities capable of conducting the Terrestrial Field Dissipation
study.  Grayson Research advised us that based on their experience and
the lack of qualified cooperators in Minnesota for dissipation work we
should consider moving the study to another pea production area having
similar soils and growing conditions.  While they identified several GLP
research facilities in North Dakota, South Dakota and Wisconsin, the two
best suited for dissipation work were in Walworth and Dane Counties,
Wisconsin.  

Recent production statistics indicate Wisconsin is ranked third
nationally, behind Washington (#1) and Minnesota (#2), for green peas
grown for processing.  The pea growing areas of Wisconsin are
predominantly in the Central, East Centra1 and South Central areas of
the state with the relative rank of individual counties having more to
do with location of processing facilities than any cultural
characteristic.  While either research facility in Walworth or Dane
Counties could conduct the study, Grayson Research indicated that based
on their experience with the two cooperators they would recommend the
Walworth County facility.  

In order to further evaluate the Walworth County facility, we asked for
soil characterization information for comparison to the Renville County,
MN study site agreed to by EPA.  Soil characterization data from last
year’s trial shows a clay loam soil to 18” with 3.3%, 2.7% and 2% in
the 0-6, 6-12” and 12-18” depths, respectively.  The soil below the
18” depth was characterized as a clay soil.  Soil characterization
data from the proposed trial site in Walworth County, WI shows a loam
soil through 24” with 2.4%, 1.9% and 1.0% in the 0-6, 6-12” and
12-18” depths, respectively.  The soil below the 24” depth is a clay
loam soil.  According to the extension service in Wisconsin, the Radford
Silt Loam (NRCS soils map classification for the proposed trial site) is
typical of pea production in the area.  Various production guides for
commercial pea production in Wisconsin, North Dakota and Minnesota
indicate peas are well adapted to most soil types, with mid-range loamy
soils preferred over more sandy or clay soils, as the roots don’t 
penetrate deeply (sands don’t hold the water) and peas are sensitive
to waterlogged soils (clay soils).  The pH of the Walworth site is 6.6,
close to the optimal soil pH (5.5 – 6.5) for pea production.

Based on the evaluation of Grayson Research, we would propose changing
the site location from Renville County, MN to Walworth County, WI.  This
will allow us to work with a conscientious Field Investigator working on
a home facility in a commercial pea production area.  If this change in
the location of the study is acceptable, please advise me on or before
March 1, 2009 so we can make final arrangements with the field
cooperator.  If this is not acceptable, and EPA targeted other specific
characteristics in their site recommendations, please notify me as soon
as possible since we would have to identify an alternate site as quickly
as possible in order to make the March 6, 2010 submission deadline.

If you have questions or need further information, please contact me.

Sincerely,

C.M. Schofield

EPA Liaison

MCPB Task Force

CMS/ama

1 Parties participating in the conference call were James Parker, Kelly
White-Sherman, Jim Hetrick and Thy Nguyen for EPA with Mike Schofield
and Bill Mahlburg representing the MCPB Task Force.

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