1 U. S. ENVIRONMENTAL PROTECTION AGENCY

Washington, D.C. 20460

OFFICE OF CHEMICAL

SAFETY AND

POLLUTION

PREVENTION

January 10 , 2012

PC Code: 061601

DP Barcode : D396402

MEMORANDUM

SUBJECT: Review of Jar Test Results for Drinking Water Assessment Purpose

FROM: James Lin, Environmental Engineer

Environmental Risk Branch 2

Environmental Fate and Effects Division (7507P)

TO: Mindy Ondish, Risk Manager Reviewer

Kable Davis, Risk Manager

Registration Divisio n (7505P)

THR OUGH : R

. David Jones, Senior Agronomist (Secondary Reviewer)

Brian Anderson, Chief

Environmental Risk Branch 2

Environmental Fate and Effects Division (7507P)

This memorandum presents the review of a non

- guideline supplemental mobility study (MRID

48659501) . The submitted study was conducted to evaluate the effects of traditional water

treatment processes on paraquat and to determine the mobility of paraquat through soil filtration

column. Th is memorandum only addresses the fi rst aspect o n the effects of using jar test s as a

mean to mimic traditional water treatment processes to determine whether the results of jar test s

are sufficient to provide the justification to refine the previous drinking water assessment.

Conclusion

14 C

- paraquat, spiked at ~30 ppb into the raw surface water samples from five representative US

CWS (community water supply) facilities, was effectively removed by a combination of typical2 water treatment processes conducted on a laboratory

- scale: the “labo ratory jar test” (coagulation

using alum with either lime or soda ash, flocculation and sedimentation), followed by duel media

filtration (anthracite atop o f filtering sand). The combination process was able to reduce the

level of 14 C

- paraquat to approximate or below the limit of detection of about 0.15μg/L (ppb).

The jar test results allow EFED to better characterize potential levels in finished water for

drinking water assessment purpose. The level of paraquat in the finish water of 0.15 μg/L

s hould be used for the drinking water assessment.

Study Summary

Raw water samples from five CWS facilities were used for the j ar t est. The five CWS are: (1)

Manatee County, Florida; (2) Wayne City, Illinois; (3) Sturgis Water Works, Kentucky; (4) Lake

Townsend, North Carolina; and (5) San Patricio PWS, Texas. Jar tests on these water samples

were conducted between August 18, 2004 and September 13, 2004 (start dates) . Before starting

the jar test, raw water samples were spiked with 14 C

- paraquat at ~30 ppb. The coagulants (soda

ash, lime, and/or alum) were simultaneously delivered into the replicate jar test beakers using a

series of disposable 3 or 10 cc size plasti c syringes. The jar tests were conducted inside a lab

without windows to reduce photolytic degradation. The steps are described below:

Jar Test Steps

1. Coagulation

– Alkalinity Adjustment (Mixing following addition of soda ash or lime)

Mixing following Alum Addition

Duration: 2 minutes; Speed (rpm): 300

2. Flocculation

Floc (precipitate) starts to form

Duration: 20 minutes; Speed (rpm): 60

3. Sedimentation

Floc settles to bottom

Duration: >60 minutes; Speed (rpm): 0

According to the study protocol, the laboratory study will use the “jar test” methods, which

include flocculation, coagulation and sedimentation. Filtration will be included only if the three

jar test steps do not adequately reduce the level of p araquat i n the spiked water.

Results

Based on jar test alone, the water samples from Illinois, Kentucky, and Texas show the

remaining paraquat contents are at about or below the detectable limit of 0.15 μg/L

. T he water samples from Florida and North Carolina show the remaining paraquat level of about

8 to 10%, w ith additional filtration, the level of paraquat is reduced to about or below the

detectable limit.