© 2013 by Pyrethroid Working Group. All rights reserved. 1 

## Development and Validation of an Approach for Modeling Pyrethroid Residues in Urban Streams

Michael Winchell 1 , Scott Jackson 2

, Gary Mitchell 3

1. Stone Environmental, Inc.

2. BASF Corporation

3. FMC Corporation

EMPM, Crystal City, VA, March 19 th , 2013

Presented by Michael Winchell on Behalf of Pyrethroid Working Group member companies: AMVAC, Bayer, DuPont, FMC, Cheminova , Syngenta, Valent, BASF

3/19/2013 Slide2 

# Contents

 

## Background

 

## Conceptual Model

 

## Inputs and Parameterization

 

## Model Application and Results

 

## Summary and Conclusions

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved3 

# Background: Models for Predicting Urban Pesticide Concentrations

 Approaches for modeling urban pesticide fate and exposure have been reviewed and are still under development. ( Cheplick et. al., 2006)

 Pesticide Root Zone Model (PRZM): US EPA

 Field scale, agricultural model

 Strength in handling of pesticide fate/transport in soils

 Used in regulatory aquatic exposure assessments

 Storm Water Management Model (SWMM): US EPA

 Watershed scale, urban water quantity and quality model

 Strength in handling of sub

- hourly runoff and flow routing

 Not historically used in pesticide regulatory modeling

 This study examines the applicability of the SWMM model



### .

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved4 

# Background: Study Location

 Aliso Viejo, Orange County, CA

 Drainage area: ~ 66.7
acres

 307 homes

 Dwelling unit density: 4.6 units/acre.

 Watershed boundary delineated during multi

year 

### monitoring study. ( Haver , 2012a)

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved5 

# Background: Study Location, Street View

 Lawns and landscaping are well maintained (i.e., watered) in this high density neighborhood.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved6 

# Background: Monitoring Data

 A report to the CA State Water Resource Control Board contained 1 year of chemical monitoring data from the Aliso Viejo site. (Oki and Haver , 2011)

 Hourly flow data was collected at the watershed outfall. ( Haver

, 2012b)

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved7 

# Background: Chemical Monitoring Data

 31 chemical samples from both dry and storm periods were collected from 10/3/2007

– 10/01/2008 and published in the 2011 report.

 A representative pyrethroid with a high percentage of detections was selected for modeling.

 Dry weather samples typically had the highest concentrations

.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved8 

# Conceptual Model: Assumptions and Approach

 Assumptions for this model:

 Pyrethroids enter urban storm drains via runoff/washoff primarily from impervious treated surfaces and potentially from pervious treated surfaces during excessive rainfall events.

 Runoff from treated surfaces can occur as a results of natural rainfall, irrigation, or outdoor residential water use occurring on impervious and pervious treated surfaces.

 Landscape features in a residential setting can be differentiated based on: pyrethroid inputs, water inputs, and hydrologic response (i.e., infiltration rate ).

 Approach:

 Divide up the neighborhood into distinct landscape units based on unique combinations of these 3 differentiating characteristics.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved9 

# Conceptual Model: Residential Layout

 Most of the different landscape units in the development fall into one of the categories labeled on the image below

.

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# Conceptual Model: Spatial Representation

 The neighborhood was first spatially delineated into 15 landscape units.

 Units were then mathematically split to allow variable treatment timing.

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# Inputs and Parameterization: Pyrethroid Applications/Water Use

 Approach: Characterize pyrethroid use and water use based on recent literature and interviews with local experts

.

 Primary Sources:

 California 2009 Urban Pesticide Use Pattern Study, PWG and Meta Research Group, 2010.

 Darren Van Steenwyk , Technical Director, Clark Pest Control; personal communication, June 1, 2012.

 Survey of Residential Pesticide Use and Sales in the San Diego Creek Watershed of Orange County, California, C. A. Wilen

, 2001.

 John Horne, California Native Yards, specialist in residential and commercial native low

- water landscape designs, lives 1⁄4 mile from Aliso Viejo site; personal communication, June 6, 2012.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved12 

# Inputs and Parameterization: Water Use

 Pyrethroid concentrations observed during “dry weather” conditions were frequently higher than the concentrations during storm events

.

 Dry weather flows result from outdoor household water use

.

 Irrigation: Assumed to occur for all lawn and landscape areas

 Depth and duration varies throughout year; 0.20

– 0.35 in/day

 Time of Irrigation: 7:00 am

– 7:30 am

 Area over

- spray: 1 foot beyond lawn/landscape area onto i mpervious

 Car washing:

 50% of homeowners wash their cars at home once per month

 volume of water used when washing a car at home is 55 gallons

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved13 

# Inputs and Parameterization: Pyrethroid Applications

 Applications at max label rate, differentiated for: foundation perimeter, patios/walkways, driveways, lawns/landscaping.

 Different fractions of each landscape class treated always (once every 6 weeks), sometimes (once every 12 weeks), or
never.

 Landscape areas in 4 different sub

- catchment zones received different timing of application treatment sequences.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved14 

# Inputs and Parameterization: Impervious Washoff Results

 Data from a study of pyrethroid runoff from concrete surfaces was used to calibrate SWMM impervious surface washoff. (Jiang et al., 2012)

 Concentrations were well

- predicted at days 1 and 47, over

predicted at days 7 and 20, and under predicted at day 89.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved From Jiang et al. (2012)15 

# Inputs and Parameterization: Pervious Washoff Results

 A field study measuring pyrethroid runoff from irrigated turfgrass was used to calibrate SWMM pervious surface washoff

. (Hanzas et al., 2011)

 Runoff volume and pyrethroid mass were calibrated from 3
over

- irrigation events, spanning 1 to 5 days after application.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved Pyrethroid Mass Calibration16 

# Model Application: Daily Flow Simulation

 Mean daily flow is well

- simulated: NSE = 0.77; Volume Bias = +5%

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved  Rainfall input from the California Irrigation Management Information System (CIMIS) Irvine hourly weather station (9 miles away ).

 Surface runoff came ONLY from impervious surfaces.17 

# Model Application: Hourly Flow Simulation, Dry Period

 Daily flow variability is due to timing of irrigation on adjacent impervious surfaces and subsurface drainage from lawns into storm drains.

 Range and variability of daily flows is adequately represented.

 Difficult to model the observed behavior precisely but general pattern is captured.

 For 10/2007

– 9/2008:

 R

- squared = 0.70

 NSE = 0.55

Nov Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved18 

# Model Application: Hourly Flow Simulation, Storm Period

 The largest storm event occurred in January, 2008.

 Given that hourly rainfall data was from 9 miles away, the hourly flows during storm events were well simulated.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved 100% of simulated surface runoff is from impervious surfaces.19 

# Model Application : Comparison with Monitoring Data

 Simulated 15

- min concentrations were averaged over 6

- hr and 24

- hr periods. The maximum 6

- hr average was taken for each day.

 Observation grab samples taken between 7 am and 11 am.

 The short duration of irrigation runoff results in mean daily concentrations significantly lower than max 6

- hr values.

 Observations generally fall within the range of the simulated mean daily and max 6

- hr concentrations

.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved20 

# Model Application: Comparison with Monitoring Data, Storm Events

 The observed concentrations on 12/1/2007, 12/7/2007, 12/19/2007, and 1/5/2008 corresponded with storm events.

 In 3 of 4 events, the observed concentration fell in between the 6

- hr max and daily mean simulated concentration

.  Sampling time was typically in late morning, which agrees well with the simulated 7am

– 12pm concentration.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved21 

# Model Application: Simulation of Pyrethroid Application BMPs

 Current pyrethroid labels require treatment of horizontal impervious surfaces to be limited to “crack and crevice” applications.

 This was simulated by reducing all impervious surface application areas 20x.

 T he new label requirements lowered predicted outfall concentrations by a factor of 20, proportional to the treated area reduction.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved22 

# Model Application: SWMM

- AGRO 30

- Year Simulations

 A 30

- year time series of hourly precipitation for Aliso Viejo (Irvine/Long Beach) was developed to run SWMM and generate a 30

- year daily time series of pyrethroid loadings from the development

.

 The outfall pyrethroid loadings from SWMM were used as input to the standard farm pond simulated by the AGRO model.

 The AGRO model was parameterized as represented in the PA5 shell.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved23 

# Model Application: SWMM

- AGRO Ecological Risk Assessment

 The 30

- year SWMM

- AGRO model was run for both the “historical” and the “current” pyrethroid application practices

.

 A nnual maximum 96

- hr EECs in the pond water column were 10

– 20 times lower for the new label application practices compared to historical practices

.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved24 

# Summary and Conclusions

 SWMM proved to be a useful, and potentially accurate tool at predicting concentrations of urban applied pyrethroids

.

 Modeling pesticide fate and transport in an urban setting required:

 Discretization of the environment into distinct landscape areas

 Ability to route flows

 Operation on a sub

- hourly time step

 Accounting for pesticide fate and transport processes

 Recent adoption of BMPs have been shown to significantly reduce pyrethroid runoff in plot field studies (PWG Pathways ID) as well as when simulated at the watershed scale

.  Linking of SWMM with a receiving water body model (AGRO) can serve as a framework for exposure prediction in ecological risk assessments.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved25 

# THANK YOU

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved (Image from: archive.cityofdavis.org)26 

# References

 Cheplick , J.M., S. Dasgupta , A.M. Ritter, and W.M. Williams. 2006. Model Review and Scenario Development for Urban/Residential Pesticide Runoff Model. Prepared by Waterborne Environmental, Inc. for Crop Life America

.  Jiang, W., D. Haver , M. Rust, J. Gan . 2012. Runoff of pyrethroid insecticides from concrete surface following simulated and natural rainfalls. Water Research 36, 645

- 652

.  Hanzas, J. P., R. L. Jones, and J. W. White. 2011. Runoff Transport of Pyrethroids from a Residential Lawn in Central California. Journal of Environmental Quality 40:587

– 597

.  Haver , D. 2012a. Watershed Boundary for Aliso Viejo Subdivision. Personal Communication, Darren Haver , South Coast Research & Extension Center.

 Haver , D. 2012b. Hourly Flow Data for Aliso Viejo Subdivision. Personal Communication, Darren Haver , South Coast Research & Extension Center.

 Oki, L, and D. Haver . 2009. Pollutants In Runoff From Residential Sources. ACS National Meeting, Washington, D.C.

 Oki, L, and D. Haver . 2011. Evaluating Best Management Practices (BMPs) Effectiveness to Reduce Volumes of Runoff and Improve the Quality of Runoff from Urban Environments.

Mar 2013 Slide © 2013 by Pyrethroid Working Group. All rights reserved