United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-87/003 Apr. 1987
&EPA Project Summary
Use of Lined Pits for Disposal
of Dilute Pesticide Waste
George R. Bierman and Narinder P. S. Malik
Modern agricultural practices rely
heavily on the use of pesticides to sus-
tain high productivity. When pesticide
containers and application equipment
are rinsed after use, the contaminated
water requires proper disposal. At Iowa
State University in Ames, Iowa, dilute
pesticide rinsates have been placed in a
concrete-lined pit for more than ten
years. The pit contains alternating lay-
ers of gravel and soil. Water evaporates
from the pit surface while pesticide
chemicals are adsorbed on soil parti-
cles, destroyed by microorganisms or
broken down chemically. Monitoring
for atmospheric and ground-water con-
tamination at the pit site has indicated
no detectable release of pesticides to
the surrounding air or water. This type
of disposal facility may be appropriate
for pesticide users generating 10,000
gallons or less of dilute pesticide waste
annually.
This report includes a review of the
design criteria for lined pesticide pits
and descriptions of pits currently in use
around the nation. These facilities are
all similar with variations in use of soil
and gravel within the pit and the addi-
tion of high density polyethylene liners
to protect ground water from possible
leakage of pit contents. Guidelines for
proper siting and operation of the pit
are also given.
This Project Summary was devel-
oped by EPA's Hazardous Waste Engi-
neering Research Laboratory, Cincin-
nati, OH, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
The pesticide disposal facility on
which the full report is based was devel-
oped in the 1960s at the Horticulture De-
partment of Iowa State University in
Ames, Iowa. The system, called simply
a "pesticide disposal pit" by its develop-
ers, was created to provide a safe alter-
native to the practice of disposing of
waste pesticide solutions by indiscrimi-
nately dumping them on unused fields
or field fringes. The pits were intended
to be particularly useful to farmers who
generate relatively small quantities of
waste pesticide solutions at any given
time and for those who use a variety of
pesticides on different crops. A demon-
stration facility was built at Iowa State
University in 1970 and has been in con-
tinuous use since then. No major oper-
ating nor pollution problems have oc-
curred at the demonstration pit. A
detailed technical report on the Iowa
State Facility entitled Safe Disposal
Methods for Agricultural Pesticide
Wastes (No. PB 81-197584) is available
through the National Technical Informa-
tion Service.
The pesticide disposal pit represented
here is intended for use by individual
farmers and others who generate
10,000 gallons or less dilute pesticide
waste annually. Any pit will be subject
to all applicable federal, state and local
environmental laws and regulations. If
the user intends to dispose of pesticide
wastes that have been designated as
hazardous materials under the Re-
source Conservation and Recovery Act,
a permit to build and operate the pit
may be required. To assist in determin-
ing whether or not a permit is needed,
the state agencies responsible for haz-
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I
ardous waste management are listed in
Appendix A in the full report. Corre-
sponding federal organizations in re-
gional offices are listed in Appendix B.
Pit Design
In the late 1960s, the Department of
Horticulture at Iowa State University de-
veloped a concept for disposing waste
pesticide solutions. A facility based on
the concept was built in 1970 at the Uni-
versity's Horticulture Research Station
and has been in continuous use since
that time with satisfactory results. It is
essentially the Iowa State design for the
waste pesticide pit that is described
here, with some modifications from the
original. In addition, a few variations on
the design that have been developed
and used by others are included.
The Iowa State University
(ISU) Design
The ISU design is a rectangular, open-
top tank constructed of concrete and
partially filled with alternating layers of
heavy gravel and soil. See Figure 1. The
pit is about three feet deep and is set
into the ground so that only about the
upper six inches of the walls rise above
the surface of the ground. In operation,
waste pesticide solutions are loaded
into the pit to a depth of not more than
two inches over the top gravel layer.
The water evaporates and the pesticide
chemicals are destroyed by bacteria
and by photolytic action (depending on
exposure of the liquid to sunlight).
Variations On The ISU Design
Numerous interested parties have ob-
served the ISU pit and have reviewed
the design. A few have built essentially
identical pits. Others have built similar
pits but have introduced their own de-
sign concepts, some of which can prove
to be practical and useful.
At the University of Florida's Ft. Laud-
erdale Agricultural Research Station, for
example, variations have been intro-
duced in both construction, fill material,
and loading arrangement. The pit bot-
tom is of concrete, poured with a six-
inch curb. The walls are of concrete
block, built up to a height of 36 inches
above the top of the curb. The concrete
block walls require special attention for
positive sealing against leaks. This is ac-
complished by the application of hy-
draulic sealing materials and by an inte-
rior liner. The liner consists of two
layers of 8-mil black polyethylene. The
pit is filled to a depth of 24 inches with
alternating layers of gravel and soil.
A pit design variation that is a major
departure from the ISU concept, but is
also useful is one in which a layer of soil
is initially placed in the pit, then waste
pesticide solutions are fed into the pit
until a liquid depth of 18-24 inches
above the top of the soil layer is intro-
duced. In this concept, characterized by
pits used at the University of Florida's
Sanford Research Station and at the
Agway Corporation's Farm Research
Center at Tully, New York, pesticide
solids settling out of the solution will be
anaerobically degraded by microbial ac-
tivity in the soil layer, while the water
evaporates. Some photolytic degrada-
tion will also take place, depending on
exposure of the liquid to sunlight. Evap-
. orationj-ates are.likely.to be slowerJihan
in the ISU concept, because of the
greater liquid depth and its resultant
ability to absorb heat without increas-
ing the vaporization rate.
Other design features of these pits
would, be similar to those of the ISU-
style pits, but a principal difference is
found in the loading arrangements. In
the Sanford Research Station's pit, the
waste pesticide solutions simply run
into the pit through a pipe that pro-
trudes through one end-wall at a height
just above the highest anticipated liquid
level. At Agway, a U-shaped, perforated
Movable Roof
PVC pipe (with the "U" nearly the length
and width of the pit) is suspended some
15-18 inches above the liquid surface.
The waste solutions are pumped into
this suspended pipe and allowed to
drain into the pit, with good distribution
provided by the length and width of the
U-shaped pipe run.
Siting, Operation and
Maintenance
The location and maintenance of a
pesticide pit can affect the facility's effi-
ciency and length of useful service. If a
permit is required for the pit, stringent
requirements may be included for siting
and operating the pit. In the absence of
..permit requirements, .the following fac-
tors should be considered.
Locate Pit away from Wells
Locate Pit away from Residences
and Property Lines
Locate Pit away from Surface Water
Bodies
Expose Pit to Sunlight
Unrestricted Air Flow
Control Pit Liquid Level
Equipment Wash Racks - Control
Wash water Quantities
Record Pit Loadings
Monitor for Leaks
Sump
Samp/ing Riser
Longitudinal Cross Section
Sampling Riser -^ /- Sump
Roof Rails
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Transverse Cross Section
Figure 1. The Iowa State University pesticide waste disposal pit.
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George R. Bierman andNarinder P. S. Malik are with Engineering and Economics
Research. Inc.. Vienna. VA 22180.
Brian A. Westfall is the EPA Project Officer (see below).
The complete report, entitled "Use of Lined Pits for Disposal of Dilute Pesticide
Waste," (Order No. PB 87-145 926/AS; Cost: $11.95. subject to change)
will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Hazardous Waste Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/600/S2-87/003
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