HomeMy WebLinkAboutElement 9 BMP-C154BMP C154: Concrete Washout Area
Purpose Prevent or reduce the discharge of pollutants to stormwater from concrete
waste by conducting washout off-site, or performing on-site washout in a
designated area to prevent pollutants from entering surface waters or
ground water.
Conditions of Use Concrete washout area best management practices are implemented on
construction projects where:
Concrete is used as a construction material
It is not possible to dispose of all concrete wastewater and washout
off-site (ready mix plant, etc.).
Concrete trucks, pumpers, or other concrete coated equipment are
washed on-site.
Note: If less than 10 concrete trucks or pumpers need to be washed out
on-site, the washwater may be disposed of in a formed area awaiting
concrete or an upland disposal site where it will not contaminate
surface or ground water. The upland disposal site shall be at least 50
feet from sensitive areas such as storm drains, open ditches, or water
bodies, including wetlands.
Design and
Installation
Specifications
Implementation
The following steps will help reduce stormwater pollution from concrete
wastes:
Perform washout of concrete trucks at an approved off-site location or
in designated concrete washout areas only.
Do not wash out concrete trucks onto the ground, or into storm drains,
open ditches, streets, or streams.
Do not allow excess concrete to be dumped on-site, except in
designated concrete washout areas.
Concrete washout areas may be prefabricated concrete washout
containers, or self-installed structures (above-grade or below-grade).
Prefabricated containers are most resistant to damage and protect
against spills and leaks. Companies may offer delivery service and
provide regular maintenance and disposal of solid and liquid waste.
If self-installed concrete washout areas are used, below-grade
structures are preferred over above-grade structures because they are
less prone to spills and leaks.
Self-installed above-grade structures should only be used if excavation
is not practical.
Education
Discuss the concrete management techniques described in this BMP
with the ready-mix concrete supplier before any deliveries are made.
Educate employees and subcontractors on the concrete waste
management techniques described in this BMP.
Arrange for contractor’s superintendent or Certified Erosion and
Sediment Control Lead (CESCL) to oversee and enforce concrete
waste management procedures.
A sign should be installed adjacent to each temporary concrete
washout facility to inform concrete equipment operators to utilize the
proper facilities.
Contracts
Incorporate requirements for concrete waste management into concrete
supplier and subcontractor agreements.
Location and Placement
Locate washout area at least 50 feet from sensitive areas such as storm
drains, open ditches, or water bodies, including wetlands.
Allow convenient access for concrete trucks, preferably near the area
where the concrete is being poured.
If trucks need to leave a paved area to access washout, prevent track-
out with a pad of rock or quarry spalls (see BMP C105). These areas
should be far enough away from other construction traffic to reduce
the likelihood of accidental damage and spills.
The number of facilities you install should depend on the expected
demand for storage capacity.
On large sites with extensive concrete work, washouts should be
placed in multiple locations for ease of use by concrete truck drivers.
On-site Temporary Concrete Washout Facility, Transit Truck
Washout Procedures:
Temporary concrete washout facilities shall be located a minimum of
50 ft from sensitive areas including storm drain inlets, open drainage
facilities, and watercourses. See Figures 4.1.7 and 4.1.8.
Concrete washout facilities shall be constructed and maintained in
sufficient quantity and size to contain all liquid and concrete waste
generated by washout operations.
Washout of concrete trucks shall be performed in designated areas
only.
Concrete washout from concrete pumper bins can be washed into
concrete pumper trucks and discharged into designated washout area
or properly disposed of off-site.
Once concrete wastes are washed into the designated area and allowed
to harden, the concrete should be broken up, removed, and disposed of
per applicable solid waste regulations. Dispose of hardened concrete
on a regular basis.
Temporary Above-Grade Concrete Washout Facility
Temporary concrete washout facility (type above grade) should be
constructed as shown on the details below, with a recommended
minimum length and minimum width of 10 ft, but with sufficient
quantity and volume to contain all liquid and concrete waste
generated by washout operations.
Plastic lining material should be a minimum of 10 mil
polyethylene sheeting and should be free of holes, tears, or other
defects that compromise the impermeability of the material.
Temporary Below-Grade Concrete Washout Facility
Temporary concrete washout facilities (type below grade) should
be constructed as shown on the details below, with a recommended
minimum length and minimum width of 10 ft. The quantity and
volume should be sufficient to contain all liquid and concrete
waste generated by washout operations.
Lath and flagging should be commercial type.
Plastic lining material shall be a minimum of 10 mil polyethylene
sheeting and should be free of holes, tears, or other defects that
compromise the impermeability of the material.
Liner seams shall be installed in accordance with manufacturers’
recommendations.
Soil base shall be prepared free of rocks or other debris that may
cause tears or holes in the plastic lining material.
Maintenance
Standards
Inspection and Maintenance
Inspect and verify that concrete washout BMPs are in place prior to the
commencement of concrete work.
During periods of concrete work, inspect daily to verify continued
performance.
Check overall condition and performance.
Check remaining capacity (% full).
If using self-installed washout facilities, verify plastic liners are
intact and sidewalls are not damaged.
If using prefabricated containers, check for leaks.
Washout facilities shall be maintained to provide adequate holding
capacity with a minimum freeboard of 12 inches.
Washout facilities must be cleaned, or new facilities must be
constructed and ready for use once the washout is 75% full.
If the washout is nearing capacity, vacuum and dispose of the waste
material in an approved manner.
Do not discharge liquid or slurry to waterways, storm drains or
directly onto ground.
Do not use sanitary sewer without local approval.
Place a secure, non-collapsing, non-water collecting cover over the
concrete washout facility prior to predicted wet weather to prevent
accumulation and overflow of precipitation.
Remove and dispose of hardened concrete and return the structure
to a functional condition. Concrete may be reused on-site or hauled
away for disposal or recycling.
When you remove materials from the self-installed concrete washout,
build a new structure; or, if the previous structure is still intact, inspect
for signs of weakening or damage, and make any necessary repairs.
Re-line the structure with new plastic after each cleaning.
Removal of Temporary Concrete Washout Facilities
When temporary concrete washout facilities are no longer required for
the work, the hardened concrete, slurries and liquids shall be removed
and properly disposed of.
Materials used to construct temporary concrete washout facilities shall
be removed from the site of the work and disposed of or recycled.
Holes, depressions or other ground disturbance caused by the removal
of the temporary concrete washout facilities shall be backfilled,
repaired, and stabilized to prevent erosion.
Figure 4.1.7a – Concrete Washout Area
Figure 4.1.7b – Concrete Washout Area
Figure 4.1.8 – Prefabricated Concrete Washout Container w/Ramp