Pumping Station aids green project
The Delaware Solid Waste Authority (DWSA) is near completion of
an environmentally green project of constructing a landfill
phyto-cap (vegetative covering) over a landfill for the purpose
of treating leachate generated by rainwater and decomposition of
materials at the Solid Waste Management Center in
Sandtown,
Del.
The landfill location, known as Area A/B, generates an average
of 8,000 gallons of leachate each day. Before the project,
leachate was collected in storage tanks and taken periodically
by tanker to a treatment facility in Wilmington. Considered
wastewater due to its acidity and chemical makeup, authorities
cannot dump Leachate into streams because it is not of drinking
water quality.
When landfills near capacity, they are covered with either a geo
synthetic cap, or a natural earth cap depending on the age of
the landfill as mandated by the Environmental Protection Agency.
Given the age of this particular landfill, a natural cap,
technically known as a “phyto cap” was the answer utilizing an
environmentally friendly leachate treatment system that avoids
having to transport and store the waste.
The process treating the leachate consists first of a 3-cell vertical
Wetland Biofilter System that sits atop the phyto cap that
filters the leachate. The phyto cap is 25-acres in size and
consists of man-made wetlands and over 10,000 planted trees that
play a crucial role in the water recycling process. The treated
fluid from the Biofilter System will drain into an existing
storage pond, which is covered. From there the water is pumped
to irrigate the phyto cap’s trees and plant life. The plants
absorb this water and release uncontaminated water below the
roots.
Working
together with Engineer GeoSyntec of Portland, Contractor Tetra
tech EC, Inc., of Cranston, R.I., Metropolitan Industries, Inc.
of Romeoville, Ill., supplied a prefabricated housed irrigation
pump station that takes the treated leachate from the storage
pond and pumps it through an irrigation system that waters the
phyto cap’s trees and plant life.
The irrigation pump station was completely factory built at
Metropolitan's Romeoville plant requiring only water and power
connections once the station was delivered to the site.
Prefabricating the system in-house provided the added benefit of
having a controlled environment during manufacturing which saved
time and cut costs.
“A prefabricated system benefits the customer by eliminating the
headaches during scheduling, logistics and varying site
conditions. The result is a system delivered on-time because we
eliminate these problems up front,” says Metropolitan National
Sales Manager Mike Tierney who oversaw the sale of the
equipment.
The station includes a modular building; all pumps, motors, valves,
internal
piping,
electrical distribution equipment and a variable speed pump
control system.
The station was delivered with the intent that the irrigation
system supplier would provide an interface control panel to
coordinate the operation of the main pumps with the field
installed irrigation spray nozzles.
Metropolitan Industries installed a vacuum prime system on the two
vertical multi-stage pumps used in this system for their easy
accessibility for service and maintenance.
“Using the vacuum prime system put all equipment in one room on the
floor so, it is accessible. This benefit will be realized during
maintenance and repair work,” says Tierney.
The primer system used is a .6 hp vacuum pump, with a 30 gallon
vacuum storage tank, simplex control panel, (2) automatic air
release valves and a water level control switch.
The two vertical multi-stage pumps each rated 350 gallons per
minute (GPM), total system flow of 700 GPM @245’ total dynamic
head, pump the water from the storage pond through the
irrigation system and finally to the plants and vegetation.
A Metropolitan custom-designed variable-speed control panel controls the
entire system. It came complete with a touch screen interface,
logic controller and two variable speed drives each rated 30HP.
Variable speed systems are fast becoming the first choice for both
operating and design engineers due to the advantage of reduced
equipment maintenance costs, reduced energy costs, and variable
speed’s ability to maintain accurate pressure settings.
Variable speed water pressure systems use a transducer to sense
pressure and automatically adjust the speed of the pump in order
to maintain a constant discharge pressure regardless of demand
or flow. During off-peak usage, the pump system will sit idle
reducing energy consumption and pump wear and tear.
The prefabricated building was constructed of steel using a Sandex
finish and measured 18’ ½ long x 10’ W x 8’ 2’’ D. All equipment
was installed inside the building and was tested on
Metropolitan’s test lab and operational before delivery.
Another unique aspect of the prefabricated housed system was the
installation of a filtration system. This system removes any
small solids that remain in the water after treatment by the
Wetland Biofilter System. Using a unique backwash process, the
filter removes small solids that could clog the irrigation
sprinkler heads and prevent water from reaching areas of the
phyto cap’s plant life.
Other accessories inside the building included HVAC with
thermostatic control, indoor and outdoor lighting, a drain kit,
smoke alarm and a portable crane for moving the pumps.
Metropolitan Industries manufactures a variety of factory
pre-fabricated water and wastewater pump systems such as booster
systems, self-priming pump stations, submersible pumping
systems, above and below-grade sewage valve vaults, custom
control panels and more for the municipal, commercial and
industrial markets.
