Heavy-duty porous asphalt and vortex
separators control stormwater
A reconstructed high-traffic,
lakeside road needed improved stormwater controls.
Installing heavy-duty porous asphalt
and vortex separators eliminated either captured pollutant-laden water or
separated out much of the contaminants.
four-lane wide, 1.6 km- (mile-) long stretch of Warren County’s Beach Road
located along the southern shore of Lake George in New York needed to be
reconstructed, it presented the opportunity to implement innovative and
protective measures to reduce the effects of polluted stormwater runoff. The
existing roadway originally drained directly to the lake, resulting in the
deposition of roadway contaminants such as salt, sediment, and the deleterious
particles that are attached to the sediment directly into the lake.
project is a major step in protecting the pristine nature and water quality of
the lake, which is of paramount importance to Warren County, Lake George, and
the nearby New York State Department of Environmental Conservation’s (NYSDEC)
Million Dollar Beach, a pair of favorite summer tourist destinations.
address this concern, Thomas Baird, project manager and chief engineer in the
Albany office of Barton & Loguidice (Syracuse, N.Y.), and his project team
designed a solution for the road surface and drainage involving a heavy-duty,
pervious pavement system coupled with conveyance relief areas and offsite
contamination protection systems.
porous pavement system was designed to capture and store 125 mm (5 in.) of rain
in a 24-hour period, and then allow the stormwater to infiltrate the subgrade
below. The relief areas would convey any excess runoff from larger storms that
may occur into a drainage network that discharges directly into Lake George.
design offered the best solution given the challenges of the project, which
included property acquisition restraints, continuous high traffic, the close
proximity to the lake, the flatness of the site, and the high potential for
treat the rest
a highway reconstruction project, the original project scope did not include
separate stormwater quality treatment structures in the relief areas, though
the project team recommended a more proactive and fail-safe approach for
improved runoff quality. Intersecting roadways that are paved with conventional
impervious pavement would generate sediment-laden runoff that could overburden
the pervious pavement in certain areas. In other areas, runoff from the
conventional pavement would not flow over any pervious pavement and would
instead be discharged directly into the lake without treatment.
with the many brands of stormwater treatment devices approved for use using
Federal Highway Administration, New York State Department of Transportation,
and Warren County funds, the design team had a particular vortex separator in
mind as a best fit for the project.
publicly bid projects using public funds carry requirements for competitive
opportunities. Once the project was out to public bid, the contractor selected
the Downstream Defender® based on the stringent requirements of the
project and what the project site demanded. This is the same choice the project
team had come to, so the design team approved the plan and the project
proceeded into the construction phase.
Downstream Defender is an advanced vortex separator, manufactured by Hydro
International (Portland, Maine) and designed to remove hydrocarbons, total
suspended solids, and their associated pollutants, such as metals, from
stormwater runoff. It is a low-headloss separator, making it a good fit for
this project due to the limited elevation in the drainage profile.
precast, offsite design and construction, and small footprint of the vortex
were key factors in it
being chosen — the site was limited in both space and elevation. The separators’
inlet/outlet configuration requires very little hydraulic drop and fit within
the overall drainage profile, and the round shape allowed more flexibility for
inlet/outlet pipe angle orientation.
units were installed in the first phase of the project — a 1.8-, 2.4-, and 3-m
(6-, 8-, and 10-ft) unit — each one size larger than what the NYSDEC design
standards required. (See figure, p. 84.)
design team elected to use one model size larger in the two smaller 1.8- and
2.4-m (6- and 8-ft) locations because they expected high concentrations of
sediment to be present in the off-site generated runoff, and the separator
systems discharge directly into the lake. With the larger units, there is
little concern that they would be overburdened between cleanings, which will
take place twice a year. The relative costs were minimal to achieve a
reasonable factor of safety in sediment storage and with that assurance also
came a higher water quality treatment rate.
Warren County, the project’s sponsor and lead agency, also
received funding from the New York State Environmental Facilities Corporation’s
Green Innovation Grant Program to support these green innovations, and to set
up a testing program to ensure actual results.
When the $7.5-million project is completed, Beach Road
will be the first heavy-traffic roadway in New York State paved with porous
asphalt. Beach Road will be under a 3-year monitoring program to measure runoff
volumes and quality of the discharge. The two additional units specified would
be installed along the porous pavement in a subsequent construction phase
should area rainfall amounts increase, if the area’s watershed significantly
increases the volume of stormwater runoff, or if the porous pavement is not
renewed or replaced at the end of its life cycle.
“The Beach Road project is a model for integrating green
and gray stormwater management techniques for a cost-effective, low-impact
design. This public–private initiative is raising the bar for projects in
sensitive areas, where satisfying the minimum is simply not enough,” Baird
treatment benefits Thailand sugar cane mill
: A sugar cane mill needed a wastewater treatment
: Install an anaerobic wastewater treatment system that
transforms wastes into energy.
Reusing wastes has produced many rewards for a sugar cane
mill located in Khon Kaen, Thailand. The United Farmer and Industry Co. Ltd.
(Chaiyaphum, Thailand) mill was commissioned to be built earlier this year. The
mill was designed for a capacity of 3500 m3/d containing 22,750 kg/d
chemical oxygen demand (COD).
Because sugar cane processing now uses less water than it
has in the past, the wastestream has an increased concentration of carbon. This
higher carbon content in the wastestream enabled the mill to use an anaerobic
system to produce biogas while its effluent volume decreased.
“We are now
getting toward the stage where instead of having a series of huge anaerobic and
aerobic lagoons impacting the environment, we can treat the effluent in contained
anaerobic reactors where biogas is extracted and influent wastewater is cleaned
of most of its impurities without release to the environment,” said Jean Pierre
Ombregt, CEO of Global Water Engineering (GWE; Bangkok). Large lagoons result
in odor, land use, and environmental leaching, he added.
After examining anaerobic systems, the mill installed
GWE’s anaerobic wastewater treatment system, the ANUBIXTM B reactor.
During the anaerobic biological treatment process,
bacteria break down organic material without oxygen. GWE’s system, a closed
reactor operating under regulated temperatures and specific process control
parameters, is designed to optimize waste consumption and gas generation during
the process. The reactor includes an influent screen, equalization, acidity
control, anaerobic treatment, biogas flare, and two-stage biogas sweetening
through the Bio-SulfurixTM followed by activated carbon filtration.
The medium- to high-loading rate upflow anaerobic sludge bed reactor is used at
the mill for most low- to medium-strength influent containing mainly soluble
The system, which can be installed at any facility with a
biological waste stream with high organic carbon or high COD of natural origin,
produces a high-quality effluent and biogas. The mill has achieved a minimum
85% removal of COD with loads reduced from 6500 mg/L to 975 mg/L COD.
“In addition to substantial environmental benefit ... the
United Farmers Plant achieves a supply of green energy that delivers energy
savings virtually in perpetuity,” Ombregt said.
1 ton of COD anaerobically digested generates 350 Nm3 of methane,
which equals approximately 312 L of fuel and can generate about 1300 kWh of
green electricity, according to Ombregt. At the mill, biogas production
currently is building to 9000 Nm3/d, 75% of which is methane. The
biogas is used to fuel several steam boilers.
Since installation, the factory has experienced permanent
and ongoing purchased fuel savings. Typical installations like this one produce
enough green energy to pay for the cost of installation in 1 to 2 years,
Ombregt said. In addition to wastewater treatment and cost savings, the
facility has reduced its carbon footprint.