Most
construction in most states is now subject to the provisions of the National
Pollutant Discharge Elimination System (NPDES). The initial phase involved sites
of 5 acres and greater, and Phase II, implemented in 2003, affects projects as
small as a single acre. The result is that in recent years, many more people
have had to become aware of erosion and sediment control issues and how to
effectively deal with them.
Sedimentation
occurs naturally, both on large and small scales. A single raindrop striking the
ground can cause tiny bits of soil to splash and move, and a sudden heavy
downpour can quickly produce a strong torrent of moving groundwater that
transports large amounts of soil.
According
to the Tennessee Department of Environment and Conservation (TDEC), the natural
geologic rate of soil erosion averages about 400 pounds per acre per year, which
is offset by a roughly equivalent amount of soil creation from the weathering of
bedrock and other natural material. However, construction activities can
increase soil loss exponentially, with major projects leading to as much as 150
to 200 tons of lost soil per acre.
An
astounding 5 tons is lost when one millimeter of soil is removed from 1 acre,
according to TDEC. Moving soil not only can carry off important nutrients needed
for revegetation after construction is complete, but also may necessitate
trucking in replacement soil. In addition, an assortment of potential
environmental hazards include:
- Metal and pesticide
pollutants sorbed to soil particles entering streams and
wetlands
- Siltation of aquatic
habitats
- Damage to sewers and
ditches
- Increased water treatment
costs for municipalities
To
combat these problems, a variety of solutions are available, from replacing lost
ground cover to a host of best management practices (BMPs), which can
significantly reduce sediment runoff.
Virginia
Road Realignment
Lewis
G. Manhart, environmental monitor for the Virginia Department of Transportation
(VDOT), describes a complex road improvement project that involved both
horizontal and vertical realignment. “Some sections went from two lanes to four
lanes,” he says, “with cuts and fills on the project. The road is the major
access to a mountain recreation resort with lots of
traffic.”
 |
| Photo: Todd Erickson,
EnerCrest |
Installing matting on Darby Mountain in Wyoming |
Water
volume and water velocity were two elements of concern with this project. “Water
volume we could not do much about. We had few or no options to reduce the volume
of water. We could affect water velocity and flow direction.” The solution that
Manhart used in this case was the Erosion Eel sediment control barrier from
Friendly Environment.
“We
used the Erosion Eels in three applications,” he explains, “for curb inlet
protection, ditch lines, and perimeter control. As inlet protection, we used it
to slow water velocity as it came to the curb inlet. Slowing the water resulted
in some ponding around the inlet out into the road way.” Not surprisingly, this
was a matter of concern to inspectors because of potential interference with
traffic.
Manhart
notes that some Erosion Eels have higher flow rates, which likely would have
minimized the ponding effect. He adds that they functioned well as sediment
control barriers. He also found them easy to install, maintain, and
remove.
“In
ditch lines, the Eels were used to reduce water velocity,” Manhart explains.
“Slowing the water allows sediment to settle out behind the Eels. Single Eels
worked well in small, short ditches when installed correctly. There must be a
good contact between the Eel and the soil surface to reduce the potential of
water running under the Eel. Stones and clods prevent good soil contact. Longer,
wider, and larger ditches required more Eels. In one case, we used multiple Eels
to create a large check dam. In a ditch line, when installed according to
manufacturer’s specifications, they worked well, were easy to install, easy to
maintain—just clean out the trapped sediment—and somewhat easy to move.” He
notes, though, that waterlogged Eels with trapped sediment can get quite
heavy.
For
perimeter control, Manhart primarily used a silt fence, but added Erosion Eels
to close gaps in the fence. Some gaps in the silt fence were intentional,
serving as temporary pass-throughs. “[Crews] pulled the Eels out of the way when
they needed to pass through and returned them when they were through working,”
he says. “In another case, some silt fence was torn up, and they used the Eels
for immediate replacement in short sections of perimeter control. Eels worked
well in both cases.”
Occasional
intense rainstorms resulted in additional maintenance of the Eels, but Manhart
notes that such storms are a problem for most erosion and sediment control
products.
Whereas
in some parts of the country regulatory inspection is a bit spotty, Manhart
says, “We have good and consistent inspection and monitoring. Most of our
projects are inspected and monitored regularly—weekly in most cases and more
frequently when rainstorms pass through. Most of our contractors are pretty good
at doing erosion control work needed after inspection and monitoring. Many needs
are identified and the work repair is scheduled based on the contractor’s
inspection. Contractors and inspectors are Virginia State erosion and sediment
control certified.”
He
adds, “All of our road projects require SWPPP [stormwater pollution prevention
plan] documents. The plans are followed, but they are modified as field
conditions unfold during the construction process. Plans are based on the
information available at the time they are prepared. During the actual
construction, field conditions are sometimes different. We make changes
regarding the erosion and sediment controls needed and used during the
construction process based on the actual field conditions. Sometimes we use
more, less, or different controls than what was specified in the initial plan
based on our actual field-conditions assessment. Plans are always the starting
point for erosion and sediment controls for the contractor, VDOT inspection
staff, and environmental monitors.
“Based
on my experience,” he continues, “all VDOT-approved controls work well when
installed according to manufacturer
specifications. All erosion controls
have problems during intense rain events. The heavier the rain event, the less
likely controls are going to work as planned and designed. VDOT does not
normally specify which controls a contractor must use, but controls used must be
approved for that application if a contractor wants to get paid. The contractor
can decide to use Eels, dikes, silt fence, filter barrier, or rock check dams
for ditch line controls. We can require contractors to replace controls if they
are not working.”
Fierce
Desert Winds
Jim
Anderson of BMP Solutions was recently involved with a pair of residential
construction projects, the Old Stone and the Seville communities in metropolitan
Phoenix. It may not rain often in the Arizona desert, but when it does, it can
come fast and furious.
“This
past January, we had two or three good rains, with about an inch and a half of
rain each time,” Anderson says. Strong winds sometimes occur as well. Anderson
prepared for both possibilities by combining the use of a silt fence with the
GatorGuard sediment control device.
He
chose a silt fence with a filter fabric and wire back. “This is as good as you
can get,” he explains. He spaces the posts about 8 feet apart and buries them 5
to 6 inches into the ground. Depending on need, he may use the silt fence
together with the GatorGuard. As he describes, “We’ve had winds up to 75 miles
per hour, and the fence will not blow out.”
Anderson
estimates that he has used more than 25,000 feet of the GatorGuard product. He
has found that it stands up well to the occasional rain soakings he encounters
and that trucks can drive over it without major problems. “It can take quite a
bit of abuse,” he notes.
Proper
sediment control is crucial, he explains, because in recent years, pollution
limits have been exceeded in Arizona. He notes that county and state regulators
have been stepping up to bring Arizona into compliance with federal laws, and
the EPA has been very strict when it comes to regulatory enforcement. As a
result, he says, he is seeing more and more BMP products used to comply with
SWPPPs.
For
Anderson, SWPPP plans are definitely not static. “It’s a living document—if ‘A’
doesn’t work, we go to ‘B,’ and if ‘B’ doesn’t work, we go to
‘C.’”
Surviving
a Tornado
Robb
Brown is the director of environmental services for Cornerstone Environmental
Services in Florida and works with a variety of residential construction
projects. “Like everyone, we use standard silt fence very regularly, and like
everyone, we realize that it is far from a perfect solution for every problem,”
he explains. “We have in the past suggested rock dams or rock pads as ways to
filter sediment from the runoff in areas where replacing silt fence over and
over is impractical.”
Brown
explains that a major issue he faces is what to “do in areas where traffic
volume is too high or the building site is too compact to keep vendors from
running over and ruining silt fence on a regular basis. In Florida, we also have
the problem of UV rays quickly deteriorating silt fence and high winds tearing
fence from the stakes.”
To
solve these problems, Brown turned to the SiltShield reinforced fence, which he
found has succeeded in addressing these issues. “We have used it at curbsides in
both single-family and multi-family building settings and have seen our
maintenance drop to minimal levels in those areas. Where silt fence may only
last a few minutes or a few days in high-traffic areas, SiltShield has been
holding up for a few months.”
An
interesting episode occurred in his first encounter with the product. “We did
our test run of SiltShield just a few days before a tornado hit the exact site
where we installed it,” Brown explains. “We went back to check on it, and there
were pieces of vinyl fence scattered all over the community. One of the homes
under construction had a block wall blow down. We spent a full day out there
repairing and/or replacing nearly every foot of silt fence. And the SiltShield
held up perfectly through all of that. I wish I had taken pictures. I was sold
before that, but really
sold after that!”
Regarding
other BMP solutions, Brown says, “Silt fence of course works well in certain
applications, but it has limitations. We have had success with filtering rock
bags and filter-sock-covered perforated PVC for ‘last stop before the inlet’
type protection. We have tested a couple of other inlet protection devices with
little success. We try not to get too caught up in the newest innovation,
because our experience has been that the price point changes significantly while
the effectiveness changes marginally, if at all—and sometimes not for the
better. After testing SiltShield, I can honestly say that it is the first
product that I have recommended to my clients as a new innovation product that
is so different it is worth the money. I showed it to one county inspector and
he loved it.”
Brown
notes that local regulatory inspection and enforcement is less than ideal.
“Enforcement in our area has been pretty lax in the past, but inspections have
significantly picked up recently. Florida’s enforcement strategy leaves
something to be desired, I think. It seems that only sites that file an NOI
[Notice of Intent] with the state experience any enforcement at all. Sites that
do not get the required permits tend to stay under the radar. It is ironic that
the sites that take at least some of the right steps are virtually penalized for
doing so, while companies who know about this are essentially incentivized to
disregard permitting obligations.
 |
Photo: Robb Brown, Cornerstone Environmental Services |
Testing a silt fence’s strength with a water truck |
“For
onsite enforcement, we have had very positive experiences,” he continues. “I
know of some fines levied by the state, but I don’t have any personal experience
with sites that I work with being fined or any other action [taken] other than
regulatory inspections. I think ‘inconsistent’ is probably the best way to
describe inspections and enforcement here. Some sites are closely watched,
others are never more than a name on a piece of paper. Not to mention that all
municipalities and counties either have their own regulations or their own
interpretations of the state regulations.”
He
adds, “SWPPPs are required for all projects in Florida that are over 1 acre, or
part of a larger common plan of development, and that have the potential to
discharge to any water of the state or MS4 [municipal separate storm sewer
system]. SWPPPs do need to be updated regularly as the project progresses. City
and county inspectors rarely, if ever, look for a SWPPP. State inspectors go
through them with a fine-tooth comb checking for all necessary documentation. I
think that inspectors from reputable companies doing weekly and after-rain
inspections see the SWPPP as the backbone of pollution control for the site and
take it seriously. State inspectors also take them seriously. Some of the
construction companies who need to implement the SWPPP on a day-to-day basis
surely see them as a formality, but I think even that is changing for the
better.”
Protecting
a Pristine Mountain Creek
In
the remote Wyoming Range, an oil and gas company needed to build a 1.7-mile
access road to reach its drilling site. Much of this road was to run parallel to
Fish Creek, a pristine trout stream in an area managed by the US Forest Service.
In some portions, the creek was only a few feet from the proposed
road.
EnerCrest,
in Big Piney, WY, was assigned the task of ensuring proper protection of the
creek during road construction. Chief operating officer Todd Erickson explains
that although the oil and gas industry has been exempted from federal stormwater
regulations, the states of Wyoming and Colorado passed legislation in 2005 to
“unexempt” this industry. The result, Erickson says, is that “Companies in this
field went from not having to comply at all to having to comply. Our company
fills that niche, assisting companies in proper
compliance.”
One
of the challenges the project faced was that much of the site was very steep. In
addition, the area receives perhaps 4 to 5 feet of snow in the winter, so when
it melts in the spring, this causes a significant amount of
runoff.
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Photo: Lew Manhart, Virginia DOT |
Erosion Eel used on a slope |
To
deal with these issues, EnerCrest utilized a combination of solutions. Working
ahead of the earthmoving equipment to protect the creek and surrounding
wetlands, it installed more than half a mile of silt fence, some by hand and
some with the use of a tommy Silt Fence Machine from Devon Distributing in Iowa.
Erickson explains that his company presently has four of these machines, with a
fifth on order.
Other
BMPs employed include matted slopes, utilizing cut and fill, hydromulching and
hydroseeding, and the SedimentSTOP biodegradable filtration system. In addition
to hundreds of straw bales used in conjunction with the silt fence, EnerCrest
also made use of riprap chutes, gabion baskets, retention ponds, and water
diversion channels to slow the flow of water and to reduce sediment
runoff.
Because
of the delicate nature of the environment in the area, Erickson says, “There was
a lot of scrutiny of our work, since we were essentially the project stewards.
We were watched very carefully, by both the US Forest Service and the Army Corps
of Engineers.”
Erickson
comments that the Wyoming Department of Environmental Quality has not always
closely enforced regulations, but he says that the Bureau of Land Management,
which is the surface rights owner in many areas, has been very diligent in the
area of enforcement. “They regulate all aspects of energy development, and they
have a high interest in seeing that erosion control is done properly. They have
the ability to withhold permits and to slow down the development process. You
have to prove that you’re a good actor.”
A
post-construction site tour demonstrated that the silt fence installed adjacent
to Fish Creek, in addition to the other control measures, had effectively
prevented sediment from entering the stream. Erickson proudly announces, “We’ve
changed the way people think about BMPs.”
On
Both Sides of the Regulatory Process
Jonathan
Hunt spent several years working as a government inspector for a local
conservation district in Pennsylvania. Such conservation districts have been
delegated by the state Department of Environmental Protection to act as agents
overseeing regulatory compliance.
Now,
Hunt finds himself on the other side of the desk, working as the business
development manager for erosion control products for River Valley Organics in
south-central Pennsylvania. His firm works with many new construction projects
that must put controls in place to prevent runoff.
 |
Photo: Jonathan Hunt, River Valley Organics |
A visible outline in the grass where the filter sock was moved due to rain |
One
recent project, which he termed a “linear” job, involved an extensive amount of
piping for a sanitary sewer. “It runs along a low-lying area,” he says, “where
no one wants to build, and it includes some wetlands.”
Hunt
explains that because of difficult weather and steep slopes, “the contractor was
struggling with silt counts, having difficulty keeping silt and sediment runoff
under control. I advised that they consider the use of Filtrexx FilterSoxx, and
the contractor elected to install around 4,500 feet. It very much impresses
me.”
On
the other hand, Hunt has a dim view of the traditional silt fence. “It is very
difficult to work with,” he says. “One regulator with over 16 years of
experience once told me that he had seen silt fence correctly installed
throughout a project just twice in his entire professional experience. When silt
fence fails—and it does—it fails dramatically with a ‘whoosh’ of sediment. I
joined River Valley after personal in-the-field experience with FilterSoxx,
because I wanted to promote a BMP that actually does work quite well and is
forgiving.”
He
explains that the product “works much better than a silt fence, because it lies
on the ground rather than standing up like a silt fence. It can handle up to 50%
more water flow than a silt fence. If a silt fence fails and goes flat, you can
have a sudden torrent of water and sediment flowing downhill, whereas a partial
failure of a FilterSoxx won’t cause nearly the same
damage.”
As
an example, Hunt related an incident at a retirement home construction project
in which an astounding 3.5 inches of rain fell overnight, the majority of it
over a brief 45-minute period. According to residents of the retirement home,
there was mulch coming in from the front door. The filter sock that had been
laid down was subjected to approximately 24 times its design limit, yet still
held reasonably well. A 56-foot-long section had its stakes pulled out, and the
sock had been pushed about 13 feet but was still essentially doing its job. Had
a silt fence been in place, Hunt is quite confident that it would have been flat
and useless.
Although
the product Hunt uses is not approved for NPDES control, he says that it has
been accepted for this purpose, and it is expected that when the next NPDES
manual comes out, the filter sock will be one of the approved BMPs. “It
performs,” he says emphatically, “and helps the contractor stay in compliance
much better than other products.”
He
does advise, though, that when placed for perimeter control, the product not be
driven over. “If this happens once, you can probably kick it back in shape and
it will be all right. You likely have not destroyed its integrity. But if it’s
driven over a second time, or if a vehicle spins its tires over the sock, then
there will be problems. Of course, if you drive over a silt fence, it’s over. If
you cause a small gash in a silt fence, it can become virtually useless, whereas
a small gash in the FilterSoxx, because it is three-dimensional, may not be a
problem at all.”
People
in his firm must attend training sessions annually to obtain and retain
certification to use the Filtrexx product, because it is sold only to certified
installers. Properly used, he claims, it traps up to 99.99% of all particulate
solids, and 50 to 75% of all suspended solids—“the goo that may not consist of
particulate matter, but turns a stream brown.”
Asked
about regulatory consistency, Hunt has quite a bit to say about his local
regulatory environment. “There are significant variations in regulatory methods
across Conservation District lines due to a variety of factors, including
district challenges and priorities, district personnel experience, training and
tenure, as well as personality, culture, and regulatory approach among district,
state, and individual personnel,” he acknowledges. “These things all lend
themselves to the perception of regulatory inconsistency. Another aspect of this
is due to the inherent nature of people and politics. In the mid-Atlantic area,
the tendency is the closer you get to the Chesapeake Bay, the higher the bar is
held. In the district where I worked, we were known for being ‘tight’ on
environmental regulations. At the same time, my observations are that different
approaches, even very diverse approaches, can be effective—or not!—in achieving
the environmental objectives. There is probably no single ‘correct’ approach,
although if you get five regulators in a room together, you might get six
‘correct’ approaches.”
Regarding
how carefully SWPPP documents are followed, Hunt says, “It depends. Wal-Mart has
a formal SWPPP project document requiring SWPPP training for all subcontractors
and daily inspection logs.” On the other hand, other projects he has encountered
get by with self-inspections just weekly and after significant
rainfall.
“When
I inspected projects without a formalized SWPPP document,” he recalls, “I
requested to see and flip through their maintenance log looking for date gaps.
If there were missing dates, they received two citations. One was for failure to
follow the plan and permit, and the second citation was for potential for
pollution.”
Hunt
adds, though, “most contractors try to do the right thing. If a project is
overwhelmed by an extreme storm event and runoff occurs, you’re not considered
out of compliance if you had a proper plan in place. Of course, you still have
to clean it up. But the contractors who try to get by without proper controls in
place can be shut down completely.”
Roadside
Ditch Runoff
Missouri
has a lot of miles in its highway system, and most of those highways are
accompanied by roadside ditches that require sediment runoff control. Countless
streams and rivers crisscross the state, and it is critical that these waters
remain free of silt and sediment buildup.
Part
of this task falls to Randy Stiers, vice president of operations for Wehmeyer
Farms. His choice of BMP is largely determined by the nature of the ditch he is
working on. For relatively shallow, flat ditches, he prefers the Triangular Silt
Dike, a 12-inch-high foam impediment to sediment runoff. “I think I use more of
this than anybody,” Stiers says.
He
says that the Missouri Department of Transportation (MODOT) has approved the
Triangular Silt Dike as a type II ditch check. More commonly, a ditch check dam
is composed of rocks placed 18 inches high and the width of the ditch, but
Stiers has found that the job can be accomplished more economically by lining a
ditch with several of the dikes. However, if a ditch is too steep, he’ll resort
to the rock check dam.
“The
Triangular Silt Dike has open ends,’ he says, “so it is possible to slip the
foam into the sleeves of the dike next to it—you can make this as long as you
want.” When appropriate, he’ll often use them as a long continuous barrier. At
Wal-Mart construction sites, he may combine enough of these dikes to create a
barrier as long as 100 to 200 feet. “These work much better than placing straw
or hay bales back to back,” he explains.
However,
when there is a tremendous amount of flow, Stiers has found that a silt fence
works better, because a standard silt fence stands 3 feet high. He rarely uses
the dikes on residential work, but has used “hundreds and hundreds” with MODOT
projects on ditch lines.
One
problem he has encountered with the dikes, however, is that with excessive rain,
they can come loose from the adjacent pieces. “In the case of a 3-inch rain, the
pieces will all blow out together,” Stiers says.
He
says matter-of-factly that MODOT doesn’t particularly care that a barrier fell
apart when it was constructed properly; they just want it to work. So Stiers had
to come up with a solution. “We used to zip-tie them together, but then we found
that these tended to freeze in the winter. Now, we use small hog rings and tie
the pieces together after slipping one dike inside another, and this has worked
well. It’s not part of any written maintenance policy, but it’s something we
came up with that works.”
Stiers
handles stormwater reports for all of his commercial and residential projects,
and this involves a weekly inspection and walk-through, checking all BMPs. In
addition, inspections are required after a significant rainfall. How much rain
triggers a required inspection that varies by county. In St. Louis County, an
inspection must be done after even a 0.25-inch rain, while in other surrounding
counties, a 0.5-inch requirement is more the norm. MODOT inspectors are careful
to sit in on each job to ensure proper installation and effectiveness, but
Stiers has found them to be reasonable in their expectations from contractors.