More Stringent Controls On the Way
As summarized by the EPA, “This rule requires construction site owners and operators to implement a range of erosion and sediment control measures and pollution prevention practices to control pollutants and discharges from construction sites. In addition, the rule requires certain construction site owners and operators to sample stormwater discharges and comply with a numeric standard for the pollutant turbidity in these discharges.”
Turbidity from construction site runoff occurs when microscopic particles, or suspended solids, are introduced into the water source, giving it a cloudy appearance. Initially, the EPA set a number of 280 nephelometric turbidity units (NTUs) as the maximum limit for turbidity in discharges from a large construction site but, upon re-examination of available data, backed off that number as being too low. Federal guidelines will supersede those which some states may already have in place, ultimately leading to a national minimum standard.
Dr. Richard A. McLaughlin, a professor and extension specialist in the Department of Soil Science at North Carolina State University, said Effluent Limitations Guidelines are being implemented on schedule.
“The court ordered the EPA to either revise their turbidity requirement (280 NTU) or better support that number. The schedule depends on when each state has its Construction General Permit (CGP) renewed. Permits are renewed every five years on a staggered schedule. For some states, the ELG will be in place starting in August of this year,” said McLaughlin.
States needing to finalize their CGP before the effective date of the corrected numeric limit are being advised by the EPA to issue those permits without the numeric limit. They are also being asked to consider shortening their permit term in order to incorporate the corrected limit in less than five years. States that must propose their permit in advance of the effective date are being asked to follow an EPAapproved procedure that will allow them to include the corrected limit in their final permit.
McLaughlin identified three primary areas of concern with ELG.
The primary option is for companies to retrofit engines with exhaust emission control devices, of which there are three commonly used types: diesel oxidation catalyst (DOC), flow-through filters and diesel-particulate filters.
“Turbidity maximum in discharges is 99 percent of what most people are concerned about. Providing surface outlets for basins is a new requirement for most states [although] North Carolina has had it in place for four years now. [There must be] ground cover within 14 calendar days. States have a wide variation on this requirement, so this will create a minimum,” McLaughlin said.
Asked how the advent of ELG will directly impact the landscape sector, McLaughlin responded by saying that he conducts numerous workshops at North Carolina State’s Sediment and Erosion Control Research and Education Facility (SECREF) devoted specifically to answering that question. Workshops are limited to 30 attendees who receive both classroom and hands-on instruction. SECREF can have artificial rainfall events and turn loose muddy water as needed.
“Generally, stormwater discharges during construction have not been regulated in most states, but there had to be an erosion and sediment control plan in place that had to be followed. This included silt fence, diversion ditches, sediment traps and basins, etc., which were designed to trap only the heavy fraction of sediment,” said McLaughlin, referring to the larger particles that settle when water ponds.
The new guidelines address the control of finer fractions of suspended sediment. “This means that additional efforts will have to be included to reduce turbidity, mainly some form of chemical treatment to drop the fine fraction out.”
“This is old technology used for water treatment, but not widely applied for construction site runoff. There are many approaches and we cover those in our workshops,” McLaughlin said.
One erosion technique is the passive application of polyacrylamide (PAM). It is applied as a liquid, in combination with mulch and seeding via common erosion control equipment such as hydroseeders or hydromulchers. Research is under way to determine if PAM can be used successfully in conjunction with erosion control measures such as straw blankets and sediment basins. Another possibility worthy of consideration would be the addition of qualified professionals to oversee site drainage design and implementation throughout all phases of construction.
Under the new guidelines, it is clear that change will have to start with the bidding process and continue through site preparation and all phases of construction until project completion.
What should contractors do now so they will be fully prepared once the guidelines are in place? For lack of a better term, McLaughlin said companies should appoint a “Turbidity Commander,” who has the complete authority to install turbidity controls as a construction site develops, particularly right before expected storms.
“The first thing to do is to designate people to be in charge of meeting the new requirements and get them fully educated on the approaches available to meet the turbidity limit as well as their individual state requirements. A general contractor or grading contractor may want to look for a subcontractor who can handle this for them; this is a business opportunity for those interested in providing a ‘complete’ erosion, sediment, and turbidity control service,” McLaughlin said.
“The engineers and designers will have to incorporate turbidity control into their plans, but the people who install it will have to know how it works to be sure it is installed correctly. As the site develops, the grading contractor and the turbidity subcontractor, if there is one, have to constantly adjust the practices to be sure the runoff is being treated,” he said.
And, ELG isn’t the only rule contractors need to remain cognizant of. “Each state may have more stringent rules on construction site runoff, particularly in sensitive areas. These are under constant review and revision, so contractors need to keep up through their local and state erosion and sediment control programs,” McLaughlin noted.
In the final analysis, enhanced guidelines and cost-effective long term solutions to erosion and sediment control are clearly necessary.
Without them, a slippery slope awaits that nobody desires to negotiate.
...when it comes time to buy new equipment, it may well be time to consider the new generation of hybrid and electric equipment that has rolled out in the past year or two...
EPA emissions regulations calling for the 90 percent reduction in nitrous oxides (NOx), the gaseous pollutants formed during diesel combustion, continue to be phased in during a seven-year period that began in 2008. The construction industry is impacted at all levels, since the guidelines cover non-road machinery ranging from smaller commercial landscaping implements such as diesel lawn tractors to bulldozers, graders, backhoes and frontend loaders.
The EPA definition of the non-road engine is based on mobility/portability, and includes engines installed on self-propelled equipment; on equipment that is propelled while performing its function; or on equipment that is portable or transportable, as indicated by the presence of wheels, skids, carrying handles, dolly, trailer or platform.
While a significant step forward in pollution control, the full impact of these regulations may not be realized for another 15 to 20 years. Construction equipment is built to last for decades, and many older machines still have plenty of life left in them.
The primary option is for companies to retrofit engines with exhaust emission control devices, of which there are three commonly used types, diesel oxidation catalyst (DOC), flowthrough filters and diesel-particulate filters.
The diesel oxidation catalyst is the most commonly used of the three technologies, and can reduce carbon dioxide emissions by as much as 75 percent. A flowthrough filter has been shown to eliminate more particulate matter than a DOC, which has a range of CO emission reduction of 50 to 89 percent. A diesel-particulate filter has been demonstrated to cut particulate matter emissions by more than 85 percent.
EPA cost estimates for added emission controls were a modest one to three percent of total equipment cost. For example, bringing a bulldozer costing $300,000 into compliance would likely require no more than a $9,000 expenditure to retrofit with advanced emission controls.
Additional options include rebuilding and making routine upgrades on engines; using cleaner diesel fuels, biodiesels or emulsifiers; swapping out old engines for newer ones; and reducing or eliminating idling time on jobsites.
Finally, when it comes time to buy new equipment, it may well be time to consider the new generation of hybrid and electric equipment that has rolled out in the past year or two by Caterpillar, Komatsu, JCB, Hitachi and Volvo, among others.
Caterpillar’s D7E costs $600,000, or about 20 percent more than its conventional counterpart, and features a hybrid drive designed to reduce carbon emissions. It underwent more than 70,000 hours of lab and field tests before being deemed market ready. For an extra $50,000, it can be outfitted with a heated seat, GPS and autopilot blade controls. Komatsu’s hybrid excavator can cut fuel consumption by 25 to 40 percent. Volvo’s hybrid wheel loader checks in with a modest 10 percent fuel reduction.
Regardless of how contractors choose to bring their equipment into compliance, today’s smart investments yield future benefits for us all.