Jesse - 

The drainage areas were usually 1-2 acres for those basins, with some fluctuations as grading 

progressed. 

There are a number of reasons that the turbidity was not as well controlled on that site as has been the 

case for subsequent projects. First, we had just completed a series of tests under controlled conditions 

using the PAM logs and found great success, so we continued working with them for the most part. As 

we learned over time, they are not as "robust" as the more successful powder on wattle system we now 

promote. They tend to harden and become insoluble when exposed to sun and drying conditions, and 

often they get coated in sediment and debris. 

Second, as we also now know, without good cooperation from the contractors, there is little hope in 

achieving good turbidity control. In that situation, with miles of construction underway, this was quite 

evident in the behavior of different contractors we encountered on different sections. Sometimes they 

would bend over backwards to make adjustments in the plans to accommodate our systems, but mostly 

they ignored or even thwarted our efforts (not intentionally - they were just doing what they had always 

done or had to do to build the road). On this site, as with most we've been on, contractor cooperation 

was voluntary and usually deadlines and progress were more important than our project. 

And finally, since this site was about 3 hours away, it was not unusual for major "insults" to anything we 

set up to occur prior to storm events without our knowing, reducing or eliminating any effects of our 

Re: question on I-485 project 

Rich McLaughlin 

to: 

Jesse Pritts 

06/16/2011 01:32 PM 

Cc: 

'Melanie McCaleb', Scott King, "Jamie_Stansell@Ncsu. Edu" 

Hide Details 

From: Rich McLaughlin <sscram@ncsu.edu> 

To: Jesse Pritts/DC/USEPA/US@EPA 

Cc: 'Melanie McCaleb' <melanie.mccaleb@gmail.com>, Scott King <seking3@ncsu.edu>, 

"Jamie_Stansell@Ncsu. Edu" <jamie_stansell@ncsu.edu> 

Please respond to rich_mclaughlin@ncsu.edu 

History: This message has been replied to and forwarded. 

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systems. One of our most successful basins had great results while everything we installed remained 

intact, but as the grading operation took out parts of it (ditches, forebay, eventually even the skimmer 

outlet) the performance declined. 

As a result of our experience on that and many other sites, one of the key elements we emphasize in our 

training is maintaining control over the drainage system, because it is where most turbidity control will 

occur using PTS. This means that somebody has to have authority to quickly repair or replace areas that 

are impacted. If a utility line excavation cuts through a diversion ditch, that runoff needs to be directed 

into another treatment ditch. If a road cut diverts water from a treatment ditch, treatment has to be 

installed in the road or storm drain system. These are not difficult or particularly expensive to use, but it 

is a different way of thinking as you can no longer assume that as long as the runoff hits a silt fence or 

sediment basin, you are in compliance. Unless you are collecting all the water and using an active 

treatment system, which might be preferable to some developers or in some circumstances. 

Overall, the more control we have over the drainage system the better our results. The mountain road 

project was a good example because all the drainage was captured in a single ditch, so the PTS 

functioned almost perfectly throughout the monitoring period. Perhaps we could install and monitor 

PTS on the next EPA building project to show how well it works! 

I hope this helps. Let me know if you need more details. 

Rich 

On 6/15/11 4:47 PM, Pritts.Jesse@epamail.epa.gov wrote: 

Hi RichI have a couple of follow-up questions on this site and the data you 

collected. First, do you know generally what the drainage area of the 

basins were? I don't need the exact number for each of the six basins 

using PAM, but a general sense would be helpful. Second, in general the 

performance of the basins w/ PAM in terms of effluent turbidity was much 

lower (meaning higher turbidity in the treated discharge) than the other 

sites you've looked at. Can you offer any insights into the reasons why 

performance was generally not as good as the other sites evaluated? Is 

it just that this site was larger, with more intensive earthwork and/or 

more intense or larger storms, or was there some differences in the 

technologies employed at this site that gave poorer performance? Or, 

would you characterize the performance of the basins w/ PAM as being 

good, and is the higher effluent turbidity just a reflection of the 

capabilities of the technology? Any perspective you can offer would be 

helpful. 

ThanksJesse 

Jesse W. Pritts, P.E. 

U. S. Environmental Protection Agency 

Office of Water 

1200 Pennsylvania Ave. NW (4303T) 

Washington, DC 20460 

tel 202-566-1038 

fax 202-566-1053 

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www.epa.gov/waterscience

Courier/FedEx: 

1301 Constitution Ave., NW 

Room 6233AA EPA West 

Washington, DC 20004 

-- 

Richard A. McLaughlin, Ph.D. 

Professor/Extension Specialist 

Soil Science Department 

North Carolina State University 

100 Derieux Street 

Box 7619 

Raleigh, NC 27695-7619 

919-515-7306 

919-515-7494 fax 

919-215-5090 cell 

http://go.ncsu.edu/richmclaughlin web 

http://go.ncsu.edu/estcworkshops training 

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