[USCC] runoff reduction

[William (Bill) Carter]

Our research does not directly address the question of assigning a modified CN for land treated with compost blankets as opposed to other treatments, but we did create regression lines representing the rainfall/runoff relationship for 3 treatments, including compost blankets. We used data from 16 storms over a 2-year period on replicated test plots of the following treatments: 2" compost/mulch blended blankets, hydromulch, and bare seeded soil, all at a quarry reclamation site with an 8:1 slope. The results are in figure 4.4 of our report at http://www.tceq.state.tx.us/compliance/monitoring/nps/projects/quarry.html. 

These compost blankets  do flatten out the regression line or "curve" by facilitating infiltration. Since they also have tremendous water-holding capacity, they also move the regression line's intersection with the X-axis significantly to the right. meaning that runoff did not even begin until around 7/10 of an inch of rain on average, as opposed to about 2/10 of an inch for hydromulch or bare soil.



P   Please consider whether it is necessary to print this e-mail
Bill Carter
Nonpoint Source Team    MC 203
Texas Commission on Environmental Quality
P.O. Box 13087
Austin, TX  78711-3087
Phone:  512-239-6771
Fax:  512-239-4410
wcarter at tceq.state.tx.us



>>> "Lindquist, Perry" <PLindquist at waukeshacounty.gov> 1/22/2009 10:03 AM >>>
Is the curve number you reference (55) a temporary affect? If so, how long does it last?

Perry Lindquist
Land Resources Manager
Waukesha County WI

-----Original Message-----
From: compost-bounces at mailman.cloudnet.com [mailto:compost-bounces at mailman.cloudnet.com] On Behalf Of Britt Faucette
Sent: Wednesday, January 21, 2009 9:50 PM
To: compost at mailman.cloudnet.com
Subject: Re: [USCC] runoff reduction

There are a few published studies on compost blankets that quantify their effect on runoff volume (among other storm water characteristics). These studies report rainfall and runoff amounts. If rainfall and runoff depth are known, you can calculate the runoff curve number (CN) based on the USDA-SCS TR55 methodology. Based on the values reported in these studies, an average CN of 55 has been determined for hydrologic soil group B.  This CN is similar to a public green space, 75% brush covered area, and a woodland according to CN book values provided by the USDA SCS TR55.

I am not sure I understand your question about obtaining credit for infiltration. Are you trying to calculate infiltration or rainfall absorption of a compost blanket?Dr. Britt Faucette, Ecologist, CPESC, LEED AP Director of Research & Technical Services Filtrexx International 551 East Lake Drive Decatur, GA 30030 ph: (678) 592 7094 www.filtrexx.com > From: sandy.syburg at whiteoakfarmorganics.com> To: compost at mailman.cloudnet.com> Date: Tue, 20 Jan 2009 14:48:58 -0600> Subject: [USCC] runoff reduction> > Are there any studies out there that prove there is a reduction in curve> number if a "green space" has a compost blanket rather than just mulch or> matting? If so what would that curve number be and also what kind of credit> can you get for infiltration.> > > Sandy Syburg> > > > White Oak Farm Premium Organics> > W360 N8515 Brown Street> > Oconomowoc, WI 53066> > > > > > Voice 920-355-4042> > Fax 920-355-4043> > > > email sandy.syburg at whiteoakfarmorganics.com> > web site www.w