20050732 Ver 11_Email_20111109

Strickland, Bev
From: Lucas, Annette
Sent: Wednesday, November 09, 2011 8:46 AM
To: Landry, Natalie
Cc: Strickland, Bev
Subject: 05-0732v11 Briar Chapel Middle School
Attachments: RE: Briar Chapel Middle School
Natalie,
To follow up on our phone conversation about this yesterday, I think there are a number of issues with this design:
The flow is slightly underestimated. By my calculations,the maximum flow out of the 3" pipe after the one-inch storm
should be about 0.5 cfs (as opposed to the 0.17 cfs stated in the Level Spreader Supplement Form). This would not be
very significant except for the other issue I see which is that the filter strip should have been characterized as wooded
rather than thick vegetation. By current standards, a wooded filter strip should not exceed 5%slope and it looks as
though this one may(the previous standard was 6%max slope for wooded filter strips). By current standards,the level
spreader should be 25 feet long rather than the 13 feet provided on this site.
I think the errors in design are magnified by the highly erodible soils on this site.
My recommendation would be to provide a level spreader with an engineered filter strip designed to the current
standards in Chapter 8. This will result in a 10-foot level spreader with 30 feet of engineered filter strip (graded and
sodded) downslope. Preferably the entire filter strip would be placed outside of the riparian buffer, but I think it would
be reasonable to allow the engineered filter strip to extend into Zone 2 if there were no practical alternative.
Please let me know if you have questions. I will be glad to speak or meet with the engineer if you think that would be
helpful.
Thanks,
Annette
From: Landry, Natalie
Sent: Monday, November 07, 2011 11:28 AM
To: Lucas, Annette
Subject: Briar Chapel Middle School
Hi Annette,
I was hoping you could help me out. The level spreader at Briar Chapel Middle School in Chatham County is not working
properly. It appears that too much water is discharging to the level spreader, overwhelming the device and eroding a
ditch and the stream bank below. I issued an NOV for sediment deposition in the stream resulting from the eroded ditch
and stream bank. They have since cleaned up the stream but the level spreader is not functioning properly. Do you
have any advice?
Thanks! Natalie
Natalie Landry
NCDWQ Raleigh Regional Office
3800 Barrett Drive
Raleigh, NC 27609
i

phone: [phone]
email: natalie.landry@ncdenr.�ov
2