20110891 Ver 1_Staff Comments_20120103

Lucas, Annette
From Lucas Annette
Sent Tuesday January 03 2012 12 29 PM
To Witherspoon Lauren
Cc Lucas Annette
Subject 11 0891 Cardinal Oaks SD — SW & DIFFUSE FLOW CONDITION
Attachments 11 0891 Cardinal Oaks SD — SW & DIFFUSE FLOW CONDITION docx
Lauren
I have looked over the Cardinal Oaks SD project and have seen their request for a conditional 401 for diffuse flow I have
attached a condition to this email
Thanks
Annette
Annette M Lucas PE
Environmental Engineer
NCDENR I DWQ I Wetlands and Stormwater Branch
1650 Mail Service Center Raleigh NC 27699 1650 (Mail)
512 N Salisbury St Raleigh NC 27604 1 9th Floor (Location & Parcels)
Phone [phone] Fax [phone] Email Annette Lucas@ncdenr gov
Website htty / /portal ncdenr org /web /wQ /swp /ws /401
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11 0891 Cardinal Oaks SD — SW & DIFFUSE FLOW CONDITION
AML comments
January 3 2012
1 Stormwater Management Plan (SMP) Approval Required
Please provide one copy of the approved SMP including plan details on full sized plan sheets
with proof of the City of Durham s approval The approved SMP must be submitted to the DWQ
WeBSCaPe Unit before any impacts authorized in this certification occur The following
requirements also apply
The approved SMP must be constructed and operational before any permanent building or
other structure is occupied at the site
The approved SMP as well as drainage patterns must be maintained in perpetuity
The SMP may not be modified without prior written authorization from the City of Durham
A copy of the approval letter and the modified SMP must be submitted to the DWQ
WeBSCaPe Unit prior to the commencement of the modifications
2 Diffuse Flow Plan Approval Required
Per the requirements of the Neuse Riparian Buffer Rule all stormwater drainage from this site
must be discharged through either a correctly designed level spreader or a BMP that provides
appropriate control of sediment and nutrients (a minimum of 30% removal of TN and TP) If the
stormwater management plan approved by the City of Durham per Item (1) above meets the
nutrient control requirement then no further action is required Otherwise please provide a level
spreader — vegetated filters strip (LS VFS) at each stormwater discharge point for review by the
DWQ The LS VFS must meet the design requirements in Chapter 8 of the North Carolina
Stormwater BMP Manual available at http / /portal ncdenr orXLweb/wg/ws/su/bmp manual
Please provide one Level Spreader Supplement Form for each proposed level spreader available
at http / /portal ncdenr org/web /wq /ws /su/bmp manual Please include the Required Items
checklist and all items listed therein The DWQ WeBSCaPe Unit must approve the diffuse flow
plan before any new stormwater conveyances are discharges through the protected Neuse
Riparian Buffer