20060961 Ver 2_Stormwater Approval_20100831

P'l
AMA
NCDENR
North Carolina Department of Environment and Natural Resources
Division of Water Quality Dee Freeman
Beverly Eaves Perdue Coleen H. Sullins Secretary
Governor Director
August 31, 2010
DWQ # EXP 06-0961v2
Wake County
Ms. Patricia Hanchette
Lennar Carolinas, Inc.
1201 Edwards Mill Rd., Suite 301
Raleigh, NC 27607
Subject Property: 40/Wade - Lots 4 & 5 (Inside Wade Townhomes)
APPROVAL OF DIFFUSE FLOW PLAN
On August 7, 2006, the Division of Water Quality (DWQ) issued a 401 Water Quality Certification and
Neuse River Riparian Buffer Authorization for the subject project to place fill within or otherwise impact
0.032 acres of wetland, 314 linear feet of perennial stream, 37,904 square feet of protected Zone 1 Neuse
River basin riparian buffer and 26,470 square feet of protected Zone 2 Neuse River basin riparian buffer.
Condition 7 of the Certification and Authorization requires stormwater management plan (SMP) for each
phase of the entire project while Condition 8 requires all constructed stormwater conveyance outlets to be
directed and maintained as diffuse flow at non-erosive velocities through the protected stream buffers.
In an effort to meet the above-stated conditions for SW and diffuse flow provisions, on August 30, 2010,
the 401 Oversight/ Express Review Permitting Unit of the DWQ received your SMP application dated
August 6, 2010 along with supporting design calculations, plan sheets and signed and notarized Riparian
Buffer-Level Spreader Operation and Maintenance (O & M) agreement for review and approval. The
DWQ has reviewed the application and supporting documents and approves the level spreader device to
meet the diffuse flow provision.
This approval is for the purpose and design that you described in your application. If you change your
project, you must notify us and you may be required to send us a new application. If the property (or a lot
on the property) is sold, the new owner must be given a copy of this approval letter and is thereby
responsible for complying with all conditions. This approval requires you to follow the conditions
listed in the Water Quality Certification and Neuse River Riparian Buffer Authorization issued for
the project and the following additional conditions listed below.
Additional Conditions:
1. Stormwater Management Plan:
a. The proposed wet detention pond discharging to the level spreader-riparian buffer system shall
be designed to meet 90% TSS removal as described in your application. The wet pond shall be
approved by the DWQ or the City of Raleigh prior to any impacts in this phase of the project
occurring.
401 Oversight/Express Review Permitting Unit One
NorthCarolina
1650 Mail Service Center, Raleigh, North Carolina 27699-1650 Natumllff
Location: 2321 Crabtree Blvd., Raleigh, North Carolina 27604
Phone: [phone] FAX: [phone]
Internet: http://h2o.enr.state.nc.us/ncwetlands/
An Equal Opportunity 1 Affirmative Action Employer
40/Wade-Lots 4 & 5 (Inside Wade Townhomes)
Wake
Page 2 of 2
August 31, 2010
b. If the wet detention pond design information submitted with your application is approved by the
City of Raleigh without any changes, then you are required to submit an approval letter from the
City along with a notarized operation and maintenance agreement for the wet detention pond.
c. If there are any changes required by the City of Raleigh in the design information for the wet
detention pond, you must submit the City's approval letter along with the complete stormwater
management information including the design calculations, plan sheets as well as the operation
and maintenance agreement for the proposed wet detention pond.
2. Diffuse Flow Plan:
All stormwater shall be directed as diffuse flow at non-erosive velocities through the protected stream
buffers and will not re-concentrate before discharging into the stream as identified within Neuse
River basin Buffer Rule 15A NCAC 2B .0233(5).
In an effort to comply with the diffuse flow provisions of the Buffer Rule you have provided the
DWQ with SMP (sheet #s PD-1 to PD-5 with revision date August 24, 2010) having a 23-ft concrete
level spreader device that receives flow from a wet detention pond. The proposed level spreader then
disperses the concentrated flow through the downstream riparian buffer. The DWQ believes that, if
implemented as per the August 24, 2010 plans, the diffuse flow requirement will be achieved. At no
time shall stormwater from other areas of the proposed development be piped directly through the
buffer without prior DWQ written authorization.
Operation and Maintenance of BMPs:
Maintenance activities for the proposed BMPs shall be carried out in accordance with the Level
Spreader Riparian Buffer O&M agreement signed by Ms. Patricia Hanchette on August 3, 2010, as
well as the Wet Detention Pond O & M agreement (to be submitted when approved). These O & M
agreements must transfer with the sale of the land or transfer of responsibility for the BMP facilities.
DWQ must be notified promptly of every transfer.
Thank you for your attention to this matter. If you have any questions or wish to discuss these matters
further please do not hesitate to call Joseph Gyamfi or Lia M. Gilleski at 919-733-1786.
Sinc ly,
Ian McMillan, Acting Supervisor
401 Oversight/Express Review Program
IJM/jg
cc: USACE Raleigh Field Office
File copy
DWQ Raleigh Regiona Office
City of Raleigh, Public Works - Stormwater Utility Division
Jeremy Finch, PE, The John R. McAdams Company, Inc. P.O. Box 14005 RTP, NC 27709