20010357 Ver 1_More Info Received_20091210

A
;0'?I BSC GROUT
????`,;? 970 Trinity Road
December 9, 2009 r Raleigh, NC 27607
Ms. Lauren Witherspoon DE C 1 0 2009 Tel: 919-854-o811
NC Division of Water Quality
2321 Crabtree Boulevard DENR-WATER QUALt1Y 800-288-812;
yVE-I LMOS AND SI OR"A7ERi Fax: [phone]
Raleigh, NC 27604-2260
Re: Upchurch Farms Subdivision, Wake County, NC www.bscgroup.com
401 Water Quality Certification DWQ #01-0357
Response to Compliance Status Letter dated September 2, 2009
Dear Ms. Witherspoon:
On behalf of Upchurch Farms Homeowners Associates, Inc. and Triton Upchurch,
LLC, BSC Group has provided a response to the Compliance Status Letter, dated
September 2, 2009, for the above referenced project. Below are the responses to the
issues and how they have been addressed. The following items have been provided in
response to the Compliance Status Letter.
1. One (1) original and One (1) copy of the Response Letter
2. Two (2) copies of the bypass pipe design
3. Two (2) copies of the forebay embankment design
4. Two (2) copies of the forebay embankment stabilization calculations
5. Two (2) copies of the construction sequence
6. Two (2) copies of the DWQ Compliance Status Letter
Comment: "Maintenance of the facility needs to be performed. Specifically, the
pool-side slope between the forebay and stormwater pond has eroded and needs to be
stabilized and vegetation needs to be established on the bare portions stormwater
pond side slopes."
RESPONSE: Based on visual observation during on-site meetings with the
developer, Edge Development, D. Miller & Associates, and BSC Group a low
volume of flow spills over the existing berm days after a rain event. This flow Engineers
saturates the top layer of soil and reduces the soil's ability to bond and
ultimately establish adequate vegetative cover. To convey this flow it has been Environmental
suggested that a permanent 12-in bypass pipe with an inverted riser be installed dentists
at the end of the forebay adjacent to Luke Meadow Lane and discharge directly c1S Consultants
to the pond. The installation of the bypass pipe should allow for the
conveyance of this flow, while the berm conveys the volume of water generated landscape
during a storm event. BSC Group has prepared a drawing detailing the design Architects
of the bypass pipe for review and approval. As for the forebay embankment, D. Planners
Surveyors
Upchurch Farms Subdivision, Wake County, NC
401 Water Quality Certification DWQ #01-0357
December 9, 2009
Page 2 of 2
Miller & Associates has prepared a detailed plan to correct the eroded areas
and help stabilize the existing slope. Edge Development assisted by preparing a
construction sequence that outlines the necessary steps to provide corrective
action.
We wish to thank you for your assistance in getting this problem resolved. Should
you or any of the other staff members have any other question or comments, please
give us a call or send an email and the requested information will be provided
promptly.
Very truly yours,
BSC GROUP
C400 w
Cameron M. Rice, P.E.
Project Manager/Associate
cc: Mr. Michael Jones, Triton Upchurch, LLC
Ms. Cecilia Gray, Community Association Services, Inc.
Mr. William Pollock, Cranfill Sumner & Hartzog LLP
Mr. Timothy P. Grady, G2 Design, P.A.
Mr. Marc Burke, Edge Development
Mr. Kumar Turlapati, D. Miller & Associates
BSC File # 02063.00
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UPCHURCH FARM FOREBAY WEIR REPAIR
CONSTRUCTION SEQUENCE
1) Open riser drain valve to lower permanent pool and fully expose slope toe of forebay
weir. Drain valve should remain open until forebay weir repair, listed in Sequence # 5
below and detailed on Sheet # S-1, are completed. Pump down forebay surface water
level and maintain an elevation of at least 4 feet below top of weir until installation of the
forebay draw down pipe, listed in Sequence # 3 below and detailed on Sheets # X-1, X-2,
and X-3, is completed.
2) Minimize disturbance by removing the smallest amount of existing P550 erosion control
matting, littoral shelf plantings and soil required to properly install the forebay draw
down pipe, listed in Sequence # 3 below and detailed on Sheets # X-1, X-2, and X-3.
Discard the P550 matting and retain the plantings and soil for reuse.
3) Install 12 inch, double wall, high density polyethylene (HDPE forebay draw down pipe
per Sheets # X-1, X-2, and X-3. Backfill retained excavated soil in 8 inch thick layers
(post compaction and compact to 95 percent of the Standard Proctor maximum dry
density test. Excess soil can be used to complete the forebay weir repair, listed in
Sequence # 5 below and detailed on Sheet # S-1.
4) Remove and discard the existing P550 erosion control matting and bench cut the
underlying saturated soil from the eroded, unstable area of the forebay weir embankment,
as shown on Sheet # S-1. Waste the excavated soil by evenly grading the material in a _<
3 inch layer, along the mid to upper pond slope contours, and stabilize with winter rye
and fescue seed, lime, fertilizer and straw mulch.
5) Backfill the bench cuts listed in Sequence # 4 with soil (permeability < 1x10-7 centimeter
per second, > 30 percent passing a number 200 standard sieve, liquid limit > 30, plastic
index > 15 inches in 8 inch thick layers (post compaction and compact to 95 percent of
the Standard Proctor maximum dry density test and within 3 percent of the optimum
moisture content, as detailed on Sheet # S-1. Cover the repaired forebay weir with winter
rye, lime, fertilizer, soil specific water soluble anionic polyacrylamides, and North
American Green C350 erosion control matting.
6) Apply winter rye and fescue seed, lime, and fertilizer to the area backfilled during the
forebay draw down pipe installation, described above in Sequence # 3, install North
American Green P550 erosion control matting, and replant the littoral shelf.
7) All remaining areas disturbed during work activities should be graded to remove ruts and
excessive surface compaction and covered with winter rye and fescue seed, lime and
fertilizer.
8) To be completed during the 2010 growing season (Spring-Summer: place Bermuda sod
over the C350 erosion control matting, described in Sequence # 5, to obtain 100 percent
vegetative coverage, and insert sod staples through C350 and into underlying soil.
KNEW
Forth Carolina Department of Environment and Natural Resources
Division of Water Quality
Beverly Eaves Perdue
Governor
Dee Freeman
Secretary
Coleen H. Sullins
Director
September 2, 2009
Upchurch Farms
Ms. Cecilia Williford
207 West Millbrook Road, Suite 110
Raleigh, NC 27609
Subject: Upchurch Farms Compliance Status
Dear Ms. Williford:
On May 9, 2002, the NC Division of Water Quality (DWQ) issued a 401 Water Quality Certification (WQC)
(DWQ Project # 01-0357) to place fill in 0.2122 acre of wetlands, 2899 linear feet of perennial streams, and 396
linear feet of intermittent unnamed tributaries to White Oak Creek to construct the Upchurch Farms Subdivision
in Wake County, NC.
On August 7, 2002, the DWQ approved a strormwater management pond and level spreader described in plans
dated July 2, 2002 to meet Condition I of the 401 WQC.
On April 19, 2007, Annette Lucas and Lauren (Cobb) Witherspoon from the DWQ conducted a site inspection at
the above referenced site. Specifically, DWQ inspected the stormwater management facility and stream down
gradient of the stormwater management facility. During this site inspection, Ms. Lucas and Ms. Witherspoon
observed that the stormwater management facility was not constructed according to the plans and specifications
that were approved by the DWQ on August 2, 2002 and that sediment measuring approximately 3-6 inches had
been deposited into the stream down gradient from the level spreader.
On May 7, 2007, DWQ issued a Notice of Violation (NOV) to the developer of the property and 401 WQC
applicant Triton Upchurch, LLC (Mike Jones) for 401 WQC violations and other waste (in-stream sediment)
violation (NOV-2007-WQ-0026). As a result of subsequent site visits, DWQ determined that the in-stream
sediment was not a result of erosion from the stormwater facility, but was due to natural stream sediment
transport.
Two responses dated June 4 and 15, 2007 were submitted to DWQ by Mike Jones as required in the NOV. Plans
dated July 13, 2007, to resolve the issues documented in the NOV and to modify the original stormwater
management plan were submitted to DWQ by BSC Rice Associates, an behalf of Triton Upchurch, LLC. Revised
stormwater plans were submitted by BSC Rice Associates and received by DWQ on December 13, 2007 and
approved by DWQ on January 10, 2008.
On August 21, 2008, DWQ received plans to modify the stormwater management plan by D. Miller & Associates,
PA on behalf of Triton Upchurch, LLC. These plans were approved by DWQ on August 22, 2008.
On November 18, 2008, BSC Group submitted a Wet Detention Pond Engineer's Certification to the Town of
Cary stating that the Upchurch Farms Subdivision - Tract 4 Phase 2 permitted facility had been completed.
North Carolina Division of Water Quality
Internet: www.ncwaterquality.org
No'" hCarob
aurally
Raleigh Regional office Surface Water Protection Phone [phone] Customer Service
1628 Mail Service Center Raleigh. NC 27899-1828 FAX [phone]
An Equal Opportunity/Affirmative Action Employer - 50% Recycled/t0% Post Consumer Paper
September 2 ,
Paim 2 ctf
On August 26, 2009, Ms. Lucas and Ms. Witherspoon conducted a site visit to determine the compliance status of
the stormwater management facility. During this site inspection, DWQ staff observed that the stormwater
management facility had been constructed per the approved plan but maintenance of the facility needs to be
performed. Specifically, the pool-side slope between the forebay and stormwater pond has eroded and needs to be
stabilized and vegetation needs to be established on the bare portions of stormwater pond side slopes. During the
site inspection, Triton Upchurch, LLC representatives (specifically Mike Jones), D. Miller & Associates, PA
representatives, and DWQ discussed stabilization techniques to be utilized on the eroding slopes between the
forebay and stormwater pond. Triton Upchurch, L.LC, has stated they are prepared to perform the work necessary
to bring the site into compliance.
It is DWQ's understanding that the Upchurch Farms Subdivision Homeowner's Association (HOA) is the owner
of the parcel that occupies the stormwater management facility. Therefore, the purpose of this letter is to assist
HOA with compliance requirements and to formally notify the HOA of following items: 1) the current
compliance status of the stormwater management facility, 2) the HOA's has responsibility to adhere to the
conditions of the approved 401 WQC, and 3) the specifications set forth in the approved Stormwater Management
Plan. Items in the paragraph above must be addressed in order forthe site to be brought into compliance. Please
understand, like with all stormwater ponds, periodic maintenance of the stormwater pond will be required in the
future. Finally, be aware that the only alterations that can be made to the stormwater management facility must be
in keeping with the most recent stormwater management plan, as approved by DWQ. Any modifications made
to the stormwater management facility that are not approved by DWQ will be in violation of the 401 WQC
- Stormwater Management Plan and is subject to a civil penalty assessment of up to $25,000.00 per day for
each violation.
Thank you for your attention to this matter. Should you have any questions regarding these matters, please
contact me at [phone] or Annette Lucas at [phone].
Sincerely,
t'
Lauren Witherspoon
Surface Water Protection Section
cc: DWQ RRO file copy
John Hennessy, NPS Assistance and Compliance Oversight Unit
Annette Lucas, 401 Oversight/Express Review Permitting Unit
Mr. Mike Jones, Triton Upchurch, LLC, 5660 Six Forks Road, Suite 202, Raleigh, NC 27609
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j REVISIONI
N0. REFERENCE DATE
I 08-331-0623-00 711108
3 OR-331-0623-01 7118/08
3 09-331-1641-00 11/30/09
church Farms Ca C p ~ rY~
~,~,~'CAR~~~''~,
M~n.l ~ ~o~~H°°SSI~(/~9~~:
$ l Replaced Erosion Control Mat by
(see Note 9)
°0 033237 0 ~
Top Width °QQ:
Top of Embankment '~~,~MqR
Existing Erosion Control Mat Replaced Erosion C
m°^°~e°~e~P~~ Existing 3(H):1(V) Slope(Max) (see Not, iced Erosion Control Mat (see Note 9J
Existing Geosynthetic
Existing Failure Plane Top or Embankment Reinforcement La ers Exisitn Elev. 351 Exi tin Ero i n ntrol Mat 3o Elev. 351 ~ i ~
INOnh nmerlean ~aeenPS°Al (Approximate) s g s o Co Fo~ebay Side
/ ~ ~
ExistingEerm Foreba Side a~
-
-ff--
Pool Side / lev. 346
~ . ® ~
Foundation Soil Proposed ~ ~ ~
3(H):1(V) Slope or Flatter Existing
3(H):1(\~') Slope(Max) C~ ~ i,
Compacted EXIStIng e~
impermeablesoil EXISItng Toe Drain 1 ® ~
Filter Fabric Elev. 344 Pool Side ~ ~ _ ~ ~
Normal Pool Lev I Approximate Limits of ~ ~
- - - - - - - - - - Previously Reomved soils and
Re laced with Com acted Not To Scale - p P ~ ~
Impermeable soil
v ~ ~ ro
4 G ~ ro ~
s F ~
w ei y ® ~
I ~
p.
To Width p
I' I
Existin Failure Plane Existin 3 H :1 V Slo e Max 9 g O O p( ) (approximate) Existing Geosynthetic
To of Embankment Existin Elev. 351 , Not To Scale ~ i i
Reinforcement La ers 9 n r I Mat Existing Erosion Cot o , NoMAmen'an Geen PSb~ I
_ / 3'to5'
(TY )
Existing Berm Foreba Side
3~ 6' Desa n Zonell ~TYP) Zonel Design ssumptions: ~ ~ 1 ~ r
/ 1, The assi 1, The assigned soil properties; ~ , o
Pool Side / Zone I Zone I Friction angle ~ = 25°, Cohesion, c = 200 psf, Moist unit weight y =120 pcf, permeability =1 e-07 cm/sec or less ~ ~
lev. 346 , Zone II Zone II Friction angle ~ = 25°, Cohesion, c = 200 psf, Moist unit weight y =120 pcf, permeability =1 e-07 cmisec or less
8" Min. ( } - a
Foundation Soil The abc The above soil properties were assigned based on our Atterberg limits (ASTM D-4318) and ~ ~
sieve ar sieve analysis tests (ASTM D-422), conducted during the original design phase and construction
observa observation phase.
Existing Compacted Existing Toe Drain impermeable soil Filter Fabric
Elev. 344 2. The asst Normal Pool Level 2. The assumed soil properties for the proposed slope repair: 'i
Zone II* Zone II* Friction angle ~ = 25°, Cohesion, c = 200 psf, Moist unit weight y =120 pcf, permeability =1e-07 cm/sec or less i
Approximate Limits of The above soil ro oerties shall be verified b the onsite eotechnical en ineer or his re resentative rior to i
Previously Reomved soils and The abo~ Not To Scale p p Y 9 g p p commencement of excavation. v
Replaced with Compacted commen a a 4
Im ermeable soil p Based or Based on BSC Group's Design Calculations, $ ~ G
Length o Length of Berm = 30 feet and Width of Berm = 8 feet (Min.) j
Top Elev Top Elevation of the Berm = 351 0
Discharg Discharge, Q (Cubic feetlsec) = 96.6 for 2 year storm,121.1 for 10 year storm, 150.3 for 50 year storm and 163.1 for 100 ~ c
year stop year storm j
Velocity, Velocity, v (feetlsec) = 4.6 for 2 yera storm, 5 for 10 year storm, 5.6 for 50 year storm, 5.4 for 100 year storm
Nead , H Head , H(ft) = 0.7 for 2 year storm, 0.8 for 10 year storm, 0.9 for 50 year storm and 1 for 100 year storm
8`
Key Trench per Manfacturer
General Notes for iope Reconstruction
Re laced Erosion Control Mat Replaced Erosion Control Mat Recommnedations General P (see Note 9) EXIStIng 1. LOOSe a 1. Loose and wet soils in the failure area of the slope on the pool side and the existing erosion control mat shall be removed. The ~ '
Existing Geosynthetic 3 H :1 V Slo e Max existin existing slope on pool side shall be cut in benches in general accordance with OSHA guide lines.
Pro osed Bench Cuts p ( ~ g P Te otEmbankment Elev. 351 Reinforcement La ers 2, The la 2, The placement of controlled fill shall be started immediately after the removal of existing slope materials. ~ f N ~
(Per OSHA Guide Lines) p 'Remove ExistingMatandall Foreba Side 3. The suitability of the soils to be used for reconstruction shall be verified by a professional geotechnical engineer prior to the ~ ~ °
loose soils in the failure area. a Sul' Tne Excavation must meet Existing Erosion Control Mat eomme commencement of construction. I ~ ~
(NO~n Amenwnfxeen PS`A~ OSHA Excavation Guide Lines. 4. A signe 4. A signed and sealed soil verification report shall be submitted to D. Miller & Associates PA (DMA) prior to the commencement ~ ~ cn ~ ° %
Elev. 348.38 Existing Berm Of COnS of construction if the soils will be verified by a geotechnical engineer other than DMA. ~ ~ ~ ~ ~
Pool Slde 100 r. Flood elevation ( y ~ Zone I I' 95% compacted impermeable soil Zone I 5. The fi II i 5. The fill materials for the proposed new slope shall be placed in 8-inch thick layers after compaction and compacted to i ~ ~ ~ ~
in 8-inch thick lifts a mmirr a minimum of 95 percent of maximum dry density of the standard Proctor test and at or greater 3 percentage points of ~ ~ ~ ~
Proposed Elev. 346 optimur optimum moisture content. Each lift shall be keyed into the bench cut line. ~ ~ ~ o~ ~
3(H):1(V) Slope or Flatter r, ' 6. The Pla 6. The Plasticity index of the fill in the proposed embankment should not be less than 15 and liquid limt should be greater than or ~ ? ~ 'a~ ~
8 Mln. I equa tt: equal to 30. i ~ ~ ~
Foundation Soil 7. Structur 7. Structural fill placement shall extend to approximately 5 feet beyond the final planned slope,
5 Min. Be and No a 8. Once th ' rm I Pool 8. Once the fill placement is completed, the compacted fill shall be cut back to the final designed slope 3(H): 1(V) or Flatter slope. ~ ~ ~
Repalced Replaced 9. Install e compacted Re laced 9. Install erosion control mat such as North American Green P550 or equivalent down the final designed slope from the top to ~ i ~ ~ W
impermeable soil p Toe Drain bottom bottom to the extents illustrated after slope construction is completed.The existing erosion control mat shall be removed and ~ ~
Elev. 344 Filter Fabric replace Normal Pool Lev I replaced at the failure area of the berm and damaged portions of the mat. The on-site geotechnical engineer or his i
represe representative shall verify the condition of the erosion control mat at the time of construction and determine the serviceability of ,j
the mat the mat.
Approximate Limits of Not To Scale 1 . The erc 0 Remove and Replace the 11. The sic 10. The erosion control mat shall be secured properly to the final slope in accordance with manufacturer's recommendations.
Previously Reomved and the per 11. The slope shall be vegetated immediately. The vegetation density shall be greater than or equal to 95 percent. Please note that
Replaced soils the performance of erosional control mats such as P550 is generally low under unvegitated condition (less than 95 percent).
12. In the e 12. In the event a geotechnical engineer other than DMA monitors the slope reconstruction, the onsite geotechnical engineer or his
represF aspect representative should remain on-site during the entire slope repair to document all aspects of the design. If any aspect of the design is noncompliant, DMA must be contacted immediately for review and possible slope design modification. PfeieCt oa-3st-is~z-ooR
13. The da 13. The daily reports produced by the on-site geotechnical engineer shall be provided to DMA concurrently as construction ` I Date: Deoember zoos
procee proceeds. ~ ~r,~o
14. The by 14. The hydraulic loading conditions, water elevations and embankment design were provided to DMA by the engineer of the record s
(BSC G (BSC Group). DMA analyzed the slope for global stability of the embankment and provided recommendations to minimize the
erosion erosion control based on the hydraulic loading conditions and embankment design.
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