20061144 Ver 7_More Info Received_20101004

o(.0 - It'+ L?
ARCADIS
Infrastructure, environment, buildings
Mr. Jamie Shern
Raleigh Regulatory Field Office
US Army Corps of Engineers
3331 Heritage Trade Drive, Suite 105
Wake Forest, North Carolina 27587
919.554.4884
Subject:
DE Benton Stream Restoration
Dear Jamie:
a?[EGWP
0 C T 4 2010
DENR . WATER QUALITY
WETLANDS AND STORM.WATER BRANCH
The purpose of this letter is to provide background information and recommended
solutions related to the intermittent stream that was impacted due to failed erosion
control measures, as noted in the Notice of Violation (NOV) issued by the North
Carolina Division of Water Quality (NCDWQ) on February 16, 2010 (NOV-2010-PC-
0192). The Action ID Numbers associated with this project are 200320193,
200620626-200620628, and Nationwide Permit Numbers 12 and 39. The NCDWQ
Project Number associated with this project is 06-1144.
ARCADIS conducted a site assessment on February 26, 2010 in response to the
NOV to quantify impacts and provide recommendations for restoration. ARCADIS
submitted a letter to NCDWQ on March 30, 2010 detailing the impacts and
recommended restoration at the DE Benton site. The stream restoration consisted of
placing log step structures along the length of the impacted stream (approximately
100 linear feet), grading and installation of erosion control matting on the stream
banks, and planting the stream banks with live stakes. Sediment was also removed
from the wetland downstream of the impacted stream. The restoration work began
on June 9, 2010 and was completed on July 9, 2010.
The week of August 23, 2010 the site received over 4 inches of rain and the log step
structures experienced severe erosion, causing bank failure in several places. The
stream bed also scoured out between some of the log structures. The sediment that
eroded during this storm event was washed downstream into the wetland just north
of the sewer easement. This is a portion of the same wetland that sediment was
removed from during the restoration activities in June 2010. Based on our phone
conversation on Friday September 10, 2010, ARCADIS is proposing to use rip-rap
Imagine the result
ARCADIS G&M of North Carolina,
Inc.
801 Corporate Center Drive
Suite 300
Raleigh
North Carolina 27607
Tel [phone]
Fax [phone]
www.arcadis-us.com
Water Resources
Date:
September 30, 2010
Contact:
Ben Furr
Phone:
919.630.1680
Email:
[e-mail]
Our ref:
N C703027.1000
ARCADIS G&M of North Carolina, Inc.
NC Engineering License N C-1869
NC Surveying License N C-1869
g:\wwm\703027.1000\impact analysisVetter to jamie shern.doc
ARCADIS
stabilization along the length of the channel to stabilize the stream bed and banks, as
opposed to repairing the log steps. The rip-rap should provide better stream stability
in the near term and long term scenarios. The sediment that was deposited in the
wetland will be removed by hand using shovels, buckets, and wheelbarrows, as
before.
The attached figure depicts the stream profile prior to construction of the water
treatment plant (Original/Proposed Profile), overlain with the stream profile that was
surveyed immediately after issuance of the NOV (Existing Profile). Cross sections
were also surveyed immediately after issuance of the NOV and are depicted on the
figure. The profiles show that the stream incised between 0.5' and 2.0' in several
areas after the DE Benton Water Treatment Plant was constructed. The stream
banks depicted on the cross sections provide a good representation of existing
conditions because very little bank erosion had occurred at the time the survey was
completed. As shown in the Proposed Cross Sections, ARCADIS will excavate
approximately 24 inches of the stream bed and banks, where necessary, and replace
with Class II rip-rap to restore the stream to original contours. The excavated
material will be disposed of off-site. Geotextile fabric will be placed underneath the
rip-rap as required in the Erosion and Sediment Control Manual. I have also
attached design calculations that show the channel dimensions associated with the
10 year storm. The rip-rap will extend along the stream banks to approximately 1
foot above the elevation of the 10 year storm. Class II rip-rap will comply with
NCDOT Standard Specification Section 1042 (attached).
Once we have received written approval of this plan from the USACE and NCDWQ,
ARCADIS will coordinate with the City of Raleigh to begin the stream stabilization
and removal of sediment from the wetland. If you have any questions please contact
me at 919.630.1680.
Sincerely,
ARCADIS GSM of North Carolina, Inc.
Ben Furr
Environmental Scientist
Copies:
Ian McMillan - NCDWQ
Perry Allen - City of Raleigh
GAMA703027-1000Umped AnW paUtter to Janie Sham.tloc
Natalie Landry - NCDWQ
File
Mr. Jamie Shern
September 30, 2010
Page:
2/2
Channel Report
Hydraflow Express Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. Tuesday, Sep 28 2010
X-2 10 Year Flow
C
User-defined Highlighted
Invert Elev (ft) = 222.50 Depth (ft) = 1.46
Slope (%) = 5.85 Q (cfs) - = 34.59
N-Value = 0.043 Area (sqft) = 5.13
Velocity (ft/s) = 6.74
Calculations Wetted Perim (ft) = 6.99
Compute by: Known Q Crit Depth, Yc (ft) = 1.64
Known Q (cfs) = 34.59 Top Width (ft) = 6.07
EGL (ft) = 2.17
(Sta, El, n)-(Sta, El, n)...
(0.00, 230.00)-(0.10, 227.40, 0.043)-(3.00, 226.80. 0.043)-(5.00, 225.20, 0.043)-(7.00, 223.30,0.043)-(8.00, 223.00, 0.043)-(8.20, 222.70, 0.043)
-(8.50, 222.50, 0.043)-(8.70,222.70, 0.043)-(10.30,222.80, 0.043)-(12.00, 223.70, 0.043)-(14.00, 225.10, 0.043)-(16.00, 225.00, 0.043)-(18.00, 224.50, 0.043)
-(18.10, 230.00, 0.043)
Elev (ft) Section
231.00
230.00
229.00
228.00
227.00
226.00
225.00
224.00 0 ---
223.00
Depth (ft)
8.50
7.50
6.50
5.50
4.50
3.50
2.50
1.50
0.50
222.00 -0.50
221.00 1 50
2 0 2 4 6 8 10 12 14 16 18
20 22
Sta (ft)
Channel Report
Hydraflow Express Extension for AutoCAD® Civil 308 2009 by Autodesk, Inc. Tuesday, Sep 28 2010
X-1 10 Year Flow + 13)
User-defined Highlighted
Invert Elev (ft) = 219.60 Depth (ft) = 2.01
Slope (%) = 5.85 Q (cfs) = 34.59
N-Value = 0.043 Area (sqft) = 5.19
Velocity (ft/s) = 6.67
Calculations Wetted Perim (ft) = 7.24
Compute by: Known Q Crit Depth, Yc (ft) = 2.16
Known Q (cfs) = 34.59 Top Width (ft) = 5.28
EGL (ft) = 2.70
(Sta, El, n)-(Sta, El, n)...
(0.00, 230.00)-(0.10, 223.80, 0.043)-(5.00, 222.00, 0.043)-(7.50, 221.10,0.043)-(8.50, 220.80, 0.043)-(9.00, 219.70, 0.043)-(9.50,219.60,0.043)
-(10.50, 219.90, 0.043)-(11.00, 221.10, 0.043)-(12.00, 222.50, 0.043)-(14.00, 224.40, 0. 043)-(16.00, 224.40, 0.043)-(16.10, 230.00, 0.043)
Elev (ft) Section
231.00
229.00
227.00
225.00
223.00
221.00
219.00
217.00
Depth (ft)
11.40
9.40
7.40
5.40
3.40
1.40
-0.60
_o an
0 2 4 6 8 10 12 14 16 18 20
Sta (ft)
Section 1040
1040-7 WATER
Water shall meet the requirements of Article 1024-4.
1040-8 MORTAR
Mortar used in all brick masonry and block masonry shall be proportioned as shown
below for either mix No. 1 or No. 2. All proportions are by volume. Do not add any more
water than is necessary to make a workable mixture.
Mix No. 1: 1 part portland cement
1 /4 part hydrated lime
3 3/4 parts mortar sand (maximum)
Mix No. 2: 1 part portland cement
1 part masonry cement
6 parts mortar sand (maximum)
The requirements of Articles 1040-4, 1040-5, 1040-6, and 1040-7, are applicable to all
cement, hydrated lime, mortar sand, and water.
For the hydrated lime and cement portion of Mix No. l,the Contractor may substitute
Type M or Type S masonry cement that meets ASTM C270 For Type S masonry cement the
minimum compressive strength of the test specimens shall be 2500 psi at 28 days and the
test specimens shall be composed of 1 part Type S masonry cement and 3 parts sand.
Furnish a .Type 3 certification for the Type M or Type S masonry cement.
1040-9 CEMENT GROUT
Use cement grout that consists of a mixture of 1 part portland cement to 3 parts mortar
sand with no more water than is necessary to make a workable mixture.
Apply the requirements of Article 1040-4, 1040-6, and 1040-7 to all cement, mortar
sand, and water.
SECTION 1042
RIPRAP MATERIALS
1042-1 PLAIN RIPRAP
Stone for plain riprap consists of field stone or rough unhewn quarry stone. The stone
shall be sound, tough, dense, resistant to the action of air and water, and suitable in all other
respects for the purpose intended. Where broken concrete from demolished structures or
pavement is available, it may be used in place of stone provided that such use meets with the
approval of the Engineer. However, the use of broken concrete that contains reinforcing
steel will not be permitted.
All stone shall meet the approval of the Engineer. While no specific gradation is
required, there should be equal distribution of the various sizes of the stone within the
10-83
Section 1042
required size range. The size of an individual stone particle will be determined by
measuring its long dimension.
Stone or broken concrete for riprap shall meet the requirements of Table 1042-1 for the
class and size distribution.
TABLE 1042-1
ACCEPTANCE CRITERIA FOR RIPRAP
AND STONE FOR EROSION CONTROL
REQUIRED STONE SIZES - INCHES
CLASS MINIMUM MIDRANGE MAXIMUM
A 2 4 6
B 5 8 12
1 5 10 17
2 9 14 23r
No more than 5.0% of the material furnished can be less than the minimum size
specified nor no more than 10.0% of the material can exceed the maximum size specified.
1042-2 TESTING
Test riprap materials in accordance with the requirements of this section and
Sections 1005-4(E) Resistance to Abrasion, and 1005-4(F) Soundness. Satisfactory
resistance to abrasion will be considered to be a percentage of wear of not greater than
55 percent. Satisfactory soundness will be considered to be a loss in weight of not greater
than 15 percent when subjected to 5 alterations of the soundness test.
SECTION 1044
SUBSURFACE DRAINAGE MATERIALS
1044-1 SUBDRAIN FINE AGGREGATE
The subdrain fine aggregate shall meet the gradation requirements for No. 2S or
No. 2MS sand as shown in Table 1005-2.
1044-2 PIPE AND FITTINGS--GENERAL
Pipe and fittings may be, at the option of the Contractor, either concrete, corrugated
steel, bituminized fiber, or corrugated plastic.
1044-3 CONCRETE PIPE AND FITTINGS
Non-perforated concrete pipe and pipe fittings shall meet the requirements of
AASHTO M86 for standard strength nonreinforced concrete pipe.
Perforated concrete pipe shall meet the requirements of AASHTO M175 for standard
strength perforated nonreinforced concrete underdrainage pipe.
Joint materials shall meet the requirements of Section 1028.
10-84
Non-Woven Geotextile Fabric: The non-woven geotextile fabric shall meet the following:
PHYSICAL PROPERTIES Units Results
Grab Tensile Strength kN (Ibs) 0.900 (203)
ASTM D 4632
Grab Tensile Elongation % 50
ASTM D 4632
Mullen Burst Strength kPa (psi) 2619 (380)
ASTM D 3786
Trapezoidal Tear Strength kN (Ibs) 0.355 (80)
ASTM D 4533
Puncture Strength kN (Ibs) 0.575 (130)
ASTM D 4833
UV Resistance after 500 hrs. % Strength 70
ASTM D 4355
HYDRAULIC PROPERTIES
Apparent Opening Size (AOS) mm (US Sieve) 0.150 (100)
ASTM D 4751
Permittivity ASTM D 4491 sec -1 1.5
Flow Rate ASTM D 4491 gal/min/sf 110
I/min/sm 4470
Roll Width m (ft) 4.57 (15)
5.5(18)
Roll Length m (ft) 91.5 (300)
76(250)
Est. Gross Weight kg (lb) 134 (295)
Area m2 (yd2) 418(500)
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