HomeMy WebLinkAbout20020312 Ver 1_COMPLETE FILE_20020301F WAIF
O 9QG Michael F. Easley
Governor
co William G. Ross, Jr., Secretary
> Department of Environment and Natural Resources
Gregory J. Thorpe,.Ph.D., Acting Director
Division of Water Quality
March 8, 2002
DW Q# 02-0312
Buncombe County
Georgia M. Bustle
Mountain Retreat Association
P.O. Box 969
Montreat, NC, 28757
APPROVAL of 401 Water Quality Certification
Dear Ms. Bustle:
You have our approval, in accordance with the attached conditions, to place fill in 0.02 acre of waters in order to
excavate accumulated sediment and place temporary and permanent check dams and a temporary access ramp in Lake
Susan in Buncombe County, as described in your application received by the Division of Water Quality on March 1, 2002.
After reviewing your application, we have determined that this fill is covered by General Water Quality Certification Numbers
31,06 and 3114, which can be downloaded from our web site at http://h2o.enr.state.nc.us . This Certification allows you to
use Nationwide Permit Numbers 18 and 33 when issued by the U.S. Army Corps of Engineers. This approval is also valid
for the Tar-Pamlico River Buffer Rules (15A NCAC 2B .0259). In addition, you should get any other federal, state or local
permits before you go ahead with your project including (but not limited to) Sediment and Erosion Control, Non-Discharge
and Water Supply Watershed regulations. Also this approval will expire when the accompanying 404 permit expires unless
otherwise specified in the General Certification.
This approval is only valid for the purpose and design that you described in your application. If you change your
project, you must notify us 'in writing and you may be required to send us a new application for a new certification. If the
property is sold, the new owner must be given a copy of the Certification and approval letter and is thereby responsible for
complying with all conditions. If total wetland fills for this project (now or in the future) exceed one acre, compensatory
mitigation may be required as described in 15A NCAC 2H .0506 (h). For this approval to be valid, you must follow the
conditions listed in the attached certification.
If you do not accept any of the conditions of this certification, you may ask for an adjudicatory hearing. You must act
within 60 days of the date that you receive this letter. To ask for a hearing, send a written petition which conforms to
Chapter 150B of the North Carolina General Statutes to the Office of Administrative Hearings, P.O. Box 27447, Raleigh,
N.C. 27611-7447. This certification and its conditions are final and binding unless you ask for a hearing. -
This letter completes the review of the Division of Water Quality under Section 401 of the Clean Water Act. If you have
any questions, please telephone Mike Parker in our Asheville Regional Office at 828-251-6208 or Cyndi Karoly in Raleigh at
919-733-9721.
cerely,
Attachments
occ: Corps of Engineers Washington Regulatory Field Office
Washington DWQ Regional Office
Central Files
File Copy
020312
North Carolina Division of Water Quality, 401 Wetlands Certification Unit.
1650 Mail Service Center, Raleigh, NC 27699-1650 (Mailing Address)
0201 rl-r,>- ?:'!-i Gr?io r non 974Zn,1.99rn n
MAR
U.S. ARMY CORPS OF ENGINEERS
WILMINGTON DISTRICT
1MW
Action rd. 200230397- Nationwide Permit 18 county Buncombe
200230398- Nationwide Permit 33
0201
GENERAL PERMIT (REGIONAL AND NA ONW DE) VCERIFICATION
Property owner: Mountain Retreat Association, Attn: Ms. Georgia M. Bustle
Address: Post Office Box 969
Montreat, North Carolina 28757
Telephone No.: (828)765-3000
Size and Location of project (water body, road name/number, town, etc.): The approximate 2 acre Lake
Susan located off of Highway 9 in the Montreat Conference Center in Montreat, North
Carolina (N35°38'10", W82°18106").
Description of Activity: to excavate accumulated sediment from Lake Susan. The project will
allow for the inspection and evaluation of the dam, as well as provide future sediment
storage capacity. Discharges of fill material include a temporary check dam, a permanent
check dam, and a temporary access ramp which will be removed upon.project completion.
All sediment removed is to be disposed of at the Buncombe County landfill.
Applicable Law: X Section 404 (Clean Water Act, 33 U.S.C.1344).
(check all that apply) Section 10 (River and Harbor Act of 1899).
Authorization: Regional General Permit Number.
18/33 Nationwide Permit Numbers.
Your work is authorized by this Regional General (RGP) or Nationwide Permit (NWP) provided it is accomplished in strict
accordance with the attached conditions and your submitted plans, and those conditions outlined in the attached February
6, 2002 NC Wildlife Resources Commission letter. If your activity is subject to Section 404 (if Section 404 block above a
checked), before beginning work you must also receive a Section 401 water quality certification from the N.C. Division of
Water Quality, telephone (919) 733-1786.
Please read and carefully comply with the attached conditions of the RGP or NWP. Any violation of the conditions of the
RGP or the NWP referenced above may subject the permittee to a stop work order, a restoration order, and/or appropriate
legal action.
This Department of the Army RGP or NWP verification does not relieve the permium of the responsibility to obtain any
other required Federal, State, or local approvals/permits. The permittee may need to contact appropriate State and local
agencies before beginning work.
If there are any questions regarding this authorization or any of the conditions of the General Permit or Nationwide Permit,
please contact the Corps Regulatory Official specified below.
Date 2/12/02
Corps Regulatory Official David Baker Telephone No. (828) 2714980, eatension 6
Expiration Date of Verification 2/11/03
CESAW Foam 991
r
PRE-CONSTRUCTION
NOTIFICATION
APPLICATION
SEDIMENT REMOVAL
Lake Susan
Montreat, North Carolina
Contents.
1. Transmittal Letter for Pre-Construction Notification Application
2. Pre-Construction Notification (PCN) Application Form
3. Site Vicinity Map (Portion of USGS Montreat, NC Quadrangle)
4. Sediment val Construction Plan for Sediment Removal
6. Site Plap ting Affected Areas of Lake Susan
1*01
MARKS ENTERPRISES
S... Geotechnical Engineering - Dam Design - Wildlife Control - Consulting
January 7, 2002
US Army Corps of Engineers
Asheville Regulatory Field Office
151 Patton Avenue, Room 208
Asheville, North Carolina 28801-5006
Attention: Mr. David Baker, P.E.
Reference: PRE-CONSTRUCTION NOTIFICATION APPLICATION
Sediment Removal Construction Plan
Remedial Dam Repair Design and Construction
Lake Susan Dam
Montreat, North Carolina
Job No. MEEC - 01- 023
Dear Mr. Baker:
Marks Enterprises of NC, PLLC (Marks Enterprises) is submitting herewith a Pre-
Construction Notification Application package for approval to remove sediment from
selected areas of Lake Susan at the Montreat Conference Center campus in Montreat,
North Carolina. A copy of this application is being submitted concurrently to Mr. Owen
Anderson, mountain region coordinator with the North Carolina Wildlife Resources
Commission.
The purpose of removal of sediment from selected areas of Lake Susan is two-fold. First,
sediment must be removed from the upstream toe area of the dam to allow inspection and
evaluation of concrete associated with the overall remedial dam repair design and
construction project for Lake Susan Dam Secondly, sediment will be removed from an
area at the upstream end of the lake to allow for future sediment storage. A permanent
check dam constructed of riprap size stone, No. 57 gradation stone, and non-woven
geotextile will be constructed in the straightened creek channel to promote future
One Palatka Drive - Arden, North Carolina 28704
f PRE-CONSTRUCTION NOTIFICATION APPLICATION January 7, 2002
Lake Susan Dam Sediment Removal and Remedial Repair Job No. MEEC-01-023
Montreat, North Carolina
'Iftow
sediment deposition at the upstream end of the lake. A temporary check dam of similar
construction will be used to protect the outlet during sediment removal and a temporary
access ramp will be constructed to provide access for construction equipment. These
temporary structures will be removed at the completion of sediment removal.
This application package contains a Site Vicinity Map, the PCN Application Form, a
Sediment Removal Construction Plan, and a detailed Site Plan. The Mountain Retreat
Association (owner of Lake Susan and Lake Susan Dam) desires to remove sediment and
refill the lake prior to March 1, 2002 to coincide with planned activities on the Montreat
Conference Center Campus. As such, we request a review of this application as soon as
possible.
If there are questions concerning this application, or if we can provide additional
?. information concerning this application, please do not hesitate to contact us at your
convenience.
Respectfully,
Marks Ent;p? of NC,
$. Dan Marks, PhD., P.E.
Manager/Geotechnical Consultant
cc: Mr. Owen Anderson
Mountain Region Coordinator
North Carolina Wildlife Resources Commission
20830 Great Smokey Mountain Expressway
Waynesville, NC 28786
N%W
2
11*.
1. Check all .of the approval(s) requested for this project:
Section 404 Permit
Section 10 Permit
401 Water Quality Certification
F] Riparian or Watershed Buffer Rules
2. Nationwide, Regional or General Permit Numter(s) Requegted: A/??t1o?J b1?fl? ?8 +f ?3
3: If this notification is solely a courtesy copy because written approval for the 401 Certification
is not required, check here:
4. If payment into the North Carolina Wetlands Restoration Program (NCWRP) is proposed for
mitigation of impacts (see section VIII - Mitigation), check here: E
,v" r ,
pp .4_W, ? r a ion
Telephone Number:
E-mail Address: c,
„"ay %,: i r fit,„a-..o t..4? s.? .. ;::?
P%44 *-Jh1-'WV3vP'A? 4-W. over
0- jai
-.11 nu :A Cw
'Name: _ '?7f
,??tt?? t1Qll' : s .. ? ? •• •.
0°!?•??:c ?'? ??`• * ? ? a?t1.y,??r?'?? r:t?? y e -?- i-r? ? y= a ? s 'i?
must be
Telephone Nuin
E-mail Address:
Office Use Only' Form Version October 2001
USACE Action ID No. DWQ No.
If any particular item is. not applicable to this project, please enter "Not Applicable" or "N/A" rather than
leaving the space blank.
1. Processing
Page 5 of 5
-C USACEa-, Inn accordance with the
a ?,, N?tira oi*.Iune.and;fi*ation of Nationwide
"`?' . '' rlnu ulillsl2e ii he 1 edera BIZ gi -ter oil March 9, 2060; mitigation will be required when
necessary to ensure that adverse effects to the aquatic environment are minimal, Factors
including size and type of proposed impact and function and relative value of
aquatic resource will be co,
n. ii. Bete irrg arc h drW acted
t •: a ?, .,. ?? ? rpriate ancticable
mittdafion-as prop&§ed. Exanipl s o iYUfigation t int may be appropriate and practicable include,
but are not limited tm reducing the size of the project; establishing and maintaining wetland
and/or -upland vegetated buffers to protect open waters such as streams; and replacing losses of
aquatic resource functions and values by creating, restoring, enhancing, or preserving similar
functions and values, preferable in the same watershed.
If mitigation is required for this project, a copy of the mitigation plan must be attached in order
for USACE or DWQ to consider the application complete for processing. Any application
lacking a required mitigation plan or NCWRP . concurrence shall be placed on hold as
incomplete. An applicant may also choose to review the current guidelines for stream restoration
in DWQ's Draft Technical Guide for Stream. Work in North Carolina, available at
http://h2o.enr.state.nc-us/ncwetlandststrmgide.html.
1. Provide a brief description of the proposed mitigation plan. The description should provide
as much information as possible, including, but not limited to: site location (attach directions
and/or .map, if offsite), affected stream and river basin, type and amount (acreage/linear feet)
of mitigation proposed (restoration, enhancement, creation, or preservation), a plan view,
preservation mechanism (e.g., deed restrictions, conservation easement, etc.), and a
description of the current site conditions and proposed method of construction. Please attach
a separate sheet if more space is needed.
2. Mitigation may also be made by payment into the North Carolina Wetlands Restoration
Program (NCWRP) with the NCWRP's written agreement. Check the box indicating that
You would like to pay into the NC Please note--that reviewed and approved ?efor It payment
intot e 1C WRP must be
Nom,-xg4 ?. .. c be QC fy`
tl mi1%at4a ?4Tt mant , Applicants
" _ `?'x = "tvtlIbe ntt?d 'eaily view process by the 40I/Wetlands Unit if payment NCWRP is available as an option. For additional information regarding the application
process for the NCWRP, check the NCWRP website at http [2o.enr.state.nc udwrprmdex htm. If
use of the NCWRP is proposed, please check the appropriate box on page three and provide
the following information:
Amount of stream mitigation requested (linear feet): .-?- .
Amount of buffer mitigation requested (square feet):_
Amount of Riparian wetland mitigation requested (acres): --
Amount of Non-riparian wetland mitigation requested (acres):
Amount of Coastal wetland mitigation requested (acres):
10. D e the purpose of the
S?E,7?'lw4? s
11. List e t of equi went to be
j •iCoM ?. ?
12. Describe the land use.in the Zi
IV. Prior Project History
work:
>E 7-
L_to con
the project`
X04,
If jurisdictional determinations and/or permits have been requested and/or obtained for this
project (including all prior phases of the same -subdivision) in the past, please explain. Include
the. USACE Action ID Number, DWQ Project Number, application date, and date permits and
certifications were issued or withdrawn. Provide photocopies of previously issued permits,
certifications or other useful information. Describe previously approved wetland, stream and
buffer impacts, along with associated mitigation (where applicable). If this is a NCDOT project,
list and describe permits issued for prior segments of the same T.I.P..project, along with
conshvcyon schedules..
Ir
t - .a! wE :'SF..?ik•n2- s?• !:'6?.. r.`: -'?'
V. Future Project Plans
If .fan
Are any f4ture pe}mit'krequests antici a fortlp pro :tz.
* ;wd?7?a'de justrfia#on for the etc o,is work thecu`ion:
at: ;xl
VI.
t
ticipated work,
It is the applicant's (or agent's) responsibility to determine, delineate and map all impacts to
wetlands, open water, and stream channels associated with the project. The applicant must also
provide justification for these impacts in Section VII below. All proposed impacts, permanent
and temporary, must be listed herein, and must be clearly identifiable on an accompanying site
plan. All wetlands and waters, and all streams (intermittent and perennial) must be shown on a
delineation map, whether or not. impacts are proposed to these systems. Wetland and stream
evalVation and delineation forms should be included as appropriate. Photographs may be
'4a*ded at#ii applicant's discretion. If this proposed impact is strictly for wetland or stream
ixiitigation,`list and describe the impact in Section VIII below. If additional space is needed foi
listing or description, please attach a separate sheet.
Page 7 of 7
Proposed Impacts to Waters of the United States/Waters of the State
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3. Open Water impacts, including Lakes, Ponds, Estuaries, Sounds, Atlantic Ocean and any
other Water of the M .S.
g??al
Open Water Impact
Site Number
(indicate on map)
Type of Impact*
11 Area of
Impact
(acres)
.03 Name of Waterbody
(if applicable)
#,Vx 1_Jo J Type of Waterbody
(lake, pond, estuary, sound,
bay, ocean; etc.)
La.K .
- l d
but Fern not lim itpA tn- fill- excavation- dred¢inLy_
e
* List each impact separately and identify temporary unpacts. Impacts Fnc u ,
flooding, drainage, bulkheads, etc.
4. Pond Creation
If construction of a pond. is proposed, associated wetland and stream impacts should be
included above in the wetland and stream impact sections. Also, the proposed pond should
be described here and illustrated on any maps included with this application.
Pond to be created in (check all that apply): ? uplands ? stream' - Elwetlands
Describe the method of construction (e.g., dam/embankment, excavation, installation of
draw-down valve or spillway, etc):
Proposed use or. purpose of pond (e.g., livestock watering, irrigation, aesthetic, trout pond,
local stormwater requirement, etc.):
Size of watershed draining to pond: Expected pond surface area:
VII. Impact Justification (Avoidance and Mipimization)
Specifically describe measures taken to vvvbld the proposed impacts. It may be useful to provide
information.related to site constraints such as'topography, building ordinances; accessibility, and
financial viability of the project. The applicant may attach drawings of alternative, lower-impact
site layouts, and explain why these design options were not feasible. Also discuss how. impacts
were minimized once the desired site plan was developed. If applicable, discuss construction
techniques to be followed during construction to reduce impacts.
VIII. Mitigation
DWQ - In accordance with 15A NCAC 2H .0500, mitigation may be required by the NC
Division of Water Quality for projects involving greater than or equal to one acre of impacts to
freshwater -tell-piids or greater than or equal to 150 linear feet of total impacts to perennial
`..? streams. ''-
Page 9 of 9
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IX. Environmental Documentation (DWQ Only)
`gym/
X.
,?. 7UF 6.. a. f.: ....1Does the project involve an. expenditure of public funds or the use of public (federal/state/local)
?R*..3;? k• =?? Zone nouL,?feCt PL?rpegd?°'ofn sear bof cfi?dnf? one 2 etetls'n
y R r
n , ,ct 2 feet from ttie &gepf Zane '
land?
Yes [] No
If yes, does the project require preparation of an environmental document pursuant to the
requirements of the National or North Carolina Environmental Policy Act (NEPA/SEPA)?
Note: If you are not sure whether a NEPA/SEPA document is required, call the SEPA
coordinator at (919) 733-5083 to review current thresholds for environmental documentation.
Yes n No ?
If yes, has the document review been finalized by the State Clearinghouse? If so, please attach a
copy of the NEPA or SEPA final approval letter.
Yes No [)
Proposed Impacts on Riparian and Watershed Buffers (DWQ Only)
It is the applicant's (or agent's) responsibility to determine,. delineate and map all impacts to
required state and local buffers associated with the project. The applicant must also provide
justification for these impacts in Section VII above. All proposed impacts must be listed herein,
and must be clearly identifiable on the accompanying site plan. All buffers must be shown on a
map, whether or not impacts are proposed to the buffers. Correspondence from the DWQ
Regional Office may be included as appropriate. Photographs may also be included at the
applicant's discretion.
Will the project impact protected riparian' buffers identified within 15A NCAC 2B .0233
(Neuse), 15A NCAC 2B .0259 (Tar-Pamlico), 15A NCAC 2B .0250 (Randleman Rules and
Water Supply Buffer Requirements), or other (please identify )?
Yes n No n If you answered "yes",.provide the following information:
Identify the square feet and acreage of impact to each zone of the riparian buffers. If ibuffer
mitigation is required calculate the required amount of mitigation by applying the buffer
multipliers.
Zone* Impact
(square feet)
Multiplier Required -
Mitigation
I 3
Total `
?t
r
.. t a
D.... 1 1 of 1 7
If buffer mitigation is required, please discuss what type of mitigation is proposed .e I --/
of Property, Conservation Easement, Riparian (i., Donation
Payment into the Riparian Buffer Restoration Fund).r PlRestorati ease attaon / ch alnlhancement, Preservation or
identified within 15A NCAC 2B .0242 or.0260. appropriate inform tion as
?• Stormwater (DWQ Only)
Describe impervious acreage (both existing _
Discuss stormwater controls proposed in orde r to Protect versus totalacreage on the site.
downstream from the property, waters and wetlands
XII- Sewage Disposal (DWQ Only)
Clearly detail the ultimate treat
wastewater generated from the n
methods and disposition non-discharge P
NI- roject, or available capacity of the subject facil tYge) of
MR* Violations (DWQ Only)
Is this site in violation of D WQ Wetland Rules 0 5A NCAC 2H .0500) or
Yes [] No ? any Buffer Rules?
Is this an after-the-fact permit application?
Yes E] No
MV. Other Circumstances (Optional):
It is the applicant's responsibility to submit the a
construction dates to allow pplicatiOII sufficiently in advance of desired
choose to list processing time for these permits However, an
applicant constraints associated with construction or sequencing that May limits may
schedules (e.g., draw-down schedules for
impose limits on
work s lakes, dates associated with
Threatened S cies, accessibility problems, or other=issues outside of the a lic Endangered and
1 rr ant's control
A r 31
Applicaii
SI afore Y
(Agent's Signature is valid only if an authorization letter from the applicant is Date
provided)
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SEDIMENT, REMOVAL
CONSTRUCTION PLAN
LAKE SUSAN IMPOUNDMENT
Montreat, North Carolina
Job No. MEEC - 01- 023
Prepare For:
Mountain Retreat Association
Post Office Box 969
Montreat, North Carolina
Prepared By:
Marks Enterprises of NC, PLLC
One Palatka Drive
Arden, North Carolina 28704
(828) 684 - 9804
Email: drbdannbellsouth.net
November 12, 2001
MARKS ENTERPRISES
Geotechnical Engineering • Dam Design • Wildlife Control • Consulting
November 12, 2001
Mountain Retreat Association
Post Office Box 969
Montreat, North Carolina 28757
Attention: Ms. Georgia Bustle
Reference: SEDIMENT REMOVAL CONSTRUCTION PLAN
Lake Susan Impoundment
Montreat, North Carolina
Job No. MEEC - 01- 023
Dear Ms. Bustle:
Marks Enterprises of NC, PLLC (Marks Enterprises) has completed the authorized
evaluation of sediment loading within the Lake Susan impoundment and developed a
plan for removal of the sediment from the impoundment. This sediment load evaluation
and removal plan project was authorized, and conducted in general accordance with, the
Proposal for Professional Services dated March 27, 2001 and approved September 13,
2001.
This report presents a brief description of the findings of the sediment depth investigation
conducted by S&ME, Inc. reported on January 24, 2001, a narrative description of the
recommended sediment removal plan, and sediment removal volume estimates for the
project. In addition to these primary areas of the report, a construction sequence is
provided for use by the contractor during removal of the retained impoundment sediment.
This report also contains an illustration of the recommended sediment removal plan.
One Palatka Drive • Arden, North Carolina 28704
SEDIMENT REMOVAL PLAN November 1, 2001
No. MEEC-01-001
Lake Susan Impoundment Job
Montreat, North Carolina
IMPOUNDMENT SEDIMENT INVESTIGATION
In January 2001, S&ME, Inc. was retained to determine depths of retained sediments
within the Lake Susan impoundment immediately upstream of the concrete spillway
structure. Based upon this investigation, sediment depths within the approximately 70
feet by 85. feet area were determined to vary from less one foot to as much as nine feet in
depth.
Marks Enterprises utilized the sediment depth data to evaluate the quantity of sediment
present in this area of the impoundment. Based upon planimetric measurements of the
contoured sediment depths, a total of about 1000 cubic yards of sediment was determined
to be present within a distance of about 70 feet immediately upstream of the spillway
structure. According to the planimetric measurement method utilized, the greatest
,?. volumes of sediments were associated with sediment depths of about three to six feet.
Areas occupied by sediment depths greater than about six feet were relatively small and
the large areas of relatively shallow sediment deposits produced smaller volumes of
sediment. Based upon these measured sediment depths and previous experience with the
characteristic of the Lake Susan impoundment bottom contours, Marks Enterprises
estimated depths of sediments present in other areas of the impoundment where sediment
should be removed to, provide some future storage and control of sediment deposition.
These estimated depths were used to evaluate the quantity of sediment recommended for
removal during this sediment removal project. These areas include the primary sediment
removal area immediately upstream of the spillway, a streambed channel to be extended
from the stream inlet to the spillway structure, a primary sediment storage area at the inlet
side of the impoundment, and shoreline areas around the perimeter of Lake Susan.
Sediment volumes to be removed from these four critical areas have been estimated to
total about 4500 cubic yards.
Vr.W
2
SEDIMENT REMOVAL PLAN
Lake Susan Impoundment
Montreat, North Carolina
SEDIMENT REMOVAL PLAN
November 1, 2001
Job No. MEEC-01-023
The Sediment Removal Plan for the Lake Susan impoundment involves the identification
of recommended critical areas from which sediment should be removed and
characterization of the configuration of the sediment removal areas. The recommended
areas of sediment removal include the following:
1. The Primary Sediment Removal Area immediately upstream of the
Spillway Structure;
2. The Streambed Channel Area that extends from the Spillway Structure
Bottom Drain Sluice Gate to the Inlet Stream Channel;
3. The Primary Sediment Storage Area near the upstream Inlet Stream; and
4. The Lake Susan Perimeter Areas that extend around the perimeter of the
?'. Primary Sedimenra rea
The Primary Sediea is an approximately 75 feet by 90 feet in plan
dimensions and e ll len h of the spillway structure and upstream of the
structure approxi . A tot , of approximately 1000 cubic yard of sediments is
estimated to be re thisarea to depths less that. one foot toas much as nine
feet. The sedimenhis area must extent to the bottom of the upstream toe of
the concrete spillway structure that must be clearly exposed for inspection and potential
remedial repair. The impoundment sides of this sediment removal area that are not bound
by the spillway structure and perimeter rock walls shall be sloped no steeper than 4:1
(horizontal to vertical) to provide stability of the remaining sediment. This area shall be
excavated as uniformly level in the bottom as possible based upon the presence of
residual materials and partially weathered rock in the bottom of the impoundment.
Excavations shall not be extended below the top of footings for the perimeter walls for a
distance of ten feet beyond the perimeter walls.
*rr
3
SEDIMENT REMOVAL PLAN November 1, 2001
Job No. MEEC-01-023
Lake Susan Impoundment
Montreat, North Carolina
Streambed Channel Excavation
Sediment shall be excavated to form a Streambed hannel that ' -extend from the
spillway bottom drain sluice gate to the et str c e at t stream end of Lake
Susan. The Streambed Channel shall be excavat d as straight as poss' le and shall have a
bottom width' of at least twenty feet. The Stre d Ch been estimated to
require an average depth of sediment removal (excavation) of four feet. The side slopes
of the Streambed Channel shall be no steeper than 4:1 (horizontal to vertical). A riprap
stone detention dam approximately three feet in height shall be constructed across the
upstream inlet of the Streambed Channel at the intersection with the Primary Sediment
Storage Area. The riprap stone detention dam shall consist of four to eight inch diameter
riprap stone overlain on the upstream slope by six inches of No. 57 gradation filter stone.
The front and back slopes of the detention dam shall be no steeper than 1.5:1 (horizontal
to vertical) and the crest width shall be a minimum of two feet. Excavation of the
Streambed Channel has been estimated to require approximately 1500 cubic yard of
sediment.
Primary Sediment Storage Area
The Primary Sediment Storage Area will be transverse to the Streambed Channel at the
upstream inlet end of the Lake Susan impoundment. The future sediment storage area
will be approximately 40 feet (bottom width) by 150 feet and shall have side slope no
steeper than 4:1 (horizontal to vertical). Based upon an estimated average excavation
depth of four feet, an estimated 1500 cubic yards of sediment must be removed from this
Primary Sediment Storage Area. The Primary Sediment Storage Area will be separated
from the Streambed Channel by the previously described riprap stone detention dam.
Impoundment Perimeter Areas
Sediment shall be removed to a minimum depth of three feet (or to the top of perimeter
wall foundation) around the entire perimeter of Lake Susan. This sediment removal shall
extend a minimum distance of ten feet into the impoundment area except at the upstream
side of the earthen embankment portion of the dam where the sediment removal area
shall extend twenty feet into the impoundment area. Based upon site inspection
4
SEDIMENT REMOVAL PLAN
Lake Susan Impoundment
Montreat, North Carolina
November 1, 2001
Job No. MEEC-01-023
observations, the depth of sediment removal around the perimeter of Lake Susan will
average approximately two feet. As such, the estimated quantity of sediment to be
removed around the perimeter of the impoundment is about 500 cubic yards.
Summary of Sediment Removal Quantities
Based upon planimetric measurements of contoured sediment depths in the previously
investigated area, inspection of sediment depths along the perimeter of the impoundment,
and previous experience with the characteristics of the bottom profile of the Lake Susan
impoundment, the following quantities of sediment have been estimated for removal from
the recommended removal. areas.
1. Primary Sediment Removal Area ------------------- 1000 cubic yards
2. Streambed Channel Excavation ------------------- 1500 cubic yards
3. Primary Sediment Storage Area. -----=------------- 1500 cubic yards
4. Perimeter Sediment Removal Areas ---------------- 500 cubic yards
Total 4500 cubic yards
Note that some of the sediment depth estimates were based upon extrapolation of
available sediment depth data. - As such, actual quantities of sediment that must be
removed may vary from those estimated by volume calculations.
SEDIMENT REMOVAL CONSTRUCTION SEQUENCE
While it is not the intent of Marks Enterprises to direct the work of the Contractor, the
following sequence of construction is provided to assist the Contractor in development of
a Construction Plan and. Construction Schedule that will be satisfactory to the Owner and
provide for successful completion of the Sediment Removal Plan. Some of the indicated
activities can be conducted concurrently even though presented in a sequenced manner.
5
SEDIMENT REMOVAL PLAN November 1, 2001
Lake Susan Impoundment Job No. MEEC-01-023
Montreat, North Carolina
1. Lake Susan shall be lowered from the normal pool elevation to a
completely drained condition by gradually opening the bottom drain sluice
gate in the spillway structure. The rate of drawdown shall not exceed
about one foot per day to preclude to potential for rapid drawdown failure
of the rim of the impoundment and/or the perimeter rock walls. Employees
of the Mountain Retreat Association (Owner) shall control dewatering of
Lake Susan so that the rate of drawdown can be closely controlled.
2. Prior to excavation of sediment from the Primary Sediment Removal
Area, the Contractor shall construct a temporary sediment detention check
dam upstream of the spillway bottom drain sluice gate. The sediment
detention check dam shall be constructed in accordance with the North
Carolina Erosion and Sediment Control Manual and/or as directed by the
Engineer (Marks Enterprises).
3. Sediment removal shall begin in the Primary Sediment Removal Area and
continue in a sequential manner to other removal areas, upstream and
laterally from the Primary Sediment Removal Area.
4. During the sediment removal and transport process, the Contractor shall
maintain all roads (North Carolina Highway 9) free of removed sediment.
This may require that the tires of all trucks be washed with high-pressure
water hoses prior to accessing North Carolina Highway 9. Owner
representatives and the Engineer will conduct routine inspections of all
access roadways.
6
November 1, 2001
SEDIMENT REMOVAL PLAN Job No. MEEC-01-023
r Lake Susan Impoundment
Montreat, North Carolina
CLOSURE
Again, Marks Enterprises of NC, PLLC is appreciative of the opportunity to be of
professional geotechnical engineering service on this project. If there are questions
concerning this report and/or the presented Sediment Removal Plan, or if we can provide
additional information, please contact us at your convenience.
Respectfully,
of N6-
B. eas?oo
Dan Marks, PhD., P.
Manager/Geotechnical Co NC Registration No. 964,1. oawsop0?
Attachment: Sketch of Sediment Removal Plan
8
LAKE SUSAN @ MONTREAT
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