20070410 Ver 1_More Info Received_20090409

07- 0 410
chnabe/
COSY
11-A Oak Br,
Greensboro,
?? n
is t=om
.+`•'?
Schnabel Engineering South, PC
April 6, 2009
Mr. Andy Williams
U.S. Army Corps of Engineers
3331 Heritage Trade Drive, Suite 105
Wake Forest, NC 27587
SUBJECT: City of Greensboro Lake Townsend Dam Spillway Replacement
Individual 404 Permit (SAW# 2007-00895-241)
Dear Mr. Williams:
As a follow-up to my letter to you on February 13, 2009 and your phone call to me on April 1, 2009,
this letter is to provide additional clarification regarding the disposal of materials resulting from
partial demolition of the spillway, pump station, and embankment during construction. This letter
and my previous letter of February 13 is in reference to Special Condition No. 8 of the approved
Section 404 Permit (SAW# 2007-00895-241) for the Lake Townsend Dam Replacement project.
Attached you will find three figures for clarification. The hatched area in Figure 1 shows the limits of
the dry disposal area. The hatched area in Figure 2 shows the limits of the area where clean material
(inert concrete that may contain rebar) can be placed. That area will be underwater after the new
spillway is constructed downstream and the gates are opened in the existing dam. The underwater
disposal area is located within the permitted impact area between the existing and proposed spillways
as previously proposed and would provide beneficial fish habitat for Lake Townsend. The hatched
area in Figure 3 shows where the existing embankment will be excavated below water level. Also
attached for your information is Section 02 41 16 of our Specifications for the project, entitled
Demolition. This section provides relevant information regarding demolition of the existing concrete
structures and earthen embankment. We have highlighted specific requirements in that section which
may be of special interest to you. Section 3.9 identifies which materials are suitable for on-site
disposal and which materials must be disposed of off-site. On-site materials can be placed in the dry
disposal area or in the underwater disposal area between the old and new spillways, as shown on
Figure 2. No additional impacts to waters of the U.S., including wetlands, will occur as a result of
on-site disposal of demolition debris or excavated material.
I hope this information provides you with the information you requested. If everything is suitable, we
would appreciate your providing us with an email or letter letting us know. Thank you for your
support in this matter.
"We are committed to serving our clients by exceeding their expectations."
Geotechnical 0 Construction Monitoring • Dam Engineering • Geoscience 0 Environmental
If you require any additional information or have any questions please feel free to contact at (336)
274-9456.
Sincerely,
Schnabel Engineering South, PC
J1.4rl Cvw4-1
Robert P. Cannon
Project Manager
RC/FS
Attachments
cc: Ian McMillan, DWQ;
Melinda King, City of Greensboro;
Shearin Dramby, Brown and Caldwell
FILE: G:\2006_ PROJECTSM210017(CITY OF GREENSBORO LAKE TOWNSEND)\CORRESPONDENCE\CORPS OR SEPA PERMITTING AGENCIESWILLIAMS 02-ADDRIONALINFORMATION ON BENEFICIAL
FILL-EXCAVATION.DOC
2
i SOUTH
BORROW -
AWA
SOUTH
BORROW AREA

MV, Iq
LAKE TOWNSEND
ME Approximate limits of disposal area; soil and debris to
be covered with minimum 2 feet of common fill
For Information LAKE TOWNSEND DAM PROJECT DISPOSAL AREA AT
Only
Not for Construction City of Greensboro EMERGENCY SPILLWAY
Greensboro, NC Figure 1
aAL
• .%

;-:--
ON& PM Uw
alum 040w -
k
up=
to"
FAMUS"
M 1K wi
Noma {M
PROMM

Approximate limits of disposal area to elevation 695.5;
maximum thickness of approximately 14 feet
For Information LAKE TOWNSEND DAM PROJECT DISPOSAL AREA BETWEEN
Only
Not for Construction City of Greensboro OLD AND NEW DAM
Greensboro, NC Figure 2
rrg:"Lrti'nt1b?
r
i
0111UL TOOL ta/r
MAom ow"
woff
I
0 AML
t
Lx'? IYr.OF'l111FJM1,OISIIMaN1CE
0,
11oV "
M 11[ wi
.s i .:?'K ? ,',kit'.. ?''_ $y'-•" 7?YYYYY':'?li?
i- -MUM VY FDN
PIIOPOSm 11011
.. ` IIIOFJI11?110t I I

Approximate limits of excavation of existing soils to elevation 695.5 ft. Normal pool
elevation is 715 ft. Contractor may opt to complete some of this excavation in the dry.
LAKE TOWNSEND DAM PROJECT AREAS OF EXISTING
For Information Only EMBANKMENT SOILS TO BE
Not for Construction City of Greensboro EXCAVATED BELOW WATER LINE
Greensboro, NC Figure 3
SECTION 02 41 16
STRUCTURE DEMOLITION
PART 1 GENERAL
1.1 SUMMARY
A. Work shall consist of disassembly or demolition, backfill, removal and disposal of structures
and equipment secured or within those structures at locations shown on Drawings, including:
1. South Retaining Wall
2. North Retaining Wall
3. Spillway Gates and Piers
4. Pump Station and Intake including equipment
5. Guide rails, fencing, pipelines, conduits, utilities and poles, and other
miscellaneous items within the limits of work.
B. Work includes demolishing existing 36-inch diameter raw water line from existing Pump
Station to just north of junction with new pump station water line and sealing end of 36-
inch diameter raw water line.
C. Related Sections:
1. Section 31 23 16 -Excavation
2. Section 31 23 24 - Flowable Fill
1.2 SUBMITTALS
A. Meet the applicable requirements of Section 013 3 00 - Submittal Procedures and Section
01 70 00 - Execution and Closeout Requirements.
B. Submit qualifications of subcontractor selected for demolition work, including
qualification of the person responsible for planning demolition activities and preparing
demolition plan.
C. Submit a Demolition Plan, indicating:
1. Schedule of demolition activities.
2. Required preparatory tasks.
3. Coordination with other construction activities such as erosion and sediment
control and stream diversion.
4. Proposed demolition methods for each structure or facility, including equipment
needs.
5. Material disposal plans.
6. Any interruptions required for utility and other services.
Lake Townsend Dam Project Structure Demolition
024116-1
7. Procedures, personnel and equipment planned to meet the requirements of
Section 01 57 19 -Temporary Environmental Controls.
D. Demolition Plan shall also address the following project requirements:
1. Demolition includes removal of reinforced concrete, brick and mortar, steel
framing, and hoists and other equipment.
2. Disposal of concrete debris will be allowed in the reservoir as specifed herein.
3. An asbestos survey and lead paint assessment of existing Intake and Pump
Station has been completed and results shall be addressed and incorporated into
Demolition Plan.
4. Contractor shall be responsible for any required permits and for meeting all
applicable federal and state requirements.
5. Blasting will not be permitted.
6. Demolition is planned in three phases as shown on Drawings.
7. The start of each phase depends on completion of specific precursor construction
activities.
8. Some demolition will be completed in the dry, downstream of the reservoir.
9. Some demolition will be completed above the water line within the reservoir.
10. Some demolition will be completed below the water line within the reservoir,
11. Backfilling of partially demolished structures will be required as shown on the
Drawings.
12. Reinforcing steel shall not be left exposed in submerged debris or on submerge(
faces of structures and features to be only partially demolished.
13. Remove 36" diameter raw water pipeline from existing Pump Station to beyond
limits of the earth dam. Seal end of raw water line with a concrete bulkhead.
E. Submit Shop Drawings including:
1. Demolition and removal sequence.
2. Location and construction of temporary work and environmental controls.
F. As part of Closeout Submittals, provide Project Record Documents that accurately record
actual locations of:
1. Final configuration of partially demolished structures
2. Capped utilities
3. Concealed utilities discovered during demolition
4. Subsurface obstructions
5. Other unexpected conditions
6. Records and photos of demolition and backfilling activities
Lake Townsend Dam Project Structure Demolition
0241 16-2
7. Contents, lines and grades of materials disposed in the on-site disposal area
8. Types, volumes and locations of materials disposed of in the existing reservoir
1.3 QUALITY REQUIREMENTS
A. Shop Drawings shall be prepared under supervision of a Professional Engineer
experienced in structure demolition or, a demolition specialist with at least five years of
experience in demolition of concrete structures.
B. All shop drawings and calculations shall be signed and scalcd by a Professional Engineer
licensed in the State of North Carolina.
C. Shop Drawings shall be reviewed and approved by Engineer prior to commencement of
demolition work.
D. Obtain required permits from authorities having jurisdiction.
1.4 QUALIFICATIONS
A. Demolition shall be completed by personnel or a firm having a minimum of three years
experience in the demolition and disposal of reinforced concrete structures in marine
environments, including protection of sensitive waterways.
1.5 EXISTING CONDITIONS
A. Conditions existing at time of inspection for bidding purposes will be maintained by
Owner in so far as practicable. However, variations within facilities may occur by
Owner's removal and salvage operations prior to start of demolition work.
PART 2 PRODUCTS
2.1 GENERAL
A. Contractor shall be responsible for calculation of the required materials and supplies
based on Drawings, Shop Drawings, experience on similar projects, environmental
controls, and other factors as identified by the Contractor.
B.
C.
of Section 01 57 19 -Temporary
Lake Townsend Dam Project Structure Demolition
0241 16-3
The Contractor shall be responsible for all costs associated with delays or material
quantity shortfalls due to miscalculations, or required re-work resulting from not meeting
material or placement specifications.
PART 3 EXECUTION
3.1 EXAMINATION
A. Meet requirements of Section 01 30 00 - Administrative Requirements
B. Verify existing conditions before starting work.
3.2 PREPARATION
A. Prior to start of demolition, provide a 10 day notice to the Health Hazards Control Unit of
the North Carolina Department of Health and Human Services, as EPA representative.
B. Notify any affected utility companies before starting work and comply with their
requirements.
C. Arrange with each affected utility company or Owner to discontinue service and provide
for capped terminations and permanent shut offs, unless otherwise noted or as directed by
authorities having jurisdiction or Owner.
D. Preserve in operating condition active utilities and drainage transversing project site
including but not limited to mains, sewers, manholes, catch basins, valve boxes, poles,
guys, and other appurtenances.
E. Previously abandoned lines need not be removed, unless noted. Seal existing and
abandoned pipes with concrete plugs.
F. Mark location and termination of utilities.
G. Erect, and maintain temporary barriers and security devices, including warning signs and
lights as needed, and similar measures, for protection of on-site and visiting personnel.
H. Install oil booms, turbidity curtains, as specified in Section 01 57 19 - Temporary
Environmental Controls.
3.3 PROTECTION
A. Ensure protection of reservoir water from dust and debris during demolition activities.
B. Conform to permit requirements for environmental protection during demolition
activities.
C. Provide safe passage of persons around area of demolition.
D. Do not interfere with use of adjacent buildings. Maintain free and safe passage to and
from adjacent buildings.
E. Conduct operations to prevent injury to people and damage to adjacent buildings,
structures, and other facilities.
Lake Townsend Dam Project Structure Demolition
0241 16-4
F. Prevent movement, settlement or collapse of adjacent structures. Provide and place
bracing or shoring and be responsible for safety and support of structures. Assume
liability for such movement, settlement, damage, collapse or injury.
G. Provide shoring, bracing, or supports to prevent movement, settlement or collapse of
structures to be demolished until ready to be demolished.
H: Existing landscaping materials, structures, and appurtenances which are not to be
demolished shall be protected and maintained as necessary.
3.4 FIELD QUALITY CONTROL
A. Provide surveyor's support to demolition work to ensure demolition is taken to the lines
and grades as shown on Drawings or approved Shop Drawings.
B. Any repairs, rework or replacement of structural, landscaping, or other materials that may
be required due to Contractor's failure to meet requirements of these specifications shall
be at the discretion and direction of Engineer.
C. Such repairs, rework and/or replacement shall be completed by Contractor as directed by
Engineer at no cost to Owner.
3.5 SALVAGE
A. Items designated for salvage to Owner shall be removed in a workmanlike manner and
neatly stored. Items not designated for salvage to Owner shall become property of
Contractor and shall be removed from site.
B. Owner has designated the following for salvage:
1. One set of spillway bulkheads consisting of a matched upper and lower panel.
Remove and store at Lake Brandt Dam maintenance yard after spillway
bulkheads arc no longer needed.
2. Ten AUMA spillway gate operators and associated electric motors, shafting and
shaft guards. Not included are right angle gear drives, pedestals, stems and
remaining portions of spillway gates and operators. Locate and store as directed
by Owner.
3. Portions of existing spillway aluminum grating to be reused in new outlet works.
4. Remove and salvage elevation numbers embedded in concrete adjacent to staff
gages on existing downstream south retaining wall and north upstream retaining
wall for possible reuse on new construction headwater and tailwater staff gages.
C. Contractor shall temporarily salvage and store existing aluminum spillway stop logs on
site until existing spillway gates are no longer needed for diversion.
D. Items capable of disassembly shall be dismantled into individual components or
subsections.
Lake Townsend Dam Project Structure Demolition
0241 16-5
E. Conduct salvage operations before demolition begins to remove materials Owner chooses
to retain.
3.6
3.7
F. Except as otherwise provided, Contractor shall be permitted to salvage materials
proposed for demolition and removal at his discretion.
G. Contractor shall be allowed to temporarily stockpile salvaged materials at locations
approved by Engineer. Neither Engineer nor Owner shall assume responsibility for
protection and safekeeping of such material.
H. All salvaged materials must be removed from the property before final acceptance of the
work.
SELECTIVE REMOVALS
A. Conduct selective removals in accordance with approved Demolition Plan and Shop
Drawings.
B. Completely remove all items and appurtenances indicated for removal in an orderly and
careful manner. Such items include intake and pump station motors, equipment, cabinets,
piping, conduits, and any other loose or detachable items; the stop log trolley and hoist;
and spillway gates once no longer needed for regulating releases.
C. Remove from site and legally dispose of all removed items, appurtenances and other
materials resulting from removal operations that are of no salvage value to Owner.
D. Repair damage to adjacent structures cause as the result of this work at no cost to Owner.
DEMOLITION
A. Conduct demolition in accordance with approved Demolition Plan and Shop Drawings.
B
C.
D.
E.
F.
Demolish structures in a manner to prevent damage to adjacent sound concrete,
appurtenances, facilities, or equipment.
Contractor may use any method to demolish structures, except as noted, provided its
operations do not damage underlying or adjacent concrete or any portion that is to remain
in place.
Reinforcing steel or other embedments may be encountered in portions of concrete to be
removed and no additional compensation will be allowed for concrete demolition
containing steel or embedments.
Cease operations immediately if and when any structure or facility appears to be in
danger and notify the Engineer immediately.
Cap and identify abandoned utilities at termination points when utility is not completely
removed.
Lake Townsend Dam Project Structure Demolition
0241 16-6
G. Annotate Record Drawings indicating location and type of service for capped utilities
remaining after demolition.
H. Backfill and compaction for partially demolished structures shall be in accordance with
Section 31 23 24 - Flowable Fill and Section 31 23 23 - Fill Placement.
1. Remove temporary work.
3.8 BACKFILL OF PARTIALLY DEMOLISHED STRUCTURES
A. The pump station and intake will be only partially demolished. Pump station and intake
shall be completely demolished to limits shown on the Drawings. Portions below
elevation noted on the drawings shall have all equipment, piping, fixtures, and
miscellaneous debris removed.
B. Complete backfill of interior of remaining pump station and intake using flowable
backfill as indicated on Drawings and specified in Section 31 23 24 - Flowable Fill or as
directed by Engineer.
3.9 REMOVAL AND DISPOSAL
A.
B.
C.
D.
E
Site debris, rubbish, and other materials resulting from demolition operations shall be
removed and disposed of in compliance with all applicable laws and regulations.
Do not burn materials on site.
Dispose of materials as indicated on the following table:
Demolition Material
Disposal Options
Lake Townsend Dam Project Structure Demolition
0241 16-7
F. Disposal of approved materials near the existing emergency spillway shall be performed
with the following requirements:
1. Mass concrete, brick and concrete block shall be crushed to a size smaller than
eighteen inches prior to disposal.
2. Debris shall be mixed with soil to minimize void space.
3. A minimum of 3 feet of Common Fill shall be placed over the debris for closure
of the disposal area.
4. Final grades in the disposal area shall have a maximum slope of 5 horizontal to 1
vertical, provide positive drainage, and shall not exceed elevation 723.0.
5. Final grades shall receive 6 inches of topsoil and permanent vegetation in
accordance with Section 32 92 19, Seeding.
G. Disposal of approved materials between the existing primary spillway and the proposed
primary spillway shall be performed with the following requirements:
1. Mass concrete, brick and concrete block shall not be placed above elevation
695.5 feet.
2. Materials shall be crushed so that the maximum dimension is 36 inches. Material
shall be placed uniformly over the disposal area in a manner to minimize voids.
Maximum slopes of 3 horizontal to 1 vertical shall be maintained.
3. Disposal materials shall not be placed within 25 feet of the proposed spillway.
END OF SECTION
Lake Townsend Dam Project Structure Demolition
0241 16-8