HomeMy WebLinkAboutCC AG PKT 2004-09-27 #T AGENDA REPORT
DATE: September 27, 2004
TO: Honorable Mayor and City Council
THRU: John B. Bahorski, City Manager
FROM: Mark K. Vukojevic, P.E., Interim Director of Public Works /City Engineer
SUBJECT: SAND RETENTION GROIN REHABILITATION PROJECT
No. 50147 DESIGN UPDATE — RECEIVE AND FILE
SUMMARY OF REQUEST:
The proposed action will receive and file the design update for the Sand Retention Groin
Rehabilitation Project No. 50147.
BACKGROUND:
On its February 23, 2004 meeting, the City Council received and filed additional information
regarding the status of the Sand Retention Groin Rehabilitation Project. In addition, Council was
briefed on the 2001 Groin Feasibility study, which helped secure the grant funding from the
Department of Boating and Waterways (DBAW). Moffat and Nichol Engineers, the City's
Coastal Engineering Consultant has prepared a Rehabilitation Study also known as a preliminary
design report for the Sand Retention Groin Rehabilitation Project. Staff and the consultant have
worked closely together in providing the information on the repair alternatives, environmental
impacts, and permit requirements. The consultant has also discussed the project with the
California Coastal Commission and the Department of Boating and Waterways. A copy of the
report is attached.
The Study recommends alternative 7 as the most feasible alternative. This will include the
reinforcement of the outer 252 -feet by the installation of new sheet piles on one side, installation
of new sheet piles on the opposite side of the damaged piles, construction of a new cap for 350 -
feet and repairing the remainder of the cap. However, construction will require the use of large
cranes and the closure of the Pier during construction. The study has also identified the need for
sequential permits from Regional Water Quality Control Board (RWQCB), California Coastal
Commission (CCC) and US Army Corps of Engineers (USACE). A California Environmental
Quality Act (CEQA) review also indicates the project will likely require a Mitigated Negative
Declaration as it may cause environmental impact that can be mitigated.
Staff is negotiating costs with the City's on -call environmental consultant for these
environmental services, as they are the next steps in the process. Processing of the CEQA, the
potential Mitigated Negative Declaration and the various permits is expected to take 8 to 12
months. Funding from the Department of Boating and Waterways expires in January 2007.
Agenda Item r
FISCAL IMPACT:
Funds are available within the Project No. 50147 of the approved Capital Improvement Program.
The estimated total cost of the project including design, environmental, permitting, construction
and inspection $1,067,000 which is funded by $800,000 from DBAW. $267,000 was funded
from the undesignated general fund reserve as authorized by City Council on February 10, 2003.
No additional work will be performed unless adequate funding is available in the project budget.
Any funds remaining at the end of this phase of the project will be returned to DBAW and the
City's General Fund.
RECOMMENDATION:
It is recommended that the City Council receive and file the design update for the Sand Retention
Groin Rehabilitation Project No. 50147.
Prepared By:
Raymond H. Velasco
Associate Engineer
Reviewed By:
/v/7'
M. K. Vukojevic, P.E.
Interim Director Public Works /City Engineer
NOTE r ND APPR ED:
41
J o /41B. Bahorski
• Manager
Attachment: Groin Rehabilitation Study, August 2004
Agenda Item
GROIN REHABILITATION STUDY
SEAL BEACH, CALIFORNIA
Prepared For:
CITY OF SEAL BEACH
211 8th Street
Seal Beach, CA 90740
Prepared By:
MOFFATT & NICHOL
250 West Wardlow Road
Long Beach, CA 90807
M &N File: 3874 -11
August 2004
EXECUTIVE SUMMARY
The beaches within Seal Beach serve as major local and regional attractions. The
beaches provide recreational opportunities for residents and visitors, as demonstrated by
the million plus visitors who come to visit the beaches each year. In addition to the
recreational benefit, a sandy beach provides natural protection for the adjacent public and
private property against coastal flooding and storm wave damages.
A concrete sheet pile groin was constructed by the US Army Corps of Engineers in 1959,
as part of a beach erosion control project. The purpose of the project was to mitigate the
impacts of the construction of adjacent navigation structures at Anaheim Bay on beach
erosion. Without the groin, it is anticipated that East Beach would retreat significantly,
placing both public and private property at risk.
The groin is now over 45 years old and in need of repair. A recent feasibility study for
the groin repair clearly established through a benefit cost analysis that the repair was
warranted (5 to 1 benefit -to -cost ratio). Groin repair was identified as the least cost
alternative with a net economic benefit. This alternative is also environmentally superior
to the other alternatives.
The purpose of the present study is to evaluate the various repair or replacement
alternatives that meet the long term repair goals of the City, are consistent with local,
state and federal environmental quality guidelines, and can be fully implemented within
the $800,000 project budget.
The results of the study are summarized on the table included on the following page.
With the funds currently available it is not feasible to replace the entire groin. There are
several repair, reinforcement, and replacement alternatives that can be accomplished
within the funds available and are considered feasible. These include:
• Alternative 2 - Replacement of the outer 252 feet of the sheet piles and 350 feet of .
cap, and repair of the cap landward of that section.
• Alternative 6 - Reinforcement at damaged piles only with a new cap over the entire
length.
• Alternative 7 - Reinforcement of the outer 252 feet by installing new sheet piles on
one side, plus installing new sheet piles on the opposite side at damaged piles, and
constructing a new cap for 350 feet and repairing the remaining cap.
We recommend that the reinforcement alternative (Alternative 7) be chosen as it will
result in a stronger, longer- lasting structure. If more funds become available, we
recommend that the remainder of the cap also be replaced. We further recommend
against the alternative of replacing the damaged sheet piles, as this alternative may be
impossible to construct and would then require changing the alternative while the cap is
already removed and the groin is vulnerable.
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TABLE OF CONTENTS
EXECUTIVE SUMMARY i
1.0 INTRODUCTION 1
1.1 Background 1
1.2 Purpose 2
1.3 Scope 2
2.0 STATEMENT OF THE PROBLEM 3
2.1 Historic Setting 3
2.2 Shoreline Dynamics 3
2.3 Sand Management Program 3
2.4 Importance of the Groin in Maintaining the Public Beach 5
3.0 EXISTING GROIN CONDITION 6
3.1 Original Groin Construction 6
3.2 Summary of Past Observations 6
3.3 Present Groin Condition 7
4.0 DESIGN WAVE LOADING 10
4.1 Water Levels 10
4.2 Wave Conditions 10
4.3 Wave Forces 10
5.0 ALTERNATIVES ANALYSIS 11
5.1 Without- Project Alternative 11
5.2 Repair or Replacement Alternatives 11
6.0 CONSTRUCTION AND STAGING ISSUES 30
6.1 Construction Equipment and Access 30
6.2 Construction Staging 30
7.0 CONSTRUCTION AND MAINTENANCE COSTS 32
7.1 Construction Cost Summary 32
7.2 Detailed Cost Estimate for Alternatives 33
7.3 Maintenance Cost 42
8.0 PERMIT REQUIREMENTS 44
8.1 Sections 10 and 404 Permit from the U.S. Army Corps of Engineers 44
8.2 California Environmental Quality Act 44
8.3 Section 401C Certification from the Regional Water Quality Control Board 45
8.4 Coastal Development Permit from the California Coastal Commission 45
9.0 SUMMARY AND RECOMMENDATIONS 46
1.0 INTRODUCTION
1.1 Background
Seal Beach is located in northern Orange County, California, between the City of Long
Beach and the Seal Beach Naval Weapons Station (SBNWS). Approximately one mile
of coastline lies along the southwest City boundary. The City's beaches serve as major
local and regional attractions. The beaches provide recreational opportunities for
residents and visitors, as demonstrated by the million plus visitors who come to visit the
beaches each year. In addition to the recreational benefit, a sandy beach provides natural
protection for the adjacent public and private property against coastal flooding and storm
wave damages.
A concrete sheet pile groin was constructed by the US Army Corps of Engineers in 1959,
as part of a beach erosion control project. The purpose of the project was to mitigate the
impacts of the construction of the SBNWS navigation structures at Anaheim Bay on
beach erosion. The groin is located immediately to the west of the Seal Beach Pier and
helps stabilize the sandy shoreline by reducing the erosion rate of sand from East Beach.
Without the groin, it is anticipated that East Beach would retreat significantly, placing
both public and private property at risk.
The groin is now over 45 years old and deteriorated. A portion of the groin failed in
March of 2001, resulting in a large gap between sheet piles. The gap presented a
transport path for sand eroded from East Beach, a point of undermining of adjacent sheet
piles, and a very significant hazard to swimmers and surfers. It was temporarily repaired
by installing steel sheet piles on each side of the breach.
The City of Seal Beach recently entered a Beach Erosion Control Construction
Agreement with the State of California Department of Boating and Waterways (DBAW)
for repair or replacement of the groin. DBAW is authorized under the Harbors and
Navigation Code Section 65.2 to cooperate with a municipal agency to plan and construct
beach erosion projects for the best interest of the State. The feasibility study for the groin
repair, attached as an appendix to this report, clearly established through a benefit cost
analysis that the repair was warranted (5 to 1 benefit -to -cost ratio). Other alternatives
evaluated in the feasibility study included groin repair and extension, an offshore sand
retention reef, and beach nourishment. Groin repair was identified as the least cost
alternative with a net economic benefit. This alternative is also environmentally superior
to the other alternatives. The DBAW policy establishes a maximum 75 percent share and
a minimum 25 percent local agency match. The maximum amount of the agreement for
the groin repair is $800,000.
The without - project condition, as described in the preceding feasibility study, must be
considered to comprise removal of the groin, since allowing the groin to continue to
deteriorate and pose significant public safety risk is unacceptable. Removal of the groin
will result in an increase in the sand erosion rate from East Beach on the order of 50
percent. The beach at the narrowest portion of East Beach could be lost within a matter
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of a few years, thereby exposing the public promenade, public street ends and private
residences to coastal flooding and wave - induced damage without significant beach
renourishment and accelerated backpassing from West Beach. As stated above, the
benefit to cost ratio of repairing the groin is five times that of the no- project alternative of
groin removal with increased renourishment.
1.2 Purpose
Given that groin repair is the appropriate course of action, this report represents the first
step in the long -term groin rehabilitation project. The purpose of this report is to evaluate
the various repair / replacement alternatives that meet the long term repair goals of the
City, are consistent with local, state and federal environmental quality guidelines, and can
be fully implemented within the project budget.
1.3 Scope
The following summarizes the scope of the groin rehabilitation study:
1. Review existing studies and data relevant to site conditions and the existing
structure.
2. Observe the present condition of the groin.
3. Estimate design loads for the groin structure.
4. Develop a range of alternatives for the groin repair or replacement. Include
discussion of groin removal and no- repair options.
5. Provide a preliminary assessment of environmental impact issues.
6. Conduct a review of field conditions and constructability assessment.
7. Estimate construction and maintenance costs.
8. Determine permit requirements for the project.
9. Prepare a report summarizing the study findings, including a recommendation
for the final design alternative.
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2.0 STATEMENT OF THE PROBLEM
2.1 Historic Setting
Construction of navigation structures and flood control improvements has resulted in
significant impacts to the littoral processes in the vicinity of Seal Beach. Construction of
jetties on both sides of Seal Beach has transformed the shoreline into a pocket beach,
which is almost totally isolated from sand transport from adjacent beaches. In addition,
upstream flood control improvements to the San Gabriel River and its tributaries have
caused a dramatic decrease in the amount of sand supplied by the river to the beach.
Figure 2 -1 illustrates these features on a site map.
The U.S. Army Corps of Engineers constructed the pre- stressed concrete sheet pile groin
in 1959 to mitigate erosion caused by the construction of the Anaheim Bay west jetty and
to prevent serious beach erosion. The groin retains a higher and wider beach at East
Beach than would otherwise occur. The beach provides both public recreation
opportunities and increased protection to public and private property from wave and
flood damage.
2.2 Shoreline Dynamics
The Long Beach offshore breakwater shelters Seal Beach from waves approaching from
the west. This significantly reduces the amount of easterly sand transport, which would
otherwise tend to nourish the eastern segments of East Beach and West Beach.
Additionally, the Anaheim Bay west jetty has resulted in a local increase in westerly sand
transport at the eastern end of East Beach. This increase is attributed to reflection of wave
energy off the jetty. Waves approaching from the west are reflected off the jetty and
redirected westward. The wave energy in the vicinity of 13th Street and Dolphin Street is
amplified due to constructive interference between intersecting wave trains.
Consequently, longshore sediment transport to the west is increased at this specific
location, causing localized erosion. The farthest landward position of the MLLW contour
lies between 13th and Dolphin Streets, while the areas adjacent to the San Gabriel River
and the Anaheim Bay West Jetty are consistently wide beaches. According to a previous
sediment budget analysis', East Beach is losing material which moves around and over
the Pier groin, offshore and through the west jetty of Anaheim Bay, at a rate of 4,200 to
7,800 cubic yards per year. This causes the beach to recede at roughly 1.75 to 3.25 feet
per year.
2.3 Sand Management Program
The City of Seal Beach has facilitated protection of a public promenade, public street
ends and private residences directly behind East Beach from winter storms by
Moffatt & Nichol (1984), The Winterization of Seal Beach, prepared for City of Seal Beach.
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-4-
constructing a sand dike on the beach between the residences and the ocean. The dike is
generally effective, but occasionally becomes overtopped by large waves during high
tides. Sporadic replenishment of the cell from maintenance dredging from the mouth of
the San Gabriel River and Anaheim Bay, and backpassing from the West Beach have
created periods of high nourishment followed by long periods of minor or no
nourishment. The material from the maintenance dredging is often fine sand and is
therefore quickly carried offshore. This allows the beach to erode to dangerously low
levels where the dike is subject to wave attack and overtopping. Severe stone waves
have flooded the promenade and damaged residences in the past.
The City also purchases beach fill material if funds are available when the beach becomes
extremely narrow and /or economical purchase opportunities exist, such as adjacent
dredging projects implemented by the U.S. Navy and/or the U.S. Army Corps of
Engineers. This precarious beach condition was substantially improved in 1997 -98 by
beach replenishment funded by DBAW. As a result of the beach replenishment and
ongoing backpassing, the beach is now significantly wider than in recent history, and
affords improved protection to coastal properties.
2.4 Importance of the Groin in Maintaining the Public Beach
Retention of sand on East Beach is greatly augmented by the Seal Beach groin, a 750 -
foot long concrete sheet pile groin constructed immediately adjacent to the Seal Beach
pier. Again, the purpose of constructing the groin by the US Army Corps of Engineers
was to reduce the sand loss at East Beach caused by construction of adjacent Federal
navigation structures.
The groin has not been maintained since its construction in 1959 and is now experiencing
severe deterioration; emergency repairs were constructed in July 2001. The groin has
deteriorated enough to potentially collapse, which would cause rapid and catastrophic
losses of sand on both East Beach and consequent loss of public beach and damage to
coastal properties. Such a failure would also pose public safety issues considering the
popular swimming and surfing activities on the beach immediately adjacent to the groin.
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3.0 EXISTING GROIN CONDITION
This section summarizes the original groin construction and describes its present
condition.
3.1 Original Groin Construction
The pre - stressed concrete sheet pile groin was constructed in 1959. The groin is 750 feet
long, with a top elevation ranging from +13 feet above mean lower low water (MLLW) at
the near shore end to +5 feet MLLW at the offshore end. Five pile sections were
designed for various locations in the groin. These varied from 3 feet wide by 9 inches
thick to 2 feet wide by 22 inches thick; pile lengths range from 22 to 44 feet. The piles,
weighting from 4 tons to 12 tons, were jetted into place using a rubber tire crane on the
pier. The concrete pile cap was poured in place and structurally connected to the piles by
means of continuous reinforcement.
3.2 Summary of Past Observations
Moffatt & Nichol inspected the groin in 1985. The inspection revealed deterioration of
the cap, spalling of the concrete cap and sheet pile and rusting of reinforcement. Concern
was raised for the potential of sheet pile failure resulting from cap failure, which would
create a gap within the sheet piles which would allow transmission of sand away from
East Beach. Wearing of shear keys was also observed.
The groin was inspected again in 1994, confirming that these conditions had progressed.
The City also noted deterioration of the chain -link fence along the pile cap. The 1985
inspection report indicated that without repair, the shear keys would be severely worn and
portions of the cap could be lost. The groin was inspected again in 2000, confirming that
these conditions had progressed.
By March 2001, a portion of the groin failed. At a point approximately across the pier
from the lifeguard tower, from Station 9 +10 to Station 9 +50 as identified in the 1985
inspection report, the cast in place concrete cap for the groin had completely broken
apart. A section over four sheet piles had fallen off and exposed the now unsupported
piles. One of the exposed piles had failed leaving a gap in the wall through which water
passed at high velocities both ways during the passing of each wave. The portion of the
cap section that remained had rotated and appeared ready to fail under severe wave
action. This condition not only presented a hazard to surfers and swimmers, but a
potential conduit for loss of sand from East Beach and a precursor to more extensive
groin failure. A temporary repair at the gap was constructed in July, 2001 using steel
sheet piles, wales, clamping bolts, and temporary fill material. The cost to the City was
approximately $110,000.
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3.3 Present Groin Condition
Photos 1 through Photo 4 are representative photographs of the current groin condition,
including the 2001 groin repair. The following summarizes our observations of the groin
condition during a —1.0 feet mean lower low (MLLW) tide on February 16, 2004.
1. The concrete cap is spalled at the top and bottom corners extensively over its
entire length.
2. There is one sheet pile that is spalled and cracked, though no reinforcing or
strands were observed to be exposed. In general, the sheet piles were not
observed to be significantly deteriorated. There is some spalling and rust staining,
though the staining could be from the corrosion in the cap.
3. The sheet piles that were observable were in useable condition except at the
temporary repair area.
4. The seaward end of the groin should be inspected if repairs include the existing
structure. The cap must be inspected at this outer end to determine the extent of
corrosion.
5. Regarding evaluation of the pile condition, it may be prudent if their remaining
life expectancy is an issue to conduct chloride concentration testing. The same
thing could be used for the cap although the cap is obviously spalling. This will
require careful evaluation.
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-8-
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-9-
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4.0 DESIGN WAVE LOADING
This section evaluates the environmental loading conditions to be included in the
evaluation of the groin repair design.
4.1 Water Levels
Tide characteristics consist of semi - diurnal tides with an average daily range of
approximately 6 feet. The annual extreme tides are generally slightly above +7 feet,
MLLW. The highest tide recorded at the nearest tide station (Los Angeles) was +7.96
feet, MLLW on January 27, 1983. This event has a recurrence interval of approximately
100 years. The 20 -year recurrence interval water elevation is +7.7 feet MLLW. These
water levels include El Nino Southern Oscillation effects and storm surge, but do not
include local wave - induced setup.
4.2 Wave Conditions
Waves approach the project site from a directional window oriented to the south through
the northwest. Northwest swell and southerly seas typically approach the site in winter;
southern hemisphere swell and tropical hurricane swell approach in summer. Large
waves are usually due to the combination of northern swell and locally generated seas
during the winter. Most storm damage is due to these large waves which have breaking
wave heights as high as 18 feet for an event with a 10 -year recurrence interval. The
locally generated seas have wave periods ranging from 6 to 14 seconds and the swells
have periods ranging from 12 to 22 seconds. Flooding and damage to Seal Beach
typically occurs during times of combined high waves and high tides in winter.
4.3 Wave Forces
Based upon the effective performance of the groin since its construction in 1959, the
wave force formulation used in that design is appropriate for the current design. The
wave force calculations prepared for the original design will be applied to this design and
updated as appropriate. The proposed groin repair or replacement alternative will be
comparable in design capability and structural capacity to the original design, and the
project will perform in a similar fashion.
-10-
5.0 ALTERNATIVES ANALYSIS
The following summarizes our assessment of the viable long -term repair alternatives for
the groin. Included as a baseline for comparison is the without- project alternative.
5.1 Without - Project Alternative
Allowing the groin to continue to deteriorate is not an acceptable long -term solution due
to the significant public safety risk and liability associated with the potential for
catastrophic failure of the groin. Therefore, the without- project alternative comprises
removal of the groin before catastrophic failure occurs and accelerated beach
nourishment and sand backpassing from West Beach to offset the increased erosion rate
at East Beach. The erosion rate at East Beach was estimated to increase by
approximately 50 percent, from 6,000 cubic yards per year to 9,200 cubic yards per year.
As described in the groin repair feasibility report appended to this study, the benefit to
cost ratio for groin repair is 5 to 1, using the without - project described above as the
baseline condition.
From an environmental standpoint, the accelerated beach nourishment and sand
management requirements will increase impacts to air quality from earth moving
equipment and public access.
There will also be a significant regulatory issue associated with the removal of the groin
since its construction was a 100 percent federally - funded and constructed project.
5.2 Repair or Replacement Alternatives
A range of alternatives are considered for either the repair or replacement of the existing
groin structure. The new groin sheet piles are either replacements to the existing concrete
sheet piles, or positioned adjacent to the existing sheet piles, depending on the alternative.
These alternatives, including variations, are described below.
5.2.1 Alternative 1 - Replace Entire Groin
This alternative consists of removing the entire cast -in -place concrete cap, extracting the
existing prestressed sheet piles and disposing of them at an appropriate waste facility,
installing new prestressed sheet piles in the location of the removed sheet piles, and
casting a new concrete cap for the entire groin (see Figure 5 -1).
Advantages:
1. The finished groin is identical in appearance and footprint to the original.
2. All new materials throughout.
3. Longest service life.
-11-
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- 1 2-
Disadvantages:
1. Most costly alternative exceeds maximum groin repair budget.
2. Construction stability of new sheet piles. Jetting for removal of existing
piles, and subsequent jetting for installation of the new piles will
temporarily increase the length of fixity for the new concrete sheet piles.
Environmental forces may also add to the instability, until the sand returns
to its more compacted state.
3. Groin does not fully function while under construction.
4. Longest construction time.
5.2.2 Alternative 2 - Replace Seaward Portion of Groin
This alternative option replaces only the last 252 feet of concrete sheet piles and 350 feet
of cap. The end section of the groin exhibits the greatest damage from storm and decay.
The cap for the section of groin not being replaced will have its cracks and spalls repaired
(see Figure 5 -2).
Advantages:
1. Other than concrete coloring, the finished groin has a consistent
appearance and identical footprint.
2. New materials for the end groin section, where environmental forces are
greatest. Replaces all damaged and previously repaired sheet piling as
indicated in the inspection report'.
3. Long service life for end of groin section. Extend near -shore cap service
life through repairs.
Disadvantages:
1. Near -shore groin sheet pile service life is not extended.
2. Short-term construction instability of the newly replaced sections, as
described for Alternative 1.
3. Costly alternative, but meets maximum agreed groin repair cost.
4. The offshore half of the groin does not fully function while under
construction.
5. Long construction time.
2 Seal Beach Pier Seawall Inspection, Blackledge Diving, December 9, 2003.
-13-
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-14-
5.2.3 Alternative 3 - Replace Damaged Sheets In -Place
This alternative consists of removing the entire cast -in -place concrete cap, extracting the
existing damaged prestressed sheet piles, installing new prestressed sheet piles in the
location of the removed sheet piles, and casting a new concrete cap for the entire groin
(see Figure 5 -3).
Advantages:
1. The finished groin is identical in appearance and footprint to the original.
2. Uses the minimum amount of new materials.
3. Short construction time.
4. Lowest construction cost if successful.
Disadvantages:
1. May not be able to extract existing sheet piles.
2. May be impossible to drive new sheet piles between existing piles.
3. Does not extend service life of other sheet piles.
-15-
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-16-
5.2.4 Alternative 4 - Install New Sheet Piles Each Side Seaward
Portion of Groin With Full Cap Replacement
This alternative consists of removing the entire cast -in -place concrete cap, installing new
prestressed sheet piles on each side of the existing 12 -inch thick sheet piles for the outer
252 feet of groin, and casting a new concrete cap for the entire groin (see Figure 5 -4a and
Figure 5 -4b).
Advantages:
1. Does not require removing existing sheet piles.
2. Only slight visual change from existing.
3. Provides maximum service life for most vulnerable section of groin.
4. Half the construction time of Alternative 1.
Disadvantages:
1. Slight visual change from existing.
2. Larger footprint at sand level (340 square feet added).
3. Exceeds construction budget.
-17-
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-18-
/'_' -New Cast -Jn -Place Reinforced Concrete Cap
/".„.„
;' New Prestressed Concrete 8 "x3' Sheetpile (Typical)
f ,
'...-- Concrete Fill At Broken Sheetpile
- -Existing Concrete 12 "x3' Sheetpiles
TOP VIEW - ALTERNATIVE 4
Not To Scale
- ---New Cast -In -Place Reinforced Concrete Cap
Dowels Grouted Into Holes Cast In Sheetpiles
___ Structural Z4x3x1/2x0' -6" Each Side
/ ' W /Clamping Bolt - 2 Each Pile
_
l New Prestressed Concrete 8 "x3' Sheetpile (Typical)
,—
�` Water Level Varies
/ - Existing Concrete 12 "x3' Sheetpiles
/ter Sand Level Varies
/ :
TYPICAL SECTION - ALTERNATIVE 4
Not To Scale
Figure 5 -4b
Figure 5 -4b. Alternative 4
-19-
5.2.5 Alternative S - Install New Sheet Piles Each Side Seaward
Portion of Groin With Partial Cap Replacement
In order to reduce some of the rehabilitation cost, there exists the opportunity to replace
only the last 350 feet of cap, and repair the remaining portion (see Figure 5 -5a and Figure
5 -5b). This will provide the following advantages and disadvantages:
Advantages:
1. Does not require removing existing sheet piles.
2. Sheet piles will have only slight visual change from existing.
3. Provides maximum service life for most vulnerable section of groin.
4. Reduces cost over entire cap replacement.
Disadvantages:
1. Visual change between new and repaired cap.
2. Slight visual change from existing sheet piling.
3. Larger footprint at sand level (340 square feet added).
-20-
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-21-
- ...-----New Cast -In -Place Reinforced Concrete Cap
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---....„____ Existing Concrete 12 "x3' Sheetpiles
TOP VIEW - ALTERNATIVE., 5
Not To Scale
��.- -- New Cast -In -Place Reinforced Concrete Cap
• Dowels Grouted Into Holes Cast In Sheetpiles
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fif ill W /Clamping Bolt - 2 Farh Pile
8 / /1 --- - -- New Prestressed Concrete S "x3' Sheetpile (Typical)
i
Water Level Varies
"~ Existing Concrete 12 "x3' Sheetpiles
/ ----- Sand Level Varies
. r / r 4,-
TYPICAL SECTION - ALTERNATIVE 5
Not To Scale
Figure 5 -5b
Figure 5 -5b. Alternative 5
_11_
5.2.6 Alternative 6 - Install New Sheet Piles Each Side of Damaged
Sheets
This alternative consists of removing the entire cast -in -place concrete cap, installing three
or four new prestressed sheet piles on each side of the existing 12 -inch thick sheet piles,
and casting a new concrete cap for the entire groin (see Figure 5 -6a and Figure 5 -6b).
Advantages:
1. Small change in footprint (16 square feet) compared to the original groin.
2. Does not require removing existing sheet piles.
3. Relatively low construction cost.
4. Short construction time.
Disadvantages:
1. Areas of repair are obvious due to thickened sections over short lengths.
2. Slightly larger footprint at sand level.
-23-
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-24-
7 ., ›New Cast -In -Place Reinforced Concrete Cap
/ ,
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\�----- Existing Concrete 12 "x3' Sheetpiles
TOP VIEW - ALTERNATIVE 6
Not To Scale
New Cast -In -Place Reinforced Concrete Cap
r'
Dowels Grouted Into Holes Cast In Sheetpiles
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--� New Prestressed Concretc 8 "x3' Shectpile (Typical)
' / Water Level Varies
41 00 '` ---- -- Existing Concrete 12 "x3' Sheetpiles
V
mo t- Sand Level Varies
- :.14-: : / ..
TYPICAL SECTION - ALTERNATIVE 6
Not To Scale
Figure 5 -6b
Figure 6 -5b. Alternative 6
-25-
1
5.2.7 Alternative 7 - Install 252' New Sheet Piles One Side Plus 45'
On Other Side At Damaged Sheets
This alternative is a compromise between alternatives 5 and 6. New sheet piles are
installed adjacent to the existing on one side of the existing sheets for the outer 252 feet,
and new sheets are installed on the opposite side to encapsulated damaged piles and
replace only the last 350 feet of cap (see Figure 5 -7). This will provide the following
advantages and disadvantages:
Advantages:
1. Does not require removing existing sheet piles.
2. Sheet piles will have only slight visual change from existing.
3. Provides extended service life for most vulnerable section of groin.
4. Reduces cost over entire cap replacement, and is within construction
budget.
Disadvantages:
1. Visual change between new and repaired cap.
2. Slight visual change from existing sheet piling.
3. Larger footprint at sand level (198 square feet added).
-26-
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-27-
5.2.8 Steel sheet pile option:
Repair alternatives consisting of adding sheet piles on each side of the existing groin can
be constructed using steel sheet piles rather than prestressed concrete (see Figure 5 -8).
The advantages and disadvantages versus the concrete option are as follows:
Advantages:
1. Sheet piles are easier to install.
2. Requires lighter equipment on pier for installation.
3. Shorter installation time.
4. Reduces footprint (191 square feet for Alternative 4; 9 square feet for
Alternative 6; 110 square feet for Alternative 7).
Disadvantages:
1. Visual change in groin due to shape of sheet piles.
2. Requires protective coating on outside face of sheet piles.
3. Requires concrete fill between steel sheet piles and existing.
-28-
New Cast -1n -Place Reinforced Concrete Cap
�Eiisting Concrete 12'x3' Sheetpiles
/7 / _-- New PZ22 Steel Sheetpile (Typical)
•
\ ` \ `\- -- Concrete Fill At Broken Sheetpile
Concrete Fill In Cell
TOP VIEW - ALTERNATIVE 6 WITH STEEL SHEET PILE
Not To Scale
Note: Alternative 4 Similar With Steel Sheetpiles Continuous
New Cast -In -Place Reinforced Concrete Cap
• 111 _r— Dowels Welded to Sheetpiles In Concrete Filled Cells
/ — - Clamping Bolt - 1 Each Pile
_ ---- New PZ22 Steel Sheetpile (Typical)
�— Water Level Varies
/ r
i
' ~ Existing Concrete 12 "x3' Sheetpiles
Sand Level Varies
/
TYPICAL SECTION
ALTERNATIVE 4:6 WITH STEEL SHEET PILE
Not To Scale
Figure 5 -8
Figure 5 -8. Alternative 4 & 6 With Steel Sheet Pile
-29-
6.0 CONSTRUCTION AND STAGING ISSUES
6.1 Construction Equipment and Access
It is impractical and dangerous to attempt to do the construction using floating equipment
due to the open coast location and surf conditions at the groin. It is therefore imperative
that the construction must be done from the deck of the existing pier or from a temporary
trestle. A trestle is a temporary steel pier that is constructed next to the work as a
platform for the cranes and other equipment above the water and waves. This pier is
removed when the work is completed. However, the estimated cost to construct,
maintain, and remove the trestle will be between $250,000 and $500,000. For a project
of this size it is difficult to justify this added expense. Therefore, construction from the
existing pier is the only practicable approach for this project.
Since the original groin was constructed using the pier as the working platform, it has
been assumed that the equipment necessary to construct the proposed repair alternatives
will be adequately supported on the pier. To confirm this assumption, we analyzed the
configuration and load characteristics of three different cranes capable of handling the
required construction elements. The outrigger loads from cranes capable of handling the
concrete sheet piles and driving equipment will be too great to be supported directly on
the deck and stringers of the pier. As a result, it will be necessary for the crane to use
mats that span from pile cap to pile cap to distribute the loads to the pile caps and piles.
The outrigger spread and matting will occupy virtually the entire deck width except at the
widened areas such as the platform supporting the lifeguard tower.
Since the crane will occupy the deck during construction, the outer end of the pier will be
inaccessible except by boat unless a temporary cantilever walkway is constructed on the
eastern side of the pier in the area of the crane and supporting mats. A temporary
walkway should be a movable structure, long enough to get around the crane operation,
rather than extend over the entire construction length. Even with a temporary cantilever
walkway, it may be necessary to close the outer end of the pier while the crane is working
in close proximity to the lifeguard tower, if the tower prevents installation of the
walkway. At the end of the workday the outriggers can be retracted and provide passage
past the crane on the mats themselves. Closure of a section of the pier would occur for
up to two months, and temporary access could maintain sufficient recreational resources.
In summary, this project can be constructed using the existing pier as a working platform
provided matting is used to support the crane loads between pile caps. Access to the end
of the pier will be impacted by the construction and extra measures will have to be taken
if access must be maintained.
6.2 Construction Staging
The contractor will require a storage and staging area near the foot of the pier. This area
should have sufficient room for storage and sorting of one day's worth of sheet piles plus
a yard crane, storage trailer or shipping container, and room for other miscellaneous
-30-
equipment and supplies. If the manufacturing schedule cannot be coordinated with the
construction schedule, there would also need to be a storage yard in the vicinity for all of
the concrete sheet piles.
The East Beach parking lot has been used for this function in the past, and would serve
well again for this project. A contractor will use all of the space he is given, but a
reasonable minimum area would be six thousand square feet. The proportions will
depend on the space available and the operational needs of the contractor. A normal
configuration, when a parking lot is used, is to occupy two rows of parking and the aisle
between them for a length sufficient for the needs of the project.
-31-
7.0 CONSTRUCTION AND MAINTENANCE COSTS
7.1 Construction Cost Summary
The following two tables summarize the estimated construction costs for the various
repair /replacement alternatives studied. Alternatives that result in a construction cost
exceeding the agreed maximum cost of $800,000 are italicized.
Alternative Description Opinion of
Probable
Construction Cost
No Project Remove entire groin and accelerate beach Undetermined *
nourishment and sand management Future Cost
1 Replace entire groin 51,955,000
2 Replace seaward 252 feet of groin, replace seaward $745,000
350 feet of cap
3 Replace only damaged sheets, replace full cap $361,000
4 Encapsulate seaward 252 feet of groin with 51,139, 000
concrete sheet piles, replace full cap
Alternative 4 with steel sheet piles 51,696,000
5 Encapsulate seaward 252 feet of groin with 51,1 03,000
concrete sheet piles, replace outer 350 feet of cap
6 Encapsulate only damaged groin sheet piles with $506,000
new concrete sheet piles
Alternative 6 with steel sheet piles $491,000
7 Install 252 feet new sheets 1 side, 45 feet other side $795,000
and replace 350' cap
* Cost includes cost of groin removal and present value of annual cost increase in sand
management, storm damages and emergency response relative to groin repair. Costs
based on 2001 Feasibility Study (attached as appendix).
-32-
7.2 Detailed Cost Estimate for Alternatives
72.1 Alternative 1 - Replace Entire Groin
Alternative 1 replaces the entire groin with new construction. This is the most expensive
alternative, and its associated construction costs are shown below.
ITEM UNIT
NO. ITEM DESCRIPTION QUANTITY UNITS PRICE TOTALS
❑ Mob /Demob & Site Preparation
1 Mobilization 1 LS $ 30,000 $ 30,000
2 Pier Traffic Control 13 WKS $ 2,000 $ 26,000
3 Site Clean -up 1 LS $ 15,000 $ 15,000
Subtotal: $ 71,000
❑ Demolition & Removals
4 Remove Temporary Repair 1 LS $ 5,000 $ 5,000
5 Demolish & Dispose Cap 187 CY $ 300 $ 56,041
6 Extract & Dispose Sheetpiles 271 EA $ 900 $ 243,900
Subtotal: $ 304,941
❑ Construct New Groin
7 Furnish New 12 "x3' Sheetpiles 106 EA $ 2,800 $ 296,800
8 Furnish New 14 "x3' Sheetpiles 32 EA $ 3,000 $ 96,000
9 Furnish New 19 "x2' Sheetpiles 112 EA $ 2,200 $ 246,400
10 Furnish New 22 "x2' Sheetpiles 44 EA $ 2,400 $ 105,600
11 Install Sheetpiles 294 EA $ 750 $ 220,500
12 Construct New Cap 187 CY $ 750 $ 140,104
Subtotal: $ 1,105,404
Base Total: $ 1,481,345
10% Contingency: $ 148,135
TOTAL CONSTRUCTION:I $ 1,629,480
20% Design, Construction Management & Inspection: $ 325,896
TOTAL ESTIMATE: $ 1,955,375
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72.2 Alternative 2 - Replace Seaward Portion of Groin
This alternative is a modification to Alternative 1, where only the offshore section of
groin (outer 252 feet of sheet pile, and outer 350 feet of cap) is replaced with new
construction. The near shore groin sheet piles are left in place, and their associated
concrete cap is repaired at damaged and decayed locations.
ITEM UNIT
NO. ITEM DESCRIPTION QUANTITY UNITS PRICE TOTALS
❑ Mob /Demob 8s Site Preparation
1 Mobilization 1 LS $ 30,000 $ 30,000
2 Pier Traffic Control 8 WKS $ 2,000 $ 16,000
3 Site Clean -up 1 LS $ 15,000 $ 15,000
Subtotal: $ 61,000
❑ Demolition & Removals
4 Remove Temporary Repair 1 LS $ 5,000 $ 5,000
5 Demolish & Dispose Cap 89 CY $ 300 $ 26,666
6 Extract & Dispose Sheetpiles 84 EA $ 900 $ 75,600
Subtotal: $ 107,266
❑ Construct New Groin
7 Furnish New 12 "x3' Sheetpiles 84 EA $ 2,800 $ 235,200
8 Furnish New 14 "x3' Sheetpiles 0 EA $ 3,000 $ -
9 Furnish New 19 "x2' Sheetpiles 0 EA $ 2,200 $ -
10 Install Sheetpiles 84 EA $ 750 $ 63,000
11 Repair Landside Cap 1 LS $ 25,000 $ 25,000
12 Construct New Offshore Cap 97 CY $ 750 $ 72,916
Subtotal: $ 396,116
Base Total: $ 564,382
10% Contingency: $ 56,438
TOTAL CONSTRUCTION:I $ 620,820
20% Design, Construction Management & Inspection: $ 124,164
TOTAL ESTIMATE: $ 744,984
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7.2.3 Alternative 3 - Replace Damaged Sheets In -Place
This alternative replaces only the damaged concrete sheet piles. The entire cap is
replaced.
ITEM UNIT
NO. ITEM DESCRIPTION QUANTITY UNITS PRICE TOTALS
❑ Mob /Demob & Site Preparation
1 Mobilization 1 LS $ 30,000 $ 30,000
2 Pier Traffic Control 3 WKS $ 2,000 $ 6,000
3 Site Clean -up 1 LS $ 15,000 $ 15,000
Subtotal: $ 51,000
❑ Demolition & Removals
4 Remove Temporary Repair 1 LS $ 5,000 $ 5,000
5 Demolish & Dispose Cap 187 CY $ 300 $ 56,041
6 Extract & Dispose Sheetpiles 3 EA $ 900 $ 2,700
Subtotal: $ 63,741
❑ Construct New Groin
7 Furnish New 12 "x3' Sheetpiles 3 EA $ 2,800 $ 8,400
8 Install Sheetpiles 3 EA $ 3,333 $ 10,000
9 Construct New Cap 186.81 CY $ 750 $ 140,104
Subtotal: $ 158,504
Base Total: $ 273,245
10% Contingency: $ 27,325
TOTAL CONSTRUCTION:( $ 300,570
20% Design, Construction Management & Inspection: $ 60,114
TOTAL ESTIMATE: $ 360,683
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7.2.4 Alternative 4 - Install New Sheet Piles Each Side Seaward
Portion of Groin With Full Cap Replacement
This alternative installs 8 -inch thick concrete sheet piles on both sides of the offshore 252
feet of the existing groin. The voids in the damaged sheet piles are replaced with a
concrete fill. A new wider cap replaces the entire existing cap.
ITEM UNIT
NO. ITEM DESCRIPTION QUANTITY UNITS PRICE TOTALS
❑ Mob /Demob & Site Preparation
1 Mobilization 1 LS $ 30,000 $ 30,000
2 Pier Traffic Control 6 WKS $ 2,000 $ 12,000
3 Site Clean -up 1 LS $ 15,000 $ 15,000
Subtotal: $ 57,000
❑ Demolition & Removals
4 Remove Temporary Repair 1 LS $ 5,000 $ 5,000
5 Demolish & Dispose Cap 187 CY $ 300 $ 56,041
Subtotal: $ 61,041
❑ Construct New Groin
6 Furnish New 8 "x3' Sheetpiles 166 EA $ 2,760 $ 458,160
7 Furnish 8 "x1.5' Sheetpiles 4 EA $ 2,070 $ 8,280
8 Concrete Fill 4 CY $ 400 $ 1,600
9 Install Sheetpiles 170 EA $ 750 $ 127,500
10 Construct New Cap 249.07 CY $ 600 $ 149,444
Subtotal: $ 744,984
Base Total: $ 863,025
10% Contingency: $ 86,303
TOTAL CONSTRUCTION:) $ 949,328
20% Design, Construction Management & Inspection: $ 189,866
TOTAL ESTIMATE: $ 1,139,193
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The following alternative is similar to Alternative 4, but uses steel sheet piles instead of
concrete sheet piles for the existing groin encapsulation.
ITEM UNIT
NO. ITEM DESCRIPTION QUANTITY UNITS PRICE TOTALS
❑ Mob /Demob & Site Preparation
1 Mobilization 1 LS $ 15,000 $ 15,000
2 Pier Traffic Control 5 WKS $ 2,000 $ 10,000
3 Site Clean -up 1 LS $ 10,000 $ 10,000
Subtotal: $ 35,000
❑ Demolition & Removals
4 Remove Temporary Repair 1 LS $ 5,000 $ 5,000
5 Demolish & Dispose Cap 187 CY $ 300 $ 56,041
Subtotal: $ 61,041
❑ Construct New Groin
6 Furnish New PZ22 Sheetpiles 276 EA $ 1,610 $ 444,360
7 Epoxy Coat One Side 276 EA $ 113 $ 31,050
8 Concrete Fill 1363.56 CY $ 300 $ 409,066
9 Install Sheetpiles 276 EA $ 425 $ 117,300
10 Construct New Cap 249 CY $ 750 $ 186,805
Subtotal: $. 1,188,581
Base Total: $ 1,284,622
10% Contingency: $ 128,462
TOTAL CONSTRUCTION:I $ 1,413,084 I
20% Design, Construction Management & Inspection: $ 282,617
TOTAL ESTIMATE: $ 1,695,701
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72.5 Alternative 5 - Install New Sheet Piles Each Side Seaward
Portion of Groin With Partial Cap Replacement
This alternative is similar to Alternative 2, but it encapsulates the offshore section of the
groin instead of replacing it. The outer 252 feet of sheet pile are encapsulated, and outer
350 feet of cap is replaced with new construction. The remaining near shore groin sheet
piles are left in place. The remaining concrete cap is repaired at damaged and decayed
locations.
ITEM UNIT
NO. ITEM DESCRIPTION QUANTITY UNITS PRICE TOTALS
❑ Mob /Demob & Site Preparation
1 Mobilization 1 LS $ 30,000 $ 30,000
2 Pier Traffic Control 6 WKS $ 2,000 $ 12,000
3 Site Clean -up 1 LS $ 15,000 $ 15,000
Subtotal: $ 57,000
❑ Demolition & Removals
4 Remove Temporary Repair 1 LS $ 5,000 $ 5,000
5 Demolish & Dispose Cap 187 CY $ 300 $ 56,041
Subtotal: $ 61,041
❑ Construct New Groin
6 Furnish New 8 "x3' Sheet Piles 166 EA $ 2,760 $ 458,160
7 Furnish 8 "x1.5' Sheet Piles 4 EA $ 2,070 $ 8,280
8 Concrete Fill 4.00 CY $ 400 $ 1,600
9 Install Sheetpiles 170 EA $ 750 $ 127,500
10 Construct New Cap 130 CY $ 750 $ 97,222
11 Repair Near Shore Cap 1.00 LS $ 25,000 $ 25,000
Subtotal: $ 717,762
Base Total: $ 835,803
10% Contingency: $ 83,580
TOTAL CONSTRUCTION:I $ 919,383 1
20% Design, Construction Management & Inspection: $ 183,877
TOTAL ESTIMATE: $ 1,103,260
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72.6 Alternative 6 - Install New Sheet Piles Each Side ofDarnaged
Sheets
This alternative installs 8 -inch thick concrete sheet piles on both sides of the existing
groin, only in the vicinity of the damaged piles. The voids in the damaged sheet piles are
replaced with a concrete fill. A new cap replaces the entire existing cap.
ITEM UNIT
NO. ITEM DESCRIPTION QUANTITY UNITS PRICE TOTALS
❑ Mob /Demob & Site Preparation
1 Mobilization 1 LS $ 30,000 $ 30,000
2 Pier Traffic Control 3 WKS $ 2,000 $ 6,000
3 Site Clean -up 1 LS $ 15,000 $ 15,000
Subtotal: $ 51,000
❑ Demolition & Removals
4 Remove Temporary Repair 1 LS $ 5,000 $ 5,000
5 Demolish & Dispose Cap 187 CY $ 300 $ 56,041
Subtotal: $ 61,041
❑ Construct New Groin
6 Furnish New 8 "x3' Sheetpiles 20 EA $ 2,760 $ 55,200
7 Concrete Fill 4 CY $ 400 $ 1,600
8 Install Sheetpiles 20 EA $ 1,400 $ 28,000
9 Construct New Cap 249.07 CY $ 750 $ 186,805
Subtotal: $ 271,605
Base Total: $ 383,646
10% Contingency: $ 38,365
TOTAL CONSTRUCTION:I $ 422,011
20% Design, Construction Management & Inspection: $ 84,402
TOTAL ESTIMATE: $ 506,413
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The following alternative is similar to Alternative 6, but uses steel sheet piles instead of
concrete sheet piles for the regions where the existing groin requires encapsulation.
ITEM UNIT
NO. ITEM DESCRIPTION QUANTITY UNITS PRICE TOTALS
❑ Mob /Demob & Site Preparation
1 Mobilization 1 LS $ 15,000 $ 15,000
2 Pier Traffic Control 3 WKS $ 2,000 $ 6,000
3 Site Clean -up 1 LS $ 10,000 $ 10,000
Subtotal: $ 31,000
❑ Demolition & Removals
4 Remove Temporary Repair 1 LS $ 5,000 $ 5,000
5 Demolish & Dispose Cap 187 CY $ 300 $ 56,041
Subtotal: $ 61,041
❑ Construct New Groin
6 Furnish New PZ22 Sheetpiles 36 EA $ 1,610 $ 57,960
7 Epoxy Coat One Side 36 EA $ 75 $ 2,700
8 Concrete Fill 21.73 CY $ 100 $ 2,173
9 Install Sheetpiles 36 EA $ 850 $ 30,600
10 Construct New Cap 249.07 CY $ 750 $ 186,805
Subtotal: $ 280,238
Base Total: $ 372,279
10% Contingency: $ 37,228
TOTAL CONSTRUCTION: $ 409,507
20% Design, Construction Management & Inspection: $ 81,901
TOTAL ESTIMATE: $ 491,408
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72.7 Alternative 7 - Install 252' New Sheet Piles One Side Plus 45'
On Other Side At Damaged Sheets
This alternative is a compromise between alternatives 5 and 6. New sheet piles are
installed adjacent to the existing on one side of the existing sheets for the outer 252 feet,
and new sheets are installed on the opposite side to encapsulated damaged piles and
replace only the last 350 feet of cap.
ITEM UNIT
NO. ITEM DESCRIPTION QUANTITY UNITS PRICE TOTALS
❑ Mob /Demob & Site Preparation
1 Mobilization 1 LS $ 30,000 $ 30,000
2 Pier Traffic Control 5 WKS $ 2,000 $ 10,000
3 Site Clean -up 1 LS $ 15,000 $ 15,000
Subtotal: $ 55,000
❑ Demolition & Removals
4 Remove Temporary Repair 1 LS $ 5,000 $ 5,000
5 Demolish & Dispose Cap 97 CY $ 300 $ 29,166
Subtotal: $ 34,166
❑ Construct New Groin
6 Furnish New 8 "x3' Sheetpiles 98 EA $ 2,760 $ 270,480
7 Furnish New 8 "x1.5' Sheetpiles 2 EA $ 2,070 $ 4,140
8 Concrete Fill 4 CY $ 400 $ 1,600
9 Install Sheetpiles 100 EA $ 1,400 $ 140,000
10 Construct New Cap 130 CY $ 750 $ 97,222
Subtotal: $ 513,442
Base Total: $ 602,608
10% Contingency: $ 60,261
TOTAL CONSTRUCTION:I $ 662,869 1
20% Design, Construction Management & Inspection: $ 132,574
TOTAL ESTIMATE: $ 795,443
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7.3 Maintenance Cost
The relative maintenance performances of the presented alternatives are listed below, in
order of lowest relative maintenance cost to highest relative maintenance cost.
Lowest 1. Alternative 1— Replace entire groin. This alternative is an entirely new
Relative groin structure. Because of the availability of higher strength concrete
Cost with lower water -to- cement ratios, corrosion performance is enhanced
over the existing groin sheet piles that they replace. This alternative also
mitigates for any potential damage to the sheet piles below that mudline
that were not observed during the underwater inspections.
2. Alternative 4 — Encapsulate entire groin with concrete sheet piles. The
maintenance cost is slightly more for this alternative since the existing
sheet piles which are in good condition remain in place. Because the
encapsulation is continuous along the groin, maintenance issues are
greatly reduced. The new concrete sheets driven adjacent to the existing
sheets also structurally enhance the performance.
3. Alternative 2 — Replace offshore portion of groin. This alternative has two
sections: a new offshore portion of the groin, and the existing near shore
half which will not be replaced. The maintenance issues of the offshore
portion will be low. The near shore section will have increased
maintenance demands, as will the interface between the new and existing
sections.
4. Alternative 5 — Encapsulate offshore portion of groin with partial cap
replacement. This alternative has a higher associated relative maintenance
cost over Alternative 2, since the existing concrete sheet piles remain
exposed landward of the encapsulated area.
5. Alternative 7 — New concrete sheets one side, encapsulate damaged
sheets. Because 82% of the existing sheets in the outer zone have one face
exposed, maintenance cost will be higher than Alt. 5.
6. Alternative 4 (with Steel Sheet Piles). Because this option uses steel sheet
piles, there is an increased corrosion concern with this alternative over the
concrete sheets used in Alternative 4. The steel sheets are continuous
along the length of groin, which reduces maintenance issues.
7. Alternative 6 — Encapsulate only damaged sections of the groin with
concrete sheet piles. Since the encapsulation sheets do not run
continuously along the existing groin, there is a higher probably of
maintenance issues at the interface between the ends of the new sheet
piles, and side of existing sheet piles. Wave forces can concentrate at this
interface, and degrade the integrity of the connection over time.
8. Alternative 3 — Replace damaged sheets only. If this alternative can be
constructed, it does nothing to extend the life of the existing sheetpiles,
except those that are already damaged. Maintenance cost on the
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remaining will continue to increase over time as the sheetpiles age and
work.
9. Alternative 6 (with Steel Sheet Piles). The maintenance performance of
this alternative is similar to Alternative 6. However, the added corrosion
potential of the steel encapsulation sheet piles may increase the
maintenance costs.
Highest 10. No Project. The no- project alternative includes removal of the existing
Relative groin that will increase the sediment loss rate at East Beach on the order of
Cost 50 percent. Maintenance costs must therefore account for increased beach
nourishment and sand management activities, which will be significant.
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8.0 PERMIT REQUIREMENTS
The project will require permits from several agencies with jurisdiction over the activity.
Permit requirements are specified below. Coordination with and approval by the
California Department of Fish & Game and the U.S. Fish & Wildlife Service will occur
as part of the permitting effort.
8.1 Sections 10 and 404 Permit from the U.S. Army Corps of
Engineers
The U.S. Army Corps of Engineers (USACE) has jurisdiction over "waters of the U.S."
from the Clean Water Act, the Rivers and Harbors Act, and the National Environmental
Policy Act (NEPA). The USACE issues a Sections 10 and 404 permit for construction in
navigable waters, and placement of fill in waters of the U.S., respectively. The USACE
analyzes the project under NEPA for environmental effects and can either prepare a
Finding of No Significant Impact ( FONSI) document for non - impacting projects, an
Environmental Assessment (EA) for projects that may cause impacts but that are
mitigable, or an Environmental Impact Statement (EIS) for projects to cause significant
impacts that are not mitigable. This project will likely require a FONSI. The USACE
also requires the RWQCB permit to be secured. Securing the Sections 10 and 404 permit
can take up to three to six months and no fee is required.
Adding an incremental amount of fill to subtidal habitat for the preferred alternative
(approximately 340 square feet, or less than 0.01 acre) should not be restrictive as the
habitat is a shifting sand environment with no eelgrass or surfgrass present. The City will
have to justify the need for the repair, the reasons for selecting the preferred alternative,
and information about existing biology at the site to agencies when applying for the
permit.
Marine growth (e.g. mussels) has colonized on the existing groin, typical of structures in
the tidal zone. The various repair and /or replacement alternatives will impact this habitat
by varying degrees. However, it is expected that any new structure would soon be re-
colonized with similar organisms to present levels. This temporary impact is not
anticipated to require mitigation.
8.2 California Environmental Quality Act
The City of Seal Beach is considered the Lead Agency for the project and will have to
meet requirements of the California Environmental Quality Act (CEQA). CEQA requires
projects of a certain magnitude and impact to be reviewed for environmental impacts.
This project is not exempt from CEQA. The type of document to be prepared depends on
the degree of potential environmental impact identified in the CEQA Initial Study. A
Negative Declaration (ND) is prepared for projects will not cause significant impacts,
while a Mitigated Negative Declaration (MND) is required for projects that may cause
significant impacts that can be mitigated. An Environmental Impact Report (EIR) is
prepared for projects causing potentially significant impacts that cannot be mitigated.
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This project may be appropriate for a Mitigated Negative Declaration as it may cause
impacts, but they should be mitigable. The time period for completion and certification
of an MND is approximately four to six months depending on preparation and review
periods. Public review is 30 days long.
8.3 Section 401C Certification from the Regional Water Quality
Control Board
The Regional Water Quality Control Board (RWQCB) permits activities covered under
Section 401 of the Clean Water Act. The RWQCB issues a Section 401C Certification
for construction projects proposing fill in jurisdictional waters. The permit is a
prerequisite for securing permits from federal agencies. The RWQCB considers whether
existing water quality will be impaired by the project and requires conditions to minimize
possible impacts, such as monitoring. They can also require mitigation if impacts are
documented. Approximately three months is required to secure the permit assuming one
month for clarification of the initial permit application, and two months to process the
permit. A fee will also be required and varies depending on the proposed action.
8.4 Coastal Development Permit from the California Coastal
Commission
The California Coastal Commission (CCC) has jurisdiction over activities within the
Coastal Zone, extending approximately one mile inland. This is required unless the City
has an adopted Local Coastal Program (LCP), in which case it can issue its own permits
with the CCC having authority to appeal. Seal Beach does not have an adopted LCP so
permits must be secured from the CCC. The CCC examines the project's consistency
with the Coastal Act, and potential effects to public access, recreation and the
environment. The permit can take four to six months to secure, depending on the level of
potential controversy or impact. Requirements to secure this permit are possession of the
RWCQB permit and a certified CEQA document.
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9.0 SUMMARY AND RECOMMENDATIONS
With the funds currently available it is not feasible to replace the entire groin from the
equipment crossing gap to the outer end. There are several repair, reinforcement, and
replacement alternatives that can be accomplished within the funds available and are
considered feasible. These include:
• Alternative 2 - Replacement of the outer 252 feet of the sheet piles and 350 feet of
cap, and repair of the cap landward of that section. The 350 foot dimension was
chosen because it is the point where the cap first reaches its top elevation.
• Alternative 6 - Reinforcement at damaged piles only with a new cap over the entire
length.
• Alternative 7 - Reinforcement of the outer 252 feet by installing new sheet piles on
one side, plus installing new sheet piles on the opposite side at damaged piles, and
constructing a new cap for 350 feet and repairing the remaining cap.
The outer 252 feet of the groin has suffered the most damage. This area has the deepest
water and therefore the greatest wave activity, and it is the most flexible structural section
with twelve inch thick sheet piles. There are two alternatives which will restore the
service life of this outer section to a new condition. One replaces the sheet piles with
new sheet piles, and the other places new sheet piles on each side of the existing piles,
and both replace the cap for the outer 350 feet.
The replacement alternative (Alternative 2) will result in a finished groin that is almost
identical in appearance to the original construction. Since the sheet piles will be the same
thickness as existing it will have approximately the same flexibility as the original, and
therefore may be subject to interlock damages similar to those currently proposed for
repair. Once the existing sheet piles are removed, the wave climate will make it more
difficult to install the new sheet piles in the desired location. It is also likely that some of
the existing piles will be impossible to remove and would require the new section to be
offset around them.
The reinforcement alternative (Alternative 7) will result in a finished groin that is similar
in appearance to the original, but with an only slightly larger footprint. The structural
section will be significantly stiffer than the original and should result in a much longer
service life. The installation of the new sheet piles will be easier to control with the
existing sheet piles in place to guide and shield the operation.
The alternative that only repairs or reinforces the broken sheet piles (Alternative 6) leave
the remaining piles vulnerable to additional damage. However, the rate of damage will
be reduced by the new cap.
We recommend that the reinforcement alternative (Alternative 7) be chosen as it will
result in a stronger, longer - lasting structure. If more funds become available, we
recommend that the remainder of the cap also be replaced. We further recommend
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against the alternative of replacing the damaged sheet piles, as this alternative may be
impossible to construct and would then require changing the alternative while the cap is
already removed and the groin is vulnerable.
Ocean water quality should not be impacted from project construction as sheetpiles will
be driven, minimizing turbidity. Use of concrete and any chemicals will be managed to
prevent incidental spills to the ocean. The concrete sheetpiles will not need to be
chemically treated.
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(insert comparison matrix as 11.17 on following page)
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