HomeMy WebLinkAboutAGENDA REPORT 2002 0116 CC REG ITEM 10AITEM /O- A,
AGENDA REPORT
CITY OF MOORPARK
TO: The Honorable City Council
FROM: Walter Brown, City Engineer
DATE: January 4, 2002 (Council Meeting 1- 16 -02)
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SUBJECT: Consider Approval of the Re- design of the Retaining Walls
for the Los Angeles East Improvement Project [Project
8012]
BACKGROUND
On June 2, 1999, the City Council considered a number of alternative
design concepts for the required retaining walls. The option
selected was a "Keystone" type concrete block (see Exhibits 1 - A
and B). On July 21, 1999, the City Council revised that design by
directing that "tiered" landscaping be incorporated into the wall
design.
MWMARY
The use of reinforced concrete soil nailed simulated rock cut walls
in lieu of Keystone walls offers advantages in:
• Appearance, shown by comparing exhibits 1, 3 and 4.
• Cost, saving approximately $308,000 as shown in the tables in
the `Discussion' section of this report.
• Ease of construction and reduced disturbance of adjacent
properties.
The recommendation of this change to the project was initiated as a
result of a value and constructability analysis of the retaining
walls. The analysis required the plans to be brought to a high
level of detail.
DISCUSSION
The retaining walls required for the subject project range in height
from four feet (4') to twenty -seven feet (27'). The earth behind
most of the walls will continue to slope upward from the top of the
L— A— East5 —wa112 000238
L A East Project: Retaining Wall Re- Design
January 4, 2002
Page 2
walls. The optimal design for the retaining walls should provide
attractive appearance and stable slopes at the least cost and not
disturb existing buildings or require extensive removal and re-
compaction of the hillside.
During the design process, as the level of detail of the Los Angeles
Avenue East construction plans increased, the need to provide
shoring to protect one of the adjacent residences during
construction of a retaining wall fronting became apparent. The
shoring was needed to support the building during the construction
of both Keystone and conventional type retaining walls. As a matter
of cost control design alternatives that would eliminate the need
for shoring were considered. The soil nailing, some times called
tie -back, option was originally considered for only the support of
the residence. When the costs to mobilize the equipment and
tradesmen used for soil nailing were considered and the cost -
effectiveness of reinforced concrete soil nailed retaining walls
were calculated it became evident that concrete soil nailed
retaining walls are a viable choice for this project. Alternative
wall designs and their ability to achieve the design objectives are
discussed in the following sections.
A. Keystone Wall Design
Examples of the Keystone retaining wall system are shown on
Exhibits 1 - A and B. This type of retaining wall relies on the
installation of patented concrete blocks retained in place by 18"
horizontal layers of compacted soil and "construction fabric ". The
Keystone wall concrete blocks use layers of construction fabric to
anchor the wall to the retained earth. The installation of the
construction fabric requires the removal of earth to create a 1 to 1
(horizontal to vertical) slope to assure the stability of the slope
during construction. Additionally the sloped earthen face needs to
be excavated back from the wall approximately 8 feet for each 10
feet of wall height to allow for the installation of the
construction fabric. The above described removal and re- compaction
of the retained slope will result in more disturbance to the
existing hillside than is necessary for the construction of vertical
reinforced concrete retaining walls or soil nailed walls. The
excavation will require temporary shoring of some existing buildings
(see Exhibits 2 - A and B). The shoring is expensive and carries
some risk of damage, or claims of damage, to the shored buildings.
The estimated construction cost for the Keystone retaining walls,
including excavation, landscaping, right -of -way and other costs
directly attributable to the Keystone wall, is $1,540,000. The costs
associated with shoring and repairing potential damage to the
buildings affected by the installation are not included in the
estimated amount. A summary of costs follows:
L_A_East5_wa112
0 02 439
L A East Project: Retaining Wall Re- Design
January 4, 2002
Page 3
A V=im Ctnn= Wall
Wall:
2,870
x
13.00 =
37,310 SF
@ $17.00
/SF =
$634,270
x
Excavation:
2,870
x
15.59 =
44, 743 C
@ $5.00
/CY =
$223,717
x
Leveling Pad
2,870
x
0.14 =
399 C
@ $12.50
/CY =
$4,983
x
Backfill:
2,870
x
11.13 =
31,943 CY
@ $5.00
/CY =
$159,716
x
Right-of-Way
2,870
x
10.90 =
31, 283 SF
@ $7.50
/SF =
$234,623
x
Landscape
2,870
x
21.80 =
62, 566 SF
@ $4.44
/SF =
$277,793
6.59%
Desi n
$0
x
6.29%
_
$0
TOTAL:
_
$1,181,606= $31.67/S.F
TOTAL:
$1,535,100= $41.14 /S.F.
B. Reinforced Concrete Cantilevered Retaininq Wall
Reinforced concrete cantilevered retaining walls use the weight
of the wall and the soil over the footing of the wall to counter
balance the forces of the soil retained by the wall. The
installation of the reinforced concrete wall requires the
removal of earth to create a 1 to 1 (horizontal to vertical)
slope to assure the stability of the slope during construction
(see Exhibits 2 - A and C) . This wall type would not include
the cascading or tiered wall landscaping which was to be
incorporated into the Keystone wall. The wall would have a flat
surface with no decorative features. The estimated
construction cost for "standard" reinforced concrete retaining
walls, including excavation, landscaping, right -of -way and other
costs directly attributable to the retaining wall for this
project is $ $1,180,000. A summary of costs follows:
R r."+- il=c=c Rctaininn Wall
Concrete:
2,870
x27.8/27=
2,955CY @$229.00/CY =
$676,703
Rebar:
2,870
x
67.00
=192, 290 LB@
$0.53
/LB=
$101,914
Excavation:
2,870
x
10.77
= 30,910CY@
$5.00
/CY =
$154,550
Backfill:
2,870
x
5.67
= 16,273CY@
$5.00
/CY =
$81,365
Right-of-Way
2,870
x
2.00
= 5,740SF@
$7.50
/SF=
$43,050
Landscape
2,870
x
4.00
= 11,480SF@
$4.44
/SF=
$50,971
Design
$1, 108,552x
6.59%
_
$73,054
TOTAL:
_
$1,181,606= $31.67/S.F
C. Reinforced Concrete Cantilevered Retaining Wall with Simulated
Quarried Rock Facing
There is no structural difference between the "standard"
reinforced concrete retaining walls and the reinforced concrete
L A East5 wa112 000 240
L A East Project: Retaining Wall Re- Design
January 4, 2002
Page 4
cantilevered retaining wall with simulated quarried rock
facing. The installation of this wall requires the removal of
earth to create a 1 to 1 (horizontal to vertical) slope to
assure the stability of the slope during construction (see
Exhibits 2 - A and C) . The thickness of the wall is increased
by the depth of the pattern. The simulation of quarried rock is
achieved by the use of rubber or Styrofoam lined forms that
mold the concrete into the shape of the selected pattern. After
the concrete has set, it is etched and stained with a weather
resistant dye. Several patterns of stonework are available.
This wall type would not include the cascading or tiered wall
landscaping which was to be incorporated into the Keystone
wall. Some examples of aesthetic wall treatments that can be
applied are attached as Exhibits 3 - A and B. The surface
treatment recommended by staff is Sedona. The addition of a
simulated quarried rock facing to a standard cantilever
retaining wall will increase the cost of the wall by
approximately $13.00 per square foot of wall surface. The
estimated construction cost for reinforced concrete retaining
walls with simulated quarried rock facing, including
excavation, landscaping, right -of -way and other costs directly
attributable to the retaining wall for this project is
$1,580,000. A summary of costs follows:
r rmn+ -i 1 avar Tlannrati va Ratai ni nff Wal 1
Concrete:
2,870
x 27 . 8/27
= 2, 955 CY @ $229.00 /CY=
$676,703
Rebar:
2,870
x
67.00
= 192,290LB@
$0.53
/LB=
$101,914
Stone -Crete
Decorative
Finish
2,870
x
13.00
= 37,310SF@
$10.00
/SF=
$373,100
Excavation:
2,870
x
10.77
= 30, 910CY@
$5.00
/CY =
$154,550
Backfill:
2,870
x
5.67
= 16,273CY@
$5.00
/CY =
$81,365
Right-of-Way
2,870
x
2.00
= 5, 740 SF@
$7.50
/SF=
$43,050
Landscape
2,870
x
4.00
= 11, 480 SF@
$4.44
/SF=
$50,971
Design
$1, 481,652x
6.29%
_
$93,196
TOTAL:
_
$1,574,848 = $42.21/S.F
D. Reinforced Concrete Soil Nailed Simulated Rock Cut Wall
The reinforced concrete soil nailed simulated rock cut wall is
actually a vertical concrete slab attached to the soil and
retained with corrosion resistant steel anchors. The soil nails
are installed as the soil is excavated. This allows the wall to
be constructed while minimizing the disturbance of the area
behind the wall. The anchors are inserted into drilled holes
which are then pressure grouted. The design is widely used in
Europe and has seen increased use in the United States over the
L_A— East5_wa112 000241L
L A East Project: Retaining Wall Re- Design
January 4, 2002
Page 5
past few years. The simulation of a rock cut is achieved by
hand sculpting of the concrete into realistic native rock
shapes. The concrete can be colored with integral color and /or,
after the concrete has set, etched and stained with a weather
resistant dye. An example of a soil nailed simulated rock cut
wall is located along the westerly side of I -405 adjacent to the
Getty Museum. This wall is shown on Exhibits 4 - A and B. This
is the surface treatment recommended by staff. This wall type
would not include the cascading or tiered wall landscaping which
was to be incorporated into the Keystone wall, however planting
pockets can be incorporated into the wall to achieve a similar
effect. The estimated construction cost for reinforced concrete
soil nailed simulated rock cut wall, including excavation,
landscaping, right -of -way and other costs directly attributable
to the retaining wall for this project is $1,290,000. A summary
of costs follows:
n Rnil Nail Gniilntnd R,-taininQ Wall
F. Re- Design
Each of the wall types mentioned in items A through D is an
individual design. The Keystone wall design is presently
completed. Each of the wall types can be constructed within the
area of the easement documents that are already prepared. The
negotiations for acquisition of the easements may warrant the
cost of preparation of new easements documents. Revisions to the
wall easements, slope easements and construction easements along
the north side of the street would require preparation of 47
000242
L A East5 wa112
2, 870
x
13. 00 =
37, 310 SF @
$32. 00
/CY =
$1, 193, 920
Wall -
Includes Tie-
back bars
(Supply,
Drill, Grout,
Test &
Tension),
Reinforcing,
8" Shot -
Crete,
Backdrain &
Sculpting
Face
Excavation:
2,870
x
0.06 =
178CY@
$10.50
/CY =
$1,868
Backfill:
2,870
x
0.06 =
178CY@
$3.50
/CY =
$623
Right-of-Way
2,870
x
0.67 =
1, 923 SF@
$7.50
/SF =
$14,422
Landscape
2,870
x
0.00 =
0SF@
$4.44
/SF =
$0
Design
$1,210,833
x
6.43%
_
$77,857
TOTAL:
_
$1,288,689= $34.54/S.F.
F. Re- Design
Each of the wall types mentioned in items A through D is an
individual design. The Keystone wall design is presently
completed. Each of the wall types can be constructed within the
area of the easement documents that are already prepared. The
negotiations for acquisition of the easements may warrant the
cost of preparation of new easements documents. Revisions to the
wall easements, slope easements and construction easements along
the north side of the street would require preparation of 47
000242
L A East5 wa112
L A East Project: Retaining Wall Re- Design
January 4, 2002
Page 6
descriptions and plat maps. The cost to prepare the
descriptions and plat maps would be $37,600. Redesign efforts
include the required changes to the plans. The redesign efforts
are included in the estimated cost of the walls. The costs of
the redesign efforts are based on a percentage of the estimated
construction costs.
G. Fiscal Impact
1. Wall Selection: A summary of the cost differentials of the
retaining wall designs follows:
Wall SE?1PCtion Cost Differentials
Type of Wall
Estimated
Cost Change from
To Date Future Total
Cost
Keystone Wall
Keystone Wall
$1,597,035
$0
Cantilever Retaining
$1,181,606
- $415,429
Wall
Cantilever Decorative
$1,574,848
- $22,186
Retaining Wall
(Adjusted for 2003 Construction Date &
Soil Nail Sculpted
$1,288,689
- $308,345
Retaining Wall
2. Current Total Project Cost Summary: A summary of the total
estimated project costs [2003 construction costs] is as
follows:
Current Total Project Cost Summary
Work Description
Costs
To Date Future Total
Design
$268,362
78,000
346,362
Right -of -Way - Preliminary Estimate,
$0
1,500,000
1,500,000
No Appraisal Data Available
Construction Using Soil Nail Wall
(Adjusted for 2003 Construction Date &
0
3,460,000
3,460,000
with 15% Contingency)
Construction Administration &
0
519,000
519,000
Inspection (15% of Construction Cost)
Totals
$268,362
$5,557,000
$5,825,362
STAFF RECOMMENDATION
Approve the redesign of the retaining walls to provide for the
construction of reinforced concrete soil nailed simulated rock cut
wall. Use existing easement documents and defer preparation of new
easement documents unless right -of -way costs exceed the cost of
their preparation.
L A East5 wa112 0002
Keystone Wall
Exhibit 1 -A
Keystone Wall
Exhibit 1 -B
Exhibit 2 -A
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000246
Exhibit 2 -B
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`- HANDRAIL CETAIL
2% z orf ON SHEET 2
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SEE DRAINAGE—
PLANS i
GEO —GRID PER Q,
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WALL PLANS
ALTERNATE 1
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N.T.S.
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Exhibit 2-C
6.5'
ALTERNATE 2
SECTION 2-2
N.T.S.
LOT 115
SEE WALL AND
HANDRAIL DETAIL
ON SHEET 2
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000243
Cast Concrete Detail
Exhibit 3 -A
Sedona Pattern
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A
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Ni
Sculpted Soil Nail Wall
Exhibit 4 -A
Wall along I -405 at the Getty Center
Sculpted Soil Nail Wall
Exhibit 4 -B
Close -up of wall along I -405 at the Getty
Center
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,A C- .�- �- �r -� >�r ITEM
MINUTES OF THE CITY COUNCIL
Moorpark, California December 20, 2001
An Adjourned Meeting of the City Council of the City of Moorpark was
held on December 20, 2001, in the Community Center Conference Room
of said City located at 799 Moorpark Avenue, Moorpark, California.
1. CALL TO ORDER:
Mayor Hunter called the meeting to order at 6:05 p.m.
Mayor Hunter announced that the adjourned meeting was called to
discuss Item 9.A. which was continued from the December 19,
2001, regular meeting with the public hearing closed, due to
lack of a voting quorum, and one closed session item.
2. ROLL CALL:
Present: Councilmembers Harper, Mikos, Wozniak and Mayor
Hunter.
Absent: Councilmember Millhouse.
Staff Present: Steven Kueny, City Manager and Deborah
Traffenstedt, Assistant to the City
Manager /City Clerk.
3. PUBLIC COMMENT:
None.
9. PUBLIC HEARINGS:
C. Consider the Status of Interim Prohibition of Wireless
Telecommunications Facilities and Extension of Ordinance
No. 272 and Amendment of Ordinance No. 273, Enacting a
Moratorium on the Issuance of Permits for Construction or
Placement of Wireless Telecommunications Facilities. Staff
Recommendation: 1) Open the public hearing, take public
testimony, and close public hearing; and 2) Adopt
Ordinance No. 275, extending Ordinance No. 272 and
amending Ordinance No. 273, enacting a moratorium on the
issuance of permits for construction or placement of
Wireless Communications Facilities in the City and
declaring the urgency thereof. (4/5's vote required for
adoption of ordinance) Continued from December 19, 2001,
with Public Hearing Closed.
MOTION: Councilmember Harper moved and Councilmember Mikos
seconded a motion to approve the staff recommendation with a
revised extension date for the moratorium from April 14, 2002,
to April 18, 2002. The motion carried by voice vote of 4 -0,
Councilmember Millhouse absent.
0002!k3
Minutes of City Council
Moorpark, California Page 2 December 20, 2001
MOTION: Councilmember Harper moved and Councilmember Mikos
seconded a motion to introduce Ordinance 275 for first reading
and to waive full reading of the ordinance. The motion carried
by voice vote of 4 -0, Councilmember Millhouse absent.
MOTION: Councilmember Harper moved and Councilmember Wozniak
seconded a motion to adopt Ordinance No. 275. The motion
carried by voice vote of 4 -0, Councilmember Millhouse absent.
13. CLOSED SESSION:
Mr. Kueny announced that the City Council would be going into
closed session for discussion of Item 13.F. on the agenda.
MOTION: Councilmember Harper moved and Councilmember Wozniak
seconded a motion to adjourn to closed session for a discussion of
Item 13.F. on the agenda. The motion carried by voice vote of 4 -0,
Councilmember Millhouse absent. The time was 6:08 p.m.
F. PUBLIC EMPLOYEE PERFORMANCE EVALUATION
Title: Assistant City Manager, Assistant to City
Manager /City Clerk, City Manager, City Attorney, City
Engineer, Chief of Police, Director of Administrative
Services, Director of Community Development, Director of
Community Services, and Director of Public Works.
Present in closed session were Mayor Hunter, Councilmember
Mikos, Councilmember Harper, and Councilmember Wozniak; Steven
Kueny, City Manager; and Deborah Traffenstedt, Assistant to the
City Manager /City Clerk.
The Council reconvened into open session at 6:12 p.m. Mr.
Kueny stated that there was no action to report.
14. ADJOURNMENT:
Mayor Hunter adjourned the meeting at 6:12 p.m.
Patrick Hunter, Mayor
ATTEST:
Deborah S. Traffenstedt
City Clerk
000254
MINUTES OF THE CITY COUNCIL
Moorpark, California January 9, 2002
A Special Meeting of the City Council of the City of Moorpark was
held on January 9, 2002, in the Community Center of said City
located at 799 Moorpark Avenue, Moorpark, California.
1. CALL TO ORDER:
Mayor Hunter called the meeting to order at 5:35 p.m.
2. ROLL CALL:
Present: Councilmembers Harper, Mikos, Millhouse,
Wozniak and Mayor Hunter.
Staff Present: Steven Kueny, City Manager; Deborah
Traffenstedt, Assistant to City Manager /City
Clerk.
3. PUBLIC COMMENT:
None.
4. PRESENTATION /ACTION /DISCUSSION:
A. Consider Rejection of Claim: Robyn Tholander. Staff
Recommendation: Reject the claim and direct staff to
send a standard rejection letter to the claimant.
MOTION: Councilmember Harper moved and Mayor Hunter seconded
a motion to approve the staff recommendation. The motion
carried by unanimous voice vote.
5. ADJOURNMENT:
Mayor Hunter adjourned the meeting at 5:36 p.m.
Patrick Hunter, Mayor
ATTEST:
Deborah S. Traffenstedt
City Clerk
000255