HomeMy WebLinkAboutCC AG PKT 2010-06-14 #BAGENDA STAFF REPORT
DATE: June 14, 2010
TO: Honorable Mayor and City Council
THRU: David N. Carmany, City Manager
FROM: Sean P. Crumby P.E., Director of Public Works
SUBJECT: MCGAUGH ELEMENTARY SCHOOL TENNIS COURTS
CONDITION UPDATE (Shanks)
SUMMARY OF REQUEST:
Receive and file the update condition of the tennis courts at McGaugh
Elementary School.
BACKGROUND:
At the April 26, 2010 City Council Meeting, the City Council awarded construction
to Commercial Aquatic Services to rehabilitate the pool site at McGaugh
Elementary School. This construction is currently in progress. The pool was
drained of water beginning May 17, 2010. During this City Council meeting a
request was made to have staff evaluate the Tennis Courts at the site.
The City of Seal Beach operates two tennis courts adjacent to the pool site. The
underlying soil beneath the tennis courts have been saturated with water leaking
water from the pool. The Los Alamitos School District currently is storing
equipment and parking passenger vehicles on the tennis courts and has been for
approximately the past two years. This equipment and material storage is
related to a modernization project currently in construction (separate from the
City's pool project) by the Los Alamitos School District.
The School District prepared a geotechnical report for the tennis courts. This
report provided recommendations on improvements needed for the tennis courts
to make them able to withstand loading if the area is made into a parking lot.
The geotechnical firm and School District removed one section of concrete and
found a void and water under the concrete slab. The report assumes that this
void exists under the entire tennis court area and recommends that material be
injected to fill the void and stabilize the pad.
Agenda Item B
Page 2
Staff has reviewed the geotechnical report and at this time is not able to
determine the validity of the recommendations. It is not apparent where voids
underneath the concrete slab actually exist. Further investigation is necessary if
determining the location of these voids is desired. Additionally, if the use of the
tennis courts remains as tennis courts and not subject to vehicle loading staff is
unsure as to the urgency of filling the voids.
The School District currently has placed equipment and passenger vehicles on
the tennis courts. This construction equipment is likely heavier than the loading
that was intended for the parking lot itself. It is probable that if the concrete slab
can withstand the loading of these construction vehicles the slab will be more
than capable of operating as a tennis court with the only loading being tennis
players. Further study will be needed to fully determine the structural integrity of
the slab.
The condition of the surface of the tennis courts is cracked, faded, and has
pieces chipping off around the cracks. At this time staff is recommending that
tennis play not be allowed to begin. The cracking of the surface material is not
associated with the structural integrity of the concrete slab. The surfacing of the
tennis courts was at the end of its useful life prior to the School District's
renovation construction, and not designed to withstand loading from construction
equipment. Public Works and Community Service staff will meet with the
contractor that resurfaced the Seal Beach Tennis Center to assess whether
these courts can be resurfaced. Any resurfacing project will be competitively bid.
FINANCIAL IMPACT:
None with this action.
RECOMMENDATION:
Receive and file the update condition of the McGaugh Elementary School tennis
courts and direct staff to conduct an inspection of the tennis courts.
SUBMITTED BY:
Sean P. Crumby P.E.
Director of Public Works
NOTED AND APPROVED:
David N. Carmany
City Manager
Attachments:
A. McGaugh Tennis Court Geotechnical Report (LAUSD)
A
a Wr
TGR GEOTECHNICAL, INC.
GEOTECHNICAL - MATERIALS - ENVIRONMENTAL
January 5, 2010
Los Alamitos Unified School District
10652 Reagan Street
Los Alamitos, CA 90720
Fax: (562) 799 -4599
Attention: Mr. Lary Atherton
Project No. 09 -2598
Subject limited Geotechnical Distress Investigation, Tennis Courts Northwest Side of Swimming Pool,
McGaugh Elementary School, 1698 Bolsa Avenue, Seal Beach, California.
Dear Mr. Atherton,
In accordance with your request, TGR Geotechnical, Inc. (TGR) has completed the limited geotechnical
distress evaluation of the Tennis Court Slab at the subject site. The work was performed in accordance with
our proposal dated December 16, 2009 and your subsequent authorization to proceed. It is our
understanding that cracks had developed within the tennis court slab adjacent to the swimming pools. The
purpose of the current investigation is to evaluate the condition of the subsurface soils supporting the subject
slab and provide mitigation recommendation.
SCOPE OF SERVICES
The following were performed at the subject site.
1. Site reconnaissance.
2. Concrete coring at five (5) locations within the tennis court.
3. Sampling and logging five (5) hand auger borings to a depth of approximately 5 feet below
existing slab.
4. Laboratory testing of selected samples to include: in -situ moisture denslty and optimum moisture
content.
5. Preparation of this limited geotechnical distress investigation report, summarizing current sub-
surface soil conditions, findings, and presenting mitigation measures.
SITE EXPLORATION
On December 22, 2009 field exploration was performed by coring the concrete slab at five (5) different
locations, and drilling to a depth ranging from approximately 5 feet to 6 feet below bottom of existing slab,
and obtaining representative soil samples. The borings were backfilled with cuttings. Patching the borings
was not within the scope of services, and was performed by others. The approximate locations of the borings
are shown on the Boring Location Map, Plate 1.
Relatively undisturbedlgrab samples of soils were extracted using modified California Ring Sampler (CRS),
3 -inch outside diameter, and 2.42 -inch Inside diameter. Ail samples were secured in moisture - resistant bags
as soon as taken to minimize the loss of field moisture while being transported to the laboratory and waiting
to be tested. The borings were backfilled with excess excavated soils.
3037 S. Harbor Boulevard - Santa Ana - CA 92704 - Ph.: 714.641.7189 - Fax. 714.641.7190
09 -2598
SUBGRADE SOIL
The sub -grade soil generally consists of dark brown to reddish brown silty sand. The descriptions of the earth
materials encountered, along with the densities and moisture contents, are presented in the table below. Soil
collapse and erosion was observed in boring B -1 from the subgrade level to approximately 2 feet below the
bottom of the tennis court slab.
LABORATORY TESTING
Moisture and Densn Determination Tests: Moisture content and dry density determinations were
performed on relatively undisturbed samples obtained from the test borings. The results of these tests are
presented below. Where applicable, only moisture content was determined from "undisturbed" or
disturbed samples.
Sample
Location
Soil Description
Moisture (%)
Dry
Dense
(pCf)
Relative
Compaction
N
B-1 @ SG
No Recovery. Voids and Free Standing
Water to 2 ft below Grade.
-
-
-
B-1 @ 4-
Dark brown silty SAND
17.5
-
-
B -2 Q SG
Reddish brown silty SAND
12.7
111.9
88
B -2 @ 4-
Reddish brown silty SAND
10.9
1202
94
B-3 (cif SG
Dark brown silty SAND
10.0
112.5
88
B-3 @ 4-
Reddish brown silty SAND
9.8
120.0
94
B-4 @ SG
Dark brown silty SAND
18.1
109.8
86
B-1 @ 4-
Reddish brown silty SAND
12.5
119.4
94
B-5 @ SG
Reddish brown silty SAND
9.3
110.1
86
B-5 @ 3-
Dark brown silty SAND
9.6
113.0
89
B-5 @ 5'
Brown Silty SAND
11.8
120.8
95
Maximum Density Tests: The maximum dry density and optimum moisture content of typical materials were
determined in accordance with ASTM Test Method D1557. The results of these tests are presented in the
Maximum Dry + Optimum
Sample Sample Description Density moisture content
Location (pcf) N
B-4 (0 to 41 Silty Sand 127.5 9.5
EVALUATION AND RECOMMENDATION
Based on our field observation, encountered voids and water, in-situ moisture content, and change in
moisture content with lateral and vertical distance it is TGR's professional opinion that the encountered water
Is a result of leakage from the adjacent swimming pools.
Evidence of water and soil erosion/collapse was present in boring B- ladvanced at the southwest Comer of
the tennis court in the mast distress area located adjacent to the swimming pools. The erosion/collapse and
free standing water extended to approximately 2 feet below slab bottom. The subsurface• mtture content is
-2- L
III
TGR GEOTECHNICAL, INC.
091 -2598
significantly above optimum moisture content in the upper 4 feet where adjacent to the swimming pools and
at the southwest comer of the subject tennis court. The subsurface relative compaction varies from 86
percent to 88 percent in the upper 2 feet of the subgrade, with the exception of boring B-1.
In order to protect the upper 2 to 3 feet of subgrade from additional seepage water we recommend placing a
"French - Drain' at approximately 2 feet below existing grade adjacent to the existing swimming pools. The
drain pipe shall be perforated and wrapped in ' /.-inch crushed aggregate. The recommended location of the
drain is presented on Plate 1, attached. The drain should outlet to an approved drainage area.
The slab may be leveled using void filling/compaction grouting. The grout points shall be in a grid like pattem
and shall be spaced at 4 feet on center in two-directions. The recommended limit of the grout points is
presented on Plate 1, attached. The maximum depth of compaction grouting should be 10-feet below existing
grade, and the grout shall be pumped at 2 feet vertical intervals. The grouting operation shall be performed
under the full time observation of TGR to ensure that the intent of this report and the recommendations
presented in this report are implemented during construction.
CLOSURE
This report has been prepared for the exclusive use of Los Alamitos Unified School District and their
'design consultants relative to the subject project No portion of this report may be used by other parties or
for other purposes.
The findings contained in this report are based upon the information obtained from the limited number of
test borings and the results of laboratory testing and engineering analysis. As part of the engineering
analysis, It has been assumed, and Is expected, that the geotechnical conditions, which exist across the
site, are similar to those encountered in the exploratory borings drilled. However, no warranty is expressed
or implied as to the conditions at locations or depths other than those excavated.
Our findings were obtained in accordance with generally accepted current professional principles and local.
practice in geotechnical engineering. We make no other warranty, either express or implied.
This report Is subject to review by the controlling authorities for the project We thank you for this
opportunity to be of service to you on this project If you have any questions regarding this report, please
do not hesitate to call this office.
Respectfully submitted,
TGR GEOTECHNICAL, INC.
Aa co7o387
EXP q_,J(), fd
Zaher J. Yazeji, PE, 70387
Senior Project Engineer
Attachment Plate 1 — Coring Location Map
Distribution: (4) Addressee
A,
-3- A t
TGR OEOTECHNICAL. INC.
McGaugh Elementary School Parking Evaluation
EAST PARKING LOT — EXISTING CONDITIONS
46 Staff Stalls (includes 2 ADA stalls)
2 CDC short-term Stalls
Total: 48 stalls
ADMINISTRATION AREA — EXISTING CONDITIONS
8 Staff stalls (includes 2 ADA stalls)
Total: 8 stalls
WEST PARKING LOT— EXISTING CONDITIONS
26 Staff stalls
9 Stalls - west of the courts (used by City)
16 Visitor stalls - north of the courts (includes 2 ADA stalls)
3 Parent auction stalls - at east fence
Total: 54 stalls
SUMMARY — EXISTING CONDITIONS
80 Staff stalls
9 Stalls .(used by City)
2 CDC short-term Stalls
14 Visitor stalls
3 Parent auction stalls
Total parking 110
NO CHANGES PROPOSED TO EAST AND FRONT LOTS
WEST PARKING LOT — PROPOSED CONDITIONS
69 Staff stalls (+ 43)
26 General parking (+ 26)
9 Stalls - west of the courts (used by City) (+ 0)
10 Visitor stalls - north of the courts (Includes 4 ADA stalls) (- 6)
3 Parent auction stalls - at east fence (+ 0)
Total: 117 stalls
REVISED SUMMARY - PROPOSED CONDITIONS
123 Staff parking
26 General parking (SELPA, YA (KC), volunteers, visitors, pool maint., pool /gym users)
9 Stalls - west of the courts (used by City)
2 Short term parking CDC
10 Visitor stalls
3 Parent auction stalls
Total parking 173 (+ 63 spaces)
- - - -+
FIRE LANE
WEST PARKING LOT - PROPOSED CONDITIONS i -- —i
69 Staff stalls (+ 43)
26 General parking (+ 26) t I
9 Stalls - west of the courts (used by City) (+ 0)
10 Visitor stalls - north of the courts (Includes 4 ADA stalls) (- 6)
3 Parent auction stalls - at east fence (+ 0) -..- -- -- I
Total: 117 stalls
ii
Al i1
I
x
I
I
x
x X
(E) CUSTODIAN
\� BLDG. G