HomeMy WebLinkAbout3557; Carlsbad Blvd Las Encinas Creek & Bridge; Carlsbad Blvd Las Encinas Creek & Bridge; 2010-06-28201
Bridge Revetment Monitoring Report
for the City of Carlsbad and the
Califomia Coastal Commission
as Encinas Creek Bridge
Br. No. 57C-0790L
Bridge Elevation - 6/10/2010
Jack L. Abcarius
Nolte Associates, Inc.
June 28, 2010
June 28, 2010
State of California - The Natural Resources Agency
Califomia Coastal Commission
San Diego Area
7575 MetropoHtan Drive, Suite 103
San Diego, CA 92108-4421
SUBJECT: Baseline Report - Bridge Revetment Monitoring
Las Encinas Creek Bridge along Southbound Carlsbad Boulevard
Bridge No. 57C-0790L
City of Carlsbad, California
In accordance with the Special Condition No. 2 set by the Califomia Coastal Commission to approve
the City of Carlsbad's Application No. 6-09-051, NoUe Associates, Inc. is submitting this baseline
report for the Revetment Monitoring Program for the Las Encinas Creek Bridge. Although this
special condition states that "the monitoring report shall be submitted to the Executive Director and
City of Carlsbad Engineering Department yearly after each winter storm season but prior to the of
May starting with May 1, 2010", this report is being submitted now because construction was
completed on May 28, 2010. All four subsequent reports shall be submitted prior to May 1^' of future
years.
Condition of Revetment
The newly placed rip-rap along the West edge of Carlsbad Boulevard starts at Station 104+20.00 to
105+37.50 and 105+81.00 to 110+08.00. The stationing is measured along the centeriine of
southbound Carlsbad Boulevard, and runs from north to south. Bridge construction was completed on
May 28, 2010. In order to control the location of the toe of slope on the beach side, the contractor
placed sheet piles 5r-10"± from the centerline roadway prior to the installation of the rip-rap. This
dimension coincided with the High Tide Contour Line of 4.(NGVD29) or 7.65' (MLLW) as
surveyed during the design phase of this project in 2009.
Following are some photos post-constmction, showing the current condition of the rip-rap, and
establishing the baseline for comparison against future year surveys.
View looking North from Southern end of new rip-rap
Rip-Rap from Stations 104+20.00 to 105+37.50
Rip-Rap from Stations 105+81.00 to 110+08.00
Rip-Rap from Stations 105+81.00 to 110+08.00
Revetment Survev
For the 5 year rip-rap monitoring plan, a control system was established and an initial survey was
made on JunelO-11, 2010. Control was established by GPS based on CCS83, Epoch 1991.35
coordinates per City of Carisbad Survey Control, ROS 17271. The Benchmark is OC-147 (ROS
17271 point #1433), having a NGVD 29 elevation of 50.56'. Five control points were set in the
project vicinity, but outside of the rip-rap for future surveys, including a 1" brass disc mounted on the
bridge. Additionally, six brass caps were set into boulders of the rip-rap and surveyed both
horizontally and vertically for future monitoring. The control points were documented
photographically as well as surveyed for future use.
A High Definition Survey (HDS) was performed along the rip-rap as well as the adjacent street and
beach to survey the as-buih location of the rip-rap. For the HDS survey, a Leica "Scanstation 2" 3-D
laser scanner was used and over 22,000,000 points were collected. These points create a "point
cloud" of points with 3-D coordinates, which were translated into the same coordinate and elevation
system as the control survey (see Figures). The point cloud was then edited to remove obstructions
and other "noise" and a Triangulated Irregular Network (TFN) mesh was created from the points to
create a 3-D model of the rip-rap. Together with the brass caps on the 2-Ton and 4-Ton rocks, this
model can be compared to a similarly collected model in future years of monitoring to detect changes,
either horizontal or vertical, in the location of the rip-rap.
Bridge Elevation View Looking North-East
FW--^FAA:
Jpeg image of the High Definition Scan Model - Elevation View
Jpeg image of the High Definition Scan Point Cloud - Abut 2 Elevation
-Sta. 105-^37.50-~Sta. 105-^81 Sta. 110+08-
Approx. Sta. 104-1-20
High Definition Scan Model - Section Key
Las Encinas Creek
Bridge - Mon # M-1
06/11/2010
Brass Cap on 4-Ton Rock
Las Encinas Creek
Bridge - Mon # M-2
Future Reports
A full High Definition Scan will be performed annually over the next 4 years and each scan
will be compared to the baseline model and corresponding section views. This will allow for
measurement and recording of all rip-rap movements vertically and horizontally so that the
performance of the rip-rap can be evaluated. This evaluation will determine maintenance
strategies over the monitoring period. A report will be prepared after each scan and submitted
to the City of Carlsbad and the Califomia Coastal Commission in accordance with the CCC
conditions of approval as set forth in the CDP Application No. 6-09-051.
Should you have any questions concerning this letter report, please feel free to contact me at
(858) 385-2128.
Sincerely,
Nolte Associates, Inc.
J^k Abcarius, P£r^
ngineering Manager
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