EXHIBIT 3-A
WATER
MANAGEMENT DISTRICT
DRAFT
August 1, 2007
Scope of Work, Budget and Schedule
LONG PROFILE AND CROSS-SECTION SURVEY
CARMEL
Introduction
Most
of the riverbed and streambanks along the alluvial section (the lower 15.5
miles) of the
Because
the river bottom changes in response to the amount of sediment that flows
through it, an important aspect of managing this portion of the riparian
corridor is long-term monitoring and documentation of changes in the elevation
and width of the river bottom. Gravel
mining, main stem reservoir construction, and streambank armoring have
contributed to a sediment-starved condition in the river channel downstream of
Los Padres Dam, which is located at approximately River Mile (RM, measured from
the ocean) 25. A chronic lack of sediment from the upper watershed has been a
factor in channel incision, streambank instability, and episodes of bank
erosion downstream of Los Padres Dam over the past several decades.
One
result of this condition is that in-channel supports for basic infrastructure
(bridges with roads and utilities) have been undermined and compromised at
several locations. In addition, there
are areas along the river where scour at the base of slope protection installed
to prevent bank erosion has caused bank slumping and/or the protection appears
to be at risk of failure during high flows.
The
focus of the work proposed in this scope will be to gather cross-section and
thalweg (low point in the channel) data for use in maintaining a long-term
record and to compare to past and future monitoring data. Comparisons of repeated surveys carried out
over long periods can yield information about the long-term rate of aggradation
(i.e., sediment build-up) or degradation (i.e., loss of sediment), effects of restoration
projects along the river, and can inform decisions about infrastructure
maintenance and repairs and proposed restoration projects.
It
should be noted that a project to
retrofit the San Clemente Dam at RM 19 will affect the gradation and supply of
sediment to the lower river. The dam no
longer traps bedload sediment (the portion of the sediment load that tends to
roll or saltate) and currently, fine grained material is moving past the
dam. If the dam remains in place,
fine-grained material will continue to flow past the dam. If the dam is removed, it is likely that in
addition to fine-grained material, coarse-grained material will begin to move
past the dam in the foreseeable future.
Thalweg profiles and cross-sectional data are one of the key monitoring
methods in evaluating the effects on the streamside corridor from these
different types of sediment.
Previous MPWMD Survey Work
MPWMD
conducted the first detailed long profile thalweg survey (a survey of the
lowest point along the channel) of the lower 15.5 miles of the
In
1995, MPWMD contracted with Central Coast Surveyors to set 12 permanent survey control
points in the vicinity of six different bridge locations[1]. The bridges are located along the river as
shown below. The control points were set
using Global Positioning System receivers and referenced to a control point in
the CALTRANS High Precision Geodetic Network.
These control points serve as intermediate check points for surveys
along the river.
Bridge ___ Owner[2] ___ RM[3] Comment
Via Mallorca Hacienda Carmel 3.24 Two-lane bridge.
Valley Greens MCPWD 4.82 Two-lane bridge
Don Juan MPRPD 10.78 One-lane bridge
Rosie’s MCPWD 14.45 Two-lane bridge
It
should be noted that due to limited access into the riverbed, gathering
detailed survey work along the channel bottom may involve long hikes in
difficult terrain. If the riverbed is
dry at the time a survey is performed, MPWMD will grant access into the
riverbed near
Approach and Scope of Work
Tasks
and the percentage of the budget to be used for each task are shown below. MPWMD staff is requesting that up to $30,000
be made available for this work. The
portion of the budget to be used for each task is approximate and is intended
to be a guide in carrying out tasks. The
percentages shown may be modified based on field conditions and/or
recommendations made by the Consultant for the work.
Task 1 (50%) – Obtain Long Profile.
Gather thalweg data along the bottom of the river channel
between the upstream end of the
Profile
data shall be provided as a spatially referenced file (NAD 1983 and NAVD 1988) and in drawings at a horizontal scale
of 1 inch = 200 feet and a vertical scale of 1 inch = five feet (all drawings
no larger than 24 in. x 36 in.).
Task
2 (20%) – Obtain Cross-Sections.
Gather cross-section data at 17 bridge locations between the upstream
end of the
Cross-section
data shall be provided as a spatially referenced file (NAD 1983 and NAVD 1988) and in drawings at a horizontal scale
of 1 inch = 40 feet or 1 inch = 20 feet with a vertical scale appropriate for
the horizontal scale (i.e., at a 10:1 scale).
An acceptable alternative is to provide a file with spatially referenced
cross-section end points and cross-section data and individual cross-section drawings.
Task 3 (5%) – Conduct Pebble Counts. Pebble count data shall be gathered and
reported using the methods cited in “Application of the Pebble Count: Notes on
Purpose, Method, and Variants,” G. Matthias Kondolf, Volume 33, No. 1, pp.
79-87, February 1997, Journal of the American Water Resources Association. Pebble counts shall be conducted at locations
selected to represent the grain size distribution of the active channel (i.e.,
up to approximately the magnitude of the two- to five-year return flow) within
a reach. Reaches where pebble counts are
to be carried out shall be determined in cooperation with MPWMD staff.
Task 4 (10%) – Set Survey Control. Survey
control shall be set near the following bridge locations:
Rancho
Cañada Bridge No. 5 (farthest downstream golf cart bridge)
Survey
control points shall be set in a fashion and accuracy similar to those set with
the 1995 Central Coast Survey. Control
points shall be set by a Land Surveyor licensed by the California State Board
for Professional Engineers and Land Surveyors.
Task 5 (15%) – Prepare Report. A report shall
be prepared that presents results and describes the equipment and methods used
to gather and analyze data.
Project Deliverables:
Any
reference articles, books, publications, or software purchased specifically for
this study shall be provided to MPWMD.
Data input and output files from computer analysis shall be provided in
both a digital and paper format. A final
report shall be provided in an acceptable digital (e.g., Word, PDF) and paper
format.
Budget:
It
should be noted that the scope of Tasks 1 and 2 may be amended in order to
maintain project costs within the proposed budget. The scope of Task 3 will depend in part on
the final scope of Tasks 1 and 2. Tasks
4 and 5 are expected to be completed within the proposed budget.
Professional
Services
Up to $30,000 to be expended
on a time-and-materials basis. See
estimated costs for professional services.
Schedule:
It
is anticipated that survey work would commence soon after issuance of a notice
to proceed (i.e. during late August or early September 2007). All work will be
completed within six months of authorization to proceed and signing of standard
contract documents.
U:\staff\word\boardpacket\2007\2007boardpackets\20070820\ConsentCal\03\item3_exh3a.doc