EXHIBIT 4-A September 6, 2016
Scope of Work, Budget and Schedule
Most of the riverbed and streambanks along the
alluvial section (the lower 18 miles) of the Carmel River in Monterey County, California are
composed of loosely consolidated silts, sands, gravels and cobbles. Significant erosion along the lower 15.5
miles of river occurred at relatively low flows between the late 1970’s and the
late 1990’s and several researches have noted that the channel is sediment
starved. The Monterey Peninsula Water
Management District (MPWMD) has carried out a stream restoration program since
1984 to stabilize and restore the streamside corridor and address other water-related
problems along the
The material carried down from the
upper watershed makes up the water-bearing alluvium in Carmel Valley that is
pumped to supply Cal-Am and non-Cal-Am demand.
Because the river channel changes in response to the amount of sediment
that flows through it, an important aspect of managing and understanding this
portion of the riparian corridor is long-term monitoring and documentation of
changes in the elevation of the river bottom.
Gravel mining, main stem reservoirs,
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 watershed area above San Clemente
Dam for more than 95 years has been a factor in aquatic habitat degradation,
channel incision, streambank instability, infrastructure damage, loss of
property, and episodes of bank erosion along the river. In addition, incision and removal of alluvial
valley deposits reduces the volume of water that can be retained in storage in
the Carmel Valley Alluvial Aquifer.
One of the results of sediment starvation in the
alluvial reach 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 is to
complete a comprehensive thalweg survey (low point in the channel) to gather data
between the Carmel River lagoon and Carmel Valley Village for use in
maintaining a long-term record and to compare to past and future monitoring
data. Previous work in 2014 and 2016 was
completed in other portions of the alluvial aquifer. 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.
Survey data will be used by MPWMD staff to adjust
Carmel Valley Alluvial Aquifer parameters, monitor effects to downstream areas
from ongoing sediment retention at Los Padres Reservoir, and to set a baseline
for comparison of potential effects of alternatives being studied for the long
term management of Los Padres Dam.
It should be noted that San Clemente Dam at RM 18.6
was be removed in 2015. The dam no
longer traps 100% of the bedload sediment (the portion of the sediment load
that tends to roll or saltate) and fine grained
material and debris are now free to can move past the dam at high flows. Thalweg profiles are one of the key
monitoring methods in evaluating the effects on the streamside corridor from any
increase in sediment flow. A potential
change in sediment flow to the lower 15.5 miles is also an issue that must be
evaluated with any alternative associated with long-term management of Los
Padres Dam and Reservoir.
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 Carmel River channel in 1984. This
survey gathered data at approximately 100-foot intervals using a surveyor’s level,
but was not referenced to a spatial grid (i.e., a coordinate system). A follow-up survey referenced to the State
Plane coordinate system was conducted in 1993 along the lower five miles of the
river using an electronic distance meter and total station. The 1993 survey included data that defined the
limits of vegetation and the beginning and ends of pools, riffles, and glides. Several shorter surveys (also on State Plane
coordinates) with a similar data set have been conducted in association with
MPWMD-sponsored restoration projects. In
2007, Graham Matthews and Associates profiled approximately 10 miles of the
lower river.
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 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 can serve as intermediate check points for surveys along the
river.
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.
Vegetation along the channel bottom in some reaches has encroached
toward the center of the channel and may obstruct direct line-of-sight views
needed to set survey control and gather data.
Portions of the stream corridor are densely vegetated along the
streambanks. Poison oak, stinging
nettle, and rattlesnakes are common throughout the streamside corridor.
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 $45,000 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 (85%)
– Obtain Long Profile. Gather thalweg data along the bottom of the
river channel between the upstream end of the Schulte
Restoration Project near RM 7 and RM 12.5, downstream of the Boronda Road
Bridge. Data shall be of a
sufficient density along the profile to show pools, riffle, glides, and other
significant features. Where the channel
bottom profile is relatively constant, data shall be gathered at intervals of
no more than 50 feet between points. Work
shall proceed from downstream (near the lagoon) and shall extend upstream. Horizontal accuracy shall be to +/- one foot
and vertical accuracy shall be to +/- 0.1 foot.
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.). Data should be in an Excel
format, similar to previous thalweg profiles, with an ability to import new
data into existing data files. Drawings may be in PDF format.
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. A final report shall
be provided in an acceptable digital format (e.g., Word, PDF, Excel). All files are
to be provided electronically.
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.
Professional Services
Up to $45,000 to be expended on a time-and-materials
basis.
Schedule
It is anticipated that survey work would commence soon
after issuance of a notice to proceed (i.e. during late September 2016). All field
work shall be completed within four months of authorization to proceed and the
project shall be completed within six months of authorization to proceed.
U:\staff\Board_Committees\Admin\2016\20160912\04\Item-4-Exh-A.docx
[1].
MPWMD, May 20, 1995. Survey Control
Points Established with GPS Methods,