HomeMy WebLinkAbout1998_El_Nino_Sea_Cliff_Failure_Pacifica_201405230847392241MITIGATION OF 1998 EL NIÑO
SEA CLIFF FAILURE,
PACIFICA, CALIFORNIA
BY
PATRICK O. SHIRES, TED SAYRE
and DAVID W. SKELLY
COTTON, SHIRES & ASSOCIATES, INC. CONSULTING ENGINEERS AND GEOLOGISTS
ARTICLE REPRINTED FROM:
ENGINEERING GEOLOGY PRACTICE
IN NORTHERN CALIFORNIA (2001): EDITED BY
HORACIO FERRIZ AND ROBERT ANDERSON, PAGES 607 - 618.������������
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California Department
of Conservation
Division of Mines and Geology
Bulletin 210
Association of
Engineering Geologists
Special Publication 12
ENGINEERING GEOLOGY PRACTICE IN NORTHERN CALIFORNIA
MITIGATION OF 1998 EL NIÑO SEA CLIFF FAILURE,
PACIFICA, CALIFORNIA
ABSTRACT
Erosion of sea cliffs along the central California coastline has
become a major concern for public and private improvements
constructed in harmʼs way. Stability of the local sea cliff is adversely
affected by young, poorly consolidated sediments comprising the
bluff, vulnerability to wave attack under combined high wave and
high tide conditions, and elevated groundwater levels resulting
in seepage at the cliff face. Coastal geologic mapping and
geomorphic analysis completed by the U. S. Geological Survey,
after extensive local shoreline damage from the 1982-83 El Niño
event, correctly identified critical erosion prone and unstable bluff
areas. However, mitigation of identified hazards is often initiated
only shortly after catastrophic failures occur, when public interest
is sufficiently aroused to initiate Federal/State relief efforts.
Along Esplanade Avenue within the City of Pacifica, seven
homes were lost or demolished during the 1998 El Niño event
because of rapid sea cliff retreat. The adjacent public road, which
provides access to 21 local residential properties, was recognized
by City, State and Federal governments as being vulnerable to
active coastal erosion processes. The recognition of local hazards
(aided by daily television footage of homes perched at the edge of a
retreating cliff) resulted in funding for the design and construction
of a rock revetment (seawall) intended to guard against damage
to or loss of the public roadway. This paper presents a summary
of geologic, geotechnical, oceanographic, and practical factors
taken into consideration during the design of the subject rock
reventment.
INTRODUCTION
In February 1998, several residences on the seaward side of
Esplanade Avenue were in immediate danger of collapse due
to failure of the steep sea cliff (Figure 1). Parts of some of the
houses had already fallen over the bluff, others were overhanging
the bluff, and a few were intact near the edge of the bluff.
House-site stability at the top of the bluff is adversely affected
by the weak nature of the oversteepened alluvial sediments
comprising the lower to middle bluff, the steepness of the bluff,
groundwater seeping from the bluff face, and a 10-foot thick layer
of uncemented dune sand at the top of the bluff, upon which the
houses were built. In addition, rapid bluff retreat represented a
threat to Esplanade Avenue; consequently it was essential to
implement appropriate coastal protection measures if loss of this
public road and associated utilities was to be prevented.
The northern Pacifica coastline has been undergoing
progressive sea cliff retreat with a long-term average erosion rate
of approximately 2 feet per year (Lajoie and Mathieson, 1998).
It is not unusual for several years to pass with little noticeable
erosion, only to be followed by several feet of bluff retreat within
a single day. The segment of bluff along Esplanade Avenue was
placed in the most unstable category by the USGS in their Coastal
Stability and Critical Erosion maps as early as 1985 (Griggs and
Savory, 1985; Lajoie and Mathieson, 1998). When this area was
subdivided in 1949, the length of bluff-top back yards (west of the
house sites) was approximately 50 feet. Figure 2 illustrates local
retreat of the sea cliff between 1956 and 1998 based on aerial
photographs.
Increased rates of bluff erosion in early 1998 resulted from
severe winter waves, high tides, and El Niño ocean water thermal
expansion effects, coupled with a diminishing natural resupply
of sand to the shoreline. Some bluff segments retreated over 30
feet during two weeks in February 1998. Erosion at the base of
the bluffs, and landsliding of the undermined upper parts of the
bluffs were the primary processes of sea cliff retreat. In addition,
increased water seepage from the bluff face softened and loosened
bluff sediments, contributing to instability and retreat.
Past efforts to stabilize the bluff were largely unsuccessful. In
response to rapid local bluff retreat that occurred during the 1982
PATRICK O. SHIRES1, TED SAYRE1, AND DAVID W. SKELLY2
2Skelly Engineering
619 S. Vulcan Avenue
Encinitas, CA 92024
dwskelly@msn.com
1Cotton, Shires and Associates, Inc.
330 Village Lane
Los Gatos, CA 95030
losgatos@cottonshires.com
DIVISION OF MINES AND GEOLOGY
El Niño event, a homeowners group in cooperation with the City
of Pacifica funded construction of a rock revetment. The lack of
adequate maintenance, coupled with adverse design aspects (rock
size was relatively small and apparently not keyed into bedrock
materials), resulted in a short life-span for this structure. Although
relatively intact sections of this revetment were still visible in
1996, by March 1998 the earlier revetment had been reduced to
an irregular scattering of boulders across the narrow sandy beach
(Figure 3).
SITE GEOLOGY
The site is located along the California coastline (Figure 4),
approximately 1.3 miles south of Mussel Rock where the San
Andreas fault enters the Pacific Ocean. Steep bluffs fronted by
narrow, sandy beaches characterize this section of the coastline.
Bluff height increases from approximately 70 feet along Esplanade
Avenue to greater than 300 feet north of Mussel Rock. A terrace
surface to the northeast of the bluff is clearly warped as a result of
geologically active uplift along the tectonic plate boundary.
Conspicuous within the City of Pacifica are several broad,
relatively flat-floored valleys that open to the ocean, suggesting
periods of channel incision into bedrock followed by fluvial
deposition. During the last major ice age, sea level was more
than 100 feet lower than it is at present. Upon final melting of the
large continental glaciers (initiated approximately 15,000 years
ago), sea level rose, changing the base levels of coastal drainage
channels. Consequent reductions in stream gradients resulted in
lower flow-velocities and burial of eroded channels with alluvial
deposits. Near Esplanade Avenue, subsequent tectonic uplift and
coastal erosion has notched sea cliffs into these alluvial deposits.
This recent geologic history has resulted in the deposition and
exposure of the relatively young, poorly consolidated sediments
that form the local bluffs. Periods of rapid bluff retreat can be seen
as one consequence of this dynamic geologic setting.
In the area under study, “greenstone” bedrock of the Franciscan
Complex lies below the base of the bluff. This rock is a relatively
firm to hard altered submarine basaltic assemblage composed of
pillow lavas, flows and breccias. It is overlain partially by beach
Figure 1. Residences along Esplanade Avenue, Pacifica,
in danger of collapse in February, 1998.
ENGINEERING GEOLOGY PRACTICE IN NORTHERN CALIFORNIA
sand in the tidal zone, and by an approximately 50-foot
thick section of poorly lithified Quaternary alluvial
fan deposits (coarse basal breccia, intervals of poorly
indurated silts, and fine to medium grained sands and
gravels) exposed in the lower portion of the bluff. The
alluvial deposits are overlain by a clayey, dark brown
soil horizon, approximately 5 feet thick. Capping the
soil horizon, and extending to the current ground surface,
is a 10-foot thick layer of dune sand. Figure 5 illustrates
the stratigraphy of the sea cliff and position of the rock
revetment.
The uncemented dune sand is very weak when
unconfined, especially when it loses moisture-related
interstitial tensile forces (Figure 6). House loads provide
some confinement pressure and help contain this sand
when it is moist. When it becomes dry, it seeks its
natural angle of repose at approximately 30 degrees (or
approximately 1.7 horizontal to 1 vertical). In addition
to the weak dune sand, the underlying soil and alluvial
deposits, although stronger than the dune sand, are prone
to sloughing, and larger-scale slumping.
REVETMENT DESIGN
The following section summarizes the methodology
utilized for the design of a quarry stone revetment
(seawall) intended to reduce the potential for future, rapid
sea cliff erosion and provide protection for Esplanade
Avenue and associated utilities.
Oceanographic design considerations
The recommended coastal structure design criteria
reflect consideration of nearshore bathymetry, water level,
wave height, maximum scour elevation, beach slope, and
bedrock material properties. The design methods used in
our analysis were taken from Chapter 7 of the U.S. Army
Corps of Engineers Shore Protection Manual (U.S. Army,
1984). With this method, design criteria are developed
for a set of recurrence interval oceanographic conditions. Both 50-
year and 100-year recurrence interval oceanographic conditions
were evaluated in our analysis.
The offshore bathymetry is characterized by ridges and valleys
aligned perpendicular to the shoreline. An approximate nearshore
slope of 0.2% was assumed. The beach slope varies across the
proposed revetment site from as steep as 30% to less than 18%.
The “design water level” is the maximum possible still-
water elevation. During storm conditions, the sea surface rises
along the shoreline (super-elevation) and allows waves to break
just before, or at, the revetment structure. In this study, super-
elevation of the sea surface was accounted for by wave set-up (1.0
to 2.5 feet), wind set-up and inverse barometer (0.5 to 1.5 feet),
wave group effects (1.0 to 2.5 feet), and El Niño thermal water
expansion effects (0.5 to 1.0 feet). The 50-year recurrence interval
maximum high tide elevation is +5.4 feet MSL (Mean Sea Level)
which, when combined with the effects of super-elevation, yields
a 50-year recurrence interval water level of +7.0 feet MSL. The
100-year recurrence interval maximum tide elevation is +5.9 feet,
which could result in a maximum water level of +7.5 feet MSL.
The “maximum scour depth” is determined by the rate at which
the bedrock, that the revetment structure is founded upon, wears
down. The lower formational material at this site is greenstone
bedrock of the Franciscan Complex, a firm, but erodible material.
The down-wearing rate was estimated to be approximately 1
inch per year for the purposes of project design (the actual rate
of abrasion would be expected to diminish at depths significantly
below MSL). The elevation of the existing grade at the toe of the
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����������������Figure 2. Top of bluff retreat from 1956 to Spring 1998 (modified from
Lajoie and Mathieson, 1998)
DIVISION OF MINES AND GEOLOGY
lowest segment of the revetment is approximately 3 feet below
mean sea level. Accounting for bedrock down-wearing, and using
maximum still-water levels, the design water depth (i.e., elevation
difference between the revetment toe and maximum still-water
level) at the revetment for the 50-year recurrence interval
conditions is approximately 12 feet. The design water depth for
the 100-year recurrence interval is approximately 15 feet. These
static submergence depths are utilized in the following section for
the calculation of wave run-up.
In general, high waves in combination with high water levels
locally result in erosion of beaches and wave attack at the base of
the coastal bluffs (Figure 7). At this site, offshore wave heights
exceeding 20 feet are not uncommon during winter storms.
However, the design wave condition for a shoreline structure is
generally not the largest wave, because the largest waves break
offshore in water depths approximately equal to the wave’s height.
The largest “design wave force” will occur when a wave breaks
directly on the shoreline structure. The largest wave that can
break on the revetment is determined by the depth of water at
the toe of the structure. Using the water depths defined earlier,
the resulting design wave heights are 10.0 feet for the 50-year
recurrence interval and 12.0 feet for the 100-year recurrence
interval. Incoming wave periods vary from 9 to 20 seconds. A
design period of 20 seconds was selected because this period wave
would produce the highest run-up.
Wave run-up
As waves encounter a revetment, they break and the water
rushes up the face of the structure. Often, wave run-up and
overtopping strongly influence the design and cost of coastal
projects (Weggel, 1976). “Wave run-up” is defined as the vertical
height above the still water level to which a wave will rise on a
structure of infinite height. “Overtopping” is the flow rate of
water over the top of a revetment as a result of wave run-up.
The run-up analysis is performed to determine the design height
of the revetment so that no overtopping can occur. Overtopping
of the structure would exacerbate erosion of the alluvial deposits
comprising the middle of the bluff.
Wave run-up and overtopping for the revetment was calculated
using the U.S. Army Corps of Engineers Automated Coastal
Engineering System, (ACES). ACES is an interactive, computer-
based design and analysis system commonly used in the field
of coastal engineering. The methods to calculate run-up and
overtopping implemented within this ACES application are
discussed in greater detail in Chapter 7 of the Shore Protection
Manual (U.S. Army, 1984). The run-up estimates calculated
herein are corrected for the effect of onshore winds (i.e., wind
direction from sea to land).
Figure 3. Remnants of previous rock revetment scattered across the beach after the 1998
El Niño event.
ENGINEERING GEOLOGY PRACTICE IN NORTHERN CALIFORNIA
The empirical expression for the monochromatic-wave
overtopping rate is:
Q = Cw (g Q0* H03 )1/2 [(R+F)/(R-F)]-0.1085/∝, where:
Q = overtopping rate per unit length of structure (ft3/sec.ft)
Cw = wind correction factor,
g = gravitational acceleration (ft/sec2),
Q0*, ∝ = empirical coefficients (see SPM Figure 7-27),
H0 = unrefracted deepwater wave height (ft),
R = run-up (ft),
F = hs - ds = freeboard (ft),
hs = height of structure (ft), and
ds = water depth at structure (ft).
The correction for onshore winds is:
Cw = 1 + Wf (F/R + 0.1) sin(θ), where:
Wf = U2/1800
U = onshore wind speed (mph)
F = hs - ds = freeboard (ft)
R = run-up (ft)
θ = angle of the ocean-facing revetment slope, measured from
horizontal in degrees.
N
SITE
Pacifica
SanJose
SanFranciscoBay
Oakland
SanFrancisco
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Figure 4. Location of the Esplanade Avenue site within the City of
Pacifica.
The severity of storm impacts to the local coast are partially
dependent on the direction of wave approach and the local
shoreline orientation (Fulton-Bennet and Griggs, 1987). The
ACES analysis was performed on two sets of local oceanographic
conditions that represent typical 50- and 100-year storms. The
onshore wind speed was chosen to be 60 knots (69 mph) for each
case.
The output from the ACES analysis indicates that the maximum
wave run-up for the 50-year recurrence interval oceanographic
conditions is approximately +17 feet MSL, and for the 100-year
recurrence conditions, approximately +19 feet MSL. Based upon
this analysis, the height of the revetment for a “no overtopping”
condition should be a minimum of +20 feet MSL. A top of
revetment elevation of +26 feet MSL was selected to buttress
a lower sand lens on the bluff face, to allow for future settling
of the revetment and to increase the factor-of-safety in project
design. Site observations during storm conditions and engineering
judgement also influenced the selection of final revetment height.
Revetment geometry and stone weight
considerations
For initial design purposes, an armor stone unit weight of 165
pcf and a 50% slope for the face of the structure were selected.
The primary factor in determining the design stone weight is the
incident wave energy, which is proportional to the wave height.
The output of the ACES analysis includes the stone weight and
revetment crest width. The weight of the stone required to
withstand the design wave conditions is given by the following
formula:
W = Wr H3/[(KD(Sr-1)3cot(θ)], where:
W = Weight of the individual armor stone in the
primary cover unit (lbs),
Wr = Unit weight of the armor stone (pcf),
H = Design wave height (ft),
Sr = Specific gravity of the armor stone relative to
water (Sr = Wr/Ww),
Ww = The unit weight of water (pcf),
θ = Angle of the structure slope measured from
horizontal in degrees, and
KD = Stability coefficient which depends on the
shape of the armor stone.
DIVISION OF MINES AND GEOLOGY
?
560 EsplanadeAve.
(Qfo)
(Qs)
Moist/wet sand
Seepage fromcliff face
Greenstone Bedrock (KJfg)
??
20
40
60
0
-20
-40Elevation in feetN 72.5° W Elevation in feet80
Old Soil Horizon
20
40
60
0
-20
-40
80
0 20
20
FEETFEET Alluvial Deposits
(N) Revetment
Typ. 2 1Beach Sand
Dune Sand (Qd)
Figure 5. Stratigraphy of sea cliff and rock revetment position near the southern terminous of Esplanade Avenue.Figure 5. Stratigraphy of the sea cliff and rock revetment position near the southern terminus of
Esplanade Avenue.
ENGINEERING GEOLOGY PRACTICE IN NORTHERN CALIFORNIA
The calculated individual armor stone weight for the 50-
year oceanographic conditions is approximately 5 tons. The
crest width is approximately 12 feet, with approximately 80
armor stones per 1,000 square-feet for 50-year recurrence
conditions. The individual armor stone weight for the 100-year
wave conditions is approximately 10 tons, with a crest width of
approximately 14 feet. This results in approximately 50 armor
stones per 1,000 square feet. Ultimately, an armor stone size of
8 to 10 tons was selected for project design considering several
years of performance observarions by the Pacifica Public Works
Department, available funding, and the restricted availability of
rock in the 10-ton range.
Quarry stone selection and placement
Two weight ranges of stone are generally selected for revetment
construction: armor stone and core stone. The armor stone
weight ranged from 8 to 10 tons, whereas the core stone weight
ranged from 100 pounds to 5 tons. The smaller size fraction of
the core stone was placed deepest within the revetment. All the
stone material was examined to verify that the rock was free
of undesirable qualities that might contribute to crumbling or
breaking during handling. The armor stone consisted of select
quarry rock free of open fissures and apparent planes of weakness.
Ideally, armor stone should be rough and angular in shape, with
the shortest principal dimension not less than one-third the longest
dimension to improve interlocking qualities.
The qualitative evaluation of rock durability relates to the
geological origin of the rock, as well as specific tests to evaluate
rock properties important to longevity as a revetment component.
Rock evaluation should include consideration of the following:
1. Examination of the petrographic make-up of the rock
should be completed.
2. Evaluation should be made of the performance of the
candidate rock type in other marine structures.
3.Testing to address the Standard Practice for Evaluation
of Rock to be Used for Erosion Control (ASTM D
4992-94)should be conducted. Testing may include:
a. C 88 - Test method for soundness of aggregate
by use of sodium sulfate or magnesium sulfate;
Figure 6. Loose dune sand exposed in the upper cliff
face, immediately beneath the residence.
DIVISION OF MINES AND GEOLOGY
Figure 7. Offshore wave height may exeed 20 feet and
wave surge from shore break attacks the base of coastal
bluffs during high tides.
b. C 127 - Test method for specific gravity and
absorption of coarse aggregate;
c. C 294 - Descriptive nomenclature of constituents of
natural mineral aggregate;
d. C 295 - Practice for petrographic examination of
aggregate for concrete;
e. C 535 - Test method for resistance to degradation
of large-size coarse aggregate by abrasion and
impact in the Los Angeles machine; and
f. D 5313 - Test method for evaluation of durability
of rock for erosion control under wetting and drying
conditions.
CONSTRUCTION CHALLENGES
Suitable, large armor stones in the 8- to 10-ton size range were
difficult to obtain because significant demands for large rock had
been placed on local quarries during El Niño conditions. Rock
samples from four quarries, with haul distances of approximately
40 to 100 miles to the site, were delivered for detailed examination.
Samples included limestone, graywacke sandstone, welded
volcanic tuff and a metaconglomerate. Submitted samples,
other than the limestone, generally had favorable density and
durability properties. Due to the scarcity of large rock, favorable
rock types available from three quarries were utilized for project
construction.
Trucks delivering armor stones to the site would typically
accommodate only two large stones per load, with possibly
room for a few smaller core stones. Because the keyway for the
revetment was to extend into Franciscan bedrock located below
mean sea level, stone placement was possible only during periods
of low tide (Figure 9). Sufficient stone for the construction of
a 100-foot segment of the revetment was delivered to a staging
area high on the beach, and placement of rock into the keyway
(excavated the previous day) occurred during low tide.
Rock was placed in conformance with the following guidelines,
with the guiding principle that good craftmanship during stone
placement is essential to structural integrity: 1) rock-to-rock
contact was maximized (at least three points of contact per stone)
and the voids were minimized; 2) stones that were flat in one
dimension were preferred and round stones were avoided; 3)
stones that had one particularly long dimension were placed with
the longer dimension perpendicular to the shoreline to prevent
rolling down slope; and 4) “chink” armor stones (smaller than 3
feet in their longest dimension) were not usedvthe larger armor
stones.
MAINTENANCE
Any large engineered structure placed along the base of a sea
cliff will interact with dynamic shoreline erosional processes.
Consequently, such structures require periodic inspection and
maintenance. Inspections should be performed by an engineer
with experience in coastal structures. In addition, coastal
structures should be inspected by the property owners after any
major storm for damage caused by wave attack. When damage
is observed, an engineer should be consulted to determine the
nature and extent of necessary maintenance. Maintenance on a
quarry stone revetment would include re-shaping the revetment
to the design profile through addition or repositioning of stones.
Maintenance of the revetment should be undertaken in a manner
that will improve the quality of the profile, as well as the contact
and orientation of the individual stones. The rehabilitation of
ENGINEERING GEOLOGY PRACTICE IN NORTHERN CALIFORNIA
a revetment should be supervised by a coastal engineer. The
City of Pacifica has reportedly taken steps toward establishing a
maintenance assessment district to ensure that funding is available
for periodic upkeep of the revetment.
SUMMARY/COMMENTARY
Key aspects of revetment design included selection of adequate
armor stones, keying of imported stone below beach and alluvial
deposits well into firm bedrock, and selection of an appropriate
revetment face-slope and height. Design parameters were based
on oceanographic analysis including consideration of maximum
possible still-water levels, wave run-up, the design wave force,
and anticipated scour depth. Final quarry stone selection included
consideration of constituent mineralogy, rock density and
anticipated durability in a dynamic marine environment.
Even though the design intent of the revetment is to help protect
the nearby public roadway from coastal erosion, there may be
pressures to redevelop what remains of the top lots on the bluff.
Landsliding along the precipitous bluffs is a significant potential
hazard to adjacent residential development. One limitation for the
placement of a revetment at the base of the bluff is that it will not
significantly improve stability of the slope above the revetment
crest (elevation of 26 feet MSL). Although dewatering measures
may improve slope stability by reducing adverse groundwater
seepage from the face of the bluff, the viability of the bluff
lots for redevelopment will depend on the outcome of detailed
geotechnical studies. In addition, revetments have design-life
limitations and maintenance requirements that must be considered
during redevelopment evaluations.
Engineering efforts to arrest coastal erosion processes should
be viewed as temporary solutions that are often not free of
collateral impacts (Griggs, Pepper and Jordan, 1992). In the
case of engineered revetments or seawalls, these structures are
typically constructed at locations that already have inadequate
protective beach or dune buffer zones. The sand-deficient
beaches may become narrower and steeper with time after the
protective structure is installed. These changes may result from
increased rebound energy of waves reflected off relatively hard,
fixed engineered structures, and the reduction of cliff detritus
Figure 8. Filter fabric is being placed in the keyway and along the base of the revetment prior to stone
placement.
DIVISION OF MINES AND GEOLOGY
Figure 9. Keyway excavation below mean sea level
required strategic construction timing with respect to
tidal conditions.
descending to the beach. Consequent alteration to the beach and
near-shore profiles can ultimately undermine foundation support of
the protective structure. It is also possible that erosion of adjacent
vulnerable coastal bluffs may result in gradual outflanking of the
protective structure. With the best revetment or seawall designs,
protective success over the time period of a human life span can
occasionally be achieved. From a long-term geologic perspective,
however, protective revetments placed within wave impact zones
will eventually face inevitable consequences. Utilization of
protective design alternatives in dynamic coastal zones should
follow full consideration of a cost-and-benefit analysis, impacts to
beaches and adjacent properties, and alternative hazard avoidance/
relocation options.
ACKNOWLEDGMENTS
The authors thank Gary Griggs of U. C. Santa Cruz and Kenneth
Lajoie of the U. S. Geological Survey for their tireless efforts to
characterize California coastal hazards and to educate the public
about consequent risks of living in this dynamic environment. We
also express gratitude to the team of Section Editors who greatly
enhanced the quality of the final manuscript.
AUTHOR PROFILE
Cotton, Shires & Associates, Inc. is a geotechnical consulting
firm established in 1974 providing services from offices in Los
Gatos and Carlsbad, California. We offer expertise to engineers,
designers and local governments with regard to development,
hazard analysis and mitigation, commercial and municipal
construction and failure analysis. We also provide expert witness
testimony for litigation and arbitration related to geotechnical
engineering and engineering geology. Mr. Ted Sayre is a Certified
Engineering Geologist with 17 years of local experience. Mr.
Patrick O. Shires is the firmʼs Principal Geotechnical Engineer
with 28 years of experience addressing complex geotechnical
problems in the western United States. Mr. David W. Skelly is a
Professional Engineer with expertise in Coastal Engineering who
works with Cotton, Shires and Associates on special projects.
ENGINEERING GEOLOGY PRACTICE IN NORTHERN CALIFORNIA
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