HomeMy WebLinkAboutExecutive Summary of Shoreline Sea Level Rise Study Report
Final Draft
Shoreline Regional Park Community
Sea Level Rise Study
Feasibility Report and Capi tal Improvement Program
Prepared for
The City of Mountain View December 18, 2012
CIP 12-48
Prepared by ESA PWA
with AMEC, HDR, SCI, and HT Harvey
Final Draft
Shoreline Regional Park Community
Sea Level Rise Study
Feasibility Report and Capital Improvement Program
Prepared for
The City of Mountain View December 18, 2012
CIP 12-48
Prepared by ESA PWA
with AMEC, HDR, SCI, and HT Harvey
550 Kearny Street
Suite 900
San Francisco, CA 94108
415.262.2300
www.pwa-ltd.com
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D120470.001
City of Mountain View
City of Mountain View Shoreline Regional Park Community i ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
Table of Contents
Executive Summary ................................................................................................................................ ES-1
ES-1. Study Purpose and Background .............................................................................................. ES-1
ES-2. Study Criteria .......................................................................................................................... ES-1
ES-2.1. Baseline Conditions ................................................................................................... ES-1
ES-2.2. South Bay Salt Pond (SBSP) Restoration Project ..................................................... ES-2
ES-2.3. Sea Level Rise Scenarios ........................................................................................... ES-2
ES-2.4. Design Criteria for CIP projects ................................................................................ ES-3
ES-3. Flood Assessment Methods .................................................................................................... E S-3
ES-3.1. Previous Studies ........................................................................................................ ES-3
ES-3.2. Vulnerability Assessment Methods ........................................................................... ES-4
ES-4. Sea Level Rise Vulnerabilities ................................................................................................ ES-5
ES-5. Recommended Adaptation Projects ........................................................................................ ES-6
ES-6. Cost Estimates ........................................................................................................................ ES-8
ES-7. Project Prioritization and Phasing .......................................................................................... E S-9
1 Introduction ............................................................................................................................................ 1
1.1 Study Purpose ............................................................................................................................... 1
1.2 Background ................................................................................................................................... 1
2 Study Criteria ......................................................................................................................................... 3
2.1 Baseline Conditions ...................................................................................................................... 3
2.2 South Bay Salt Pond Restoration Project ..................................................................................... 3
2.3 Sea Level Rise Scenarios .............................................................................................................. 4
2.4 Design Criteria for CIP Projects ................................................................................................... 5
2.4.1 Coastal ............................................................................................................................. 5
2.4.2 Fluvial .............................................................................................................................. 5
2.4.3 Interior Drainage .............................................................................................................. 6
2.4.4 Geotechnical .................................................................................................................... 7
2.5 Evaluation Criteria ........................................................................................................................ 7
3 Flood Assessment Methods .................................................................................................................... 9
3.1 Previous Studies ........................................................................................................................... 9
3.1.1 FEMA Flood Mapping .................................................................................................... 9
3.1.2 USACE Flood Mapping .................................................................................................. 9
3.2 Vulnerability Assessment ........................................................................................................... 11
3.2.1 Coastal Flooding ............................................................................................................ 1 1
3.2.2 Fluvial Flooding ............................................................................................................ 1 3
3.2.3 Interior Drainage ............................................................................................................ 14
3.2.4 Geotechnical Methods ................................................................................................... 15
4 Shoreline Vulnerability to Sea Level Rise ........................................................................................... 16
4.1 Coastal Flooding ......................................................................................................................... 19
4.1.1 West Side City Boundary (Palo A lto Flood Basin & Adobe Creek) ............................. 19
City of Mountain View
City of Mountain View Shoreline Regional Park Community ii ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
4.1.2 Coast Casey North Levee .............................................................................................. 19
4.1.3 High Ground Along North Side of Landfill .................................................................. 20
4.1.4 Lower Permanente Creek .............................................................................................. 20
4.1.5 High Ground North of Golf Course Facilities ............................................................... 21
4.1.6 Lower Steven s Creek ..................................................................................................... 21
4.1.7 Sailing Lake Access Road ............................................................................................. 22
4.2 Stormwater Drainage .................................................................................................................. 22
4.2.1 Pump Stations ................................................................................................................ 23
4.2.2 Gravity Outfalls ............................................................................................................. 23
4.3 Recreational Facilities and Ha bitat Mitigation Sites .................................................................. 24
4.3.1 Sailing Lake Intake Pump Station ................................................................................. 24
4.3.2 Charleston Slough Mitigation Site................................................................................. 25
4.3.3 Mountain View Tidal Marsh and Stevens Creek Tidal Marsh Mitigation Sites ............ 26
5 Adaptation CIP Projects ....................................................................................................................... 28
5.1 Overview .................................................................................................................................... 28
5.2 Project Approaches to Managing Uncertainty ............................................................................ 29
5.3 CIP Project Descriptions ............................................................................................................ 30
1. Charleston Slough and Palo Alto Fl ood Basin Levee Improvement ............................. 30
2. Coast Casey North Levee Improvement ........................................................................ 30
3. North Landfill Erosion Protection ................................................................................. 31
4. Lower Permanente Creek Levee and Floodwall Improvements .................................... 32
5. Golf Course Facilities High Ground Augmentation ...................................................... 32
6. Lower Stevens Creek Levee Improvements .................................................................. 33
7. Coast Casey Pump Station Improvement ...................................................................... 33
8. Lower Permanente Creek Storm Drain Impr ovements (with New Pump Stations) ...... 34
9. Sailing Lake Access Road Improvement ....................................................................... 35
10. Sailing Lake Intake Pump Station Modification ........................................................... 35
11. Charleston Slough Tide Gates Improvement ................................................................. 37
6 Cost Estimates ...................................................................................................................................... 38
6.1 CIP Project Cost Estimates ......................................................................................................... 38
6.2 Potential Funding Sources .......................................................................................................... 42
6.2.1 Local Grants and Programs ........................................................................................... 42
6.2.2 State Grants and Programs ............................................................................................ 42
6.2.3 Federal Grants and Programs ........................................................................................ 43
7 Project Prioritization and Phasing ........................................................................................................ 45
8 References ............................................................................................................................................ 49
9 List of Preparers ................................................................................................................................... 51
10 Figures .................................................................................................................................................. 52
City of Mountain View
City of Mountain View Shoreline Regional Park Community iii ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
List of Tables
Table ES - 1 Vulnerability of Flood Management Elements ........................................................... ES-11
Table ES - 2 Vulnerability of Shoreline Recreational Facilities and Habitat Mitigation Sites ........ ES-12
Table ES - 3 CIP Project Cost Estimate Summary .......................................................................... ES-13
Table ES - 4 Project Cost Estimate Summary with the SBSP Restoration Project ......................... ES-14
Table ES - 5 CIP Project Prioritization and Impl ementation Considerations .................................. ES-15
Table ES - 6 CIP Implementation Timeline..................................................................................... ES-17
Table 1 Summary of Creek Flood Design Criteria From Different Agencies ........................................ 6
Table 2 Summary of Interior Drainage Design Criteria From Different Agencies. ............................... 6
Table 3 Coastal Hydraulic Analysis Elevations and Heights, in feet NAVD....................................... 13
Table 4 Vulnerability of Flood Management Elements ....................................................................... 18
Table 5 Vulnerability of Shoreline Recreational Facilities and Habitat Mitigation Sites .................... 19
Table 6 Lower Stevens Creek Levees Geotechnical Assessment ........................................................ 22
Table 7 Pump Stations, Areas Served, and Receiving Waters ............................................................. 23
Table 8 Gravity Outfalls, Areas Served , and Receiving Waters .......................................................... 24
Table 9 Restoration Site Accretion Rates ............................................................................................. 36
Table 10 Relative Costs for Project Cost Estimate Line Items .............................................................. 38
Table 11 CIP Annual Operating Budget Estimate .................................................................................. 39
Table 12 CIP Project Cost Estimate Summary ....................................................................................... 40
Table 13 CIP Project Cost Summary with the SBSP Restoration Project .............................................. 41
Table 14 CIP Project Prioritization and Im plementation Considerations .............................................. 46
Table 15 CIP Implementation Timeline ................................................................................................. 4 8
City of Mountain View
City of Mountain View Shoreline Regional Park Community iv ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
List of Figures
Figure ES - 1 Project Area – Existing Flood Management Elements ............................................... ES-18
Figure ES - 2 FEMA Special Flood Hazard Areas ........................................................................... ES-19
Figure ES - 3 Project Area Vuln erabilities ........................................................................................ ES-20
Figure ES - 4 SLR Inundation Map (Without Project) ..................................................................... ES-21
Figure ES - 5 Proposed CIP Projects ................................................................................................ ES-22
Figure ES - 6 SLR Inundation Map (With Project) ........................................................................... ES-23
Figure ES - 7 Charleston Slough, Palo Alto Flood Basin, and Coast Casey Area Project Detail ..... ES-24
Figure ES - 8 Lower Permanente Creek Project Detail ..................................................................... ES-25
Figure ES - 9 Golf Course Facilities High Ground Au gmentation Project Detail ............................ ES-26
Figure ES - 10 Lower Stevens Creek Levee Improvement Project Detail .......................................... ES-27
Figure 1 Project Area – Existing Flood Management Elements ............................................................ 53
Figure 2 FEMA Special Flood Hazard Areas ........................................................................................ 54
Figure 3 Project Area Vu lnerabilities .................................................................................................... 55
Figure 4 SLR Inundation Map (Without Project) .................................................................................. 56
Figure 5 Proposed CIP Projects ............................................................................................................. 57
Figure 6 SLR Inundation Map (With Project) ....................................................................................... 58
Figure 7 Charleston Slough, Palo Alto Flood Basin, and Coast Casey Area Project Detail ................. 59
Figure 8 Lower Permanente Creek Project Detail ................................................................................. 60
Figure 9 Golf Course Facilities High Ground Augmentation Project Detail ......................................... 61
Figure 10 Lower Stevens Creek Levee Improvement Project Detail ...................................................... 62
Attachments
Attachment A CIP Proposal Forms
Attachment B Comparison of Sea Level Rise Projections
Attachment C Coastal Flood Assessments
Attachment D Fluvial Flood Assessments
Attachment E Stormwater Drainage Assessments
Attachment F Geotechnical Assessments
Attachment G Cost Estimates
Attachment H Project Alternatives
Attachment I Funding Evaluation
City of Mountain View
City of Mountain View Shoreline Regional Park Community ES 1 ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
Executive Summary
ES-1. Study Purpose and Background
The Shoreline Regional Park Community (Shorelin e Community) Sea Level Rise Study Feasibility
Report and Capital Improvement Program (CIP) presen ts a program to address long-term flood protection
from sea level rise (SLR) for the City's Shoreline Co mmunity. This document provides of an overview of
Shoreline Community vulnerability to sea level ri se, proposed projects to provide long-term flood
protection, and estimates of future fund ing needed to implement these projects.
The Shoreline Community (Figure ES - 1) is generally bounded by Highway 101 to the south, San
Francisco Bay to the north, San Antonio Road to th e west, and Stevens Creek to the east. Within the
Shoreline Community are several large high-technol ogy corporate campuses and suburban-type office
parks, some residences, recreational facilities, closed landfills, and habitat mitigation sites. The Shoreline
Community is subject to coastal flooding from the Bay, overflow from the Palo Alto Flood Basin, and
fluvial flooding from Permanente and Stevens Creeks in the 1% (also known as the 100-year) flood event
(Figure ES - 2). The proposed CIP projects address the potential effects of SLR on coastal flooding of the
Bay shoreline, flooding for some distance upstream of the Bay in creeks that drain to the bay (backwater
effects), and on interior stormwater drainage. Th ese projects would protect the Shoreline Community’s
buildings, public infrastructure, parks, and other r ecreational amenities important to local residents.
The City of Mountain View retained ESA PWA in Ju ly, 2012, to prepare the Shoreline Community Sea
Level Rise Study Feasibility Report and Ca pital Improvement Program (CIP).
ES-2. Study Criteria
ES-2.1. Baseline Conditions
Baseline conditions for this Study assume existing site conditions plus implementation of the Permanente
Creek flood protection project (SCVWD, 2012). The Perm anente Creek project is currently underway and
has an anticipated completion date of 2016. The Pe rmanente Creek project includes raising floodwalls
and levees along Permanente Creek and increased upstr eam flood detention at three sites, Rancho San
Antonio, Cuesta Park 1 , and McKelvey Park. Baseline conditions are intended to approximate conditions
in the year 2017, approximately when the earliest proposed CIP projects would be implemented. The
planning horizon extends 50 years to 2067.
Future baseline conditions assume that flood protectio n projects in the vicinity – the Palo Alto Flood
Basin, Permanente Creek, Stevens Creek, are maintain ed in approximately their current configurations
1 While Cuesta Park was a part of the original project at the time this study took place, Cuesta Park is currently removed from
the Permanente Creek flood c ontrol project (SCVWD, 2012).
City of Mountain View
City of Mountain View Shoreline Regional Park Community ES 2 ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
and levee heights, and thus become susceptible to more frequent flood overtopping with SLR. The City’s
wetland mitigation sites are assumed to be maintained in approximately their current configurations. The
South Bay Salt Pond (SBSP) Restoration Project is not implemented under baseline conditions. In the
absence of the SBSP Restoration Project, the US Fish and Wildlife Service (USFWS) has identified the
salt pond levees bayward of the study area as high priority to be maintained (EDAW et al., 2007).
Although the pond levees were built for salt producti on and are not accredited by FEMA, they afford
some level of flood protection for the Study area. Like the future No Project Alternative defined for the
SBSP Restoration Project (EDAW et al., 2007), the baseline assumes that the USFWS would continue to
maintain the outboard pond levees in approximately th eir current state and would repair them if they
failed. With SLR, the frequency of levee failure ma y increase, increasing the frequency of high energy
wave events with the potential to erode the existing levee and landfill slopes.
ES-2.2. South Bay Salt Pond (S BSP) Restoration Project
The SBSP Restoration Project proposes to restore tidal habitat in former salt ponds located bayward of
the developed Study area by breaching the pond lev ees and constructing new flood protection features
landward of the ponds. The SBSP Restoration Project is committed to providing flood protection that
meets FEMA requirements (EDAW et al., 2007). The SBSP Restoration Project proposes to create a
gently-sloped upland habitat transition area along the bayward levee slope, between the Shoreline
Community and the ponds. The upland transition will pr ovide habitat for marsh wildlife during high tide
as well as wave energy attenuation and additional levee cross-section to enhance flood protection. If
feasible, the SBSP Restoration Project also proposes to include the City of Mountain View’s wetland
mitigation site Charleston Slough in the tidal restoration.
The SBSP Restoration Project is considered in the proposed CIP projects. The SBSP Restoration Project
and the City of Mountain View would coordinate in planning and implemen ting any SBSP Restoration
Project actions that affect the Study area.
ES-2.3. Sea Level Rise Scenarios
In March 2011, the California Ocean Protection Co uncil (OPC) published a resolution recommending that
state agencies incorporate the ri sks posed by SLR into project and program plans (OPC, 2011). The
guidance provided in the State resolution, which applies to projects funded by the state or on state
property, is considered the standard for sea level rise planning in California and has been adopted for this
Study.
The OPC (2011) provides guidance to:
Assess vulnerabilities over a range of SLR projec tions, including analysis of the highest SLR
values presented in the state guidance document; and
Avoid making decisions that would result in high risk.
City of Mountain View
City of Mountain View Shoreline Regional Park Community ES 3 ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
Because of considerable uncertainty in sea level ri se projections, this study adopts two sea level rise
scenarios to bracket the low and high ends of a re presentative uncertainty range. The two sea level rise
scenarios are:
8 inches of sea level rise between 2000 and 2067
31 inches of sea level rise between 2000 and 2067
These scenarios are from a recent report from the Na tional Research Council (NRC 2012), expected to be
adopted as official state guidance. The values are adjust ed to local site conditions and are similar to those
used in the ongoing US Army Corps of Engineers (USACE) South San Francisco Bay Shoreline Study
(SSFB Shoreline Study). The 2067 timeframe represe nts the planning horizon for this Study. Since
current information for the San Francisco Bay area do es not provide consensus on whether the severity of
local storms will change as a result of climate cha nge, this study does not consider changes to storm
runoff intensity and frequency.
ES-2.4. Design Criteria for CIP projects
Levee design criteria were developed in consulta tion with SCVWD staff to comply with SCVWD
requirements, which meet, but are slightly more c onservative than FEMA requirements. From a hydraulic
perspective, this requires that coastal an d creek levees provide adequate freeboard 1 and do not fail during
the 1% flood event. These design criteria are similar to those used for a proposed project to the north on
San Francisquito Creek. To the south, the USACE is applying a risk-based appro ach that quantifies risk
and uncertainty and enables quantified risk/cost tr adeoffs. Although different in its methodology, the
resulting flood protection is expected to be simila r to FEMA requirements. Compliance with these criteria
could be used to justify a modification of the fl ood map that removes properties and development from
the floodplain, and also alleviates requirements for flood insurance as well as building restrictions to
mitigate flood damages. A more detailed analysis w ould be required to ascertain whether there is a
Federal Interest in funding a portion of the lev ee construction (such as through the SSFB Shoreline
Study), and the design level of flood protection (e.g . levee crest elevation) that could be funded.
ES-3. Flood Assessment Methods
ES-3.1. Previous Studies
Existing FEMA studies indicate that much of the City ’s Shoreline Community is exposed to coastal flood
hazard, as indicated by FEMA’s mapping of the 1% annual chance floodplain (Figure ES - 2). Although
the salt pond levees provide some degree of prot ection from coastal flooding, these levees are not
certified by FEMA. The levees are not certified because their crest elevation is below the 1% water level
freeboard requirements and they likely do not meet geotechnical specifications. Since the levees lack
certification, FEMA considers the levees to fail at st opping or reducing the inland propagation of the 1%
1 Freeboard is an increment to the leve e elevation above the design water level to increase the likelihood of the design flood
event being contained without the levee ove rtopping. Freeboard provides a buffer to a ccommodate uncertainty in the estimated
design flood event.
City of Mountain View
City of Mountain View Shoreline Regional Park Community ES 4 ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
still water level. As a result, most of area mapped as vulnerable to flooding occurs where the land surface
within the Shoreline Community is below the 1% s till water level for the Bay. A small portion of flooded
area west of Permanente Creek and south of Charle ston Road is mapped as a fluvial flood hazard area.
FEMA flood hazard zones do not include future condi tions such as future sea level rise. FEMA is
currently revising its coastal flood maps for the Ba y. We anticipate that the area mapped into the
floodplain is likely to increase in area, inundation depth, and possibly destructive power.
The SSFB Shoreline Study has also evaluated flood risk for the City’s shoreline. The USACE flood
assessment methodology is different than FEMA’s, partic ularly in the treatment of levee failure and the
addition of sea level rise. In contrast to FEMA’s assu mption that uncertified levees fail to affect the 1%
still water level, the USACE met hodology assesses levee failure probabilis tically, thereby assigning some
degree of levee effectiveness in reducing inland pr opagation of flooding. The resulting flood levels
developed using USACE’s methods can be substantially different than those developed using FEMA’s
methods, with USACE’s methods predicting less ex tensive inundation than FEMA’s method. The SSFB
Shoreline Study is being performed by the USACE t ogether with local sponsors to recommend one or
more projects for Federal funding. The USACE is co nsidering projects that will reduce flood risk and
restore ecosystems. The flood risk assessments include sea level rise, with an upper bound of 36” by
2067. The SSFB Shoreline Study is currently focused on the area around the Town of Alviso in the far
south San Francisco Bay. The Mountain View shoreline is not currently being evaluated as a priority area
in the SSFB Shoreline Study, though the most rece nt publically-available flood modeling (USACE July
2010 as modified by errata August 2010) shows some flooding west of Permanente Creek for the high
SLR scenario. We understand that flood modeling me thods have changed as the modeling has been
refined for the Alviso area (Frank Wu, pers. comm.). Future assessments of the Mountain View area
could result in updated risk assessments.
ES-3.2. Vulnerability Assessment Methods
The Shoreline Community SLR Study used one-dim ensional hydraulic modeling, two-dimensional
hydraulic and wave modeling, and analytical met hods to assess the potential effects of SLR on coastal
flooding of the Bay shoreline, flooding along Permanente and Stevens Creeks, and on interior stormwater
drainage.
In accordance with FEMA guidelines, the coastal flood vulnerability assessment considered both still
water level (SWL) and total water level (TWL). SWL is the base elevation which does not include waves
and associated wave-driven processes. TWL is th e sum of SWL, wind setup and wave runup. The
analysis presumes that the salt pond levees are sufficien tly intact to block waves from San Francisco Bay.
If this is not the case, the waves and wave runup 1 conditions used to design the new levees would be
greater.
ESA PWA modeled 1% water leve ls on Permanente Creek and Stevens Creeks using HEC-RAS, a
USACE-developed model that is certified for FEM A flood evaluations. Existing HEC-RAS models for
both creeks were provided by Santa Clara Valley Wate r District (SCVWD) and modified to include SLR
1 ‘Wave runup’ is the uprush of water from wave action impinging on the shoreline.
City of Mountain View
City of Mountain View Shoreline Regional Park Community ES 5 ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
downstream boundary conditions for this study. This st udy tested two pairs of discharge and tidal water
level to estimate the 1% event: 1% discharge paired with 10% tidal water level and 10% discharge paired
with 1% tidal water level, per SCVWD guidance. Afte r simulating both of these pairs, the 1% water level
throughout the model domain was defined at each point as the higher predicted by the two pairs. The 1%
discharge yields the higher water level in the upstrea m portion while the 1% tidal water level yields the
higher water level in the downstream portion. The switch between these two controlling event occurs
several thousand feet upstream of wh ere the creeks enter the salt ponds.
The study area interior drainage system contains sever al pump stations and gravity outfalls that discharge
to Stevens Creek, Permanente Creek, the Palo Alto Flood Basin, and the Mountain View Tidal Marsh.
The pump station and gravity storm drain outfall locati ons were first compared with the results of the
hydraulic models developed for Stev ens and Permanente Creeks to determ ine if the outfall locations were
susceptible to the impacts of sea level rise under the low and high SLR scenarios analyzed. For pump
station outfalls falling within the portion of the creek system expected to be impacted by SLR, the pump
curves for the pump stations were analyzed to assess impacts to performance and loss of pumping
capacity. Changes in total dynamic head resulting from the increased discharge water surface elevations
and the associated decrease in pumping capacity resulti ng from this increased head were analyzed. For the
gravity outfalls discharging to the portion of the creek system expected to be impacted by SLR, the
drainage systems were analyzed for the potential of reverse flow and flooding propagating upstream from
the creeks. Note that the current study did not assess th e storm drain systems’ capacity to handle the 1%
interior drainage hydrograph. No hydraulic modeling was performed for the gravity outfalls since storm
drain geometry, hydrology and hydraulic basis of design conditions, and uns teady models were not
available. The parking lots, adjacent roads, and adj acent structures have finished grades and elevations
lower than the sea level rise projections for the co astal areas and the resulting water surface elevations
within the creeks. Therefore, vulnerability due to reverse flow was assessed based on these elevation
differences.
ES-4. Sea Level Rise Vulnerabilities
Table ES - 1 provides a summary of SLR vulnerabilit y by flood management element – organized by
coastal flood defense, stormwater pump stations, and st ormwater gravity outfalls – for the 1% flood event.
Many of the coastal flood defense elements are vulne rable to 1% flooding under baseline conditions and
become more vulnerable with SLR. All of the interi or drainage elements are not vulnerable to flooding
from the creeks’ 1% flood event under baseline a nd low SLR conditions, with the exception of the
Michael’s Parking Lot #1 and #2 Outfalls, which ar e vulnerable under baseline conditions. In addition,
several gravity outfalls and one pump station are subject to flooding under high SLR conditions. Figure
ES - 3 presents the vulnerability graphically, with color coding used to represent the extent of
vulnerability to 1% flooding for increasing SLR. Featur es shown in red are vulne rable to flooding under
baseline conditions, features shown in orange are vul nerable under low SLR conditions, features shown in
yellow under high SLR conditions, and features shown in green do not flood under high SLR conditions.
Figure ES - 4 presents inundation mapping for th e Shoreline Study area under low and high SLR
scenarios. The 1% still water level tidal boundary co ndition for each scenario was used in developing the
mapping. For the low SLR scenario, 8” was added to the baseline 1% water level, yielding 11.3 ft
City of Mountain View
City of Mountain View Shoreline Regional Park Community ES 6 ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
NAVD88 1 ; for the high SLR scenario, 31” was added to th e baseline 1% water level, yielding 13.2 ft
NAVD88. These inundation areas extend further than ex isting FEMA flood zones, primarily because they
include sea level rise whereas FEMA only considers present day conditions. While USACE flood
assessments include sea level rise, th ey also assume that a greater degree of flood protection is provided
by the uncertified levees. Therefore, the USACE asse ssments predict smaller flooding extent than both
FEMA and this study. Also note that the flood modeling methods employed by the USACE to assess
Mountain View flood risk have since been revised, but not applied to the Mountain View shoreline.
Future assessments of Mountain View flood risk with the revised methods could result in updated risk
assessments.
SLR vulnerability for the Shoreline Community recrea tional facilities and the City’s near-shore habitat
mitigation sites is described qualitatively in Table ES - 2. For the City’s mitigation sites, Charleston
Slough and Stevens Creek Marsh are most vulnerable to SLR, since muted tidal flows through culverts
limit the delivery of estuarine sediments necessary for raising the marsh with SLR.
ES-5. Recommended Adaptation Projects
Eleven CIP projects were developed to address the vul nerabilities identified in this study. The projects
were defined after consideration of a range of alternative sea level rise conditions, flood protection
alignments, and types of improvements, such as levees and floodwalls. The selection of recommended
alternatives was based largely on existing flood mana gement infrastructure, cost effectiveness, and
consistency with adjacent sen sitive wetland habitats.
The proposed CIP projects, shown in Figure ES - 5, remove the developed and recreational areas from 1%
flood inundation. The resulting inundation extents w ith the CIP projects implemented are mapped in
Figure ES - 6. The CIP projects are listed below and shown in figures as indicated. Note that the projects
are numbered according to an east-west conve ntion and not on a priority basis.
1. Charleston Slough and Palo Alto Flood Basin Levee Improvement . (Figure ES - 7) Design,
permit, and construct improvements to a 6,600 -ft section of levee that separates Charleston
Slough and the Palo Alto Flood Basin. The levee improvements include raising the crest elevation
and providing erosion protection. Because of th e shared risk across local government boundaries
at the Palo Alto Flood Basin, this aspect of the City of Mountain View’s flood exposure is best
managed through City participation in a re gional planning effort and cost sharing.
2. Coast Casey North Levee Improvement. Design, permit, and construct coastal flood levee
improvement to help protect property in the City’s northwest corner from flooding caused by San
Francisco Bay. The levee will extend 1,300 feet from the high ground of the City’s Shoreline
Park landfill to the City’s boundary with Palo Alto.
3. Landfill Erosion Protection. Design, permit, and construct erosion protection for the levees on
the north side of the East and West Landfill.
4. Lower Permanente Creek Levee and Floodwall Improvements. (Figure ES - 8) Design,
permit, and construct flood protection measure s to protect property along lower Permanente
1 North American Vertical Datum 1988 is a surv eying benchmark for el evation measurements.
City of Mountain View
City of Mountain View Shoreline Regional Park Community ES 7 ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
Creek. The measures consist of raising crest el evations for multiple levee sections (combined
length – approximately 2,500 ft), constructing one new floodwall (length – approximately 700
feet), and raising the crest elevation of th ree other floodwall sections (combined length –
approximately 650 ft).
5. Golf Course Facilities High Ground Augmentation. (Figure ES - 9) Design, permit, and
construct engineered fill to the north of the C ity-owned golf course facilities and North Shoreline
Boulevard and south of the Mountain View Ti dal Marsh to provide flood protection for golf
course facilities including buildings, sanitary sewer lift station, parking lots, and roadway.
6. Lower Stevens Creek Levee Improvements. (Figure ES - 10) Design, permit, and construct
levee improvements along lower Stevens Creek, north of Crittenden Lane. The improvements
consist of improvements to existing levees, a short section of new levee with drainage culverts, as
well as levee access and maintenance elements.
7. Coast Casey Pump Station Improvement. Design and construct a project to improve pump
station capacity at the Coast Casey Stormwater Pump Station to counter sea level rise impacts on
pump station hydraulics. Note that if flood prot ection improvements are implemented for the Palo
Alto Flood Basin, a portion of which is describ ed in CIP #1 above, then the Coast Casey Pump
Station improvement may not be necessary.
8. Lower Permanente Creek Storm Drain Improvements. Design and construct the realignment
of storm drain systems and the installation of three pump stations to evacuate interior drainage
from the storm drains to lower Permanente Creek.
9. Sailing Lake Access Road Improvement. Design, permit, and construct a buttress fill on the
west side of the Sailing Lake access road. The f ill provides additional slope stability to resist
failure due to heavy vehicle traffic and limits seepage through the levee under the road, which
helps contain the Sailing Lake.
10. Sailing Lake Intake Pump Station Modification. Design, permit, and implement alterations to
the Sailing Lake Pump Station to adapt the pum p station, intake, and suction and discharge
piping.
11. Charleston Slough Tide Gates Improvement. Revise Inner Charleston Slough tide gate
operations to maintain water le vels within targeted range.
The projects are presented with the City’s CIP proposal template in Attachment A. For projects dependent
on the magnitude of sea level rise for their design, three alternatives are presented:
Low SLR –1% flood protection with 8” of sea level rise
Low SLR ‘Plus’ –1% flood protection with 8” of sea leve l rise, but with a broader base sized for
the high SLR scenario so additional fill can be more easily added at later time
High SLR –1% flood protection with 31” of sea level rise
The projects are defined at a concept screening level. We anticipate that the projects will be refined and
may change during subsequent planning and design, pa rticularly as integration with the SBSP Restoration
Project and other regional projects evolves. Because of the need to coordinate with other projects, such as
the South Bay Salt Ponds and regional flood planning, as well as the evolving projections of sea level
rise, another sea level rise assessment is also recommended after another decade has passed.
City of Mountain View
City of Mountain View Shoreline Regional Park Community ES 8 ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
Implementation of the SBSP Restoration Project o ffers opportunities to integrate the City’s flood
management strategy with ecological restoration. Th is integration can benefit the proposed CIP projects
by providing opportunities for cost sharing, improved public access, and, wetland mitigation credit. It
would change how several of the CIP projects are im plemented and make improvements to the Charleston
Slough tide gates (CIP #11) unnecessary. The CIP pr oject proposals identify how each project may
change to integrate with the restoration.
ES-6. Cost Estimates
A summary of the proposed adaptation projects’ cost s is presented in Table ES - 3. The estimated total
cost is $43-$57 million in 2012 dollars. Total cost s are similar with implementation of the SBSP
Restoration Project (Table ES - 4), though $27-$3 2 million of improvements also benefit the SBSP
Restoration Project and have the potential to be cost shared. The estimated annual operating budget
associated with the new infrastructure is approxima tely a one third engineer position, a full time
maintenance position, and $117,0 00-130,000 in expenses.
Since the CIP projects are in the planning stage a nd an engineering design has not been completed, a
number of assumptions were made and the cost estimate is very approximate. General costs for
mobilization, design, project management, constructi on inspection, and administration were added based
on a percentage of the construction costs. The cost estimate does not include right-of-way easements or
property acquisition costs.
The cost estimates are based upon a concept screeni ng level of design and include a 20% construction
contingency and an additional 10% contingency for overall project costs. Note that the accuracy of the
cost estimate (-50% to +100%) is for the extent of construction described in the CIP proposal project
descriptions. According to the AACE International cost estimate classification system, this is a Class 4
cost estimate, which is characteristic of a 1% -15% level of project definition and suitable for a feasibility
study such as this one. There is additional uncertainty associated with future desi gn refinements that result
in a greater or lesser extent of construction than assumed, particularly for the levee components.
The strategy for meeting the funding needs of th e Shoreline Community SLR CIP projects will likely
include a combination of funding approaches. Subject to Shoreline Community Board (Mountain View
City Council) approval, the Shore line Regional Park Community may commit a portion of its unassigned,
unrestricted net assets to the CIP projects. For many of the projects, a combination of funding would be
appropriate from the Shoreline Community, local funding initiatives, as well as regional, State and
Federal grants and programs. The FloodSafe Califor nia Local Levee Assistance Program provides for
feasibility studies, geotechnical evaluation, design an d repair of critically-damaged levees and structures
to reduce flood risk. This State program generally requires a 50% cost share. The Federal government
provides funding for projects with a flood protecti on purpose, such as the SSFB Shoreline Study. As
noted above, the Mountain View shoreline is not currently identified as a priority area in the SSFB
Shoreline Study, though this is subject to change in future assessment. Funding through the SSFB
Shoreline Study will be directed first to those areas th at have been identified as the highest priority. For
flood protection projects, the USACE pays 50% of th e cost for feasibility studies and up to 65% for
City of Mountain View
City of Mountain View Shoreline Regional Park Community ES 9 ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
construction. The USACE does not cost-share for ope rations and maintenance, which is entirely a non-
federal cost.
ES-7. Project Prioritization and Phasing
The City of Mountain View will need to consider project priorities for phased implementation. The
following factors, summarized in Table ES - 5, are provided for use in prioritization:
Project Cost.
Risk of Flooding. Projects that address higher vulnerability areas will be prioritized more highly.
Potential Damages . Flood damages avoided will be considered in setting project priorities.
Integration with Scheduled Improvements. Implementing Mountain View Shoreline SLR
Study CIP projects with other improvements avoids the costs of re-working scheduled
improvements at the time the CIP project is implemented.
Likely to Require Wetland Mitigation . Because many of these projects are sited in or adjacent
to jurisdictional wetlands or waters of the U.S ., they are likely to require wetland mitigation.
Projects that are likely to require wetland habita t mitigation will require additional lead time and
coordination, and may be coordinated with th e SBSP Restoration Project for mitigation.
Consistency with SBSP Restoration Project . Projects that are related to the SBSP Restoration
Project may need to be implemented prior to r estoration, and perhaps modified, or may not be
needed.
For the proposed projects, many rank high for ri sk of flooding, since they address existing flood
vulnerabilities that only worsen with SLR. Similarly, many of the proposed projects address
vulnerabilities with high potential damages, as mo st are designed to protect densely developed
commercial areas.
An estimated CIP implementation timeline is presented in Table ES - 6, with associated costs shown in
five-year increments. Projects that integrate with ot her regional efforts are timed to correspond with those
efforts. Projects that address an existing flood risk ar e assumed to be implemented in the first five-year
interval. Projects that address flood risk under the low SLR and high SLR scenarios are assumed to be
implemented by 2037 and 2067, respectively. Note that, while the projected costs of the low SLR and low
SLR+ scenarios are less than for the high SLR scenar io, these are planning scenarios only. Should actual
SLR be greater than that used in the low SLR scenar io, additional improvements and costs (not shown in
Table ES - 6) will be required to meet flood protection criteria.
Since the CIP projects are developed to only a conceptual level of design in this study, initiation of any of
these projects will require additional data collection and engineering analysis to inform subsequent
design. Depending on the project, data collection may include topographic surveys, property line
determinations, levee ownership determinations, right-of-way re view, basemap development, and
geotechnical borings. These data would inform additi onal engineering analysis, such as the geotechnical
stability of existing levees, settlement of placed fill, and hydraulic performance. A sensitivity analysis
could be conducted to evaluate the potential impacts if climate change alters storm runoff intensity and
frequency. Using the data and engineering analyses, the project designs can be refined and the cost
City of Mountain View
City of Mountain View Shoreline Regional Park Community ES 10 ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
estimates updated. The proposed storm drain projects would also benefit from a storm drain planning
study to evaluate the potential for consolidating and improving existing storm drain infrastructure
throughout the Shoreline Community and considers th e effects sea level rise on groundwater seepage.
For the feasibility-level analysis conducted for this st udy, it is premature to identify a permitting strategy.
The most efficient permitting process, particularly for CEQA, and as if needed, NEPA, will depend on
revised project descriptions, partners, and timing. Re vised project descriptions will indicate which permits
are needed and the extent of mitigation, if any, associated with each project. Coordination with potential
partners, such as the South Bay Salt Pond Restoration Project and the USACE Shoreline Study, may
enable projects to be self-mitigating and other entities to serve as lead permit applicants. Project timing,
both of partner projects and City-only projects, can in form the decision to employ either project-based or
programmatic permitting.
While advancing on its own projects, the City should continue to coordinate with other agencies working
in the area, including FEMA (updating the Santa Clara County flood maps), SCVWD (conducting
designs for the Palo Alto Flood Basin and lower Perm anente Creek), USFWS (restoration of the former
salt ponds), and the USACE (flood assessments for the SSFB Shoreline Study). Many of these adjacent
efforts are expected to occur in the coming decade, as well as updates to sea level rise projections. In light
of these developments, it is recommended that the Ci ty conduct another sea level rise assessment similar
to the current study in another decade.
City of Mountain View
City of Mountain View Shoreline Regional Park Community ES 11 ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
TABLE ES - 1 VULNERABILITY OF FLOOD MANAGEMENT ELEMENTS
Flood Management Element
Vulnerable to 1% Flood?
Baseline
Conditions
Low SLR
(8”)
High SLR
(31”)
Coastal Flood Defense
West Side City Boundary (Palo Alto Flood Basin & Adobe Creek) Yes Yes Yes
Coast Casey North Levee Yes Yes Yes
High Ground Along North Side of Landfill 1 No Yes Yes
Lower Permanente Creek
East bank at Amphitheatre Parkway Pump Station
West Levee at High Level Ditch (WB5)2
Sailing Lake Levee
Lower Permanente Creek (WB1-WB4, WB6, WB7, EB1-EB4) 3
All other areas
No
Yes
No
Yes
No
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
No
High Ground North of Golf Course Facilities Yes Yes Yes
Lower Stevens Creek
Upstream (south) of Crittenden Lane
Crittenden Lane to East Landfill
No
Yes
No
Yes
No
Yes
Stormwater Pump Station Hydraulic Capacity 4
Coast Casey Pump Station No No Yes
High Level Ditch Pump Station No No No
Amphitheatre Parkway Pump Station No No No
Crittenden Pump Station No No No
Charleston Pump Station No No No
Stormwater Gravity Outfalls
Plymouth Street Outfall No No No
Golf Course Pump Station Outfall 5 No No Yes
Sailing Lake Outfall No No Yes
Boathouse Parking Lot Outfall No No Yes
Michael’s Parking Lot #3 and #4 Outfalls No No Yes
Michael’s Parking Lot #1 and #2 Outfalls Yes Yes Yes
La Avenida Outfall No No No
1 Vulnerable to erosion, not overtopping. Eros ion threatens integrity of waste containment.
2 Locations of WB1-7 and EB1-4 are shown in Figure ES - 8.
3 Not all reaches are vulnerable for baseline conditions, see Figure ES - 3.
4 Pump stations were evaluated for vulnerability due to in sufficient hydraulic capacity for baseline and SLR conditions;
However, pump stations may also be vulnerable to direct flooding. See text for discussion.
5 This item is included with the gravity outfalls rather than pumps because the pump discharges to a vault that drains through an
open pipe to the creek.
City of Mountain View
City of Mountain View Shoreline Regional Park Community ES 12 ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
TABLE ES - 2 VULNERABILITY OF SHORELINE RECRE ATIONAL FACILITIES AND HABITAT MITIGATION
SITES
Shoreline Element Function Description of SLR Vulnerability
Sailing Lake Intake Pump Station Water supply for recreational
Sailing Lake
Vulnerable to direct flooding in the event of levee failure
on Inner Charleston Slough. At risk of such a breach for
low and high SLR scenarios.
Inner Charleston Slough Habitat mitigation site Site ma y not drain as well, resulting in increased depth,
duration and frequency of ponding and conversion of
vegetated areas to open water.
Damped tidal exchange (through culverts) limits delivery
of estuarine sediments and ability of the marshplain to
rise with sea level. Tide gates require sufficient
operational range to avoid in creasing tidal water levels
inside the site (adjacent to the PAFB) and to provide
sufficient drainage with SLR.
Mountain View Tidal Marsh Habitat mi tigation site Site receives full ti dal inundation, maximizing resiliency
with SLR. SLR may increase the depth, duration and
frequency of tidal inundation, similar to SLR effects on
the natural marshes of the South Bay.
Stevens Creek Marsh Habitat miti gation site SLR may increase the depth, duration and frequency of
tidal inundation to a greater extent than for the Mountain
View Tidal Marsh and natural marshes of the South Bay.
As at Inner Charleston Slough, damped tidal exchange
through culverts increases vulnerability to SLR.
City of Mountain View
City of Mountain View Shoreline Regional Park Community ES 13 ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
TABLE ES - 3 CIP PROJECT COST ESTIMATE SUMMARY
Project
Cost by Scenario
Low SLR
(8”)
Low SLR plus
(8”+)
High SL R
(31”)
1. Charleston Slough and Palo Alto Flood Basin
Levee Improvement $13,077,000 $15,532,000 $16,047,000
2. Coast Casey North Levee Improvement $3,066,000 $3,541,000 $3,658,000
3. North Landfill Erosion Protection $9,607,000 $9,607,000 $10,844,000
4. Lower Permanente Creek Levee and Floodwall
Improvements $5,525,000 $5,525,000 $9,920,000
5. Golf Course Facilities High Ground
Augmentation $3,626,000 $3,626,000 $4,020,000
6. Lower Stevens Creek Levee Improvements $1,474,000 $1,485,000 $1,714,000
7. Coast Casey Pump Station Improvement $2,316,000 $2,316,000 $2,663,000
8. Lower Permanente Creek Storm Drain
Improvements (with new pumps) $2,608,000 $2,608,000 $6,598,000
9. Sailing Lake Access Road Improvement $170,100 $170,100 $170,100
10. Sailing Lake Intake Pump
Station Modification 1 $692,000 $692,000 $692,000
11. Charleston Slough Tide Gates Improvement $63,900 $63,900 $134,200
SLR Assessment $500,000 $500,000 $500,000
TOTAL $42,730,000 $45,670,000 $56,960,000
Note: All values are in 2012 dollars.
1 Assumes the low cost option of only moving the pump (but not the intake) can be select ed because this is not a function of SLR
scenario. The higher cost alternative of also re-lo cating the intake is included in Table ES - 4.
City of Mountain View
City of Mountain View Shoreline Regional Park Community ES 14 ESA / Project No. D120470
Sea Level Rise Study December 18, 2012
TABLE ES - 4 PROJECT COST ESTIMATE SUMMAR Y WITH THE SBSP R ESTORATION PROJECT
Project All SLR scenarios
Opportunity
for Cost
Share Notes
1. Charleston Slough and Palo
Alto Flood Basin Levee
Improvement
$13,077,000-$16,047,000* Yes
Rock slope protection would be replaced with
upland transition zone. Assumed the same
cost for this estimate, though may be lower.
2. Coast Casey North Levee
Improvement $3,066,000 - $3,658,000* Yes
Rock slope protection would be replaced with
upland transition zone. Assumed the same
cost for this estimate, though may be lower.
3. North Landfill Erosion
Protection $9,607,000 - $10,844,000* Yes
Rock slope protection would be replaced with
upland transition zone. Assumed the same
cost for this estimate, though may be lower.
4. Lower Permanente Creek
Levee and Floodwall
Improvements
$5,525,000 - $9,920,000* No Independent of SBSP Restoration Project.
5. Golf Course Facilities High
Ground Augmentation $3,626,000 - $4,020,000* No Independent of SBSP Restoration Project.
6. Lower Stevens Creek Levee
Improvements $1,474,000 - $1,714,000* No Independent of SBSP Restoration Project.
7. Coast Casey Pump Station
Improvement $2,316,000 - $2,663,000* No Independent of SBSP Restoration Project.
8. Lower Permanente Creek
Storm Drain Improvements
(with new pumps)
$2,608,000 - $6,598,000 * No Independent of SBSP Restoration Project.
9. Sailing Lake Access Road
Improvement $170,100 - $170,100* Yes Identical with SBSP Restoration Project.
10. Sailing Lake Intake Pump
Station Modification $1,208,000 Yes
Assume move pump station and intake with
SBSP Restoration Project. Actual cost may
be lower.
11. Charleston Slough Tide Gates
Improvement $0 NA This project is not needed with SBSP.
SLR Assessment $500,000* NA
This project would assess City needs in light
of SBSP Restoration Project design and
other agencies’ efforts.
Total subject to cost-share with
SBSP Restoration Project $27,128,000 - $31,927,000
Total independent of SBSP $16,049,000 - $25,415,000
TOTAL $43,177,000 - $57,342,000
* No change from CIP cost estimate without SBSP Restoration Project.
Note: All values are in 2012 dollars.
City of Mountain View
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S
a
i
l
i
n
g
L
a
k
e
A
c
c
e
s
s
R
o
a
d
Im
p
r
o
v
e
m
e
n
t
$1
7
0
,
1
0
0
-
$
1
7
0
,
1
0
0
E
x
i
s
t
i
n
g
Ne
e
d
e
d
t
o
im
p
l
e
m
e
n
t
o
t
h
e
r
CI
P
p
r
o
j
e
c
t
s
NA
Y
e
s
R
e
q
u
i
r
e
d
10
.
S
a
i
l
i
n
g
L
a
k
e
I
n
t
a
k
e
P
u
m
p
St
a
t
i
o
n
M
o
d
i
f
i
c
a
t
i
o
n
$6
9
2
,
0
0
0
-
$
6
9
2
,
0
0
0
L
o
w
S
L
R
Re
c
r
e
a
t
i
o
n
a
l
fa
c
i
l
i
t
i
e
s
NA
N
o
M
o
d
i
f
i
e
d
11
.
C
h
a
r
l
e
s
t
o
n
S
l
o
u
g
h
T
i
d
e
G
a
t
e
s
Im
p
r
o
v
e
m
e
n
t
$6
3
,
9
0
0
-
$
1
3
4
,
2
0
0
E
x
i
s
t
i
n
g
M
i
t
i
g
a
t
i
o
n
si
t
e
N
A
Y
e
s
I
n
c
o
n
s
i
s
t
e
n
t
NA
S
L
R
A
s
s
e
s
s
m
e
n
t
$
5
0
0
,
0
0
0
-
$
5
0
0
,
0
0
0
N
A
Sh
o
r
e
l
i
n
e
Co
m
m
u
n
i
t
y
In
t
e
g
r
a
t
i
o
n
w
i
t
h
e
v
o
l
v
i
n
g
pr
o
j
e
c
t
s
a
n
d
u
p
d
a
t
e
d
S
L
R
pr
o
j
e
c
t
i
o
n
s
No
I
n
t
e
g
r
a
t
i
o
n
p
l
a
n
n
i
n
g
1 N
o
n
-
w
e
t
l
a
n
d
h
a
b
i
t
a
t
s
m
a
y
r
e
q
u
i
r
e
m
i
t
i
g
a
t
i
o
n
;
t
h
e
r
e
i
s
bu
r
r
o
w
i
n
g
o
w
l
h
a
b
i
t
a
t
i
n
t
h
e
v
i
c
i
n
i
t
y
o
f
t
h
e
l
a
n
d
f
i
l
l
.
2 R
e
q
u
i
r
e
d
=
n
e
e
d
e
d
f
o
r
i
m
p
l
e
m
e
n
t
a
t
i
o
n
o
f
S
B
S
P
R
e
s
t
o
r
a
t
i
o
n
P
r
oj
e
c
t
;
M
o
d
i
f
i
e
d
=
w
o
u
l
d
i
m
p
l
e
m
e
n
t
d
i
f
f
e
r
e
n
t
l
y
w
i
t
h
S
B
S
P
.
3 V
a
r
i
e
s
b
y
p
r
o
j
e
c
t
.
4 Va
r
i
e
s
b
y
p
r
o
j
e
c
t
.
M
i
c
h
a
e
l
’
s
P
a
r
k
i
n
g
L
o
t
#
1
&
#
2
O
u
t
f
a
l
l
s
a
r
e
a
t
r
i
s
k
f
o
r
e
x
i
s
t
i
n
g
s
e
a
l
e
v
e
l
.
T
h
e
r
e
m
a
i
n
i
n
g
a
r
e
a
s
a
r
e
a
t
r
i
s
k
f
or
h
i
g
h
S
L
R
.
Pr
o
j
e
c
t
L
o
w
SL
R
L
o
w
SL
R
+
H
i
g
h
SL
R
2
0
1
3
‐20
1
7
2
0
1
8
‐20
2
2
2
0
2
3
‐20
2
7
2
0
2
8
‐20
3
2
2
0
3
3
‐20
3
7
2
0
3
8
‐20
4
2
2
0
4
3
‐20
4
7
2
0
4
8
‐20
5
2
2
0
5
3
‐20572058 ‐20622063 ‐2067
1.
Ch
a
r
l
e
s
t
o
n
Sl
o
u
g
h
an
d
PA
F
B
Le
v
e
e
Im
p
r
o
v
e
m
e
n
t
$1
3
,
0
7
7
,
0
0
0
$1
5
,
5
3
2
,
0
0
0
$1
6
,
0
4
7
,
0
0
0
10
‐15
2
0
%
4
0
%
4
0
%
Coordinate with SBSP & SCVWD regional effort
2.
C
o
a
s
t
Ca
s
e
y
No
r
t
h
Le
v
e
e
e
Im
p
r
o
v
e
m
e
n
t
$
3
,
0
6
6
,
0
0
0
$3
,
5
4
1
,
0
0
0
$3
,
6
5
8
,
0
0
0
5 ‐10
2
5
%
7
5
%
Coordinate with SBSP Restoration Project
3.
N
o
r
t
h
La
n
d
f
i
l
l
Er
o
s
i
o
n
Pr
o
t
e
c
t
i
o
n
$
9
,
6
0
7
,
0
0
0
$9
,
6
0
7
,
0
0
0
$1
0
,
8
4
4
,
0
0
0
5 ‐10
2
5
%
7
5
%
Coordinate with SBSP Restoration Project
4.
Pe
r
m
a
n
e
n
t
e
Cr
e
e
k
Le
v
e
e
an
d
Fl
o
o
d
w
a
l
l
Im
p
r
o
v
e
m
e
n
t
s
$5
,
5
2
5
,
0
0
0
$5
,
5
2
5
,
0
0
0
$9
,
9
2
0
,
0
0
0
5 ‐10
2
5
%
5
0
%
2
5
%
First phase are modifications to existing SCVWD project; remainder implemented prior to 8" SLR
5.
Go
l
f
Co
u
r
s
e
Fa
c
i
l
i
t
i
e
s
Hi
g
h
Gr
o
u
n
d
Au
g
m
e
n
t
a
t
i
o
n
$3
,
6
2
6
,
0
0
0
$3
,
6
2
6
,
0
0
0
$4
,
0
2
0
,
0
0
0
2 ‐5
1
0
0
%
I
m
p
l
e
m
e
n
t
e
d
prior to 8" SLR
6.
L
o
w
e
r
St
e
v
e
n
s
Cr
e
e
k
Le
v
e
e
Im
p
r
o
v
e
m
e
n
t
s
$
1
,
4
7
4
,
0
0
0
$1
,
4
8
5
,
0
0
0
$1
,
7
1
4
,
0
0
0
2 ‐5
1
0
0
%
Existing risk, no dependence on other projects.
7.
C
o
a
s
t
Ca
s
e
y
Pu
m
p
St
a
t
i
o
n
Im
p
r
o
v
e
m
e
n
t
$
2
,
3
1
6
,
0
0
0
$2
,
3
1
6
,
0
0
0
$2
,
6
6
3
,
0
0
0
2
1
0
0
%
Anticipated pump replacement life cycle
8.
Lo
w
e
r
Pe
r
m
a
n
t
e
n
t
e
Cr
e
e
k
St
o
r
m
Dr
a
i
n
Im
p
r
o
v
e
m
e
n
t
s
$2
,
6
0
8
,
0
0
0
$2
,
6
0
8
,
0
0
0
$6
,
5
9
8
,
0
0
0
2 ‐5
4
0
%
60%Michael’s Parking Lot #1 & #2 Outfalls implemented early, to address existing risk. Remainder of improvements implemented prior to 31” SLR
9.
S
a
i
l
i
n
g
La
k
e
Ac
c
e
s
s
Ro
a
d
Im
p
r
o
v
e
m
e
n
t
$
1
7
0
,
1
0
0
$1
7
0
,
1
0
0
$1
7
0
,
1
0
0
2
1
0
0
%
Existing seepage risk and in support of SBSP Restoration Project.
10
.
S
a
i
l
i
n
g
La
k
e
In
t
a
k
e
Pu
m
p
St
a
t
i
o
n
Mo
d
i
f
i
c
a
t
i
o
n
$
6
9
2
,
0
0
0
$6
9
2
,
0
0
0
$6
9
2
,
0
0
0
2
1
0
0
%
Coordinate with SBSP Restoration Project
11
.
C
h
a
r
l
e
s
t
o
n
Sl
o
u
g
h
Ti
d
e
Ga
t
e
s
Im
p
r
o
v
e
m
e
n
t
$
6
3
,
9
0
0
$6
3
,
9
0
0
$1
3
4
,
2
0
0
1
1
0
0
%
I
m
p
l
e
m
e
n
t
e
d
prior to 8" SLR
‐
SL
R
As
s
e
s
s
m
e
n
t
$
5
0
0
,
0
0
0
$5
0
0
,
0
0
0
$5
0
0
,
0
0
0
1
1
0
0
%
Implemented after 10 years.
Co
s
t
by
ye
a
r
,
do
l
l
a
r
s
in
f
l
a
t
e
d
to
ti
m
e
of
im
p
l
e
m
e
n
t
a
t
i
o
n
($
M
)
:
20
1
3
‐20
1
7
2
0
1
8
‐20
2
2
2
0
2
3
‐20
2
7
2
0
2
8
‐20
3
2
2
0
3
3
‐20
3
7
2
0
3
8
‐20
4
2
2
0
4
3
‐20
4
7
2
0
4
8
‐20
5
2
2
0
5
3
‐20572058 ‐20622063 ‐2067
Lo
w
SL
R
$
6
6
.
4
1
0
.
8
$
19
.
8
$
12
.
1
$
4.
9
$
10
.
5
$
‐
$
‐
$
‐
$
‐
$ ‐$ 8.3 $ In the event that low SLR occurs, implementation of some CIPs (e.g., 4, 5, 7, 11) could be delayed to 2067. In the event that high SLR occurs, additional improvements and costs (not quantified here) will be required after 2037 to meet flood protection criteria .
Lo
w
SL
R
+
$
7
0
.
3
1
1
.
5
$
21
.
6
$
13
.
6
$
4.
9
$
10
.
5
$
‐
$
‐
$
‐
$
‐
$ ‐$ 8.3 $ Same as for Low SLR scenario above, except that should high SLR occur, the cost of additional improvements required to meet flood protection criteria after 2037 will be less.
Hi
g
h
SL
R
$
9
6
.
2
1
5
.
2
$
23
.
1
$
14
.
4
$
8.
7
$
13
.
7
$
‐
$
‐
$
‐
$
‐
$ ‐$ 21.0 $ In the event that low SLR occurs, costs would be lower. Implementation of some CIPs (e.g., 4, 5, 11) could be delayed to 2067 and others (e.g., 7 and 8) would not need to occur before 2067.
No
t
e
s
:
Us
e
co
n
s
t
r
u
c
t
i
o
n
co
s
t
in
f
l
a
t
i
o
n
ra
t
e
of
3.
2
%
,
th
e
av
e
r
a
g
e
Sa
n
Fr
a
n
c
i
s
c
o
EN
R
CC
I
fr
o
m
19
9
1
‐20
1
1
.
As
s
u
m
e
SB
S
P
Re
s
t
o
r
a
t
i
o
n
Pr
o
j
e
c
t
im
p
l
e
m
e
n
t
a
t
i
o
n
be
g
i
n
s
in
20
1
8
As
s
u
m
e
SB
S
P
Re
s
t
o
r
a
t
i
o
n
Pr
o
j
e
c
t
pr
o
v
i
d
e
s
we
t
l
a
n
d
mi
t
i
g
a
t
i
o
n
fo
r
pr
o
j
e
c
t
s
im
p
l
e
m
e
n
t
e
d
pr
i
o
r
to
or
co
n
c
u
r
r
e
n
t
wi
t
h
th
e
SB
S
P
Re
s
t
o
r
a
t
i
o
n
Pr
o
j
e
c
t
.
As
s
u
m
e
pr
o
j
e
c
t
s
re
q
u
i
r
e
d
fo
r
lo
w
SL
R
(8
in
c
h
e
s
)
mu
s
t
be
im
p
l
e
m
e
n
t
e
d
by
20
3
7
.
As
s
u
m
e
pr
o
j
e
c
t
s
re
q
u
i
r
e
d
fo
r
hi
g
h
SL
R
(3
1
in
c
h
e
s
)
mu
s
t
be
im
p
l
e
m
e
n
t
e
d
by
20
6
7
.
As
s
u
m
e
s
hi
g
h
SL
R
pr
o
j
e
c
t
i
o
n
(3
1
"
)
.
If
ac
t
u
a
l
SL
R
ra
t
e
is
sl
o
w
e
r
,
im
p
l
e
m
e
n
t
a
t
i
o
n
fo
r
so
m
e
pr
o
j
e
c
t
s
co
u
l
d
be
de
l
a
y
e
d
.
ES
‐16
ESA / Project No. D120470 December 13, 2012
TA
B
L
E
ES
‐6 CI
P
IM
P
L
E
M
E
N
T
A
T
I
O
N
TI
M
E
L
I
N
E
Co
s
t
in
20
1
2
do
l
l
a
r
s
City of Mountain View
Ci
t
y
of
Mo
u
n
t
a
i
n
Vi
e
w
Sh
o
r
e
l
i
n
e
Re
g
i
o
n
a
l
Pa
r
k
Co
m
m
u
n
i
t
y
Se
a
Le
v
e
l
Ri
s
e
St
u
d
y
Rationale for timing
% pr
o
j
e
c
t
by
Ye
a
r
Pe
r
m
a
n
e
n
t
e
Cr
e
e
k
Le
v
e
e
an
d
Fl
o
o
d
w
a
l
l
Im
p
r
o
v
e
m
e
n
t
s
in
c
l
u
d
e
s
mu
l
t
i
p
l
e
pr
o
j
e
c
t
s
.
As
s
u
m
e
pr
o
j
e
c
t
s
im
p
l
e
m
e
n
t
e
d
wi
t
h
th
e
on
g
o
i
n
g
SC
V
W
D
pr
o
j
e
c
t
oc
c
u
r
in
Ye
a
r
s
0 ‐5,
th
e
re
s
t
ar
e
pr
i
o
r
to
lo
w
SL
R
da
t
e
.
As
s
u
m
e
no
de
l
a
y
ne
e
d
e
d
to accommodate migitation
re
q
u
i
r
e
m
e
n
t
s
fo
r
th
e
la
t
e
r
pr
o
j
e
c
t
s
.
Es
t
i
m
a
t
e
d
Du
r
a
t
i
o
n
(y
e
a
r
s
)
To
t
a
l
Co
s
t
,
In
f
l
a
t
e
d
Do
l
l
a
r
s
($
M
)
Pl
a
n
n
i
n
g
sc
e
n
a
r
i
o
Notes
;)
;)
;)
;)
;););)
"!
"!
"!"!
"!"!
"!
Palo Alto Flood Basin Charleston Slough
Pond A1 (former salt pond)
Pond A2W (former salt pond)
Mountain View
Tidal Marsh
P e r m a n e n t e C r e e k
Crittenden
Pump Station
Charleston
Pump Station
High Level Ditch
Pump Station
Amphitheatre Pkwy.
Pump Station
Stevens Creek
Tidal Marsh
A d o b e C r e e k
M a t a d e r o C r e e k
St
e
v
e
n
s
C
r
e
e
k
Moffet Field
Sailing
Lake
H
i
g
h
w
a
y
1
0
1
Charleston
Detention Pond
C r i t t e n d e n L a n e
D
r
a
i
n
a
g
e
C
h
a
n
n
e
l
(
"
M
i
t
i
g
a
t
i
o
n
C
h
a
n
n
e
l
"
)
Coast Casey
Pump Station
Sailing Lake
Gravity Outfall
Sailing Lake Intake
Sailing Lake
Access Road
A d o b e C r e e k
Landfill
West
Landfill
East
Boathouse Park Lot
Gravity Outfall GC1
GC2
GC3
GC4
Golf Course
Pump Station
A m p h i t h e a t r e P k w y .
S a n A n t o n i o R o a d
Charleston Slough Tide Gate (off map)
Coast Casey
Detention Basin
Golf Course
Facilities
C h a r l e s t o n R o a d
S h o r e l i n e B l v d .
H i g h L e v e l D i t c h
0 1,000 2,000 500
Feet
±
ESA PWA Ref # - D120470
City of Mountain View Sea Level Rise Study
Project Area - Existing Flood Management Elements
J:\D120470.00_CityOfMountainViewShorelineSLR\figures\project_area.mxd
Figure ES-1
Source: FEMA Flood Zones, SCVWD Stormwater infrastructure
FEMA Certified Levee
Existing Levees, not FEMA certified
Existing High Ground
Existing and Proposed Floodwalls
CityLimits
Creek
Drainage Channel
Storm Drain System
"!Pump Station
;)Gravity Outfalls
Palo Alto Flood Basin Charleston Slough
Pond A1 (former salt pond)
Pond A2W (former salt pond)
Mountain View
Tidal Marsh
P e r m a n e n t e C r e e k
Crittenden
Pump Station
Charleston
Pump Station
High Level Ditch
Pump Station
Amphitheatre Pkwy.
Pump Station
Stevens Creek
Tidal Marsh
A d o b e C r e e k
M a t a d e r o C r e e k
St
e
v
e
n
s
C
r
e
e
k
Moffet Field
Sailing
Lake
H
i
g
h
w
a
y
1
0
1
Charleston
Detention Pond
C r i t t e n d e n L a n e
D
r
a
i
n
a
g
e
C
h
a
n
n
e
l
Coast Casey
Pump Station
Sailing Lake
Gravity Outfall
Sailing Lake Intake
Sailing Lake
Access Road
A d o b e C r e e k
Landfill
West
Landfill
East
Boathouse Park Lot
Gravity Outfall GC1
GC2
GC3
GC4
Golf Course
Pump Station
A m p h i t h e a t r e P k w y .
S a n A n t o n i o R o a d
Charleston Slough Tide Gate (off map)
Golf Course
Facilities
Coast Casey
Detention Basin
C h a r l e s t o n R o a d
H i g h L e v e l D i t c h
S h o r e l i n e B l v d .
0 1,000 2,000 500
Feet
±
ESA PWA Ref # - D120470
City of Mountain View Sea Level Rise Study
FEMA Special Flood Hazard Areas
J:\D120470.00_CityOfMountainViewShorelineSLR\Maps\figures\Figure 2 FEMA Special FloodHazard Area.mxd
Figure ES-2
Source: FEMA Flood Zones, SCVWD Stormwater infrastructure,CA Coastal Conservancy Orthoimagery
FEMA Special Flood Hazard Areas
[See FEMA(2005) for zone definitions]
A Zone
AE Zone
AO Zone
FEMA Certified Levee
Existing Levees, not FEMA certified
Existing High Ground
Existing and Proposed Floodwalls
CityLimits
Creek
Drainage Channel
Storm Drain System
"!Pump Station
"<Gravity Outfalls
Note: Flood elevations based on 1% SWL
"!
"!
"!"!
"!"!
"!
"!
Palo Alto Flood Basin
Charleston Slough
Pond A1 (former salt pond)Pond A2W (former salt pond)
Mountain View
Tidal Marsh
P e r m a n e n t e C r e e k
Crittenden
Pump Station
Charleston
Pump Station
High Level Ditch
Pump Station
Amphitheatre Pkwy.
Pump Station
Stevens Creek
Tidal Marsh
A d o b e C r e e k
M a t a d e r o C r e e k
St
e
v
e
n
s
C
r
e
e
k
Moffet Field
Sailing
Lake
H
i
g
h
w
a
y
1
0
1
Charleston
Detention Pond
C r i t t e n d e n L a n e
D
r
a
i
n
a
g
e
C
h
a
n
n
e
l
Sailing Lake
Gravity Outfall
Sailing Lake Intake
A d o b e C r e e k
Landfill
West
Landfill
East
Boathouse Park Lot
Gravity Outfall GC1
GC2
GC3
GC4
Golf Course
Pump Station
A m p h i t h e a t r e P k w y .
Charleston Slough Tide Gate (off map)
Sailing Lake
Levee
S a n A n t o n i o R o a d
Coast Casey
Pump Station
Sailing Lake
Access Road
Coast Casey
Detention Basin
Golf Coarse
Facilities
C h a r l e s t o n R o a d
H i g h L e v e l D i t c h
S h o r e l i n e B l v d .
0 1,000 2,000 500
Feet
±
ESA PWA Ref # - D120470
City of Mountain View Sea Level Rise Study
Project Area Vulnerabilities
J:\D120470.00_CityOfMountainViewShorelineSLR\figures\Vulnerability of Flood Management.mxd
Figure ES-3
Source: FEMA Flood Zones, SCVWD Stormwater infrastructure,CA Coastal Conservancy Orthoimagery
Vulnerability
Vulnerable for Baseline, Low & High SLR
Vulnerable for Low and High SLR
Not Vulnerable for Low or High SLR
"!Pumps Vulnerable for High SLR
"!Pump Not Vulnerable for low/high SLR
Outfalls Vulnerable for Baseline, Low & High SLR
Outfalls Vulnerable for high SLR
Creek
Drainage Channel
Note: Based on 1% flood event
Palo Alto Flood Basin Charleston Slough
Pond A1 (former salt pond)
Pond A2W (former salt pond)
Mountain View
Tidal Marsh
P e r m a n e n t e C r e e k
Crittenden
Pump Station
Charleston
Pump Station
High Level Ditch
Pump Station
Amphitheatre Pkwy.
Pump Station
Stevens Creek
Tidal Marsh
A d o b e C r e e k
M a t a d e r o C r e e k
St
e
v
e
n
s
C
r
e
e
k
Sailing
Lake
H
i
g
h
w
a
y
1
0
1
Charleston
Detention Pond
C r i t t e n d e n L a n e
D
r
a
i
n
a
g
e
C
h
a
n
n
e
l
Sailing Lake Intake
A d o b e C r e e k
Landfill
West
Landfill
East
Golf Course
Pump Station
A m p h i t h e a t r e P k w y .
S a n A n t o n i o R o a d
Charleston Slough Tide Gate (off map)
Coast Casey
Pump Station
Sailing Lake
Access Road
Coast Casey
Detention Basin
Golf Course
Facilities
C h a r l e s t o n R o a d
H i g h L e v e l D i t c h
S h o r e l i n e B l v d .
0 1,000 2,000 500
Feet
±
ESA PWA Ref # - D120470
City of Mountain View Sea Level Rise Study
SLR Inundation Map (Without Project)
J:\D120470.00_CityOfMountainViewShorelineSLR\figures\project_area.mxd
Figure ES-4
Source: FEMA Flood Zones, SCVWD Stormwater infrastructure
FEMA Special Flood Hazard Area
High SLR (31") inundation zone (13.2 ft NAVD)
Low SLR (8") inundation zone (11.3 ft NAVD)
Study Area
Note: Flood elevations based on 1% SWL
"!
"!
"!"!
"!"!
"!
4
4
4
4
!
!
Palo Alto Flood Basin
Charleston Slough
Pond A1 (former salt pond)
Pond A2W (former salt pond)
Mountain View
Tidal Marsh
P e r m a n e n t e C r e e k
Crittenden
Pump Station
Charleston
Pump Station
High Level Ditch
Pump Station
Amphitheatre Pkwy
Pump Station
Stevens Creek
Tidal Marsh
A d o b e C r e e k
M a t a d e r o C r e e k
St
e
v
e
n
s
C
r
e
e
k
Moffet Field
Sailing
Lake
H
i
g
h
w
a
y
1
0
1
Charleston
Detention Pond
C r i t t e n d e n L a n e
D
r
a
i
n
a
g
e
C
h
a
n
n
e
l
Sailing Lake
Gravity Outfall
Sailing Lake Intake
A d o b e C r e e k
Landfill
West
Landfill
East
Boathouse Park Lot
Gravity Outfall
GC1
GC2
GC3
GC4
Golf Course
Pump Station
A m p h i t h e a t r e P k w y .
6
6
6
6
Project 5. Golf Course Facilities High Ground Augmentation See Figure ES-9 for detail
Project 6. Lower Stevens Creek Levee Improvement Project See Fig ES-10 for detail
6
Projects 4 and 8 Lower Permanente Creek, Sailing Lake Outfall, and Parking Lot Storm Drain Outfalls.See Figure ES-8 for details
Project 1. Charleston Slough West Levee
S a n A n t o n i o R o a d
Projects: 1,2,7,9 and 10 Charleston Slough, Palo Alto Flood Basin,and Coast Casey Area See Figure ES-7 for detail
Project 11. Charleston Slough Tide Gate (off map)
4 4
Project 3.Landfill Erosion Protection
Coast Casey
Pump Station
Sailing Lake
Access Road
Coast Casey
Detention Basin
Golf Course
Facilities
C h a r l e s t o n R o a d
H i g h L e v e l D i t c h
S h o r e l i n e B l v d .
0 1,000 2,000 500
Feet
±
ESA PWA Ref # - D120470
City of Mountain View Sea Level Rise Study
Proposed CIP Projects
J:\D120470.00_CityOfMountainViewShorelineSLR\figures\project_area.mxd
Figure ES-5
Source: FEMA Flood Zones, SCVWD Stormwater infrastructure,CA Coastal Conservancy Orthoimagery
Baseline Conditions
FEMA Certified Levee
Existing Levees, not FEMA certified
Existing High Ground
Existing and Proposed Floodwalls
Creek
Drainage Channel
Sailing Lake Pump Intake
"!Pump Station
")Gravity Outfalls
Proposed Adaptation Project
New Levee
Improved Levees
Floodwall New or Improved
Erosion Protection
!!Access Road Improvement
Fill_Areas
4 Pump Station new or improved
New Roads
Palo Alto Flood Basin Charleston Slough
Pond A1 (former salt pond)
Pond A2W (former salt pond)
Mountain View
Tidal Marsh
P e r m a n e n t e C r e e k
Crittenden
Pump Station
Charleston
Pump Station
High Level Ditch
Pump Station
Amphitheatre Pkwy.
Pump Station
Stevens Creek
Tidal Marsh
A d o b e C r e e k
M a t a d e r o C r e e k
St
e
v
e
n
s
C
r
e
e
k
Sailing
Lake
H
i
g
h
w
a
y
1
0
1
Charleston
Detention Pond
C r i t t e n d e n L a n e
D
r
a
i
n
a
g
e
C
h
a
n
n
e
l
Sailing Lake Intake
A d o b e C r e e k
Landfill
West
Landfill
East
Golf Course
Pump Station
A m p h i t h e a t r e P k w y .
S a n A n t o n i o R o a d
Charleston Slough Tide Gate (off map)
Coast Casey
Pump Station
Sailing Lake
Access Road
Coast Casey
Detention Basin
Golf Course
Facilities
C h a r l e s t o n R o a d
H i g h L e v e l D i t c h
S h o r e l i n e B l v d .
0 1,000 2,000 500
Feet
±
ESA PWA Ref # - D120470
City of Mountain View Sea Level Rise Study
SLR Inundation Map (With Project)
J:\D120470.00_CityOfMountainViewShorelineSLR\figures\project_area.mxd
Figure ES-6
Source: FEMA Flood Zones, SCVWD Stormwater infrastructure
FEMA Special Flood Hazard Area
High SLR (31") inundation zone (13.2 ft NAVD)
Study Area
Note: Inundation Mapping assumes implementation of CIP project(s) to provide flood protection within the city of Palo Alto. Without such a project(s), a large protion of the southwestern part of the Study Area would be a risk from City of Palo Alto Flooding"
"!
"!
!
!
!
!
!
!
!
!
4 4
Palo Alto Flood Basin
A d o b e C r e e k
Coast Casey
Pump Station
Sailing Lake Intake Pump Station
Sailing Lake
Access Road
Inner Charleston Slough
Pond A1 (former salt pond)
Sailing
Lake
Coast Casey
Detention Basin
0 250 500 125
Feet ±
PWA Ref # - D120470.00
City of Mountain View Sea Level Rise Study
Charleston Slough, Palo Alto Flood Basin, and Coast Casey Area Project Detail
Figure ES - 7
S:\GIS\D120470.00_CityOfMountainViewShorelineSLR\Maps\figures\Figure 6 Coast Casey and Inner Charleston Slough
Baseline Conditions
Existing High Ground
Sailing Lake Pump Intake
Existing Levees, not FEMA certified
"!Pump Station
Creek
CityLimits
Proposed Adaptation Project
Improved Levee
!!Access Road Improvement
4 Pump Station new or improved
Source: SCVWD Stormwater Infrastructure, CA Coastal Conservancy Orthoimagery
"<
"<
"<
"<
"<
"<
"<
"!
"!
"!
4
4
4
Mountain View
Tidal Marsh
P e r m a n e n t e C r e e k
High Level Ditch
Pump Station
Amphitheatre Pkwy.
Pump Station
Sailing
Lake
Shoreline
Detention Pond
Coast Cosey Pump Station
Retrofit Sailing Lake
Gravity Outfall
Sailing Lake Intake
Sailing Lake
Access Road
Landfill West
Landfill
East
Golf Coarse
Facilities
Boathouse Parking Lot
Pump Station (new)GC1
# 2
GC3
GC4 Golf Course
Pump Station
A m p h i t h e a t r e P k w y
Sailing Lake
Levee WB6
WB5
WB4
WB3
WB2
WB1 EB1
EB2
EB3
EB4
Parking Lot
Pump Stations (new)
WB7
C h a r l e s t o n R o a d
H i g h L e v e l D i t c h
S h o r e l i n e B l v d .
0 1,000 2,000 500
Feet
±
PWA Ref # - D120470.00
City of Mountain View SLR Study
Lower Permanente Creek Project Detail
Figure ES - 8
S:\GIS\D120470.00_CityOfMountainViewShorelineSLR\Maps\figures\Figure 5 Lower Permanente Creek Project Detail
Baseline Conditions
Existing High Ground
Existing and Proposed Floodwalls
"!Pump Station
"<Gravity_Outfalls
Creek
Drainage Channel
Proposed Adaptation Project
New Levee
Floodwall New or Improved
Improved Levee
4 Pump Station new or improved
Source: SCVWD Stormwater Infrastructure, CA Coastal Conservancy Orthoimagery
Mountain View
Tidal Marsh
Raise ground for low SLR
(8 inch) scenario with room
to raise in the future for
height SLR scenario
Realign road to
high ground
0 150 300 75
Feet ±
PWA Ref # - D120470.00
City of Mountain View Sea Level Rise Study
Golf Course Facilities High Ground Augmentation Project Detail
Figure ES - 9
Notes: See figure 5 for Lower Permanente Creek Project Detail, which includes stormwater infrastructure improvments in this area.
S:\GIS\D120470.00_CityOfMountainViewShorelineSLR\Maps\figures\Figure_4 Mountain Vied Tidal Marsh Project Detail
Proposed Adaptation Project
Realign Roads
Fill Areas
Source: CA Coastal Conservancy Orthoimagery
"!
Crittenden
Pump Station
Stevens Creek
Tidal Marsh
St
e
v
e
n
s
C
r
e
e
k
Moffet Field
C r i t t e n d e n L a n e
D
r
a
i
n
a
g
e
C
h
a
n
n
e
l
Landfill
East
0 250 500 125
Feet
±
PWA Ref # - D120470.00
City of Mountain View Sea Level Rise Study
Lower Stevens Creek Levee Improvment Project Detail
Figure ES - 10
S:\GIS\D120470.00_CityOfMountainViewShorelineSLR\Maps\figures\Figure 3 Lower Stevens Creek Project Detail
Baseline Conditions
Existing High Ground
FEMA Certified Levee
Existing Levees, not FEMA certified
Creek
Drainage Channel
"!Pump Station
CityLimits
Proposed Adaptation Project
New Levee
Improved Levee
New Maintenance Road
Source: SCVWD Stormwater Infrastructure, CA Coastal Conservancy Orthoimagery