stevens creek steelhead passage improvement …...stevens creek steelhead passage improvement...

Stevens Creek Steelhead Passage Improvement Project Feasibility Report

Prepared for:

Friends of Stevens Creek Trail

Prepared By:

DOMENICHELLI & ASSOCIATES

CIVIL ENGINEERING

1101 Investment Blvd., Suite 115

El Dorado Hills, CA 95762

November, 2017

Friends of Stevens Creek Trail PAGE i DOMENICHELLI & ASSOCIATES, INC.

TABLE OF CONTENTS

Table of Contents ............................................................................................................................. i

Table of Figures .............................................................................................................................. ii

Table of Tables .............................................................................................................................. iii

Section 1 – Background .................................................................................................................. 1

Introduction and Purpose ............................................................................................................ 1

Barrier Mitigation Projects ......................................................................................................... 1

Hydraulic Analyses ..................................................................................................................... 4

Flood Control Impacts ............................................................................................................ 5

Fish Passage Hydraulics ......................................................................................................... 5

Alternatives Analysis .................................................................................................................. 6

Preliminary Designs and Recommendations .............................................................................. 6

Section 2 – Detailed Project Analyses ............................................................................................ 7

Moffett Drop Structure and Downstream Channel – HL01 & HB 02 ........................................ 7

Alternative Identified for Drop Structure and Downstream Channel ..................................... 9

Hydraulic Considerations...................................................................................................... 10

Costs and Constructability Considerations ........................................................................... 12

Conclusions – Moffett Drop Structure and Downstream Channel – HL01/HB02 ............... 13

Hetch Hetchy Pipeline Drop Structure – HB 05/06 .................................................................. 14

Conclusions – Hetch Hetchy Drop Structure – HB05/06 ..................................................... 17

Highway 85 crossing (un-numbered) ........................................................................................ 18

Conclusions – Un-Numbered Crossing for Highway 85 ...................................................... 20

El Camino Real Crossing – HB 13 ........................................................................................... 21

Conclusions – El Camino Real – HB13 ................................................................................ 23

Highway 85 Crossing near Village Court – HB 15 .................................................................. 24

Conclusion – Highway 85 near Village Court – HB15 ........................................................ 26

Highway 280 Crossing– HB 20 ................................................................................................ 27

Conclusion – Highway 280 Crossing– HB20 ....................................................................... 30

Deep Cliff Golf Course – HB 28 .............................................................................................. 31

Conclusion – Deep Cliff Golf Course – HB28 ..................................................................... 33

Gauge Station Weir (HB 32) ..................................................................................................... 34

Friends of Stevens Creek Trail PAGE ii DOMENICHELLI & ASSOCIATES, INC.

Conclusion – Gauge Station Weir – HB32 ........................................................................... 35

Section 3 – Summary of Project Conclusions and Recommendations ......................................... 36

References ..................................................................................................................................... 37

Appendix A – Conceptual Design Drawings ................................................................................ 38

Appendix B – Hydraulic Calculations .......................................................................................... 38

Appendix C – Cost Estimates ....................................................................................................... 38

TABLE OF FIGURES

Figure 1. Project Location Map ..................................................................................................... 2

Figure 2. Existing Drop Structure and Fish Ladder ....................................................................... 8

Figure 3. Downstream Concrete Channel (approx. 800 lineal feet) .............................................. 8

Figure 4. Step at Downstream end of Channel past Highway 101 ................................................ 9

Figure 5. New Concrete Fish Ladder Option with Existing Denil Ladder Shown ........................ 9

Figure 6. Moffett Drop Downstream Channel Alternatives ........................................................ 10

Figure 7. Hetch Hetchy Drop (PWA, 2005) ................................................................................. 14

Figure 8. Rendering Taken from PWA Report (2005) ................................................................. 15

Figure 9. Drop Structure Option 2, Above Grade Concrete Fish Ladder ..................................... 16

Figure 10. Drop Structure Option 3, Cut-in and Baffle Weirs...................................................... 16

Figure 11. Highway 85 Crossing with no flow ............................................................................. 18

Figure 12. Highway 85 Crossing at 40 to 50 cfs........................................................................... 19

Figure 13. Existing Baffles Upstream of Highway 85 Crossing .................................................. 20

Figure 14. Culvert at El Camino Real .......................................................................................... 21

Figure 15. Baffle Option from (PWA, 2005) ............................................................................... 22

Figure 16. Rock Baffle Option..................................................................................................... 23

Figure 17. Existing Conditions at Highway 85 Crossing (PWA 2005) ....................................... 24

Figure 18. Proposed Rendering of Rock Baffles ......................................................................... 25

Figure 19. Proposed Rock Placement within Culvert .................................................................. 26

Figure 20. Highway 280 Culvert Crossing .................................................................................. 27

Figure 21. Highway 280 Culvert Crossing, Low Flow in the Arch Culvert ................................ 27

Figure 22. Highway 280 Culvert Crossing .................................................................................. 28

Figure 23. Proposed Low Flow Culvert Rock Baffles ................................................................. 29

Figure 24. Existing Golf Course Low Water Crossing ................................................................ 31

Figure 25. Rendering of Proposed Rock Baffles ......................................................................... 32

Friends of Stevens Creek Trail PAGE iii DOMENICHELLI & ASSOCIATES, INC.

Figure 26. Golf Course Rock Baffle Schematic .......................................................................... 32

Figure 27. Existing Conditions of Gauge Station Weir ............................................................... 34

Figure 28. Rendering of Proposed Rock Weirs at Gauge Station ................................................ 35

TABLE OF TABLES

Table 1. List of Projects ................................................................................................................. 3

Table 2. Fish Passage Criteria ........................................................................................................ 5

Table 3. Moffett Drop Alternatives HL01/HB02 – Flood Hydraulic Analysis Results ............... 11

Table 4. Hydraulic Results for Adult Fish Passage – Moffett Drop Structure HL01/HB02 ....... 11

Table 5. Opinion of Probable Construction Costs – Moffett Drop Structure – HL01/HB02 ....... 12

Table 6. Constructability & Permitting Issues .............................................................................. 13

Table 7. Opinion of Probable Construction Costs – Hetch Hetchy Drop Structure – HB05/06 . 17

Table 8. Opinion of Probable Construction Costs – Un-Numbered Crossing for Highway 85.... 20

Table 9. Opinion of Probable Construction Costs – El Camino Real – HB13 ............................. 23

Table 10. Opinion of Probable Construction Costs – Highway 85 near Village Court – HB15 .. 26

Table 11. Opinion of Probable Construction Costs – Highway 280 Crossing– HB20 ................. 30

Table 12. Opinion of Probable Construction Costs – Deep Cliff Golf Course – HB28 .............. 33

Table 13. Opinion of Probable Construction Costs – Gauge Station Weir – HB32 .................... 35

Table 14. Summary of Findings and Recommendations .............................................................. 37

Friends of Stevens Creek Trail PAGE 1 DOMENICHELLI & ASSOCIATES, INC.

SECTION 1 – BACKGROUND

Introduction and Purpose

Stevens Creek has been identified as a priority for steelhead population restoration by the Fisheries

and Aquatic Habitat Collaborative Effort (FAHCE), which includes federal, state and local

stakeholders. The FAHCE is in the process of developing a Fish Habitat Conservation Plan for

three local watersheds including Stevens Creek for the purpose of seeking to balance and integrate

all beneficial uses of the local water source including drinking water, flood protection, recreation

and fisheries. The Santa Clara County Creeks Coalition (SCCCC) is a local organization involved

in advancing the goals of the FAHCE and has administered the efforts involved in this study on

behalf of the Friends of Stevens Creek Trail organization.

This Study is funded by a grant from the Santa Clara Valley Water District (District), with

additional funding from the City of Mountain View, City of Cupertino, City of Sunnyvale, Mid-

Peninsula Regional Open Space District, and Friends of Stevens Creek Trail.

Since the development of the FAHCE program, significant fish passage enhancement on Stevens

Creek have been completed, however, there are still several barriers that have been identified in

past studies that are considered features that can potentially hinder steelhead migration. Studies

used as primary sources for this report include:

1. Santa Clara Valley Water District (SCVWD), Stewardship Initiative: Stevens Creek Fish

Barrier Assessment, Philip Williams & Associates, Ltd., May 19, 2005. (PWA, 2005)

2. Stevens Creek Fish Passage Assessment, Highway 101 to Moffett Drop Structure, Michael

Love & Associates, Inc., April 28, 2016. (LOVE, 2016)

Other sources gathered by SCCCC and referenced in this feasibility analysis are listed at the end

of this report.

To continue efforts to enhance steelhead passage in Steven Creek, Domenichelli & Associates Inc.

(D&A) was contracted by the SCCCC to prepare a Feasibility Report to develop preferred

alternatives at eight (8) locations on Stevens Creek chosen by the SCCCC to remediate steelhead

migration impediments. The project scope was focused on solutions that meet standard fish

passage criteria for the selected barriers. The severity of the passage impediments and a

quantitative analysis of the benefits of solutions to the overall stream system was not requested by

the SCCCC and would be beyond the scope of this study. This report provides hydraulic analyses,

conceptual drawings and opinions of probable costs for preferred projects at the selected locations.

Other alternatives identified at each location are also addressed in this report and are compared to

the selected options.

Barrier Mitigation Projects

Figure 1 provides a map of the eight locations selected for further analysis by the SCCCC. These

projects begin near the Stevens Creek stream crossing of Highway 101, and extend upstream to a

gauging station just downstream from Stevens Creek Reservoir.


Figure 1. Project Location Map

The projects include concrete channels with significant drops and shallow depths at lower flows,

major culvert crossings with flat wide bottoms creating shallow depths at low flows and a low

water (concrete) vehicular crossing. A short description of each site is provided below in Table 1.

Moffett Federal Airfield Mountain View, CA

Stevens Creek Reservoir


Table 1. List of Projects

Barrier

Number * Name

Barrier

Classification Proposed Alternatives

HL01, HB 02

Moffett Blvd Drop

Structure and

Downstream

Channel

Drop Structure

& Concrete

Channel

1. Retain existing fish ladder with low flow

channel downstream

2. New vertical slot fish ladder with low flow

channel downstream

3. Rock weirs and scour pools with low flow

channel downstream

4. Replace west concrete bank with vertical wall

and cut wider natural low flow channel

HB 05/06

Hetch Hetchy

Pipeline

Encasement

Drop Structure

& upstream

Concrete

Channel

1. Stepped rock weirs & pools

2. Fish ladder at drop

Unnumbered

Highway 85

Crossing near

Central Ave.

Box Culvert 1. Cut low flow channel into floor of culvert

2. Add upstream weir

HB 13 El Camino Real

Crossing Arch Culvert

1. Add vanes or baffles

2. Cut low flow channel into floor of culvert

HB 15

Highway 85

Crossing near

Village Court

Box Culvert 1. Add vanes or baffles

2. Cut low flow channel into floor of culvert

HB 20 Highway 280

Crossing Arch Culvert

1. Add vanes or baffles

2. Cut Low flow channel

HB 28 Deep Cliff Golf

Course

Low Flow

Vehicle

Crossing

1. Remove crossing

2. Replace with stepped rock weir and pool ladder

HB 32 Stevens Creek

Park Stream Gauge Gauging Weir 1. Add stepped rock weir and pool fish ladder

2. Deepen pool above weir

*Source of Numbering and Barrier Identifications – 1) SCVWD 2002 Draft List of Fish Passage

Impediments, 2) PWA Report 2005.


The SCVWD list referenced above as a source of the numbering, includes all eight barriers except

the Highway 85 crossing labeled “Unnumbered”. The SCVWD list described the barriers in this

study as partial barriers with low “constraint ratings” with the exception of the Moffett Drop

(ladder) and downstream channel. These were given a low to moderate rating for the drop and

ladder, and a high constraint rating for the downstream channel.

The Moffett Drop Structure and Downstream Channel is considered a higher constraint to fish

migration due to the drop height, sedimentation issues with the existing Denil ladder and the

inadequate depths of flows in the downstream trapezoidal concrete channel. These combined

issues result in a significant impediment to both migrating adult and juvenile steelhead at this reach

of Stevens Creek.

As mentioned above, the remaining seven projects are listed as barriers of varied and lesser degree

of constraints to passage, when compared to the Moffett reach. For example, the drops are all

smaller in height, from 2 to 3 feet at the Hetch Hetchy site to approximately 1 to 1.5 feet at the

Deep Cliff Golf Course and the Stevens Creek Park Gauging Station. The two structures with less

than 2 foot drops are classified as juvenile migration impediments only. These barriers are located

in the upper stream reaches where good rearing habitat exists. The Hetch Hetchy and Moffett

reaches are located farther downstream in less suitable habitat, with focus on upstream migrating

adult passage.

Of the remaining structures, four (4) are large culvert/bridge crossings where flat channel bottoms

with very little gradient create long, relatively shallow flow profiles as the stream flows recede.

Due to these hydraulic conditions, most of these culverts have a significant amount of sediment

deposition. This limits the ability to add features to direct and concentrate flow, such as baffles as

describe in previous studies (PWA 2005). Such in-stream structures would decrease flood

conveyance. In fact, at some locations, the current flood models rely on sediment transport during

high flows that would scour out the sediment down to the original culvert bottoms. Therefore,

constructing any permanent structures at the existing (observed) channel bottom elevations would

create excessive flood flow obstruction. Addressing these sites with their dynamic geomorphic

conditions are hydraulically the more challenging projects.

Although the Moffett Drop and Downstream Channel project is described as the greatest fish

passage impediment of the eight (8) selected projects discussed in this report, some of the others

are more easily mitigated relative to permitting, constructability and costs. Therefore, the ability

to address multiple lower priority barriers initially should be considered.

Hydraulic Analyses

In order for the study projects to be considered feasible, they must pass hydraulic analysis for both

fish passage criteria as well as flood conveyance neutrality. Hydraulic modeling of alternatives

for this study requires flood flow conveyance analysis as an initial check to assure that flooding

potential is not increased due to the proposed improvements. Once it is determined that the project

will not increase flood elevations (flood neutral), then a more focused hydraulic analysis of the

project features is necessary to show that the solution is effective to pass fish at lower (than flood

stage) flows per standard fish passage criteria.


Flood Control Impacts

To assess flood flow impacts, detailed HEC-RAS models were created for each site from the latest

flood control model provided by the District. These separate focused models were extracted from

the District flood model with end conditions calibrated to mirror results of the District’s overall

existing conditions model results. Some alternatives will clearly create flood impacts due to

significant obstructions to flow or increased channel roughness. Detailed modeling for these

alternatives are not presented, where the impacts can be simply identified and discussed.

Fish Passage Hydraulics

Each project alternative considered must meet a minimum requirement for fish passage to be

deemed feasible. For conventional fish ladder alternatives, standard equations are used (with

spreadsheets) to establish hydraulics to meet passage criteria. Low flow channels cut into concrete

channel bottoms can utilize the same HEC-RAS models used for the flood control analysis. When

using rock weir and pool ladder arrangements, simple weir calculations can approximate water

levels to establish surface profiles through the proposed system. For baffle systems through

culverts to concentrate low flows, the HEC-RAS models can again be used to show the

effectiveness of these features to meet depth and velocity requirements.

Criteria for steelhead fish passage are provided below in Table 2 (LOVE, 2016). The minimum

and maximum flow rates were established for the Moffett Drop and Downstream Channel project

reach in the 2016 (LOVE) study. These values were also used for the Hetch Hetchy project just

upstream for this study. The other criteria in Table 2 originated from standard criteria established

by the State Department of Fish and Wildlife.

Table 2. Fish Passage Criteria

Criteria (established by SCVWD) Juvenile

Steelhead

Adult

Steelhead

Minimum Flow Depth (feet) 0.3 ft 0.8 ft

Minimum Flow Rate (cubic feet/second) 8 cfs 16 cfs

Maximum Flow Rate (cubic feet/second) 14 cfs 70 cfs

Maximum flow velocity for sustained

swimming (feet per second) 1.5 fps 6.0 fps

Maximum flow velocity for short duration

bursts (feet per second) 3.0 fps 10.0 fps

Maximum water surface drop (feet) 0.5 ft 1.0 ft

In addition to the criteria listed above, duration for sustained and burst swimming without rest are

also important criteria. The duration is the same for both adults and juveniles; 30 minutes for

sustained swimming and 5 seconds for short bursts.

Regarding fish passage criteria, reference has been made in previous studies for providing passage

for both adult and juvenile steelhead. From review of the Stevens Creek stream conditions relative

to the location of the barrier projects, further assessment has been made to consider the practicality

of solutions relative to the benefit of meeting juvenile passage criteria. Spawning and rearing

habitat is less suitable in the lower reaches of the creek where there is more concrete lining, less

cover, anticipated higher water temperatures (farther from the cold-water source), and less coarse


gravel materials for spawning. The lower reaches also contain the more difficult passage

challenges and costly solutions such as the Moffett Drop reach and the Hetch Hetchy Crossing.

With upstream juvenile passage criteria requiring lower velocities and smaller jump heights, much

longer and complex features are required. Given the limited benefit at significantly higher costs,

this study does not provide improvements for upstream juvenile passage in the lower reaches,

downstream of the El Camino Real Crossing.

Alternatives Analysis

After defining each project alternative and completing analyses of the hydraulics relative to flood

control and fish passage feasibility, alternatives were ranked based on ability to meet hydraulic

criteria goals, preliminary costs, permit-ability, and to a lesser degree aesthetic value. Some

alternatives were eliminated for hydraulic reasons or by inspection, where an option of similar

hydraulic feasibility could be constructed at significantly less cost. Therefore, cost estimates were

not prepared for all alternatives. Preferred projects were selected from viable alternatives for each

project location. Some sites have only one option and some have several.

Preliminary Designs and Recommendations

Preliminary design drawings are provided for each preferred project. These drawings include

conceptual plans and profiles adequate to describe the features and to refine cost estimates.

A summary of recommendations including overall project costs for each site is provide at the

conclusion of this report.


SECTION 2 – DETAILED PROJECT ANALYSES

Moffett Drop Structure and Downstream Channel – HL01 & HB 02

Figures 2 and 3 provide photos of the existing Moffett Drop Structure and downstream channel.

The project barrier is comprised of: 1) the drop structure (approximately 6 feet high) with an

existing Denil fish ladder, 2) approximately 800 feet of trapezoidal concrete channel, 3) the

Highway 101 culvert crossing and 4) a second drop of approximately 2.5 feet downstream from

the Highway 101 crossing.

A previous study (LOVE 2016) indicates that the Denil ladder at the drop structure can pass adult

steelhead for approximately 60% of the target fish passage flows when the ladder and tail pool are

clear of sediment. This is a good passage total, however, in a 2010 study by the District’s Capitol

Program Service Division (FAHCE Stevens Creek Fish Passage Enhancement), it was pointed out

that the Denil type ladder is obsolete based on current fish passage standards and are now

considered partial barriers primarily due to sediment and debris blockage that can occur within the

steel weir structures of the fish ladder. As seen in Figure 2 below, the ladder is passing minimal

flow and the tailwater pool is completely filled with sediment.

The downstream concrete channel has two distinct reaches, one upstream of Highway 101 and one

downstream. The upstream reach is a trapezoidal channel where flow depths are the main issue

when the flows are less than 70cfs. The reach downstream of Highway 101 to the concrete apron

drop is a wider channel which results in shallower depth than the upstream reach. Per the 2016

LOVE report, there are no (fish passage) flows that meet the adult passage depth criteria for this

reach.

The Highway 101 culvert crossing provides a narrower flow path than the adjacent open channel

reaches, therefore the depth criteria is met once flow exceeds 40cfs. Lower flows will still result

in a depth issue for passage through the culvert.

The water surface drop at the downstream end of the concrete channel is slightly greater than the

one-foot criteria, up to approximately 60cfs. In addition, the downstream pool is relatively shallow

making the jump onto the concrete apron more difficult at lower flows.

As stated previously, mitigation for this project will include features to pass adult steelhead only.

Upstream movement of juveniles will not be addressed due to extensive costs resulting in nominal

benefit.


Figure 2. Existing Drop Structure and Fish Ladder

Figure 3. Downstream Concrete Channel (approx. 800 lineal feet)


Figure 4. Step at Downstream end of Channel past Highway 101

Alternative Identified for Drop Structure and Downstream Channel

Drop Structure Alternative- Three basic options have been identified to assist fish migration past

the drop structure. These options include:1) use the existing Denil ladder, 2) replace the Denil

ladder with an improved concrete ladder or 3) provide a (grouted) rock weir and pool ladder.

Figure 5 below shows the new fish ladder (Option 2) superimposed over the existing ladder.

Figure 5. New Concrete Fish Ladder Option with Existing Denil Ladder Shown

Concrete Channel- For the concrete channel downstream of the drop structure, all options include

a new low flow channel to maintain passage flow depths and acceptable velocities. Variations on

the type of downstream low flow channel are presented in Figure 6. Each variation could be used

with any of the three options presented above for the drop structure passage.


Figure 6. Moffett Drop Downstream Channel Alternatives

Hydraulic Considerations

The above fish passage alternatives for the Moffett drop structure and downstream concrete

channel were analyzed for flood flow impacts in this study. The proposed alternative conditions

are compared to the existing conditions to show potential impacts.

The existing conditions HEC-RAS model begins downstream of the Highway 101 bridge crossing

and extends upstream above the Moffett drop. At a 100-yr event flow of 5,500cfs, water surface

elevations reach near the top of the existing channel banks and show breach potential at several

locations. Any increase in flood elevations caused by fish passage mitigation alternative would be

considered significant impacts.

Model runs with Alternative 3 (rock weir ladder) and/or Option B (rock weir channel) were found

to be unacceptable due to increased water surface elevations during major storm events.. This was

a result of adding rocks that increased surface roughness and conveyance constraints within the

concrete channel. Therefore, the alternatives containing these features were no longer considered.

The following Table 3 summarizes results of multiple HEC-RAS models to assess the flood

impacts of the hydraulically viable alternatives. These alternatives provide combinations of the

drop structure options with appropriate downstream channel improvement options. Detailed model

output is provided in Appendix B for the preferred project and other alternatives of interest.


Table 3. Moffett Drop Alternatives HL01/HB02 – Flood Hydraulic Analysis Results

Alternative 100-yr Flow

(cfs)

Change in

100yr WSE

Meets Flood Flow

Criteria

Existing Conditions 5,500 Baseline yes

1A. Use Existing Ladder with new

Concrete low flow channel 5,500 None yes

2A. New Wider, Longer Ladder with

Concrete low flow channel 5,500 None yes

1C. Use Existing Ladder & Cut Wide

Vegetated Low Flow with vertical wall

to add conveyance

5,500 None Yes, but requires on-going

vegetation maintenance

2C. New Wider, Longer Ladder & Cut

Wide Vegetated Low Flow with vertical

wall to add conveyance

5,500 None Yes, but requires on-going

vegetation maintenance

As seen above these four alternatives listed show insignificant potential impact to flood

conveyance. However, options including the wide vegetative low flow channel would require

ongoing maintenance to assure that vegetation growth does not choke off the added conveyance.

This would result in a condition that will not meet flood flow criteria.

Relative to adult fish passage criteria, the existing drop and downstream channel do not adequately

meet depth and velocity requirements as presented previously. The Denil ladder has limitations

due to reoccurring sediment blockage. Table 4 summarizes the effectiveness of the four

alternatives to meet adult steelhead passage criteria.

Table 4. Hydraulic Results for Adult Fish Passage – Moffett Drop Structure HL01/HB02

Alternative

Channel

Meets

Minimum

Depth

Channel Meets

Velocity

Criteria

Meets Ladder flow,

jump and slope criteria

Existing Conditions Only portions at

higher flows Most flows

Ladder blockage issues

limit flows


Concrete low flow channel yes yes

Ladder blockage issues

limit flows


Concrete low flow channel yes yes yes



to add conveyance

yes yes Ladder blockage issues

limit flows


Wide Vegetated Low Flow with vertical

wall to add conveyance

yes yes yes

From Tables 3 and 4, Alternatives 2A and 2C meet all the hydraulic criteria (flood protection and

fish passage), with Alternative 2C requiring more extensive maintenance. Alternative 1A can also

meet all the passage criteria if sediment build up could be avoided.


Sedimentation Considerations

As previously stated, sedimentation and debris build up in the Denil ladder has been an ongoing

issue. Replacement with a wider ladder, with less baffles and slotted openings will improve this

condition, however, a detailed sediment analysis is recommended to show the degree of improved

operations and maintenance before proceeding with design. This would also be the case for the

low flow channel. The slope of the proposed low flow channel is steeper than the main channel

by providing a continuous grade eliminating two drops. This will provide higher velocity than in

the main channel and more energy to carry sediment downstream. However, a detailed sediment

analysis would also demonstrate the effectiveness of this feature.

Costs and Constructability Considerations

The lowest cost alternative would be to use the existing ladder and cut a low flow channel

(Alternative 1A). All others will require significant demolition and construction of major in-

channel improvements.

Table 5 below lists preliminary opinions of probable construction costs for Alternatives 1A, 2A,

1C & 2C. Detailed cost information is provided in Appendix C. Total project costs for the

preferred projects are summarized in the Conclusion of this report.

Table 5. Opinion of Probable Construction Costs – Moffett Drop Structure – HL01/HB02

Alternative

Mob/ Site

Prep and

Demolition

costs

Low Flow

Channel

costs

Fish

Ladder

costs

Total Construction

Cost with a 25%

Contingency


Concrete low flow channel $307,000 $560,000 15,000 $1,103,000


Concrete low flow channel $342,000 $560,000 $260,000 $1,453,000



to add conveyance

$479,000 $2,040,000 $15,000 $3,352,000


Wide Vegetated Low Flow with

vertical wall to add conveyance

$499,000 $2,040,000 $260,000 $3,682,000

25% contingency includes: unknowns at this conceptual level of design

When considering constructability, it is important to understand that construction issues may

increase costs over current estimates, may create obstacles that will require a different approach

or may create a permitting problem that will be difficult to overcome. Table 6 presents some

constructability issues that are identified for the three alternatives brought forward in this analysis.


Table 6. Constructability & Permitting Issues

Alternative Constructability Issues Ability to Permit

Cut Low Flow Channel &

Use Existing Ladder Channel access & dewatering

In-stream water quality

permitting issues

Moderate difficulty

Cut Low Flow Channel &

New Wider, Longer Ladder

Channel access & dewatering,

Shoring needed to stabilize

removal of existing ladder.


permitting issues

Moderate difficulty

Cut Wide Vegetated Low

Flow with vertical wall to

add conveyance & new

rock ladder

Channel access & dewatering

Removing existing channel wall

will create significant bank

stability issues, extensive haul out

of materials


permitting issues, State and

local flood control permitting

High difficulty

Permitting and Environmental Compliance

There are several permits that would be required to implement any of the alternatives. Work

performed within a streambed will require at a minimum: 1) a California Department of Fish and

Wildlife, Streambed Alteration Permit, 2) a State Regional Water Quality Control Board Permit

for addressing and monitoring water quality during construction and 3) review and approvals from

state and local agencies including the District for flood control. In addition, appropriate

encroachment permitting for work in associated rights of way will be required. Depending on the

presence of any listed species, permits could also extend to the federal level involving the US Fish

and Wildlife Service and the Army Corps of Engineers.

To comply with permitting and environmental regulatory processes will be time consuming and

costly. This project will at a minimum require a Mitigated Negative Declaration (MND) or

depending on preliminary environmental findings a complete Environmental Impact Report/ Study

(EIR/EIS).

Conclusions – Moffett Drop Structure and Downstream Channel – HL01/HB02

Based on the analyses presented above, Alternative 2A with a concrete low flow channel and a

new wider and longer conventional fish ladder best meets of all the fish passage objectives at the

least overall cost for this reach. Appendix A contains conceptual design drawings for the preferred

project. The plans show a vertical slotted ladder type for the new fishway. This type of ladder

allows for a less obstructed pathway (than the existing ladder) at a wide range of flows for fish

passage as well as for downstream flowing sediment. Other ladders such as a pool and weir type

ladder may be considered during final design.


Hetch Hetchy Pipeline Drop Structure – HB 05/06

The Hetch Hetchy Drop Structure is located approximately 1,900 feet upstream from the Moffett

Drop. This feature is comprised of a concrete structure acting as a channel grade control to protect

an existing 72-inch pipeline crossing beneath Stevens Creek. The encasement creates a 4.4 foot

drop in the channel bottom which creates a barrier for fish migration. This barrier is not as

pronounced as the Moffett Drop and includes a downstream weir that reduces the jump to between

2.3 and 2.5 feet during most migratory flows.

Similar to the Moffett Drop project, this barrier is in the lower reaches where much of the channel

is lined and upstream migration of adult steelhead is more critical. To meet the 1-foot maximum

jump, a new fish ladder with 2 or 3 jumps will be adequate. Previous analysis (PWA, 2005)

recommends a ladder that would cut into the existing structure. Figure 7 provides a photo of the

existing drop and Figure 8 is a rendering of the cut in ladder from the PWA report.

Figure 7. Hetch Hetchy Drop (PWA, 2005)


Figure 8. Rendering Taken from PWA Report (2005)

This approach would solve the barrier issue at this location with no hydraulic impact for flood flow

passage. Concerns with this alternative would be costs associated with cutting down to the

required foundation depth for the new ladder and the potential to conflict with the 72-inch pipeline

or other utilities crossing at this location. A retaining wall will also be required to support the bank

lining along the ladder, but this can be incorporated into the ladder construction. Regarding the

72-inch Hetch Hetchy pipeline, the crossing location is difficult to determine from as-built plans.

If it is close to the drop, then the cut-in ladder would not be feasible. If it is farther upstream (at

least 40 to 50 feet), then the cut-in ladder may be constructed as shown above. In fact, the ladder

shown from the PWA report is providing juvenile passage with 5 to 6-inch steps. A ladder

providing 1-foot steps would be much shorter and require less modification to the drop structure.

In any case, the San Francisco Public Utilities Commission (SFPUC), owner of the pipeline would

have to approve the modification. A properly designed concrete ladder structure that provides the

same level of protection for the pipe will be necessary. An option to the cut-in ladder would be to

construct an above grade ladder starting downstream and ending at the drop. Figure 9 below shows

this concept. This construction would be less costly and not require cutting into the drop structure,

but does protrude into the channel flow. Modeling of this alternative relative to flood flows

showed that the minor obstruction of the above grade features would cause a slight increase in the

flood water surface elevations just upstream of the drop. Given the increased water surface

elevation result, this alternative would not be considered feasible.

A third option that uses the cut in ladder approach would be to raise the existing downstream baffle

slightly and provide just one cut-in ladder step and a second short upstream baffle to provide added

upstream depth. This option shown in Figure 10 is less of an obstruction resulting in no net

increase in flood elevations, maintains structural integrity of the pipeline protection and is less

costly to construct than the other options presented. For these reasons, this third option is the

current preferred alternative. Appendix A shows a more detailed design layout for this alternative.


Figure 9. Drop Structure Option 2, Above Grade Concrete Fish Ladder

Figure 10. Drop Structure Option 3, Cut-in and Baffle Weirs

To confirm that the configuration for the preferred alternative will work properly for a wide range

of flows, detailed surveying of the downstream and upstream channel will be necessary during the

final design. Based on the photo above (Figure 7), the existing downstream baffle is submerged

with very little jump to cross into the upstream plunge pool. This is due to a raise in the

downstream channel (as shown on the as-built drawings) that is approximately 2 to 6-inches below

the top of the baffle. This allows for a raise in the baffle height as suggested for this design without

exceeding adult 1-foot step parameter. Per the PWA report, there is another critical riffle farther

upstream close to where the channel returns to an earthen bottom. Some minor grading to create

a low flow channel and one additional short baffle weir may be necessary. This can be determined

after detailed surveying during final design.

Another option to use a series of rock weirs as the ladder was also considered for this site.

However, this option would require means to anchor the rock into the existing concrete and bagged

(concrete) banks and grouting of the rock to assure they will remain during high flows. The

construction of a conventional ladder would be more reliable and use less material for significant

cost savings. Therefore, the rock system was not considered further.

Below is a summary of anticipated construction costs for the ladder installation alternatives at this

site.


Table 7. Opinion of Probable Construction Costs – Hetch Hetchy Drop Structure – HB05/06

Alternative

Mob/ Site Prep

and Demolition

costs

Ladder

Construction

costs

Fish Ladder costs

1. Cut -in ladder with 3 steps $81,300 $69,700 $189,000

2. Above grade ladder (not

Preferred due to flood flow) $69,700 $70,600 $176,000

3. Raise existing baffle and

shorter cut-in ladder $69,800 $49,000 $149,000

25% contingency includes: unknowns at this conceptual level of design

Conclusions – Hetch Hetchy Drop Structure – HB05/06

Based on the analyses presented above, Alternative 3 with a raised downstream baffle and a 2-

step cut-in ladder will be the preferred alternative for the Hetch Hetchy Drop Structure. Permits

for this project would be similar to those discussed for the Moffett Drop and Downstream Channel

Project. However, due to the reduced amount of work in the channel, the permit process and

environmental documentation should be less complex and time consuming. Obtaining approval

by the SFPUC for this project will be an added challenge.


Highway 85 crossing (un-numbered)

The Highway 85 crossing near Central Avenue is shown below and consists of a downstream weir

preceded by a drop of approximately 3 feet into a plunge pool created by the weir. This leads

upstream to a concrete box culvert under the highway. The main concerns described in previous

reports are the potential to strand fish in the plunge pool and the height of the drop. As seen in

Figure 12, the drop creates a jump greater than 1 foot (measured at 1.5 feet) during optimum

migratory flows. Relative to stranding, any time there is a plunge pool arrangement like this,

juvenile fish can be stranded and would need a means to move out of this local impediment.

Another issue observed in the field and considered a greater impediment by our study team was

the shallow depth in the culvert.

The goals for this site will be to provide a smaller jump at the drop and provide deeper water in

the upstream channel for fish to move past this location.

Figure 11. Highway 85 Crossing with no flow


Figure 12. Highway 85 Crossing at 40 to 50 cfs

The higher priority for adult passage is to provide depth upstream. In Figure 12 above, it is evident

that the wide flat bottom of the culvert creates a uniform shallow depth through the culvert even

when the flows are in the 40 to 50cfs range. At low flows, the depth would be well below

acceptable criteria.

Similar to the drop downstream of Highway 101 at the Moffett site, cutting in a low flow channel

will provide greater depth for migration at the same time reducing the jump from the plunge pool.

This will also provide more opportunity for juvenile fish to escape this location during lower flows.

The low flow channel would be in the center of the culvert and need only be approximately 0.8-

feet deep and 4-foot top width. This will add enough depth for passage and because it is a cut

section, will have no impact on flood water elevations. With this in mind, flood flow modeling

was not included for this site.

At the upstream end of the culvert, a series of baffles for fish passage exist. These baffles are not

shown on the as-built drawings and therefore, the tie in from the proposed low flow channel will

have to be determined with detailed surveying at a later date. Below is a photo of the upstream

baffle system.


Figure 13. Existing Baffles Upstream of Highway 85 Crossing

During final design, the drop structure, weir and entire culvert up to the upstream baffles will need

to be surveyed. From the field review, it appears that there is a considerable slope in the channel

through the culvert. By introducing a low flow channel, the jump at the first upstream baffle could

become higher. An intermediate jump (weir) within the low flow channel with flatter slope may

be necessary to mitigate for any passage problems within the upstream system.

Appendix A provides a schematic design for the low flow improvements for this site. No other

alternatives were considered for this location due to the limitations on what modifications would

be acceptable within the culvert relative to conveyance of flood flows.

Table 8 below provides an opinion of probable costs for the preferred project including the

additional upstream weir as described previously.

Table 8. Opinion of Probable Construction Costs – Un-Numbered Crossing for Highway 85

Description

Mob/ Site Prep/

& Demolition

costs

Low Flow

Channel

costs

Total Construction

Cost with a 25%

Contingency

Low flow Channel

(including upstream weir) $155,000 $153,000 $385,000

25% contingency includes unknowns at this conceptual level of design

Conclusions – Un-Numbered Crossing for Highway 85

Based on the analyses presented above, a cut in low flow channel with a potential for an upstream

0.8-foot weir back to existing grade will be the preferred alternative for this crossing of Highway

85. This project requires minimal streambed alterations and should result in less costly and time


consuming environmental permitting than the Moffett or Hetch Hetchy projects. However, as this

project is entirely within the Caltrans Right of Way, an encroachment permit and project design

approvals must be obtained from Caltrans.

El Camino Real Crossing – HB 13

The El Camino Crossing of Steven Creek consists of a single arch bridge opening (approximately

30 feet wide by 23 feet high). The slope through the opening is relatively flat and the bottom cross

slope is also flat, resulting in wide relatively shallow flow through the crossing. As-built drawings

provided as well as field review did not indicate a concrete bottom. However, due to sediment

build-up, a bottom apron could exist and be submerged in sediment. The photo below, Figure 14

shows the crossing from the downstream end looking upstream.

Figure 14. Culvert at El Camino Real

The concern at this crossing is that the wide flat bottom results in shallow flow, especially as flows

recede. HEC-RAS modeling results show that the minimum depth criteria is no longer met at

flows less than 40cfs for this culvert. Solutions to remedy this situation have been limited to

creating a low flow channel that is much narrower and deeper. To create the low flow channel

there are basically two approaches: 1) dredge out a narrow channel and carry the slope downstream

far enough to maintain high scour velocity or 2) create a baffle system to direct flow to one side

of the crossing to create a narrower deeper flow path. Approach 1 would be less reliable because

the low flow channel could fill back in with sediment during larger flow events. Grade control

would be necessary to maintain the desired shape of the channel; therefore, the use of a baffle

system would be more desirable.

Figure 15 shows a baffle option suggested in a previous report (PWA 2005). This arrangement

would concentrate flow to one side creating deeper channel flow through the culvert. This would

achieve the fish passage objective of deeper channel flow however, constructing baffles above the


channel invert will be an obstruction of flood flows. HEC-RAS modeling of the existing

conditions show that during a 100-year event, the culvert does not flow full and upstream water

surface elevations are not near the top of banks. When running the proposed condition with the

baffles, an increase of 0.9-feet in the 100-year water surface elevations (WSEs) occur (see

Appendix B results). This increase in WSEs does not meet the flood control criteria, therefore the

use of above grade permanent baffles will not be feasible.

Figure 15. Baffle Option from (PWA, 2005)

Another concern with the baffle option is the ability to anchor the baffles in place. If the culvert

has no concrete bottom or if it is well below the surface of the sediment, anchoring the baffles

would require deep and costly foundations.

Upon further consideration, two modifications of the baffle arrangement have been analyzed. The

first modification uses a combination of cutting a low flow channel in conjunction with

construction of a smaller (shallower) baffle. The low flow channel would counteract flow

obstruction of the baffles by adding conveyance area. The second modification would be to create

the baffles with rock to stay in place during typical winter high flow events (approximately a 2-yr

event). The rocks could be sized so that during a larger (10yr or greater) event, the rocks would

be swept downstream removing any obstruction to the flood conveyance through the culvert. The

rock baffle option is shown below in Figure 16.


Figure 16. Rock Baffle Option

The low flow channel will be designed to extend downstream beyond the end of the culvert to

maintain a positive and adequate slope to help transport sediment, while maintaining fish passage

velocities and depths. Appendix A shows a typical design for this and other culverts addressed in

this study. The maximum rock size will be approximately 12-inch diameter rock.

Table 9 provides an opinion of probable costs for the rock baffle/ low flow channel option. It

should be noted that the above rock size can be hand placed and the low flow channel could be

dug with hand tools. This could be the ongoing maintenance program in late summer when larger

storm events from the previous winter wash away the rocks. It has been suggested by local stream

stewardship groups that this could be done by volunteers.

Table 9. Opinion of Probable Construction Costs – El Camino Real – HB13

Alternative

Mob/ Site Prep/

& Excavation

costs

Baffle

Construction

costs

Total

Construction

Cost with a 25%

Contingency

Rock Baffles and low flow channel $72,200 $40,000 $130,000


Conclusions – El Camino Real – HB13

Based on the analyses presented above, a rock baffle system will be the preferred alternative for

the El Camino Real crossing. Permitting requirements for the initial construction would be similar

stream alteration and water quality permits as described for the all of the projects in this report.

Caltrans permitting process will also be included for this culvert. On-going maintenance


potentially by volunteers would likely require permitting.

Highway 85 Crossing near Village Court – HB 15

The Highway 85 crossing of Stevens Creek near Village Court consists of an approximate 24-foot-

wide by 20-foot-high box culvert. The 110-foot-long culvert was built with a curved alignment,

which concentrates the lower flows to the outside of the curve as would be anticipated due to forces

of the channel flows and resulting scour of sediment. Similar to the El Camino Real crossing, this

culvert either is an earthen bottom or sediment build up has created a condition where any concrete

channel bottom could not be found with hand tools. Figure 17 show this crossing looking

upstream. Note that curved alignment already creates a low flow channel to the outside of the

curve. This condition creates depths adequate for fish passage at lower flows than at the El Camino

Real crossing. As seen in the photo below, the depth is low at the critical riffle. Without detailed

surveying, no precise hydraulic modeling was performed at this location. However, based on field

review, we anticipate that adequate depth would be present at a flow closer to 30cfs at this culvert.

Figure 17. Existing Conditions at Highway 85 Crossing (PWA 2005)

For this culvert, the same fish passage solutions as at El Camino Real would apply to enhance

passage at lower flows. Although the culvert already has low flow concentrated to one side,

creating a better defined low flow channel that continues downstream of the culvert is desirable.

The use of rock baffles similar to the El Camino Real crossing to enhance the low flow channel

condition is proposed. Unlike the El Camino Real site, this culvert does not currently pass the

100-year flow with freeboard. The existing conditions modeling shows that the 100-year water

surface is above the soffit of the culvert which causes water surface elevations closer to the top of

bank. Again, by adding permanent baffles obstructing the flow path in the culvert, the water

surface will rise significantly (up to several feet) depending on the height of the baffles. The option

to lower the baffles and cut into the low flow to balance the conveyance area as in the proposed El


Camino Real project, would improve this condition. However, where to set the baffles relative to

anticipated sediment levels during and after major storm events is difficult to determine. In fact,

the District’s current flood model contains culvert (and bridge) openings with inverts consistently

deeper than what has been measured during site visits at low flows. This supports the premise that

during higher flows, the sediment will be scoured down closer to the levels of the channels

surveyed at the time of the original design of the system.

Due to the flood concerns addressed above and the costs related to constructing permanent baffles,

the permanent baffle option within culvert crossings is no longer considered in this study. Rock

baffles sized to be transported (scoured out and conveyed) downstream during major flood events

are recommended at this crossing. Placing the rock baffles and shaping a deeper low flow channel

along the outside of the curved culvert would not obstruct flow conveyance under current

conditions (see Figures 18 and 19 below). Keeping in mind that a major flood event will likely

remove the baffle system and the rock will need to be recovered and/or replaced. As mentioned

for the El Camino Real crossing, the rock will be sized to remain in place up to approximately the

10-yr flood event.

Figure 18. Proposed Rendering of Rock Baffles


Figure 19. Proposed Rock Placement within Culvert

Fortunately, this site already has the formation of a low flow channel due to the culvert curvature.

Enhancing the low flow channel to meet passage criteria will require less channel work than other

culvert crossings. Table 10 provides an opinion of probable costs for the rock baffle system at

this site.

Table 10. Opinion of Probable Construction Costs – Highway 85 near Village Court – HB15

Alternative

Mob/ Site Prep/

& Excavation

costs

Baffle

Construction

costs

Total

Construction

Cost with a

25%

Contingency

Rock baffles and low flow channel $56,000 $32,500 $111,000


Conclusion – Highway 85 near Village Court – HB15


the Highway 85 crossing near Village Court. Permit requirements and environmental

documentation will be similar to the El Camino Real culvert project.


Highway 280 Crossing– HB 20

The Highway 280 crossing is another crossing where flat longitudinal channel slope as well as a

flat bottom across the channel section creates shallow flow during low flow conditions. The

crossing consists of two side by side culverts, one is a concrete arch culvert and the other is a

circular shaped concrete culvert. Figures 20 and 21 below show the upstream entrance to the dual

culvert crossing.

Figure 20. Highway 280 Culvert Crossing

Figure 21. Highway 280 Culvert Crossing, Low Flow in the Arch Culvert


For this crossing, note that the circular culvert to the right in Figure 20 has no flow and that all low

flow is conveyed through the arch culvert. This is due to the configuration (alignment) of the

culverts relative to the stream alignment. Although the culverts are straight, the stream enters the

culverts at an abrupt right turn (looking downstream). This directs the flow to the left side of the

arch culvert and drops sediment to the inside of the curve in front of the right culvert, creating a

significantly lower invert in the arch culvert along the left edge (wall).

In contrast to the entrance, at the exit of the culverts, the stream takes an abrupt left turn. This

shifts the low flow in the arch culvert to the opposite side of the culvert as shown in Figure 22

looking upstream at the exit.

Figure 22. Highway 280 Culvert Crossing

Therefore, in the arch culvert the low flow channel shifts from one side to the other from the

entrance to the exit. The problem for fish passage is that in the middle section of this long flat

sloped culvert, the invert flattens and the low flow becomes shallow and flat across the entire cross-

section. See Figure 23 for the channel configuration at this crossing.


Figure 23. Proposed Low Flow Culvert Rock Baffles

The solution is similar to the previous two culverts where baffles would concentrate flow to one

side or the other within the middle section of the culvert. The difference is that the baffles would

have the most beneficial affect if they switch from the left side to the right (looking upstream) with

a transition in the middle. Figure 23 shows this configuration. Appendix A shows a more detailed

view of the recommended layout of the low flow channel with rock baffles.

Again, the 100-yr water surface elevations are a concern for this crossing. The current District

model shows the upstream flood elevations near the top of bank. This is with both culverts flowing

with no sediment. These culverts are shown with concrete bottoms in the as-built drawings and in

the HEC-RAS model. Given the shape of the culverts, this indicates a minimum of 5 feet of

sediment in the photos above. A model run with the inverts at the top of the sediment as shown in

the photos, created upstream flood levels several feet higher in an area where the 100-yr flood

flows already overtop the banks farther upstream. If any obstructions are introduced to channelize

low flow at the current sediment elevations, then the obstruction must be removed with the

sediment at the higher flows.


Rock baffles as discussed for the previous culverts are again a viable solution. Due to damaging

flood potential, the baffle rocks must be sized to move out of the arch (low flow) culvert. A

smaller size rock for this more critical flood conveyance feature is recommended to assure that

flood velocities will adequately scour out the entire culvert. Using smaller rocks sized to remain

for between a 5 to 10-year event may be appropriate. This would require inspecting the site and

replacement of rock more often to ensure effective fish passage is maintained.

Other options such as collapsing or hinged baffles, or even inflatable baffles have been discussed.

However, initial construction and ongoing maintenance costs for such features that would have

uncertain reliability were deemed infeasible at this time.

Table 11 provides an opinion of probable costs for the rock baffle system at this site.

Table 11. Opinion of Probable Construction Costs – Highway 280 Crossing– HB20

Alternative

Mob/ Site Prep/

& Excavation

costs

Baffle

Construction

costs

Total Construction

Cost with a 25%

Contingency

Rock baffles and low flow channel $79,000 $37,500 $146,000


Conclusion – Highway 280 Crossing– HB20


the Highway 280 crossing. Permitting and environmental documentation will be the same for all

of the highway culverts.


Deep Cliff Golf Course – HB 28

The Deep Cliff Golf Course is located farther upstream in the watershed and provides a greater

opportunity for spawning and rearing with much of the channel in its natural or semi-natural state.

For this location, movement of juvenile steelhead is more desirable than in the lower reaches where

upstream passage for juveniles will be difficult during most flow conditions, and rescue and

transport would likely be most effective for juvenile survival.

The crossing in question is an abandoned low water vehicular crossing. The crossing is concrete

paved and creates a jump that although not severe enough for adult passage under most flows, it

is restrictive for juvenile passage. Figure 24 shows the crossing, which has scoured away to a

degree over time, leaving the mild hydraulic jump. At lower flows, this drop is more pronounced

and measures approximately 1.5 feet high.

Figure 24. Existing Golf Course Low Water Crossing

Downstream of the drop is a plunge pool with a tail out invert elevation approximately 1.5 feet

lower than the paved surface low point. The solution for this site begins with a straight forward

approach which is to remove the concrete crossing. However, to completely remove the crossing

down to original grade would have some impact farther upstream. Over time, the upstream section

of the stream has created valuable habitat with deeper water and large trees growing at the bank’s

edge. If the jump were completely removed, lowering the water levels, potential for bank

undercutting is a concern.

A solution to remove the concrete from the center of the stream, while maintaining the overall

gradient would be to construct a rock weir stepped ladder configuration. For juvenile passage, this

would require three 6-inch steps to overcome the maximum drop of 1.5 feet at low flows. Figure


25 below shows a rendering of the design concept for this crossing. Appendix A shows a plan and

profile for the preliminary design.

Figure 25. Rendering of Proposed Rock Baffles

Figure 26. Golf Course Rock Baffle Schematic

This site design would include three rock weir structures using rock sized adequately as a base that

will not be washed away, with intermediate sized rocks to fill most of the voids. Because this

feature will replace the existing barrier to flow, no measurable impact to flood flow is anticipated

for this design. With properly sized and placed rock at this location, grouting of the rock will not

be necessary. Maintenance of the weir will likely require annual inspection and replacement of

intermediate sized rocks.

Table 12 provides an opinion of probable costs for the rock weir system at this site.


Table 12. Opinion of Probable Construction Costs – Deep Cliff Golf Course – HB28

Alternative

Mob./ Site

Prep/

Excavation/De

mob. costs

Weir &

Pool Rock

Placement

costs

Total Construction

Cost with a 25%

Contingency

Rock Weir and Pool Steps $50,100 $18,000 $88,000


Conclusion – Deep Cliff Golf Course – HB28

Based on the analyses presented above, a rock weir and pool system will be the preferred

alternative for the Deep Creek Golf Course crossing. Although in-stream alteration permitting

through the State Department of Fish and Wildlife will be required, this feature is located on

private land, therefore approvals and encroachment permitting from state and local agencies will

not be required.


Gauge Station Weir (HB 32)

Near the upper reach of the study limits is an existing gaging station. This station is located

approximately ½ mile downstream of the Stevens Creek Reservoir within a park setting. As with

the Deep Cliff Golf Course, the stream is closer to its natural state and habitat is reasonably good

for spawning and rearing of steelhead. The station consists of a drop structure with a control weir

at the top of the structure for calibrating flow at variable depths passing over the weir. The drop

provides a free weir flow condition with no backwater affect from the downstream channel.

Checking records for this station, the station appears to have been out of operation for many years.

However, given potential for future use, fish passage solution will not cut into the weir structure.

Figure 27 shows the gauge station features.

Figure 27. Existing Conditions of Gauge Station Weir

The drop at the gauge to the downstream plunge pool was measured to be between 1.5 to 1.8 feet.

To reduce the maximum jump to 6-inches for juvenile migration would require a minimum of

three jumps. Installing a fish ladder at this location would be costly, due to the fact that the plunge

pool is nearly 8 feet deep at the drop. This would require a high ladder to overcome a relatively

small lift. A more economical solution would be to construct a series of two rock weirs near the

tail out of the plunge pool (three weir jumps total). The pool is relatively long and could

accommodate two weirs, with the first weir closest to the existing drop to be constructed at

approximately 4 feet high as the pool begins to shallow and one shorter weir to follow downstream

closer to the tail out. Figure 28 shows a rendering for the weir installations. Appendix A provides

a plan and profile for this preliminary design.


Figure 28. Rendering of Proposed Rock Weirs at Gauge Station

Table 13 provides an opinion of probable costs for the rock weir system at this site.

Table 13. Opinion of Probable Construction Costs – Gauge Station Weir – HB32

Alternative

Channel

Excavation/

Restoration

costs

Rock Weir

Construction

costs

Total

Construction Cost

with a 25%

Contingency

Rock Weir Ladder $35,200 $30,000 $85,000


Conclusion – Gauge Station Weir – HB32

Based on the analyses presented above, a rock weir and pool system will be the preferred

alternative. In-stream alteration permitting through the State Department of Fish and Wildlife and

State water quality permitting will be required for this project. The project is located within a

public park, therefore encroachment permitting will also be required.


SECTION 3 – SUMMARY OF PROJECT CONCLUSIONS AND RECOMMENDATIONS

The following Table 14 summarizes the recommendations for the preferred projects for the eight

sites analyzed in this study. Cost presented below include the construction estimates from the

individual projects opinion of probable costs, as well as non-construction related cost anticipated

for each project. The percentage of construction cost for the non-construction items vary with the

size and complexity of the project. Typically, the lower the construction cost, the larger the non-

construction percentage. Engineering and Construction Management commonly varies from 25%

to 40% of the construction. We anticipate that permitting and administration costs may vary from

as low as 25% to over 50% of construction. The wide variation depends on potential

environmental impacts (currently unknown), the size and complexity of the project and the

ownership of the property and facility where the improvements are proposed. A more complex

project like the Moffett Drop and Downstream Channel is a long linear project with potentially

more impacts. It also has a crossing of a State highway. In the permitting and administration cost

estimate, this project is given a relatively high percentage even though construction costs are high.

For the Deep Cliff Golf Course project, there are no public encroachments and the potential

environmental impacts are less, resulting in lower permitting and environmental cost allocations.

As mentioned previously, although the Moffett Drop and Downstream Channel project is the

apparent greatest barrier to fish passage of the eight selected projects, it has the highest costs and

has the longest duration to implement. Completion of construction documents followed by

implementation of some of the less critical sites would be easier to fund and to complete much

faster. The SCCCC and the District can move forward with one or more projects of choice as

funding becomes available.

One of the unknown variables that can impact the long-term maintenance and overall feasibility

of the proposed projects is the sediment loading and transport within the Stevens Creek system. A

detailed sediment transport analysis of the stream system is recommended before final design of

any new constructed features, especially in the downstream reaches. This would be important not

only for fish passage enhancement but also to address impacts to flood control.


Table 14. Summary of Findings and Recommendations

Project Site

Preferred

Alternative

Estimated

Construction

Costs

Engineering

&

Construction

Management

Permitting and

Administration

Costs

TOTAL

Opinion of

Probable

Project Cost

Moffett Blvd Drop

Structure

Cut in concrete low

flow channel & new

wider, longer

conventional ladder

$1,453,000 $435,900 $435,900 $2,325,000

Hetch Hetchy

Pipeline

Encasement

Raised downstream

baffle and a 2- step

cut in ladder

$176,000 $70,400 $88,000 $344,400

Highway 85

Crossing near

Central Ave.

Cut in concrete low

flow channel with an

upstream weir jump

$385,000 $115,500 $96,250 $596,800

El Camino Real

Crossing

Rock baffles and low

flow channel $130,000 $45,500 $65,000 $240,000

Highway 85

Crossing near

Village Court


flow channel $111,000 $38,850 $55,500 $205,400,

Highway 280

Crossing


flow channel $146,000 $51,100 $65,700 $262,800

Deep Cliff Golf

Coarse

Rock weir and pool

system $88,000 $30,800 $26,400 $145,200

Stevens Creek Park

Stream Gauge

Rock weir and pool

system $85,000 $29,750 $29,750 $144,500

REFERENCES

1. Santa Clara Valley Water District (SCVWD), Stewardship Initiative: Stevens Creek Fish

Barrier Assessment, Philip Williams & Associates, Ltd., May 19, 2005. (PWA, 2005)

2. Stevens Creek Fish Passage Assessment, Highway 101 to Moffett Drop Structure, Michael

Love & Associates, Inc., April 28, 2016. (LOVE, 2016)

3. FAHCE Stevens Creek Fish Passage Enhancement, Project No. 00294001, Final Planning

Study Report, Capital Program Services Division, January 2010

4. California Department of Fish and Wildlife, CALIFORNIA SALMONID STREAM

HABITAT RESTORATION MANUAL, Forth Addition, 1996 Volume 1 and 2

5. Various As-Built Plan sets, Steven Creek Channel Improvements, provided by Santa Clara

Valley Water District.

Santa Clara County Creeks Coalition DOMENICHELLI & ASSOCIATES, INC.

APPENDIX A – CONCEPTUAL DESIGN DRAWINGS

APPENDIX B – HYDRAULIC CALCULATIONS

APPENDIX C – COST ESTIMATES

Friends of Stevens Creek Trail DOMENICHELLI & ASSOCIATES, INC.

APPENDIX A

CONCEPTUAL DESIGN DRAWINGS


Appendix A

Drawings

Moffett Drop Structure & Channel

EXISTING WEIR

EXISTING FISH LADDER

PROPOSED FISH LADDER

EXISTING DROP STRUCTURE

EXISTING BAFFLES

NEW LOW FLOW

CHANNEL

NEW TAIL POOL

8' O.C.

5'

TOP OF DROPTOE OF DROP

REMOVE PORTION

OF EXISTING WEIR

5' 8' O.C.

3'

4'

EXISTING DROP

STRUCTURE

EXISTING WEIR

EXISTING TAIL POOL

NEW TAIL POOL

NEW FISH LADDER

EXISTING

DENIL LADDER

EXISTING MAIN

CHANNEL BOTTOM

BOTTOM OF NEW

LOW FLOW CHANNEL

1.2' DEEP

1.2

'

MOFFETT DROP & CHANNEL

APPENDIX A SHEET 1 of 3

3+00 3+50 4+004+50 5+00 5+50 6+00

22

24

26

28

30

32

20

0+00 0+50 1+00 2+00 2+50 3+00

0+00

1+00

2+00

3+00

2+00

34

22

24

26

28

20

30

32

33

34

3+00

4+00

5+006+00

HWY 101 OVERPASS

22

24

26

28

20

22

24

26

28

20

MA

TC

HL

IN

E:

SE

E B

EL

OW

MA

TC

HL

IN

E: S

HE

ET

3

MA

TC

HL

IN

E:

SE

E A

BO

VE



TOP OF FISH

LADDER

EXISTING

POOL AT

FISH LADDER

EXTENT OF

CONCRETE REMOVAL

NEW CHANNELRESTING

POOL, TYP

RESTING

POOL

EXISTING SLOPED

WALLS

OUTSIDE EDGEOF

EXISTING CHANNEL

NEW CHANNEL

FLOOR

EXISTING

CHANNEL FLOOR

NEW CHANNEL

FLOOR

EXISTING

CHANNEL FLOOR

EXISTING

CHANNEL STEP

PROPOSED

POOL AT

FISH LADDER

PROPOSED

FISH LADDER

EXISTING

FISH LADDER

DR

OP

PROPOSED

FISH LADDER

EXISTING

FISH LADDER

S = 0.0013

6+00 6+50 7+00 7+50 8+00 8+50

22

24

26

28

20

HWY 101 OVERPASS

6+00

7+00

8+008+50

22

24

26

28

20

RESTING POOL

VERTICAL SIDEWALLS

SLOPED SIDEWALLS, TYP

IN TRAVEL CHANNELS

EXTENT OF

DEMOLITION & NEW

CONSTRUCTION

8.0'

2.0' 2.0'1.0'

SIDEWALLS SLOPE WILL VARY

3.5

'

EXISTING CHANNELL

FLOOR & SLOPED

SIDEWALLS, TYP

DEPTH = 1.2' TO 2.0'

2.0

'

6.0'

EMBEDDED CONCRETE LOGS (TYP)

MA

TC

HL

IN

E: S

HE

ET

2

EXTENT OF

CONCRETE REMOVAL

NEW CHANNEL

EXISTING SLOPED

WALLS

OUTSIDE EDGEOF

EXISTING CHANNEL

NEW CHANNEL

FLOOR

EXISTING

CHANNEL FLOOR

EXISTING

CHANNEL STEP

BEGINNING OF DEMO

& NEW CHANNEL

EXISTING OVERPASS

SUPPORT

VERTICAL SIDEWALLS

UNDER OVERPASS




Appendix A

Drawings

Hetch Hetchy Pipeline Drop Structure Options 2 & 3

Top of Drop

38.00

Toe of Drop

33.60

Top of New Weir

39.25

Top of Slope

37.50

40'

45'

50'

35'

30'

55'

60'

Bottom of Pool

33.50

Existing Channel Bottom

35.50

New Fish Ladder

5.0

'

8' O.C.

Lower Center 4"

New Weir

Existing Concrete

Existing Bagged Concrete

Remove Existing Baffle Weir

HETCH HETCHY CROSSING

APPENDIX A DROP STRUCTURE - OPTION 2

Top of New Weir

37.50

Toe of Drop

33.60

40'

45'

50'

35'

30'

55'

60'

Bottom of Pool

33.50

Existing Channel Bottom

35.50

Top of New Weir

38.5

Top of New Weir

36.50

Top of Existing Weir

Toe of Drop

36.00

5.0

'

Lower Center 3"

New Weir

Existing Concrete

Existing Bagged Concrete

5.0

'

1.0

'

5.0'

1.0' 1.0'

EXISTING CONCRETE SLAB

VA

RIE

S

HETCH HETCHY CROSSING

APPENDIX A DROP STRUCTURE - OPTION 3


Appendix A

Drawings

Highway 85 Crossing (Un-numbered) Plan & Profile

40'

50'

EXISTING BAFFLES

NEW WEIR

(IF NEEDED)

NEW TOP OF DROP

CUT LOW-FLOW CHANNEL, S=0.0015

EXISTING BAFFLES

NEW WEIR

(IF NEEDED)

CUT LOW FLOW CHANNEL

CUT LOW FLOW CHANNEL

END LOW FLOW

CHANNEL AT DROP

EXISTING WEIR

EXISTING WEIR

48.6'

55'

60'

65'

70'

75'

45'

40'

EXISTING CHANNEL BOTTOM EXISTING CHANNEL BOTTOM

45'

50'

55'

60'

65'

70'

75'

APPROX. 200 LF

HIGHWAY 85 CROSSING (UN-NUMBERED)

APPENDIX A


Appendix A

Drawings

Typical Box Culvert Plan & Section View

ROCK BAFFLE

LOW FLOW CHANNEL

EXISTING BOX CULVERT

MAX 1.0'

DIA ROCK

NEW ROCK BAFFLES

(ABOVE GRADE)

EMBED ROCK IN LOW

FLOW CHANNEL

LOW FLOW

CHANNEL ℄TYPICAL BOX CULVERT

APPROXIMATE LOW

FLOW CHANNEL BANK

F

L

O

W

LOW FLOW ROCK TAILOUT

GRADE CONTROL

TYPICAL BOX CULVERT PLAN & SECTION

APPENDIX A EL CAMINO REAL & HIGHWAY 85 NEAR VILLAGE CT.


Appendix A

Drawings

Highway 280 Crossing near Village Court Plan & Section View

GRAVEL BAR

GRAVEL

BAR

LOW FLOW

CHANNEL ℄

ROCK

BAFFLES

(TYP)

HW

Y 2

80

HW

Y 2

80

F

L

O

W

F

L

O

W

22' WIDE

ARCH CULVERT

22' DIAMETER

CIRCULAR CULVERT

EXISTING WALL

FLOW TRANSITION

ROCK BARRIER

EXISTING WALL

LOW FLOW ROCK TAILOUT

GRADE CONTROL

ROCK BAFFLE

1.0' MAX

DIA ROCK

LOW FLOW CHANNEL

EXISTING ARCH CULVERT

EXISTING CIRCULAR

CULVERT

EXISTING GRADE OF

SEDIMENT (TYP)

HIGHWAY 280 CROSSING (HB 20)

APPENDIX A

AutoCAD SHX Text

A

AutoCAD SHX Text

A

AutoCAD SHX Text

-

AutoCAD SHX Text

SECTION

AutoCAD SHX Text

SCALE: NTS


Appendix A

Drawings

Deep Cliff Golf Course Plan & Profile

FLOW

REMOVE CONCRETE

CROSSING

ROCK WEIRS

(TYP)

REMOVE CONCRETE CROSSING

6" DROP (TYP)

ROCK WEIRS

10' 15'

1.5' DIA. MAX

ROCK SIZE (TYP)

DEEP CLIFF GOLF COURSE (HB 28)

APPENDIX A


Appendix A

Drawings

Gauge Station Weir Plan & Profile

FLOW

NEW ROCK

WEIRS

EXISTING GAUGE

STATION WEIR

NEW ROCK

WEIRS

EXISTING GAUGE

STATION WEIR

EXISTING

BRIDGE

BR

ID

GE

STREAM

GAUGE

10' ≈ 20'

≈ 25'

1' MIN

1.5' TO 2.0'

3.5' TO 4.0'

1.5' TO 2.0'

MAX DIA ROCK

6' TO 8'

1' MIN

GAUGE STATION WEIR (HB 32)

APPENDIX A


APPENDIX B

HYDRAULIC CALCULATIONS


Appendix B

Hydraulic Modeling Results

Moffett Drop Structure

0 200 400 600 800 1000 1200 140015

20

25

30

35

40

45

50

Steven's Creek Barriers Plan: Existing Moffet 8/8/2017

Main Channel Distance (ft)

Ele

vation (

ft)

Legend

WS 100yr

Ground

ROB

RIVER-1 Reach-1

HEC-RAS Plan: Ex Moffet River: RIVER-1 Reach: Reach-1 Profile: 100yr

Reach River Sta Profile Q Total Min Ch El W.S. Elev Crit W.S. E.G. Elev E.G. Slope Vel Chnl Flow Area Top Width Froude # Chl

(cfs) (ft) (ft) (ft) (ft) (ft/ft) (ft/s) (sq ft) (ft)

Reach-1 15283.5 100yr 5750.00 31.25 44.72 41.93 46.37 0.005288 10.29 558.76 67.16 0.63

Reach-1 15183.5 100yr 5750.00 31.15 41.94 41.92 45.38 0.014097 14.86 386.83 55.77 0.99

Reach-1 15082.5 100yr 5750.00 31.05 41.90 40.72 44.49 0.003525 12.90 445.76 57.14 0.81

Reach-1 15042.5 100yr 5750.00 30.75 39.81 39.81 44.12 0.007291 16.65 345.38 40.00 1.00

Reach-1 15035 100yr 5750.00 24.75 39.28 34.28 41.00 0.002006 10.55 544.90 40.00 0.50

Reach-1 14984 100yr 5750.00 24.75 39.26 33.80 40.88 0.001798 10.21 563.02 40.00 0.48

Reach-1 14959 100yr 5750.00 24.65 39.07 35.14 40.82 0.001831 10.61 542.07 51.18 0.57

Reach-1 14883 100yr 5750.00 24.78 38.51 35.68 40.62 0.002400 11.65 493.58 50.83 0.66

Reach-1 14799 100yr 5750.00 24.75 38.31 35.65 40.39 0.002846 11.59 496.06 60.33 0.71

Reach-1 14698 100yr 5750.00 24.67 38.24 35.61 40.05 0.002286 10.80 532.33 61.59 0.65

Reach-1 14601 100yr 5750.00 24.49 38.24 34.92 39.77 0.001794 9.92 579.62 64.12 0.58

Reach-1 14587 100yr 5750.00 24.48 38.23 34.88 39.74 0.001772 9.85 584.03 65.00 0.58

Reach-1 14569 100yr 5750.00 24.46 38.21 34.86 39.70 0.001790 9.80 586.96 71.21 0.58

Reach-1 14563 100yr 5750.00 23.72 38.28 34.31 39.66 0.001618 9.40 611.53 68.15 0.55

Reach-1 14549 100yr 5750.00 23.55 37.84 33.11 39.60 0.001091 10.65 539.92 66.71 0.52

Reach-1 14400 Bridge

Reach-1 14323 100yr 5750.00 23.40 35.99 33.29 38.45 0.000676 12.59 456.70 46.99 0.66

Reach-1 14315 100yr 5750.00 23.40 35.68 38.42 0.001681 13.28 433.11 39.66 0.71

Reach-1 14300 100yr 5750.00 23.41 35.68 38.38 0.001659 13.18 436.17 40.11 0.70

Reach-1 14250 100yr 5750.00 23.38 33.73 33.73 38.10 0.003349 16.78 342.67 40.09 1.01

Reach-1 14222 100yr 5750.00 23.30 33.63 33.63 37.60 0.003184 15.99 359.55 45.64 1.00

Reach-1 14217 100yr 5750.00 21.58 33.53 33.53 37.42 0.003246 15.83 363.28 46.67 1.00

Reach-1 14213 100yr 5750.00 21.18 33.43 36.28 0.032441 13.54 424.67 49.81 0.81

Reach-1 14209.5* 100yr 5750.00 21.10 33.52 36.09 0.026367 12.86 447.23 52.96 0.76

Reach-1 14206 100yr 5750.00 21.03 33.77 35.86 0.019203 11.60 495.59 57.12 0.67

Reach-1 14202 100yr 5750.00 21.03 33.61 35.77 0.020250 11.80 487.28 56.98 0.68

Reach-1 14193 100yr 5750.00 21.34 33.64 35.54 0.016494 11.06 519.84 70.76 0.65

Reach-1 14182 100yr 5750.00 20.28 33.49 35.33 0.018017 10.91 527.07 79.73 0.68

Reach-1 14168 100yr 5750.00 20.04 33.30 35.05 0.017635 10.61 541.96 84.64 0.67

Reach-1 14155 100yr 5750.00 19.61 33.22 34.79 0.014213 10.06 571.66 83.03 0.61

Reach-1 14137 100yr 5750.00 18.92 33.18 34.49 0.011300 9.17 626.88 78.18 0.54

Reach-1 14124 100yr 5750.00 18.45 33.06 34.32 0.011821 8.98 640.09 79.11 0.52

Reach-1 14096 100yr 5750.00 18.47 32.97 33.93 0.009428 7.87 730.85 82.02 0.46

Reach-1 14032 100yr 5750.00 17.92 29.73 29.73 32.58 0.049990 13.53 424.90 74.61 1.00

0 200 400 600 800 1000 1200 140015

20

25

30

35

40

45

50

Steven's Creek Barriers Plan: Proposed Moffet Fish Ladder 8/8/2017


Ele

vation (

ft)

Legend

WS 100yr

Ground

ROB

RIVER-1 Reach-1

HEC-RAS Plan: Pro Moffet Ladde River: RIVER-1 Reach: Reach-1 Profile: 100yr



Reach-1 15283.5 100yr 5750.00 31.25 44.64 41.93 46.32 0.005428 10.39 553.33 66.84 0.64

Reach-1 15183.5 100yr 5750.00 31.15 42.54 41.92 45.44 0.011251 13.67 420.63 58.05 0.89

Reach-1 15082.5 100yr 5750.00 31.05 42.49 40.72 44.72 0.002878 11.98 479.90 58.88 0.74

Reach-1 15042.5 100yr 5750.00 30.75 40.02 40.02 44.33 0.007389 16.67 344.96 40.00 1.00

Reach-1 15035 100yr 5750.00 24.75 40.03 34.73 41.69 0.001918 10.32 557.17 40.00 0.49

Reach-1 14979 100yr 5750.00 24.75 40.05 34.02 41.54 0.001621 9.81 586.06 40.00 0.45

Reach-1 14974 100yr 5750.00 23.26 40.15 33.26 41.49 0.001385 9.27 620.55 40.00 0.41

Reach-1 14972 Inl Struct

Reach-1 14959 100yr 5750.00 23.21 39.47 35.03 41.07 0.001706 10.14 567.06 53.30 0.55


Reach-1 14883 100yr 5750.00 23.01 38.51 35.54 40.58 0.002423 11.53 498.81 50.82 0.65

Reach-1 14799 100yr 5750.00 22.80 38.31 35.50 40.34 0.002858 11.45 502.05 60.34 0.70

Reach-1 14698 100yr 5750.00 22.54 38.23 35.47 40.01 0.002315 10.68 538.41 61.57 0.64

Reach-1 14601 100yr 5750.00 22.29 38.23 34.79 39.73 0.001827 9.83 585.14 64.07 0.57

Reach-1 14587 100yr 5750.00 22.26 38.21 34.74 39.69 0.001805 9.76 589.30 64.89 0.57

Reach-1 14569 100yr 5750.00 22.21 38.19 34.71 39.65 0.001825 9.71 592.41 71.02 0.57

Reach-1 14563 100yr 5750.00 22.20 38.25 34.21 39.61 0.001640 9.37 613.96 67.71 0.54

Reach-1 14549 100yr 5750.00 22.16 37.83 32.98 39.56 0.001105 10.55 544.85 66.54 0.51


Reach-1 14323 100yr 5750.00 21.59 35.83 33.14 38.30 0.000733 12.61 455.85 45.98 0.66

Reach-1 14315 100yr 5750.00 21.57 35.51 38.26 0.001761 13.29 432.51 39.65 0.71

Reach-1 14300 100yr 5750.00 21.53 35.51 38.22 0.001749 13.22 435.06 40.10 0.71

Reach-1 14250 100yr 5750.00 21.40 33.58 33.58 37.94 0.003508 16.74 343.39 40.08 1.01

Reach-1 14222 100yr 5750.00 21.33 33.49 33.49 37.46 0.003345 16.00 359.29 45.64 1.01

Reach-1 14217 100yr 5750.00 21.30 33.51 33.51 37.40 0.003278 15.83 363.28 46.67 1.00

Reach-1 14213 100yr 5750.00 21.18 33.44 36.28 0.032397 13.53 424.85 49.81 0.81

Reach-1 14209.5* 100yr 5750.00 21.10 33.52 36.09 0.026332 12.85 447.42 52.96 0.76

Reach-1 14206 100yr 5750.00 21.03 33.77 35.86 0.019181 11.60 495.77 57.12 0.67

Reach-1 14202 100yr 5750.00 21.03 33.61 35.77 0.020224 11.80 487.47 56.98 0.68

Reach-1 14193 100yr 5750.00 21.34 33.64 35.54 0.016471 11.06 520.06 70.76 0.65

Reach-1 14182 100yr 5750.00 20.28 33.49 35.33 0.018006 10.91 527.19 79.73 0.68

Reach-1 14168 100yr 5750.00 20.04 33.30 35.05 0.017623 10.61 542.10 84.65 0.67

Reach-1 14155 100yr 5750.00 19.61 33.22 34.79 0.014208 10.06 571.73 83.04 0.61

Reach-1 14137 100yr 5750.00 18.92 33.18 34.49 0.011304 9.17 626.80 78.18 0.54

Reach-1 14124 100yr 5750.00 18.45 33.06 34.32 0.011817 8.98 640.15 79.11 0.52

Reach-1 14096 100yr 5750.00 18.47 32.97 33.93 0.009426 7.87 730.92 82.03 0.46

Reach-1 14032 100yr 5750.00 17.92 29.73 29.73 32.58 0.050070 13.54 424.65 74.58 1.00

0 200 400 600 800 1000 1200 140015

20

25

30

35

40

45

50

Steven's Creek Barriers Plan: Existing Moffet 8/8/2017


Ele

vation (

ft)

Legend

WS 16 CFS

Ground

ROB

RIVER-1 Reach-1

HEC-RAS Plan: Ex Moffet River: RIVER-1 Reach: Reach-1 Profile: 16 CFS



Reach-1 15283.5 16 CFS 16.00 31.25 31.98 31.52 32.00 0.001315 1.05 15.21 21.41 0.22

Reach-1 15183.5 16 CFS 16.00 31.15 31.79 31.47 31.82 0.002678 1.31 12.20 21.13 0.30

Reach-1 15082.5 16 CFS 16.00 31.05 31.35 31.28 31.42 0.006494 2.11 7.60 25.88 0.68

Reach-1 15042.5 16 CFS 16.00 30.75 30.93 30.93 31.02 0.016046 2.42 6.62 36.00 0.99

Reach-1 15035 16 CFS 16.00 24.75 25.48 24.93 25.48 0.000171 0.61 26.14 36.00 0.13

Reach-1 14984 16 CFS 16.00 24.75 25.47 24.93 25.47 0.000179 0.62 25.81 36.00 0.13

Reach-1 14959 16 CFS 16.00 24.65 25.46 24.89 25.47 0.000260 0.80 19.99 25.52 0.16

Reach-1 14883 16 CFS 16.00 24.78 25.41 25.06 25.43 0.000837 1.20 13.38 22.58 0.27

Reach-1 14799 16 CFS 16.00 24.75 25.33 25.02 25.36 0.001038 1.28 12.47 22.29 0.30

Reach-1 14698 16 CFS 16.00 24.67 25.18 24.96 25.22 0.001892 1.53 10.47 22.65 0.40

Reach-1 14601 16 CFS 16.00 24.49 24.99 24.78 25.03 0.002030 1.58 10.16 22.16 0.41

Reach-1 14587 16 CFS 16.00 24.48 24.96 24.75 25.00 0.002156 1.61 9.92 21.87 0.42

Reach-1 14569 16 CFS 16.00 24.46 24.78 24.78 24.91 0.013913 2.86 5.60 21.29 0.98

Reach-1 14563 16 CFS 16.00 23.72 24.10 24.00 24.16 0.004351 1.93 8.31 23.75 0.57

Reach-1 14549 16 CFS 16.00 23.55 24.10 23.85 24.12 0.001175 1.19 13.46 30.84 0.31


Reach-1 14323 16 CFS 16.00 23.40 23.67 20.87 23.74 0.005901 2.07 7.73 26.01 0.67

Reach-1 14315 16 CFS 16.00 23.40 23.61 23.68 0.008407 2.24 7.14 26.05 0.75

Reach-1 14300 16 CFS 16.00 0.00 23.41 23.53 0.012748 2.87 5.58 1.30 0.24

Reach-1 14250 16 CFS 16.00 0.00 22.53 22.72 0.020669 3.57 4.48 1.30 0.34

Reach-1 14222 16 CFS 16.00 0.00 20.67 20.67 21.51 0.107807 7.35 2.18 1.30 1.00

Reach-1 14217 16 CFS 16.00 0.00 20.36 20.61 0.026508 3.99 4.01 1.30 0.40

Reach-1 14213 16 CFS 16.00 0.00 20.32 20.52 0.020766 3.58 4.47 1.30 0.34

Reach-1 14209.5* 16 CFS 16.00 0.00 20.24 20.44 0.020811 3.58 4.47 1.30 0.34

Reach-1 14206 16 CFS 16.00 0.00 20.16 20.36 0.020863 3.59 4.46 1.30 0.34

Reach-1 14202 16 CFS 16.00 0.00 20.06 20.27 0.022276 3.69 4.33 1.30 0.36

Reach-1 14193 16 CFS 16.00 0.00 19.68 20.02 0.037409 4.66 3.44 1.30 0.50

Reach-1 14182 16 CFS 16.00 0.00 19.49 19.68 0.019802 3.50 4.57 1.30 0.33

Reach-1 14168 16 CFS 16.00 0.00 19.20 19.39 0.020532 3.56 4.49 1.30 0.34

Reach-1 14155 16 CFS 16.00 0.00 18.96 19.14 0.018195 3.37 4.75 1.30 0.31

Reach-1 14137 16 CFS 16.00 0.00 18.70 18.84 0.014251 3.02 5.31 1.30 0.26

Reach-1 14124 16 CFS 16.00 18.45 18.53 18.66 0.012695 2.83 5.65 2.66 0.34

Reach-1 14096 16 CFS 16.00 0.00 18.11 18.26 0.015377 3.12 5.12 1.30 0.28

Reach-1 14032 16 CFS 16.00 0.00 15.29 15.29 16.13 0.107816 7.35 2.18 1.30 1.00

0 200 400 600 800 1000 1200 140015

20

25

30

35

40

45

50

Steven's Creek Barriers Plan: Proposed Moffet Fish Ladder 8/8/2017


Ele

vation (

ft)

Legend

WS 16 CFS

Ground

ROB

RIVER-1 Reach-1

HEC-RAS Plan: Pro Moffet Ladde River: RIVER-1 Reach: Reach-1 Profile: 16 CFS



Reach-1 15283.5 16 CFS 16.00 31.25 31.98 31.52 32.00 0.001319 1.05 15.20 21.41 0.22

Reach-1 15183.5 16 CFS 16.00 31.15 31.79 31.47 31.82 0.002705 1.32 12.16 21.13 0.31

Reach-1 15082.5 16 CFS 16.00 31.05 31.35 31.28 31.42 0.006320 2.09 7.66 25.89 0.68

Reach-1 15042.5 16 CFS 16.00 30.75 30.94 30.94 31.04 0.015824 2.46 6.50 34.00 0.99

Reach-1 15035 16 CFS 16.00 24.75 25.32 24.94 25.33 0.000428 0.83 19.36 34.00 0.19

Reach-1 14979 16 CFS 16.00 24.75 25.29 24.94 25.30 0.000503 0.87 18.43 34.00 0.21

Reach-1 14974 16 CFS 16.00 23.26 25.29 24.37 25.30 0.000201 0.61 26.26 40.00 0.13


Reach-1 14959 16 CFS 16.00 23.21 25.19 24.31 25.20 0.000418 0.91 17.54 25.02 0.19


Reach-1 14883 16 CFS 16.00 23.01 25.09 24.14 25.12 0.001439 1.38 11.60 21.89 0.33

Reach-1 14799 16 CFS 16.00 22.80 24.86 23.93 24.92 0.004413 1.95 8.22 21.28 0.55

Reach-1 14698 16 CFS 16.00 22.54 24.39 23.69 24.53 0.003173 3.04 5.26 3.70 0.45

Reach-1 14601 16 CFS 16.00 22.29 23.99 23.44 24.17 0.004243 3.40 4.71 3.53 0.52

Reach-1 14587 16 CFS 16.00 22.26 23.92 23.41 24.11 0.004641 3.51 4.56 3.49 0.54

Reach-1 14569 16 CFS 16.00 22.21 23.80 23.36 24.02 0.005475 3.74 4.28 3.38 0.59

Reach-1 14563 16 CFS 16.00 22.20 23.87 23.31 23.94 0.006865 2.17 7.37 23.37 0.68

Reach-1 14549 16 CFS 16.00 22.16 23.85 23.25 23.88 0.002255 1.43 11.22 30.54 0.41


Reach-1 14323 16 CFS 16.00 21.59 23.08 22.73 23.31 0.002239 3.92 4.08 3.49 0.64

Reach-1 14315 16 CFS 16.00 21.57 23.06 23.29 0.002729 3.85 4.16 3.58 0.63

Reach-1 14300 16 CFS 16.00 21.53 23.01 23.25 0.002873 3.92 4.08 3.50 0.64

Reach-1 14250 16 CFS 16.00 21.40 22.80 23.08 0.003595 4.26 3.75 3.35 0.71

Reach-1 14222 16 CFS 16.00 21.33 22.52 22.46 22.94 0.006139 5.20 3.08 3.19 0.93

Reach-1 14217 16 CFS 16.00 21.30 22.49 22.49 22.90 0.007144 5.16 3.10 3.70 0.99

Reach-1 14213 16 CFS 16.00 21.18 22.26 22.28 0.005974 1.03 15.61 30.40 0.25

Reach-1 14209.5* 16 CFS 16.00 21.10 22.25 22.26 0.002607 0.82 19.51 28.54 0.17

Reach-1 14206 16 CFS 16.00 21.03 22.25 22.25 0.001009 0.59 27.03 32.23 0.11

Reach-1 14202 16 CFS 16.00 21.03 22.25 22.25 0.001025 0.59 26.89 32.23 0.11

Reach-1 14193 16 CFS 16.00 21.34 22.12 22.22 0.048027 2.49 6.43 16.37 0.70

Reach-1 14182 16 CFS 16.00 20.28 21.88 21.93 0.015149 1.81 8.84 14.79 0.41

Reach-1 14168 16 CFS 16.00 20.04 21.56 21.63 0.030380 2.11 7.58 17.10 0.56

Reach-1 14155 16 CFS 16.00 19.61 21.11 20.82 21.24 0.029580 2.87 5.58 7.43 0.58

Reach-1 14137 16 CFS 16.00 18.92 20.07 20.07 20.36 0.094201 4.33 3.70 6.43 1.01

Reach-1 14124 16 CFS 16.00 18.45 19.74 19.78 0.009786 1.55 10.33 14.43 0.32

Reach-1 14096 16 CFS 16.00 18.47 19.58 19.59 0.004473 1.07 15.00 20.56 0.22

Reach-1 14032 16 CFS 16.00 17.92 18.57 18.57 18.78 0.113419 3.64 4.40 10.72 1.00

0 200 400 600 800 1000 1200 140015

20

25

30

35

40

45

50

Steven's Creek Barriers Plan: 1) Ex Moffet 8/8/2017 2) Pro Moffet Ladde 8/8/2017


Ele

vation (

ft)

Legend

WS 100yr - Ex Moffet

WS 100yr - Pro Moffet Ladde

WS 16 CFS - Pro Moffet Ladde

WS 16 CFS - Ex Moffet

Ground

ROB

Ground

RIVER-1 Reach-1


Appendix B


Hetch Hetchy Pipeline Drop Structure

0 100 200 300 400 500 600 70035

40

45

50

55

60

Steven's Creek Barriers Plan: Existing Hetch-Hetchy 8/8/2017


Ele

vation (

ft)

Legend

WS 100yr

Ground

ROB

RIVER-1 Reach-1

HEC-RAS Plan: Ex HH River: RIVER-1 Reach: Reach-1 Profile: 100yr



Reach-1 17283.5 100yr 5750.00 42.25 57.81 58.86 0.007097 8.25 697.32 72.21 0.47

Reach-1 17083.5 100yr 5750.00 41.65 55.47 57.03 0.011584 10.02 573.95 63.89 0.59

Reach-1 17057.5 100yr 5750.00 40.95 55.14 56.90 0.001971 10.65 539.95 58.05 0.62

Reach-1 16984 100yr 5750.00 40.85 53.53 52.49 56.58 0.004055 14.01 410.52 49.16 0.85

Reach-1 16972 100yr 5750.00 40.85 52.49 52.49 56.43 0.005734 15.93 360.99 46.41 1.01

Reach-1 16971.* 100yr 5750.00 39.70 53.55 55.79 0.002685 12.03 477.88 52.44 0.70

Reach-1 16970.* 100yr 5750.00 38.55 54.03 55.58 0.001621 9.98 575.94 56.84 0.55

Reach-1 16969.* 100yr 5750.00 37.40 54.31 55.46 0.001080 8.59 669.01 60.59 0.46

Reach-1 16968 100yr 5750.00 36.25 54.49 55.38 0.000760 7.55 761.62 63.99 0.39

Reach-1 16958 100yr 5750.00 36.25 54.49 47.25 55.37 0.000762 7.56 761.05 63.97 0.39


Reach-1 16938 100yr 5750.00 36.25 54.07 55.02 0.000838 7.83 734.41 62.95 0.40

Reach-1 16923.5 100yr 5750.00 36.25 54.11 46.70 54.98 0.000732 7.47 769.84 62.45 0.37

Reach-1 16921.5 100yr 5750.00 38.25 53.76 48.56 54.95 0.001155 8.75 657.19 61.28 0.47

Reach-1 16783.5 100yr 5750.00 38.25 53.33 48.70 54.60 0.007892 9.07 633.78 63.67 0.51

Reach-1 16583.5 100yr 5750.00 36.75 47.61 47.61 51.45 0.034924 15.71 365.89 47.76 1.00

0 100 200 300 400 500 600 70035

40

45

50

55

60

Steven's Creek Barriers Plan: Proposed HH Cut 8/15/2017


Ele

vation (

ft)

Legend

WS 100yr

Ground

ROB

RIVER-1 Reach-1

HEC-RAS Plan: Pro HH Cut River: RIVER-1 Reach: Reach-1 Profile: 100yr



Reach-1 17283.5 100yr 5750.00 42.25 57.31 58.46 0.007934 8.59 669.48 70.62 0.49

Reach-1 17183.5* 100yr 5750.00 41.95 56.50 57.84 0.004728 9.26 620.74 67.59 0.54

Reach-1 17083.5 100yr 5750.00 41.65 55.49 57.09 0.012133 10.16 566.10 63.95 0.60

Reach-1 17078.5 100yr 5750.00 41.00 55.52 57.00 0.011011 9.75 589.63 64.22 0.57

Reach-1 17057.5 100yr 5750.00 40.70 55.13 56.89 0.001960 10.63 540.87 58.02 0.61

Reach-1 16996 100yr 5750.00 40.60 53.68 56.61 0.003844 13.73 418.76 49.56 0.83

Reach-1 16984 100yr 5750.00 40.35 53.48 52.48 56.54 0.004087 14.03 409.80 49.04 0.86

Reach-1 16972 100yr 5750.00 40.35 52.48 52.48 56.40 0.005717 15.89 361.82 46.37 1.00

Reach-1 16968 100yr 5750.00 36.25 54.39 55.29 0.000779 7.62 754.96 63.74 0.39

Reach-1 16958 100yr 5750.00 36.25 54.38 47.22 55.28 0.000780 7.62 754.39 63.71 0.39


Reach-1 16938 100yr 5750.00 36.25 54.06 55.01 0.000840 7.83 733.98 62.93 0.40

Reach-1 16923.5 100yr 5750.00 36.25 54.13 46.43 54.97 0.000694 7.35 782.28 62.48 0.37

Reach-1 16921.5 100yr 5750.00 38.25 53.79 48.29 54.93 0.001078 8.57 671.06 61.37 0.46

Reach-1 16783.5 100yr 5750.00 38.25 53.33 48.70 54.60 0.007893 9.07 633.76 63.67 0.51

Reach-1 16583.5 100yr 5750.00 36.75 47.61 47.61 51.45 0.034924 15.71 365.89 47.76 1.00

HEC-RAS Plan: Ex HH River: RIVER-1 Reach: Reach-1 Profile: 16 CFS



Reach-1 17283.5 16 CFS 16.00 42.25 43.34 43.37 0.006585 1.41 11.37 17.20 0.30

Reach-1 17183.5* 16 CFS 16.00 41.95 42.93 42.96 0.002835 1.40 11.44 15.78 0.29

Reach-1 17083.5 16 CFS 16.00 41.65 41.97 41.97 42.13 0.090576 3.15 5.08 16.62 1.00

Reach-1 17057.5 16 CFS 16.00 40.95 41.54 41.59 0.002062 1.79 8.95 16.34 0.43

Reach-1 16984 16 CFS 16.00 40.85 41.34 41.40 0.003247 2.02 7.92 16.89 0.52

Reach-1 16972 16 CFS 16.00 40.85 41.17 41.17 41.32 0.013792 3.16 5.07 16.44 1.00

Reach-1 16971.* 16 CFS 16.00 39.70 40.00 40.00 40.15 0.014015 3.11 5.15 17.37 1.00

Reach-1 16970.* 16 CFS 16.00 38.55 39.35 39.37 0.000484 1.07 14.93 19.59 0.22

Reach-1 16969.* 16 CFS 16.00 37.40 39.36 39.37 0.000022 0.39 41.19 23.41 0.05

Reach-1 16968 16 CFS 16.00 36.25 39.37 39.37 0.000004 0.22 72.60 27.10 0.02

Reach-1 16958 16 CFS 16.00 36.25 39.37 36.52 39.37 0.000004 0.22 72.60 27.10 0.02


Reach-1 16938 16 CFS 16.00 36.25 39.36 39.36 0.000004 0.22 72.36 27.08 0.02

Reach-1 16923.5 16 CFS 16.00 36.25 39.36 36.94 39.36 0.000005 0.21 74.57 31.78 0.02

Reach-1 16921.5 16 CFS 16.00 38.25 39.34 38.93 39.36 0.000803 1.08 14.77 27.82 0.26

Reach-1 16783.5 16 CFS 16.00 38.25 39.14 38.74 39.15 0.003520 1.04 15.44 24.94 0.23

Reach-1 16583.5 16 CFS 16.00 36.75 37.03 37.03 37.18 0.087973 3.03 5.28 19.29 1.02

0 100 200 300 400 500 600 70035

40

45

50

55

60

Steven's Creek Barriers Plan: Existing Hetch-Hetchy 8/15/2017


Ele

vation (

ft)

Legend

WS 16 CFS

Ground

ROB

RIVER-1 Reach-1

0 100 200 300 400 500 600 70035

40

45

50

55

60

Steven's Creek Barriers Plan: Proposed HH Cut 8/15/2017


Ele

vation (

ft)

Legend

WS 16 CFS

Ground

ROB

RIVER-1 Reach-1

HEC-RAS Plan: Pro HH Cut River: RIVER-1 Reach: Reach-1 Profile: 16 CFS



Reach-1 17283.5 16 CFS 16.00 42.25 43.27 43.28 0.001931 0.95 16.78 17.92 0.17

Reach-1 17183.5* 16 CFS 16.00 41.95 43.09 43.11 0.001531 1.21 13.21 14.01 0.22

Reach-1 17083.5 16 CFS 16.00 41.65 42.48 42.48 42.62 0.090062 2.97 5.40 19.11 0.98

Reach-1 17078.5 16 CFS 16.00 41.00 41.86 41.86 42.01 0.115387 3.11 5.15 19.20 1.06

Reach-1 17057.5 16 CFS 16.00 40.70 41.46 41.51 0.001940 1.77 9.05 16.01 0.41

Reach-1 16996 16 CFS 16.00 40.60 41.28 41.35 0.003461 2.06 7.75 16.75 0.53

Reach-1 16984 16 CFS 16.00 40.35 41.24 41.08 41.31 0.003360 2.04 7.83 16.64 0.52

Reach-1 16972 16 CFS 16.00 40.35 41.08 41.08 41.23 0.012400 3.06 5.23 16.22 0.95

Reach-1 16968 16 CFS 16.00 36.25 40.07 40.07 0.000002 0.17 92.18 28.81 0.02

Reach-1 16958 16 CFS 16.00 36.25 40.07 36.52 40.07 0.000002 0.17 92.18 28.81 0.02


Reach-1 16938 16 CFS 16.00 36.25 39.22 39.22 0.000005 0.23 68.72 26.75 0.03

Reach-1 16923.5 16 CFS 16.00 36.25 39.22 36.57 39.22 0.000003 0.20 81.89 31.50 0.02

Reach-1 16921.5 16 CFS 16.00 38.25 39.21 38.58 39.22 0.000181 0.70 22.94 27.53 0.13

Reach-1 16783.5 16 CFS 16.00 38.25 39.14 38.74 39.15 0.003520 1.04 15.44 24.94 0.23

Reach-1 16583.5 16 CFS 16.00 36.75 37.03 37.03 37.18 0.087973 3.03 5.28 19.29 1.02

0 100 200 300 400 500 600 70035

40

45

50

55

60

Steven's Creek Barriers Plan: 1) Pro HH Cut 8/15/2017 2) Ex HH 8/15/2017


Ele

vation (

ft)

Legend

WS 100yr - Pro HH Cut

WS 100yr - Ex HH

WS 16 CFS - Pro HH Cut

WS 16 CFS - Ex HH

Ground

ROB

Ground

RIVER-1 Reach-1


Appendix B


Bridge Crossings

0 100 200 300 400 500 600 70090

100

110

120

130

140

Steven's Creek Barriers Plan: Existing El Camino 5/15/2017


Ele

vation (

ft)

Legend

WS 100-yr

Ground

ROB

RIVER-1 Reach-1

HEC-RAS Plan: Existing El River: RIVER-1 Reach: Reach-1 Profile: 100-yr



Reach-1 25951 100-yr 5750.00 100.40 116.06 117.78 0.008794 10.51 547.34 50.52 0.56

Reach-1 25871 100-yr 5750.00 100.10 115.34 117.05 0.009377 10.49 547.90 36.01 0.47

Reach-1 25746 100-yr 5750.00 99.40 113.88 108.67 115.77 0.010790 11.05 520.47 35.99 0.51

Reach-1 25621.1 Culvert

Reach-1 25621 100-yr 5750.00 98.70 110.72 113.47 0.019414 13.32 431.80 35.98 0.68

Reach-1 25600 100-yr 5750.00 98.60 111.31 112.81 0.009472 9.83 584.70 68.07 0.59

Reach-1 25551 100-yr 5750.00 97.60 111.35 112.31 0.005344 7.85 732.20 77.55 0.45

Reach-1 25422 100-yr 5750.00 95.70 106.64 106.64 110.63 0.031254 16.03 358.73 45.06 1.00

Reach-1 25307 100-yr 5750.00 91.40 101.65 101.65 105.12 0.029621 14.95 384.73 56.19 1.01

0 100 200 300 400 500 600 70090

100

110

120

130

140

Steven's Creek Barriers Plan: Pro El Camino Baffles - HB13 8/3/2017


Ele

vation (

ft)

Legend

WS 100-yr

Ground

ROB

RIVER-1 Reach-1

HEC-RAS Plan: HB-13 Baffles River: RIVER-1 Reach: Reach-1 Profile: 100-yr



Reach-1 25951 100-yr 5750.00 100.40 117.02 118.46 0.006974 9.64 596.45 52.33 0.50

Reach-1 25871 100-yr 5750.00 100.10 116.36 117.86 0.007861 9.83 584.71 36.02 0.43

Reach-1 25746 100-yr 5750.00 99.40 113.77 110.67 116.37 0.016749 12.93 444.71 35.98 0.65

Reach-1 25621.1 Culvert

Reach-1 25621 100-yr 5750.00 98.70 109.96 109.96 114.60 0.040914 17.28 332.75 35.96 1.00

Reach-1 25600 100-yr 5750.00 98.60 111.31 112.81 0.009472 9.83 584.70 68.07 0.59

Reach-1 25551 100-yr 5750.00 97.60 111.35 112.31 0.005344 7.85 732.20 77.55 0.45

Reach-1 25422 100-yr 5750.00 95.70 106.64 106.64 110.63 0.031254 16.03 358.73 45.06 1.00

Reach-1 25307 100-yr 5750.00 91.40 101.65 101.65 105.12 0.029621 14.95 384.73 56.19 1.01

0 100 200 300 400 500 600 70090

100

110

120

130

140

Steven's Creek Barriers Plan: 1) Existing El 5/15/2017 2) HB-13 Baffles 8/3/2017


Ele

vation (

ft)

Legend

WS 100-yr - Existing El

WS 100-yr - HB-13 Baffles

WS 20 CFS - Existing El

WS 15 CFS - HB-13 Baffles

Ground

ROB

RIVER-1 Reach-1

0 200 400 600 800 1000120

130

140

150

160

170

Steven's Creek Barriers Plan: Existing Hwy 85 8/8/2017


Ele

vation (

ft)

Legend

WS 100-yr

Ground

ROB

RIVER-1 Reach-1

HEC-RAS Plan: Existing Hwy River: RIVER-1 Reach: Reach-1 Profile: 100-yr



Reach-1 31131 100-yr 5750.00 134.00 150.02 149.10 154.15 0.041406 16.30 352.76 34.03 0.89

Reach-1 30831 100-yr 5750.00 133.10 151.00 151.76 0.001647 7.03 818.22 69.82 0.36

Reach-1 30731 100-yr 5750.00 132.80 148.43 144.01 151.32 0.003513 13.63 421.85 58.45 0.61


Reach-1 30561 100-yr 5750.00 132.00 143.22 143.22 148.82 0.010652 19.00 302.56 48.43 1.00

Reach-1 30371 100-yr 5750.00 128.80 140.55 141.58 0.003543 8.16 704.52 95.22 0.53

Reach-1 30271 100-yr 5750.00 127.80 137.03 137.03 140.47 0.013842 14.89 386.29 56.27 1.00

0 200 400 600 800 1000120

130

140

150

160

170

Steven's Creek Barriers Plan: Pro Baffles Hwy 85 8/8/2017


Ele

vation (

ft)

Legend

WS 100-yr

Ground

ROB

RIVER-1 Reach-1

HEC-RAS Plan: Pro Baffles Hwy8 River: RIVER-1 Reach: Reach-1 Profile: 100-yr



Reach-1 31131 100-yr 5750.00 134.00 154.73 156.57 0.014183 10.88 528.30 40.62 0.53

Reach-1 30831 100-yr 5750.00 133.10 155.18 155.58 0.000688 5.07 1135.19 81.68 0.24

Reach-1 30731 100-yr 5750.00 132.80 153.76 144.01 155.36 0.001321 10.16 565.68 69.50 0.39


Reach-1 30561 100-yr 5750.00 132.00 143.22 143.22 148.82 0.010650 19.00 302.57 48.43 1.00

Reach-1 30371 100-yr 5750.00 128.80 140.55 141.59 0.003538 8.16 704.96 95.27 0.53

Reach-1 30271 100-yr 5750.00 127.80 137.01 137.01 140.47 0.013957 14.93 385.18 56.22 1.01

0 200 400 600 800 1000120

130

140

150

160

170

Steven's Creek Barriers Plan: 1) Existing Hwy 8/8/2017 2) Pro Baffles Hwy8 8/8/2017


Ele

vation (

ft)

Legend

WS 100-yr - Existing Hwy

WS 100-yr - Pro Baffles Hwy8

WS 16 CFS - Existing Hwy

WS 16 CFS - Pro Baffles Hwy8

Ground

ROB

RIVER-1 Reach-1

0 200 400 600 800 1000 1200240

250

260

270

280

290

Steven's Creek Barriers Plan: Existing Hwy 280 5/9/2017


Ele

vation (

ft)

Legend

WS 100-yr

Ground

ROB

RIVER-1 Reach-1

HEC-RAS Plan: Ex 280 River: RIVER-1 Reach: Reach-1 Profile: 100-yr



Reach-1 46125 100-yr 5460.00 252.80 265.43 266.27 0.003431 7.55 886.48 301.03 0.51

Reach-1 45979 100-yr 5460.00 250.00 264.11 265.31 0.003094 9.16 719.03 119.52 0.51

Reach-1 45915 100-yr 5460.00 249.00 264.39 264.94 0.001112 6.05 1009.91 113.87 0.27

Reach-1 45885 100-yr 5460.00 248.80 263.10 258.20 264.56 0.004503 9.69 563.70 56.64 0.48

Reach-1 45715 Culvert

Reach-1 45546 100-yr 5460.00 247.80 257.66 257.30 261.27 0.016360 15.23 358.44 54.60 0.94

Reach-1 45545 100-yr 5460.00 246.80 260.12 253.55 260.99 0.002162 7.46 731.86 54.97 0.36

Reach-1 45445 100-yr 5460.00 246.80 259.81 260.72 0.003028 7.65 713.66 93.84 0.49

Reach-1 45065 100-yr 5460.00 246.50 254.96 254.96 257.87 0.021790 13.71 398.38 69.13 1.01


Appendix B


Fish Ladder Hydraulic Calculations

MOFFETT FISH LADDER

Slotted Fish Ladder

Slot equation: Q= Cd(Ws*Y)* (2GH)^.5

Cd=orifice constant for slot at wall=0.58

Ws= slot width =1.5 ft slot height =2.5ft

Y= depth upstream of slot < Lfish >

H= change in WSE u/s pool to d/s pool-target =1 foot

G= 32.2 Ws > <

Q= Cw*Lfish*(H)^ 1.5 ladder section

Cw=weir constant= 3.1

Lfish = width of ladder weir above slot=3.5 ft

Headworks (ladder) Inlet : Q= Cw*Linlet*(H)^1.5 = Y HLinlet=width of the ladder opening = 5 ft =

Q= Cw*Ldrop(H)^1.5 ladder profileLdrop=width of the drop structure weir= 29.5ft

LOW FLOW (set H to 1 and vary Y until equations provides Q low)Q low= 14 to 16cfs

Q (cfs) 14.0 Q 0

Ws 1.5 L-fish 3.5

Y 2 h 0 Q 15.5 Q 0

G 32.2 L-inlet 5 L -drop 29.5

H 1 h 1 h 0

1 ft high sill weir

Total ladder Q= 14.0 cfs

Ladder % of total

14.0 cfs 100.0% OK

1

2.5 slot height

FULL LADDER FLOW (Y=4ft)

Q (cfs) 27.9 Q 19.9

Ws 1.5 L-fish 3.5

Y 4 h 1.5 Q 83.1 Q 258.7

G 32.2 L 5 L 29.5

H 1 h 3 h 2

1 ft high sill weir

Total Ladder Q 47.9 cfs

306.5 cfs 15.6% OK

3

2.5

Drop Structure Spill

Total Flow

ladder Weir bottom=

Fish Ladder Weir equation:

Drop Structure Spill

Total Stream Flow =

Upstream inlet Depth

Fish Ladder Weir

Ladder inlet capacity

Fish Ladder Slot

Upstream Depth

Ladder Weir Height

Fish Ladder Slot Fish Ladder Weir

Ladder inlet capacity

Hetch Hetchy Drop

Above Grade Slotted Fish Ladder Option

with 1 foot sill weir across top of drop

LOW FLOW

Percent of total flow in Ladder

14.0 cfs 100.0%

1

2.5

Q cfs 14.0 Q cfs 0.0 Q cfs 16.0 Q cfs 0

Ws 1.5 L 3.5 L 5 L 16

Y 2.0 h 0.0 h 1 h 0

G 32.2

h 1

Total Fish Q 14.0 cfs

Ladder Full Flow

Percent of total flow in Ladder

183.0 cfs 25.8%

3

2.5

Q cfs 27.9 Q cfs 19.3 Q cfs 83.1 Q cfs 135.8

Ws 1.5 L 3.5 L 5 L 16

Y 4.0 h 1.5 h 3 h 2

G 32.2

h 1

Total Fish Q 47.2 cfs

ladder inlet capacity Main Spill

Total Flow

Upstream Depth

Ladder Weir Height

Fish Ladder Slot flow Fish Ladder Weir flow

Main Spill

Total Flow

Upstream Depth

Ladder Weir Height

Fish Ladder Slot flow Fish Ladder Weir flow ladder inlet capacity


APPENDIX C

COST ESTIMATES

Moffett Drop Structure Project

Alternative 1A Use Existing Ladder and Construction of New Concrete Low Flow Channel

Engineer's Opinion of Probable Costs

Element Description

Estimated

Quantity Units Unit Price Estimated Amount

Storm Water Pollution Prevention Plan 1 LS 15,000$ 15,000$

Temporary Stream Diversion and Dewatering 1 LS 75,000$ 75,000$

Saw Cut Concrete Channel 1600 LF 32.00$ 51,200$

Concrete Demolition and Removal 8,400 CF 12.00$ 100,800$

Construct Concrete Low flow Channel 700 CY 800$ 560,000$

Clean and repair Denil Ladder 1 LS 15,000$ 15,000$

Subtotal: 817,000$

Mobilization, Bonds, Insurance (8%) 8% LS 65,360$ 65,360.00$

882,360$

Construction Contingency 25% LS 220,590$ 220,590$

TOTAL CONSTRUCTION COSTS 1,103,000$

Subtotal Construction:

Domenichelli and Associates 11/20/2017


Alternative 2A New Ladder and Construction of New Concrete Low Flow Channel


Element Description

Estimated






Construct Concrete Low flow Channel 700 CY 800$ 560,000$

Construct New Fish Ladder 200 CY 1,300$ 260,000$

Subtotal: 1,075,600$


1,161,648$






Alternative 1C - Use Existing Ladder and Construction of New Natural Channel Downstream


Element Description

Estimated






Earthwork 3,200 CY 45.00$ 144,000$

Construct Retaining Wall 1,540 CY 1,200.00$ 1,848,000$

Construct Natural Low flow Channel (rock and plantings) 780 CY 250$ 195,000$

Clean and repair Denil Ladder 1 LS 15,000$ 15,000$



2,680,992$






Alternative 2C - New Ladder and Construction of New Natural Channel Downstream


Element Description

Estimated






Earthwork 3,200 CY 45.00$ 144,000$

Construct Retaining Wall 1,540 CY 1,200.00$ 1,848,000$

Construct Natural Low flow Channel (rock and plantings) 780 CY 250$ 195,000$

Construct New Fish Ladder 200 CY 1,300$ 260,000$



2,945,592$





Hetch Hetchy Drop Structure Project


Element Description

Estimated





Concrete Demolition and Removal 670 CF 15.00$ 10,050$

Concrete Channel Replacement (upstream low flow) 14 CY 800.00$ 11,200$

Construct Retaining Wall 15 CY 1,500$ 22,500$

Construct New Fish Ladder 20 CY 1,800$ 36,000$ Subtotal: 139,790$


150,973$


TOTAL CONSTRUCTION COSTS 189,000$

Cut in Concrete Fish Ladder





Element Description

Estimated




Saw Cut Concrete 100 LF 36.00$ 3,600$



Raise baffle & Construct New Fish Ladder 33 CY 1,800$ 59,400$ Subtotal: 129,900$


140,292$



Above Grade Concrete Fish Ladder





Element Description

Estimated







Construct New Fish Ladder 20 CY 1,800$ 36,000$ Subtotal: 109,825$


118,611$



Raise baffle and cut in 2 Step Concrete Fish Ladder



Un-Numbered Crossing for Highway 85


Element Description

Estimated






Construct Concrete Low Flow Channel 180 CY 800.00$ 144,000$

Upstream Weir (if needed for grade control) 5 CY 1,800$ 9,000$ Subtotal: 285,150$


307,962$



Cut in Low Flow Channel



El Camino Real Culvert


Element Description

Estimated



Temporary Access, Stream Diversion and Dewatering 1 LS 55,000$ 55,000$

Channel Excavation (assume 4 ft to scour resistant material) 200 CY 75.00$ 15,000$

Foundation and achors to Culvert 40 CY 1,200.00$ 48,000$

Baffle Construction 20 CY 1,500.00$ 30,000$

Subtotal: 163,000$


176,040$



Concrete Baffles



El Camino Real Culvert


Element Description

Estimated




Channel Excavation 75 CY 75.00$ 5,625$

Rock Baffle Construction 80 CY 500.00$ 40,000$

Subtotal: 95,625$


103,275$



Rock Baffles



Highway 85 Near Village Court


Element Description

Estimated






Subtotal: 82,000$


88,560$



Rock Baffles



Highway 280 Culvert


Element Description

Estimated






Subtotal: 107,750$


116,370$



Rock Baffles



Deep Cliff Golf Course


Element Description

Estimated




Demo Crossing & Clearing 1 LS 18,000$ 18,000$


Rock Weir Construction (hand placed) 18 CY 1,000.00$ 18,000$

Subtotal: 62,500$

Mobilization, Bonds, Insurance (12%) smaller job higher percentage 12% LS 7,500$ 7,500.00$

70,000$



Rock Weir and Pool Ladder



Gauge Station Weir


Element Description

Estimated





Rock Weir Construction (hand placed) 30 CY 1,000.00$ 30,000$

Subtotal: 60,250$

Mobilization, Bonds, Insurance (12%) smaller job higher percentage 12% LS 7,230$ 7,230.00$

67,480$



Rock Weir and Pool Ladder



stevens creek steelhead passage improvement …...stevens creek steelhead passage improvement...

Documents