Fort Bragg City Council
August 24, 2026

4.1.3.2 Improvements and Timing
In order to address the deficiencies identified during the inspections, Table 7 indicates recommended improvements and timing – whether the project is recommended as a short-term project (<5-year timeframe), mid-term project (5-to-10-year timeframe), or long-term (11-to-20- year timeframe). A rough order of magnitude costs was developed for each of the recommended improvement projects based on engineering experience. Note that the packaging of improvements projects and identifying funding sources will be determined as part of the development of the capital improvement projects planning.

Table 7: Sanderson Recommended Improvements
Improvement Funding Timing Cost
Estimate
Replace MCC FRP panel <5 $5,000
Replace MCC wood structure roof and framing. Extend the roof farther past the panel to provide additional UV
protection of panels; or
<5 $5,000
Alternatively replace existing wood structure with a new ventilated prefabricated housing
6-10 $10,000
Coat the interior of the wet well structure 6-10 $15,000 Provide backup system to pump controls <5 $4,000
Provide a safety net or grate under wet well hatch <5 $1,000 Coat the upper wall of the valve vault 6-10 $1,000
Replace the valve vault piping <5 $12,000
Regrade the site entrance 6-10 $3,000
Total Cost $51,000(1)
(1) Cost assuming new housing over the electrical service.

4.1.4 Pudding Creek Pump Station

4.1.4.1 Overview of Facility
The Pudding Creek Pump Station was installed during the 1973 Pudding Creek Interceptor Project. It has two pumps rated at 465 gpm each. The pump station drains the Ft. Bragg wastewater collection system north of Pudding Creek. It discharges south over the Highway 1 Zone 7 Water City | Condition Assessment Report
Condition Assessment Findings
March 26, 2025 | 19
Pudding Creek Bridge, along Main Street (Highway 1), and west on W. Elm St. to SSM 37 (Utility Network manhole Mnhl-Chnnl-4321) on the 100 block of W. Elm St.

The pump station is composed of a below-grade wet well with two submersible duty/standby 15 hp pumps, a concrete building with concrete walls and roof over the wet well, a below-grade valve vault, a concrete building with concrete walls and roof over the abandoned drywell. The standby generator is located in the building as well as the electrical panels and automatic transfer switch. There is an asphalt roadway that comes from the main highway and into the site. Most of the surrounding site is sand and vegetation.

Figure 5 – Pudding Creek Pump Station

4.1.4.2 Overall Condition Ratings
The Pudding Pump Station was reviewed for condition and the results are summarized in Table

8. The following processes/systems/assets were assessed:

Error! Reference source not found.

Zone 7 Water City | Condition Assessment Report
Condition Assessment Findings
March 26, 2025 | 20
Table 88: Pudding Pump Station Condition Ratings
Asset Information Condition Rating
Asset Name System
Install DateMechanical/CivilStructural/ArchitecturalElectricalEvRUL Generator Building Structure NA NA <5
Generator Electrical NA NA 3 <5
UPS (battery) Electrical NA NA 2 5-10
MCC Electrical NA NA 2 5-10
Transfer Switch Electrical NA NA 2 5-10
Handrail Structure NA 2 NA 11-20
Engine Silencer Piping Mechanical NA NA 11-20
Exterior CMU Wing Wall Structure NA 3 NA 5-10
Generator Exhaust Louver Mechanical NA 2 NA 5-10
Monorail Architectural NA 2 NA 5-10
Pump Building Electrical Electrical NA NA 5 <5
Pump Discharge Piping Mechanical 3 NA NA 5-10
Wet well Roof Opening Structure NA 2 NA <5
Pump Building Walls Structure NA 2 NA
Wet well Access Hatch Structure NA 2 NA <5
Generator Building Door Architectural NA 4 NA <5
Valve Vault Structure NA 2 NA 11-20
Valve Vault Piping Mechanical 2 NA NA 6-10
Electrical conduits Electrical NA NA 2 6-10
Unk = Unknown installation date
NA = Asset not assessed by specified discipline
The following general observations and concerns from the City were noted:
• Substantial leaks from roof and from roof vents into the building • Underside of roof under eaves severely damaged and peeling • Generator has a lot of corrosion and can lead to premature failure of equipment • The UPS has been broken so there is no current electronic backup • The abandoned drywell equipment and piping is still in place. Could be removed as budget allows
• MCC replaced in 2020 so in good condition
• Hairline cracks in underside of roof and signs of leakage Zone 7 Water City | Condition Assessment Report
Condition Assessment Findings
March 26, 2025 | 21
• Transfer switch panel shows some minor surface corrosion • Handrail into drywell peeling
• Surface corrosion on piping to engine silencer
• Exterior CMU wing wall is damaged, but does not hinder access to the station • Minor surface corrosion on generator exhaust louver
• Surface corrosion on monorail
• Building over pump station. Light switches and lamp severely corroded and not functioning. No light inside building. They should be replaced as soon as possible. • Wet well piping was replaced in 2020 but showing a lot of surface corrosion • Concrete damage at the top of the grated opening over the wet well piping • Damaged coating on walls of pump building
• Access hatch over the wet well pumps is stuck. There is some surface corrosion on handles and most likely some corrosion under the hatch. Minor cleaning may loosen hatch
• Door and frame corroded
• Valve vault in good condition
• Bypass vault in good condition

4.1.4.3 Improvements and Timing
In order to address the deficiencies identified during the inspections, Table 9 indicates recommended improvements and timing – whether the project is recommended as a short-term project (<5-year timeframe), mid-term project (5-to-10-year timeframe), or long-term (11-to-20- year timeframe). A rough order of magnitude costs was developed for each of the recommended improvement projects based on engineering experience. Note that the packaging of improvements projects and identifying funding sources will be determined as part of the development of the capital improvement projects planning.

Table 9: Pudding Pump Station Recommended Improvements
Improvement Funding Timing Cost
Estimate
Remove and recoat the coatings on the
underside of the roof inside and outside
building, repair roof and wall cracks, repair
leaks through the roof vents inside generator
building
<5 $20,000
Replace or prepare and recoat generator parts
showing corrosion
<5 $10,000
Replace failed UPS (battery) <5 $5,000
Prepare and recoat transfer switch panel 6-10 $1,000
Prepare and recoat portion handrail 6-10 $1,000
Zone 7 Water City | Condition Assessment Report
Condition Assessment Findings
March 26, 2025 | 22
Improvement Funding Timing Cost
Estimate
Remove surface corrosion on engine silencer
piping
<5 $1,000
Repair top portion of exterior CMU wing wall 6-10 $1,000 Remove surface corrosion on generator
exhaust louver
6-10 $1,000
Prepare and recoat monorail 6-10 $1,000
Replace all existing electrical inside the pump
building
<5 $5,000
Prepare and recoat pump discharge piping <5 $1,000
Prepare and coat the top wall of the wet well <5 $1,000 Prepare and recoat portions of the pump
building walls
6-10 $1,500
Provide maintenance and remove surface
corrosion of the wet well access hatch
<5 $1,000
Replace generator building door <5 $2,000
Total Cost $52,500

4.1.5 Elm Pump Station

4.1.5.1 Overview of Facility
The Elm Pump Station was installed during the 1970 Regional Sewage Disposal Project. It has two pumps rated at 800 gpm each. The pump station drains the northwest portion of the Ft.

Bragg wastewater collection system south of Pudding Creek, and also receives the discharge from the Pudding Creek Pump Station. It discharges south along Stewart St. to W. Fir St., then east along W. Fir Street to SSM 54 (Utility Network manhole Mnhl-Chnnl-7076) at the intersection of W. Fir St. and Main St. (Highway 1).

The station is composed of a building (comprised of concrete walls and concrete roof) that houses two 15 hp self-priming, pad-mounted duty/standby pumps, discharge piping and valves, a standby generator, electrical panels and automatic transfer switch, a below-grade valve vault, above-grade bypass connection. The below-grade wet well extends beyond the building and houses the abandoned drywell and pumps. The PVC suction piping to the self-priming pumps is located inside the wet well. The site has a perimeter chain link fence and a combination concrete and asphalt driveway into the site.

Zone 7 Water City | Condition Assessment Report
Condition Assessment Findings
March 26, 2025 | 23
Figure 6 – Elm Pump Station

4.1.5.2 Overall Condition Ratings
The Elm Pump Station was reviewed for condition and the results are summarized in • Self-priming Pumps
• Discharge Valve Vault
• Electrical systems
• Standby Generator
• Structures
• Site Features
Table 10. The following processes/systems/assets for the well facilities were assessed:
• Self-priming Pumps
• Discharge Valve Vault
• Electrical systems
• Standby Generator
• Structures
• Site Features
Zone 7 Water City | Condition Assessment Report
Condition Assessment Findings
March 26, 2025 | 24
Table 10: Elm Pump Station Condition Ratings
Asset Information Condition Rating
Asset Name System
Install DateMechanical/CivilStructural/ArchitecturalElectricalEvRUL Asphalt Driveway Civil 4 NA NA <5
Manhole Cover Mechanical 4 NA NA <5
Inlet Slide Gate Mechanical 4 NA NA <5
Bypass Piping Connection Mechanical 2 NA NA 11-20
Handrail into Abandoned Drywell Architectural NA 5 NA <5 Perimeter Fencing Architectural NA 4 NA <5
Exterior Concrete Slab over Abandoned Drywell Structural NA 3 NA 6-10 Exterior Electric Service Panel Electrical NA NA 2 6-10 Exterior Radio Antenna Electrical NA NA 2 6-10
Exterior FRP Conduit Electrical NA NA 3 <5
Building Structural NA 2 NA >20
Louvers and Windows Architectural NA 2 NA 11-20
Building Double Door Architectural NA 4 NA <5
Self-Priming Pumps Mechanical 2 NA NA 11-20
Spare Self-Priming Pump Mechanical 2 NA NA 11-20
Pump Frames Mechanical 3 NA NA 6-10
Pump Discharge Piping Mechanical 1 NA NA >20
MCC Electrical NA NA 2 11-20
Building Roof Coating Architectural NA 3 NA <5
Building Wall/Floor Interface Architectural NA 4 NA <5
Generator Louver Mechanical 2 NA NA 11-20
Engine Silencer Piping Mechanical 2 NA NA 11-20
Entry Sidewalk Structural NA 4 NA <5
Exterior Water Piping Mechanical 2 NA NA 11-20
Electrical conduits Electrical NA NA 2 6-10
Unk = Unknown installation date
NA = Asset not assessed by specified discipline
The following general observations and concerns from the City were noted:
• The asphalt entry is in very poor condition. Could be a potential safety concern • Crack in manhole cover, but not in danger of immediate failure Zone 7 Water City | Condition Assessment Report
Condition Assessment Findings
March 26, 2025 | 25
• The inlet slide gate does not operate so it is left in an open position. Access to the gate will be difficult if the station needs to remain in service. Would potentially require bypass pumping form upstream of the station
• Minor corrosion on bypass piping
• Railing at abandoned drywell has failed and should be replaced as soon as possible for safety
• The abandoned drywell equipment and piping is still in place. Could be removed as budget allows
• Perimeter fencing and posts show corrosion
• Concrete slab over the abandoned drywell is peeling, but does not appear to impact the structural integrity of the slab
• Service panel outside building has some surface corrosion as well as the antenna pole • Exterior FRP conduit showing signs of UV damage
• Top part of the roof is damaged, but no signs or reports of leakage • Louvers and windows in good condition
• Doors severely corroded and one leaf does not move. It should be replaced as soon as possible.
• Signs of mold below the door. Would take some power washing • Pumps are self-priming type manufactured by Gorman Rupp • One pump is from 1975 but has a new motor. The second pump is from 2010 and is operated from the original re-built motor. There is one spare pump sitting on the floor • The spare pump has not been exercised
• Pumps and frames have damaged coatings
• Discharge piping was replaced a couple of years ago and is in good condition • MCC replaced in 2020 and is in good condition
• Peeling of coating on underside of roof, but does not appear to be leaking • The air bubbler agitation pump still mounted but is abandoned and can be removed • The abandoned air gap tank mounted on the wall can be removed • The interface of the lower wall and floor is wet. It is not clear if water is seeping under the wall. This should be further inspected for the source of leakage • Generator louver should be cleaned
• Surface corrosion on piping to engine silencer
• Minor hairline cracks in floor although no visible leakage through the cracks • Sidewalk leading to pump room door is severely damaged and should be replaced for safety
• Exterior water piping coating slightly damaged, but piping is in good condition • Bypass piping showing some minor surface corrosion

4.1.5.3 Improvements and Timing
In order to address the deficiencies identified during the inspections, Table 11 indicates recommended improvements and timing – whether the project is recommended as a short-term project (<5-year timeframe), mid-term project (5-to-10-year timeframe), or long-term (11-to-20- year timeframe). A rough order of magnitude costs was developed for each of the Zone 7 Water City | Condition Assessment Report
Condition Assessment Findings
March 26, 2025 | 26
recommended improvement projects based on engineering experience. Note that the packaging of improvements projects and identifying funding sources will be determined as part of the development of the capital improvement projects planning.

Table 11: Elm Pump Station Recommended Improvements
Improvement Funding Timing Cost Estimate
Replace asphalt driveway <5 $10,000
Replace manhole cover $1,000
Replace inlet slide gate <5 $10,000
Recoat bypass piping connection $500
Replace handrail into abandoned drywell <5 $5,000
Replace perimeter fencing <5 $15,000
Repair exterior concrete slab over abandoned drywell <5 $2,000 Remove surface corrosion from exterior electric
service panel
6-10 $500
Remove surface corrosion from exterior radio
antenna
6-10 $500
Replace exterior FRP conduit <5 $500
Repair small section of building roof <5 $1,500
Replace building double door <5 $2,000
Exercise spare self-priming pump <5 $500
Prepare and recoat pump frames 6-10 $1,000
Repair underside of building roof coating <5 $1,000
Check and seal the interface between the building
perimeter wall and floor
<5 $4,000
Remove surface corrosion from generator louver 6-10 $500 Remove surface corrosion from engine silencer
piping
6-10 $500
Replace concrete entry sidewalk <5 $3,000
Prepare and recoat exterior water piping 6-10 $1,000
Total Cost $60,000
Zone 7 Water City | Condition Assessment Report
Condition Assessment Findings
March 26, 2025 | 27

4.2 Noyo Point Pump Station

4.2.1.1 Overview of Facility
The Noyo Point Pump Station was installed in 1986 and has two pumps rated at 45 gpm each.

The pump station drains the homes along Noyo Point Road. It discharges east along Noyo Point Rd, across Highway 1 onto N. Harbor Dr., to SSM 116 (Utility Network manhole Mnhl-Chnnl4236) near the intersection of Highway 1 and N. Harbor Drive.

The station is composed of a precast round wet well with two submersible duty/standby 2.5 hp pumps, a valve vault, and electrical service panels mounted on a free-standing support structure. The flow coming into the wet well does not have an inlet valve. The site is next to a house and is mostly surrounded by gravel and grass.

Figure 7 – Noyo Point Pump Station

4.2.1.2 Overall Condition Ratings
The Noya Point Pump Station was reviewed for condition and the results are summarized in Table 12. The following processes/systems/assets for the well facilities were assessed:
• Below Grade Inlet and Wet well
• Discharge Valve Vault
• Electrical systems
• Structures
• Site Features
Zone 7 Water City | Condition Assessment Report
Condition Assessment Findings
March 26, 2025 | 28
Table 12: Noyo Point Pump Station Condition Ratings
Asset Information Condition Rating
Asset Name System
Install DateMechanical/CivilStructural/ArchitecturalElectricalEvRUL MCC Panel Support Structural 2022 NA 2 NA 6-10
Wet well Floats and Rails Electrical System 1990 NA 2 NA 6-10 Wet well Structure Structural 1990 NA 2 NA 11-20
Pump discharge piping Mechanical 1990 4 NA NA <5
Valve Vault Structural 1990 NA 2 NA 6-10
Valve Vault Piping Mechanical 1990 4 NA NA <5
Electrical Service Panel Electrical System 1990 NA NA 2 6-10 MCC Electrical System 2020 NA NA 2 11-20
Site Civil 1990 2 NA NA 6-10
Electrical conduits Electrical 2020 NA NA 2 6-10
Unk = Unknown installation date
NA = Asset not assessed by specified discipline
The following general observations and concerns from the City were noted:
• No sunshades over MCC or service panel so not protected from UV • Net on wet well hatch
• The wet well floats, pump rails and MCC are new and are in good condition. The rest is from the early 1990s
• Severely corroded pump discharge pipe elbows near top of wet well. Need to be replaced as soon as possible
• Pumps may have been replaced in the past
• Interior surface of wet well appears to be in good condition • Valve vault piping partly corroded
• Check valves are severely corroded and should be replaced as soon as possible • No grate at valve vault hatch. Should be added for safety • Interior walls of valve vault OK but starting to show some coating failure • Abandoned junction box inside the wet well is corroded and should be removed so it does not fall into the flow

4.2.1.3 Improvements and Timing
In order to address the deficiencies identified during the inspections, Table 11 indicates recommended improvements and timing – whether the project is recommended as a short-term Zone 7 Water City | Condition Assessment Report
Condition Assessment Findings
March 26, 2025 | 29
project (<5 year timeframe), mid-term project (5-to-10-year timeframe), or long-term (11-to-20- year timeframe). A rough order of magnitude costs was developed for each of the recommended improvement projects based on engineering experience. Note that the packaging of improvements projects and identifying funding sources will be determined as part of the development of the capital improvement projects planning.

Table 13: Noyo Pump Station Recommended Improvements
Improvement Funding Timing Cost
Estimate
Replace MCC panel support 6-10 $3,000
Replace wet well floats and rails 6-10 $4,000
Replace the pump discharge elbows <5 $1,500
Repair/recoat the valve vault coating 6-10 $1,500
Replace the valve vault piping and valves <5 $15,000
Add nets or grates under the wet well and valve vault
hatches
<5 $3,000
Provide sunshade over MCC and electrical service
panel
<5 $5,000
Regrade site 6-10 $2,000
Remove abandoned electrical junction box in wet
well
<5 $500
Total Cost $35,500
Zone 7 Water City | Condition Assessment Report
A
Appendix A – Photographs
Zone 7 Water City | Condition Assessment Report
South Noyo Pump Station

Top of Inlet
and Wetwell
Inlet
Standpipe
Bypass
Connection
Valve Vault
Valve Vault
Plug Valves
Check Valves
Signs of exposed
aggregate
Corrosion at
entrance door
Peeling coating
on ceiling
Zone 7 Water City | Condition Assessment Report
North Noyo Pump Station
Valve Vault
Plug Valves
Check Valves
Inlet
Standpipe
Bypass
Connection
Electrical
Service Panel
Zone 7 Water City | Condition Assessment Report
Sanderson Pump Station
Surface corrosion
on piping and
corrosion on
flanges
Valve Vault
Wearing of
concrete
Check Valves
Plug Valves
Wearing of
concrete
Wood Structure
(damaged roof)
Wearing of concrete
in wetwell
Structure
Footing
Zone 7 Water City | Condition Assessment Report
Pudding Creek Pump Station
Motor Control
Center
Damaged
CMU Wall
Engine
Generator
Peeling Roof
Coating
Bypass Connection
and Vault
Non-operable
UPS
Valve Vault
Plug Valves
Check Valves
Zone 7 Water City | Condition Assessment Report
Elm Pump Station
Electrical
Service Panel
Entrance
Door
Damaged
Handrail
Degraded
FRP Conduit
Engine
Generator
Radio Antenna Post
Surface Corrosion
Seepage at
Floor
Peeling
Coating
Self-priming
Pumps and
Discharge Piping
Zone 7 Water City | Condition Assessment Report
Noyo Point Pump Station
Electrical
Service Panel
Pump Discharge Piping
(Corroded elbows)
Valve Vault
Plug Valves
Check Valves
Hatch
Safety Net
City of Fort Bragg
Fort Bragg Wastewater Collection System Master Plan
August 1, 2026 | H-1
Appendix H. Climate Resilience
January 23, 2026 | i
Climate Resilience
Assessment
Technical Memorandum
Wastewater Collection System Master Plan
City of Fort Bragg
January 23, 2026
Resiliency and Climate Risks
Fort Bragg Water System
January 23, 2026 | ii
Table of Contents
CHAPTER 1.0 Introduction ..............................................................................................................1 CHAPTER 2.0 Climate Analysis .......................................................................................................2

2.1 Overview.................................................................................................................................2

2.2 Historic Climate Trends ..........................................................................................................2

2.2.1 Flooding (Coastal, Storm Surge, and Riverine) .............................................................2

2.2.2 Precipitation.....................................................................................................................4

2.2.3 Coastal Bluff Erosion (Coastal) & Landslides.................................................................7

2.2.4 Temperature / Extreme Heat ..........................................................................................9

2.2.5 Wildfire ..........................................................................................................................11

2.2.6 Drought..........................................................................................................................12

2.3 Projected/Possible Climate Scenarios .................................................................................13

2.3.1 Flooding (Sea Level Rise, Storm Surge and Riverine).................................................13

2.3.2 Precipitation...................................................................................................................15

2.3.3 Coastal Bluff Erosion (Coastal) and Landslides ..........................................................19

2.3.4 Temperature/Extreme Heat ..........................................................................................19

2.3.5 Wildfire ..........................................................................................................................20

2.3.6 Groundwater .................................................................................................................21

2.3.7 Drought..........................................................................................................................21

2.4 Conclusion/Key Findings ....................................................................................................22 CHAPTER 3.0 Climate Resilience Assessment .............................................................................24

3.1 Approach...............................................................................................................................24

3.2 Interdependency CRA ..........................................................................................................26

3.2.1 Overview .......................................................................................................................26

3.2.2 CRA Per Category ........................................................................................................30

3.2.3 Energy and Electrical ....................................................................................................31

3.2.4 Telecommunications .....................................................................................................31

3.2.5 Critical Infrastructure.....................................................................................................31

3.2.6 Impacted Communities .................................................................................................32

3.2.7 Natural Systems............................................................................................................32

3.2.8 Key Findings..................................................................................................................32

3.3 Wastewater Collection System CRA....................................................................................33

3.3.1 Overview .......................................................................................................................33

3.3.2 CRA per Assets.............................................................................................................36 Resiliency and Climate Risks
Fort Bragg Water System
January 23, 2026 | iii

3.3.3 CRA Operations and Maintenance ...............................................................................42

3.3.4 Key Findings..................................................................................................................42 CHAPTER 4.0 Recommendations..................................................................................................45

4.1 Regional Recommendations ................................................................................................45

4.2 Wastewater Collection System Recommendations .............................................................45

4.3 Next Steps/Further Studies .................................................................................................48 CHAPTER 5.0 References..............................................................................................................49 List of Tables
Table 1. Compilation of Key Climate Hazards.....................................................................................23 Table 2 - Interdependency CRA – Summary Table ............................................................................33 Table 3 - Vulnerability Per Asset Type ................................................................................................43 Table 4 - Prioritization Per Asset Type ...............................................................................................44 Table 5 - Resilience Strategies for Interdependencies .......................................................................45 Table 6 - Resilience Strategies for Sanitary Sewer Lines ...................................................................46 Table 7 - Resilience Strategies for Manholes and Junction Boxes.....................................................46 Table 8 - Resilience Strategies for Lift Stations...................................................................................47 Table 9 - Resilience Strategies for SCADA.........................................................................................47 List of Figures
Figure 1 – Project Area, City of Fort Bragg Wastewater Collection System.........................................1 Figure 2 – FEMA 100-Year Event Flood Risk .......................................................................................4 Figure 3 – Observed Annual Maximum 1 Day Precipitation [in inches] at Fort Bragg 5 N Station (1950-2023)............................................................................................................................................5 Figure 4 – Observed Total Annual Precipitation at Fort Bragg 5 N Station (1950-2023) .....................6 Figure 5 – Observed Number of Days Where Rainfall Exceed 1 Inch (blue), 2 Inches (green), 3 Inches (orange), 4 Inches (red), with Trendlines Plotted in Each Respective Color.............................6 Figure 6 – Geologic Hazards, Fort Bragg..............................................................................................8 Figure 7 – Relative Slope Instability in the Fort Bragg Area (After CGS Map 58, 2011)......................9 Figure 8 – Observed Annual Mean Maximum Temperature at Fort Bragg 5 N station (1950-2023) .10 Figure 9 – Observed Annual Mean Minimum Temperature at Fort Bragg 5 N station (1950-2023) ..11 Figure 10. Wildfire Risk. The City of Fort Bragg is circled in red.........................................................12 Figure 11 – Flooding Risk Projected: Highest Water Levels Mapped in the Regional Water Level Viewer, Equal to 10 Feet SLR over the MHHW Elevation...................................................................15 Figure 12 – Projected Total Annual Precipitation for Fort Bragg Based on Climate Scenario RCP 4.5................................................................................................................................................16 Resiliency and Climate Risks
Fort Bragg Water System
January 23, 2026 | iv
Figure 13 – Projected Total Annual Precipitation for Fort Bragg Based on Climate Scenario RCP 8.5................................................................................................................................................17 Figure 14 – Projected Number of Days with Greater Than 1 Inch of Precipitation for Fort Bragg Based on Climate Scenario RCP 4.5...................................................................................................18 Figure 15 – Projected Number of Days with Greater than 1 Inch of Precipitation for Fort Bragg Based on Climate Scenario RCP 8.5..............................................................................................................18 Figure 16 – Existing Coastal Erosion Risk ..........................................................................................19 Figure 17 – Annual Average Maximum Temperature for Mendocino County (Source: Drought Resilience Plan, Mendocino County. May 2025).................................................................................20 Figure 18 – Illustration of Steps for Developing a Climate Resilience Assessment (CRA) ................24 Figure 19 – Vulnerability Matrix ...........................................................................................................25 Figure 20 – Risk Matrix ........................................................................................................................25 Figure 21 – Regional Critical Assets....................................................................................................27 Figure 22 – Regional Asset Map and Flooding Risk ...........................................................................28 Figure 23 – Regional Asset Map of Existing Landslide and Coastal Erosion Risk .............................29 Figure 24 – Regional Asset Map of Existing Wildfire Risk ..................................................................30 Figure 25 – Wasteater Collection Assets Map ....................................................................................35 Figure 26 – Wastewater Collection Assets Map and Flooding Risk....................................................37 Figure 27 – Wastewater Collection Assets Map and Erosion and Landslide Risk .............................38 Figure 28 – Wastewater Collection Assets Map and Wildfire Risk .....................................................39 Resiliency and Climate Risks
Fort Bragg Water System
January 23, 2026 | v

EXECUTIVE SUMMARY
The Climate Resilience Assessment (CRA) for Fort Bragg’s wastewater collection system evaluates how climate change will impact infrastructure reliability and community health. Using historical climate data and future projections, the assessment identifies vulnerabilities and outlines strategies to strengthen resilience against extreme events. In summary, these vulnerabilities are:

Climate Risks and System Challenges: Fort Bragg is exposed to sea level rise, flooding, wildfires, landslides, and erosion. Rising seas accelerate erosion, increase saltwater intrusion, and shorten the lifespan of pipes and equipment. More intense storms raise flooding and infiltration risks in low-lying areas, while drought–rainfall swings increase erosion and landslide potential. Wildfires threaten pump stations and can disrupt power and monitoring systems.

Regional Infrastructure Vulnerabilities: The water treatment plant and Fire Station #2 are near wildfire-prone areas, posing risks to emergency response and system continuity. Regional transportation and energy infrastructure that supports water operations is also vulnerable. Highway 1 bridges require ongoing erosion assessment with Caltrans, and wildfire-prone energy transmission lines could disrupt pumping. Because many of these assets are not City-owned, strong interagency coordination is essential.

Wastewater Collection System Priorities: The CRA identifies sanitary sewer lines as the highest priority for resilience improvements due to their flood exposure and potential impact on underserved communities. Lift stations are highly vulnerable, with failures likely to cascade across the system.

Manholes and junction boxes, while moderately at risk, are essential for maintaining system functionality. SCADA systems require ongoing monitoring to ensure operational integrity and rapid response capability.

Strategic Recommendations: Resilience strategies focus on reducing single points of failure, enhancing redundancy, and improving adaptive capacity across interconnected systems. By addressing vulnerabilities holistically and collaborating with regional partners, Fort Bragg can maintain service continuity, protect critical assets, and safeguard public health during extreme climate events.

Key Takeaways:
• Sanitary sewer lines and lift stations are top priorities for resilience investments. • Regional collaboration is essential to address transportation and energy vulnerabilities. • Monitoring and adaptive strategies for SCADA systems will ensure operational continuity. o A One Wateri1–based integrated planning approach will protect community health and keep essential services running during extreme events by addressing potable water, stormwater, and wastewater together.
1 https://www.epa.gov/waterreuse/links-referenced-article-epa-spearheads-water-reuse-one-water-toolclimate-resilient Resiliency and Climate Risks
Fort Bragg Water System
January 23, 2026 | 1
CHAPTER 1.0 INTRODUCTION
This CRA overview provides information for the development of a Climate Action Plan that will identify and better prepare the Fort Bragg Collection System for climate-related hazards.

For this report, resiliency is defined as the ability to anticipate, prepare for, and adapt to changing conditions and withstand, respond to, and recover rapidly from disruptions. The step-by-step analysis utilizes historic climate trends to set the baseline for understanding projected future climate trends for the Wastewater System (Figure 1) and supporting infrastructure. It is based on best available information providing for a framework that can be updated with new information when available.

Figure 1 – Project Area, City of Fort Bragg Wastewater Collection System (Source: HDR GIS based on Fort Bragg database)
Resiliency and Climate Risks
Fort Bragg Water System
January 23, 2026 | 2
CHAPTER 2.0 CLIMATE ANALYSIS

2.1 Overview
The City of Fort Bragg, California, is located within Mendocino County. Positioned on the northcentral coast of California, the city’s climate is strongly influenced by the cool waters of the eastern Pacific Ocean. Fort Bragg has an estimated population of 6,970 (2021) and an official elevation of 85 feet above sea level.

This study assesses how climate change is expected to impact environmental hazards and threats to the City’s Wastewater Collection System. It examines current conditions and provides guidance on anticipated future changes driven by evolving climate patterns. The climate analysis draws on the technical memorandum prepared for the Distribution Master Plan and incorporates updated information as of October 2025.

The key hazards are listed below excluding seismic risk which is addressed in the Geotechnical section of the Master Plan:
• Flooding (SLR, Storm Surge, and Riverine).
• Precipitation.
• Landslides / Slope Instability / Erosion.
• Temperature / Extreme Heat.
• Wildfire.
• Groundwater.
• Drought.

The time horizons selected for the project align with the state-adopted planning timeframe and the 50-year design life of the Collection System. Climate scenarios were developed for baseline conditions (based on historical records), mid-term projections for 2050, and long-term projections for 2070. These scenarios are based on data from the Coupled Model Intercomparison Project Phase 5 (CMIP5), using NASA’s GDDP downscaling for Representative Concentration Pathways (RCP) 4.5 and 8.5. RCP 4.5 assumes emissions will rise until 2050 and then gradually decline, while RCP 8.5 reflects a trajectory of continuously increasing emissions through the end of the century.

2.2 Historic Climate Trends
An analysis of climatic trends provides perspective on the climate projections and evolution of anticipated future climate threats that is discussed in Section 2.3.

2.2.1 Flooding (Coastal, Storm Surge, and Riverine)
Fort Bragg’s location along the California coast at the mouth of the west-east oriented Noyo River and Pudding Creek makes it susceptible to a combination of ocean swell, storm surge, wind waves, and astronomical tides, as well as a tsunami originating anywhere within the “Ring of Fire” surrounding the adjacent Pacific Ocean. As can be seen in Figure 2, FEMA base flood elevations Resiliency and Climate Risks
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(BFEs) along the coast (Zone VE) range from 29 to 36 feet along the bluffs, 19 feet at the beach immediately north of the Noyo River mouth, and 40 feet at the mouth of the Noyo River and adjacent bluff within the bay. These values represent 100-year recurrence interval water levels at current sea level conditions, including wave setup and runup. Wave setup and runup are dependent on the slopes of the terrain, both below the stillwater level and above it along beaches and bluffs. The variability in mapped water levels is based on the differing conditions at individual transects in the FIS study, which are indicated on the map as dashed lines numbered 25 through 31 within the City.

Elevated tides and higher wave heights can occur coincidentally with high river flows on the Noyo River. The FEMA floodplain modeling and Zone designations along the Noyo River are based on mean higher-high water at current climactic conditions and do not include elevated tides or future climate changes. Therefore, when riverine flows are combined with high tides, the water levels along the Noyo River, particularly closer to the mouth of the river, may be higher than indicated by the BFEs.

An analysis of year-over-year coastal water surface elevations shows that the highest annual water surface elevations in the region are the result of thermal expansion of the Pacific Ocean during years of significant El Niño conditions (i.e., 1992, 1997-1998, 2015, and 2023).

Outside the scope of this analysis but worth noting is the threat of a tsunami, although rare, is everpresent in the region of the north-central California coast. Any one of the hundreds of earthquake faults surrounding the Pacific Rim can produce a tsunami that could reach the City of Fort Bragg.

The California State Department of Conservation maintains a website devoted to the transfer of knowledge and information regarding Mendocino County Tsunami Hazard Areas. 2 This website
provides real-time information about what to do before, during, and after a tsunami event. 2 https://www.conservation.ca.gov/cgs/tsunami/maps/mendocino Resiliency and Climate Risks
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Figure 2 – FEMA 100-Year Event Flood Risk
(Source: FIRM map at https://hazardsfema.maps.arcgis.com/apps/webappviewer/index.html?id=8b0adb51996444d4879338b5529aa9cd)

2.2.2 Precipitation
Historic climate trends are critical to setting a relationship between observed changes in the climate and projected changes in the future climate. They represent the “here and now” of climate hazards and how those hazards have changed over time in the observed record. This section investigates current and future extrapolated climate trends, so that those extrapolations can be compared with future climate scenarios for the following environmental parameters.

The National Center for Environmental Information (NCEI) was the primary source of data for historical observations, which were developed from the Fort Bragg 5 N (Station ID: USC00043161) meteorological reporting station located 5 miles north of Fort Bragg (Figure 3). The reporting station is used for a period of record (POR) from 1950 to present day for temperature and precipitation data.

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Figure 3 – Observed Annual Maximum 1 Day Precipitation [in inches] at Fort Bragg 5 N Station (1950-2023)
(Source: NCEI)
The observed maximum single day precipitation in Figure 3 shows a flat trend (neither decreasing nor increasing) from 1950 to present day. However, this trendline does not highlight the increasingly variable nature of single-day precipitation events. Precipitation events across the region and in Fort Bragg are increasing in relative intensity and variability. In other words, while a similar amount of rain may fall each year, that rain will likely be concentrated into heavy rainfall events interspersed with more intense dry periods.

This seasonal variability is also reflected in the Observed Total Annual Precipitation shown in Figure

4. While the trendline of total annual precipitation is also relatively flat, the intensity has increased dramatically in recent years. For example, in Figure 4, it is observed that since the early 1980s, there have been 15 years where the difference in precipitation from one year to the next is greater than 15 inches. Another way of measuring the increasing variability is through the standard deviation of the precipitation, or in other words, how much does the rainfall varies from year to year. In Fort Bragg, the standard deviation of the total annual precipitation from 1950-1986 was 7.68 inches. From 1987- 2023 it increased to 11.83 inches. Therefore, it is shown that statistically speaking, the amount of precipitation that falls annually in Fort Bragg is becoming more variable from year to year. [Inches] Resiliency and Climate Risks
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Figure 4 – Observed Total Annual Precipitation at Fort Bragg 5 N Station (1950-2023) (Source: NCEI)
Figure 5 – Observed Number of Days Where Rainfall Exceed 1 Inch (blue), 2 Inches (green), 3 Inches (orange), 4 Inches (red), with Trendlines Plotted in Each Respective Color (Source: NCEI)
0 5
10 15
20 25
1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 Number of Days per Year
Year
Number of Days Per Year with Rainfall > Threshold
(1950-2023) Fort Bragg, CA
1 inch 2 inch 3 inch 4 inch
Linear (1 inch) Linear (2 inch) Linear (3 inch) Linear (4 inch) [Inches]
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The number of days that experience extreme rainfall events can be associated with increasing variability and relative intensity of rainfall in the region. Figure 5 highlights the number of days each year with 1-4 inches of rainfall on a single day. The associated trendlines are especially helpful in understanding the rate of increase in the heaviest rainfall events with a slight decline in moderate rainfall. While the blue trendline (1-inch rainfall days) remains relatively flat, the green (2-inch) and orange (3-inch) trendlines decrease slightly, which gives rise to the extreme red (4-inch) trendline visible in the bottom right of the figure. This demonstrates that there has already been an increase in the extreme rainfall events in the past 20 years where we see fewer 2- and 3-inch rainfall events per year and instead see occasional 4-inch or greater rainfall days, which have historically over-stressed City water management and breached riverine flood barriers.

It is important to note that as the historic record shows an increase in storms producing greater than 4 inches of daily precipitation, the increased flows because of these storms in Virgin Creek, Pudding Creek, and the Noyo River will increase the likelihood of coincidental coastal flooding.

2.2.3 Coastal Bluff Erosion (Coastal) & Landslides
Bluff erosion is influenced by sea level rise in addition to the mechanisms that impact landslides inland and need to be evaluated concurrently. Figure 6 below documents geologic hazards with risk of erosion and landslides.

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Figure 6 – Geologic Hazards, Fort Bragg
(Source: Department of Conservation Division of Mines& Geology. 1983) Resiliency and Climate Risks
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Figure 7 – Relative Slope Instability in the Fort Bragg Area (After CGS Map 58, 2011) Figure 7 above shows the rankings from “Susceptibility to Deep-Seated Landslides” from beige to red. This is not identified landslides, but an evaluation of the risk of land sliding. Based on this map of the system, the sections near the creeks and rivers appear vulnerable. According to the 2021 Multijurisdictional Hazard Mitigation Plan (JMHMP), the areas identified as instability zones in the 2011 map may warrant reclassification to a more severe risk category, underscoring the need to elevate slope failure as a high priority concern countywide.”

2.2.4 Temperature / Extreme Heat
A similar scenario is seen with the observed temperature in Fort Bragg as has been shown with observed precipitation. The trendline is flat in the observed annual mean maximum temperature for the period from 1950-2023 (Figure 8). However, the variability of the annual mean maximum temperature is plainly seen in the last 30 years. In this case, the standard deviation of the annual mean maximum temperature nearly doubles in variability from the first half of the dataset to the most recent half. From 1950-1986 the standard deviation of temperature was 0.97 °F. From 1987-2023 it increased to 1.63 °F. Therefore, it is shown that statistically speaking, the average hottest days in Fort Bragg each year are becoming more variable.

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Figure 8 – Observed Annual Mean Maximum Temperature at Fort Bragg 5 N station (1950-2023) (Source: NCEI)
Interestingly, the observed annual mean minimum temperature (Figure 9) shows a decreasing trend, meaning that on average the coldest days are getting colder in Fort Bragg. In terms of statistical variability, there is a small increase in variability in the second half of the annual mean minimum temperature data, which is consistent with the rest of the temperature and precipitation data and supports the overall trend towards more variable weather patterns depicted in the climate section.

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Figure 9 – Observed Annual Mean Minimum Temperature at Fort Bragg 5 N station (1950-2023) (Source: NCEI)

2.2.5 Wildfire
The California Air Resources Board (CARB) has unequivocally stated that, “Climate change, primarily caused by the burning of fossil fuels, is increasing the frequency and severity of wildfires not only in California but also all over the world. Since 1950, the area burned by California wildfires each year has been increasing, as spring and summer temperatures have warmed, and spring snowmelt has occurred earlier (CARB, 2023).” As seen in the graph of annual precipitation and annual maximum temperatures (Figure 4 and Figure 8), the most recent drought in California (2020- 2022) was accompanied by increased air temperatures as well. This combination of lack of precipitation, increased temperatures, and even increasing wind events has resulted in a dramatic increase in the frequency and intensity of wildfire in all of California.

As shown in Figure 10 from the 2021 Multi-Jurisdictional Hazard Mitigation Plan (JMHMP), based on data from the California Department of Forestry and Fire Protection (Cal Fire), most of the county is characterized as having high to extremely high wildfire risk.

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Figure 10. Wildfire Risk. The City of Fort Bragg is circled in red. (Source: Mendocino County. Local Multi-Jurisdictional Hazard Mitigation Plan (MJHMP); 01-25- 2021) https://mendoready.org/oes-documents/

2.2.6 Drought
Precipitation has historically been highly variable within California. This was particularly true in the last six years, where the water year 2016-2017 produced well above normal precipitation in northern California, while 2020-2022 were years of significantly below normal precipitation. The water year 2022-2023, in turn, produced record snowfall in the Sierras and well-above normal precipitation elsewhere in the state. That year-over-year variability will continue to challenge water managers in the future and will require continued conservation efforts during times of drought.

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2.3 Projected/Possible Climate Scenarios
Climate change projections are based on global climate models using future emissions scenarios.

This study uses two Representative Concentration Pathways (RCPs): RCP 4.5, where emissions peak mid-century and then decline, and RCP 8.5, where emissions continue to rise through 2100.

Data comes from the U.S. Climate Resilience Toolkit (CRTCE, 2023), which uses CMIP5 model outputs. While CMIP6 is more current and likely shows stronger trends, CMIP5 still provides a reliable view of expected changes in temperature, precipitation, and related hazards.

2.3.1 Flooding (Sea Level Rise, Storm Surge and Riverine) Sea level rise is accelerating along the California coast and will continue to rise substantially during the 21st century, threatening coastal communities, natural resources, cultural sites, and infrastructure. State of California Sea Level Rise Guidance: 2024 Science and Policy Update (“2024 State Guidance”) was published by the California Ocean Protection Council (OPC) to provide recommendations for evaluating proposed projects against future sea level rise scenarios. The 2024 State Guidance includes relative sea level rise projections for a series of NOAA tide gauges along the California Coast. The closest tide gauge to the project location is the Arena Cove, CA gauge, located 45 miles south of Fort Bragg, which indicates 1.2 ft to 2.8 ft of sea level rise by 2070 and between 2.9 ft and 6.4 ft by 2100 under the Intermediate and high sea level rise projection scenarios, respectively. Though the exact amount of sea level rise for a specific location in a certain year is unclear, we know that water levels are rising, and communities need to be prepared. Coastal wave events and king tides, in combination with current and rising sea levels, will increase flood impacts on land, which will exacerbate the impact on coastal assets. Rising sea levels may also raise groundwater tables, cause increased flooding and lead to impacts that will further damage buried and low-lying infrastructure3.

Sea level rise projections were selected based on the 2024 State Guidance. For planning purposes, and in alignment with California Coastal Commission guidance4, the high sea level rise projection scenario was selected to determine conservative SLR projections at the Project location (OPC 2024). Sea level rise values corresponding to the nearest NOAA tide gauge to the Project location, Arena Cove, CA, were used. The high sea level rise projections for mid-, late- and end of century at Fort Bragg are as follows:
• Baseline (observed 2000-2020) 1-2”.
• 2050: 1.1 feet.
• 2070: 2.8 feet. (1.2-2.8).
• 2100: 6.4 feet. (2.9-6.4).
3https://climateresilience.ca.gov/overview/impacts.html#:~:text=The%20daily%20maximum%20average%20temperat ure,worsen%20drastically%20throughout%20the%20state.
4 https://www.coastal.ca.gov/climate/slr/vulnerabilityadaptation/infrastructure/#:~:text=The%20goal%20of%20the%20Commission's,managers%2C%20and%20other%20 stakeholders%20with
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In alignment with current guidance, this analysis evaluates a conservative range of sea level rise (SLR) projections over time to inform climate resilience planning. While the "High" scenario may not be used as the design basis for the proposed work, it has been considered in the broader assessment, particularly for critical infrastructure. It is important to note that the timing at which specific SLR values may be reached remains uncertain. As such, while the design does not require accommodation of the High scenario at this stage, an Adaptation Management Plan may be necessary at a future stage to ensure future flexibility and responsiveness to evolving conditions.

Although the implications for collection systems may be limited, the potential impacts on interdependencies—such as energy, access, and emergency response—suggest that a comprehensive approach through an Adaptation Management Plan would be prudent.

Sea level rise mapping data was pulled from the NOAA Sea Level Rise Viewer (NOAA 2022). The sea level rise values are projected over mean higher-high water (MHHW) elevations, representing sea level rise under daily conditions. This mapping of sea level rise over MHHW is shown below (Figure ) for reference, because it is the best available mapping currently for the location, although it does not correspond directly to the future BFE scenarios described above.

Sea level rise is anticipated to impact the interactions between the Noyo River and the Pacific Ocean. It is anticipated that sea level rise will cause coastal backwaters to propagate up through the Noyo River which may impact portions of the Fort Bragg’s wastewater collection system that interact with this river including intakes or outfalls. Beyond the Noyo River, sea level rise is not anticipated to have a significant impact on the wastewater collection system infrastructure.

Determining water levels in detail is beyond the scope of this planning-level study. More detailed hydraulic modeling of the combined riverine and coastal conditions is recommended when developing projects, particularly at the Noyo River and Pudding Creek. More detailed hydraulic modeling would be required to assess the relative contributions to riverine water levels from sea level rise and riverine flows.

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Figure 11 – Flooding Risk Projected: Highest Water Levels Mapped in the Regional Water Level Viewer, Equal to 10 Feet SLR over the MHHW Elevation
(HDR based on NOAA Sea Level Rise Viewer (NOAA 2022). FEMA historic flooding risk) The coincidental occurrence of heavy rains, high stream flows, SLR, storm surge, and high astronomical tides are expected to increase the threat of coastal inundation in the future. Rainfall runoff occurring simultaneously with high tides will result in inundation areas greater than what is shown. As sea levels rise, this situation is expected to be exacerbated during times of storm, king tide, or both.

2.3.2 Precipitation
California is known for its highly variable precipitation and has the highest variability of year-to-year precipitation in the contiguous United States. California’s variable precipitation is also characterized by multi-year wet or dry periods. As a result, future average precipitation is difficult to predict (figures 12 and 13) but may likely not change substantially when measured by annual precipitation.

However, there is high confidence in projections that even if precipitation remains stable or increases, drought severity and the number of dry years will increase, even as more extreme precipitation events may occur. Warming air temperatures will increase moisture loss from soil, which will lead to drier seasonal conditions even if precipitation increases. The snowpack in Resiliency and Climate Risks
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California’s mountains is a key source of surface and groundwater in the state, and rising temperatures will cause a decline in snowpack by more than a third by 2050 and more than half by 2100, even if precipitation levels remain stable5.

Figure 12 – Projected Total Annual Precipitation for Fort Bragg Based on Climate Scenario RCP

4.5 5https://climateresilience.ca.gov/overview/impacts.html#:~:text=The%20daily%20maximum%20average% 20temperature,worsen%20drastically%20throughout%20the%20state Resiliency and Climate Risks
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Figure 13 – Projected Total Annual Precipitation for Fort Bragg Based on Climate Scenario RCP

8.5 Figure 12 shows projected annual precipitation changes for Fort Bragg under RCP 4.5. Precipitation intensities rise mid-century, then stabilize as emissions decline. Figure 13 shows a similar trend under RCP 8.5, despite higher emissions. Both scenarios suggest total annual rainfall remains steady, but concentrated in fewer, more intense storms—raising flood risk.

In figures 14 and 15, the projected number of days that will see 1 inch or more of rainfall is shown for RCP 4.5 and 8.5, respectively. This set of projections shows that in either case (4.5 or 8.5) there is expected to be an increase in the number of days each year where Fort Bragg receives 1 inch or more of rain. While a single inch of rain in a day is not always cause for concern, this highlights the general trend of increasing variability where the amount of rain that falls per year is expected to be stable, but the events in which it falls are expected to be less frequent and more intense, producing periods of drought between heavier rainfall events.

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Figure 14 – Projected Number of Days with Greater Than 1 Inch of Precipitation for Fort Bragg Based on Climate Scenario RCP 4.5
Figure 15 – Projected Number of Days with Greater than 1 Inch of Precipitation for Fort Bragg Based on Climate Scenario RCP 8.5
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2.3.3 Coastal Bluff Erosion (Coastal) and Landslides
The noted increase in year-over-year precipitation variability is likely to result in bank destabilization and increase in slope instability during the water years with greater precipitation. The compound effect of drought years killing off vegetation that might otherwise stabilize a hillside followed by years of heavy precipitation that cause the soils to destabilize and produce landslide. This would be further exacerbated by drought years that produce significant wildfire in the watersheds above the city of Fort Bragg.

Bluff erosion is also driven by sea-level rise (SLR) as well as the processes that cause inland landslides. Cliff retreat data was obtained from the Coastal Storm Modeling System’s Coastal Cliff Retreat dataset (Barnard et al., 2022). This dataset assumes an unmanaged retreat scenario, where cliffs are allowed to recede regardless of existing armoring. The boundary shown in Figure 16 represents the projected uncertainty band for the future cliff-top edge.

Figure 16 – Existing Coastal Erosion Risk
(Source: Coastal Storm Modelling System (CoSMoS), US geological Survey (USGS), 2022)

2.3.4 Temperature/Extreme Heat
Annual temperature increases experienced over most of California have already exceeded 1°F, with some areas exceeding 2°F. The daily maximum average temperature, an indicator of extreme temperature shifts, is expected to rise 4.4°F–5.8°F by mid-century and 5.6°F–8.8°F by late century.

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Heat-Health Events (HHEs), which better predict risks to populations vulnerable to heat, will worsen drastically throughout the state. By midcentury, the Central Valley is projected to experience average HHEs that are two weeks longer, and HHEs could occur four to ten times more often in the Northern Sierra region6. Figure 17 illustrates that the annual mean maximum temperature is projected to increase over time.

Figure 17 – Annual Average Maximum Temperature for Mendocino County (Source: Drought Resilience Plan, Mendocino County. May 2025)

2.3.5 Wildfire
The year 2020 was the largest wildfire season recorded in California’s modern history, with nearly 10,000 fires that burned over four million acres in total. However, fewer than 40 fires accounted for most of the area burned, pointing to the accelerating severity and frequency of extreme fires. In 2021, California experienced 4 of the 20 largest wildfires in the state’s history, with 8,000 wildfires burning over 2.5 million acres. A model developed for California’s Fourth Climate Change Assessment projected up to a 77 percent increase in average area burned and a 50 percent increase in the frequency of fires exceeding 25,000 acres by 21007. 6https://climateresilience.ca.gov/overview/impacts.html#:~:text=The%20daily%20maximum%20average% 20temperature,worsen%20drastically%20throughout%20the%20state.) 7https://climateresilience.ca.gov/overview/impacts.html#:~:text=The%20daily%20maximum%20average%20temperat ure,worsen%20drastically%20throughout%20the%20state.)
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Fortunately, Fort Bragg was spared from the recent Mendocino Complex Fire but that does not mean that the threat of wildfire to the region is not being exacerbated by climate change. Per the 2021 Multi-Jurisdictional Hazard Mitigation Plan (JMHMP), report, wildfire should be a high priority county-wide.

As noted earlier in this document, the increased year-over-year variability in precipitation and air temperatures is expected to continue to increase the threat of wildfires. The greatest threat will come in years that are hot and dry following a year, much like water year 2022-2023, that has significantly above normal rainfall contributing to brush and ground cover growth. Peak months for the likelihood of wildfires in the region are from August through September during periods of strong offshore winds or during times when thunderstorms can produce dry lightning in the region.

The threat of wildfire is expected to increase. This will require resilient actions on the part of local, regional, and state agencies because the City is dependent on surface water for its drinking water supply. The intense heat related to wildfires drastically changes the runoff characteristics of a watershed and increases the threat of sedimentation and severe water quality issues. Wildfire heat will also negatively impact pipe integrity and poses a threat to the City’s raw water pipeline infrastructure.

2.3.6 Groundwater
The same factors driving increased year-over-year variability in drought and heavy precipitation will also affect groundwater availability in the region. As observed in other western locations (Jensen, M.N., 2016), groundwater supplies may be further stressed by rising evapotranspiration due to higher air temperatures.

Sea-level rise will elevate groundwater levels. The rate of this rise depends on local soil conditions, which is beyond the scope of this study. However, because most of Fort Bragg is situated at a relatively high elevation, this is likely not an immediate concern.

2.3.7 Drought
Historic year-over-year precipitation variability between years of flood and drought is expected to be exacerbated by climate change in the region. Increasing air temperatures combined with years of below normal precipitation will produce a multiplying effect on water usage through increasing demand, evaporation, evapotranspiration, and, of course, the increased risk of wildfire during drought years8.
8 Mendocino County Drought Resilience Plan, May 2025.
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2.4 Conclusion/Key Findings
Historic climate trends provide a baseline for understanding projected future conditions. Future Risks can be classified as follows:

Critical – Represents extreme, widespread impacts. Recovery is prolonged or even irreversible.

High – Represents severe and impacts that destabilize multiple systems. Recovery takes time and concerted efforts.

Medium – Represents significant damage and disruption at a more localized level. Recovery can be swift and manageable by fewer actors.

Minor – Represents impacts that are insignificant and even familiar. Recovery is almost instantaneous.

The primary climate risks identified for the Wastewater Collection System are:

Critical and High Risks
• Sea Level Rise & Landslides/Erosion: Increased saltwater intrusion may impair treatment performance. Infrastructure on steep slopes is vulnerable to damage, and landslides can block emergency access.
• Riverine Flooding (High Risk): Rising sea levels and more intense precipitation are expected to increase flood frequency and severity. Low-lying assets, such as pump stations, face heightened risk. Increased inflow and infiltration will stress the collection system. • Drought: Multi-year droughts are likely, reducing customer baseflow and causing soil drying, which may lead to joint separation and settlement issues. • Wildfires: Drought-driven fires south of the Noyo River pose severe risk.

Medium Risks to Monitor
• Precipitation: Rainfall is projected to occur in fewer but more intense events. • Tsunami: Trends remain uncertain; coastal bluff erosion could threaten WWTP structures and flood low-lying assets, including generators stored at the WWTP. • Groundwater: Levels are currently stable, but saltwater intrusion is possible. Dry wells are highly susceptible to drought.
• Winds: Strong coastal winds may damage power supply and exacerbate wildfire spread.

These risks are summarized in Table 1, which integrates quantitative climate projections from established models—per the sources cited and parameters presented in this section—with expert judgment to address information gaps, as documented in the comment column of Table 1.

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Table 1 - Compilation of Key Climate Hazards
Event Natural
Hazard
Baseline/
Observed
MidCentury
Projections
(2050s)
Long-term
Projections
(2070s)
Preliminary High Level
Impact (design, operations
& maintenance)
Comments
Ranking
Sea Level Rise 1"-2" (2000-
2020)
+1.1 .+1.2-2.8
Efficacy of biological and
sedimentation treatment with
increased saltwater
composition (from I&I).

Longevity of piping and other
infrastructure.

Tsunami Medium Medium Medium
Coastal bluff erosion,
jeopardizing WWTP
structures. Flooding of low
lying assets such as pump
stations
Trends are unknown.

Inland
Flooding/
Riverine
19' BFE 20.3' 22'
Flooding of Low lying assets
such as pump stations.

Increase in Inflow and
infiltration (I&I)
Sea Level Rise and
projected increase in
precipitation intensities
will increase flood
frequency and severity.

Extreme
Precipitation Low Medium Medium
Inflow and infiltration
surcharge. Increase in
treatment volume.

Precipitation is projected
to be delivered in fewer,
but more intense rainfall
events. (Days ≥ 1"
precip.)
Groundwater Low Medium High
Land subsidence and
differential settlement of
infrastructure. Float of pipes
and corrosion as SLR raises
groundwater level
Groundwater levels are
stable. Saltwater
intrusion is possible as a
result of SLR. Dry wells
are highly susceptible to
drying out.

Water
Stress Drought Medium High High
Baseflow in system from
Inflow and Infiltration. Lower
baseflow from customers if
water conservation measures must be taken. Joint
separation from settlement
as soil moisture pores dry.

Projected increase in
drought severity as well
as likelihood of multiyear droughts.

Landslides/
Erosion High Critical Critical
Assets within steep slopes
can be exposed and
damaged. Assets at base of
steep slopes can be
damaged by landslides.

Accessibility for hazard
response can be blocked
Higher risk for
compound impact of
drought and projected more extreme rain events
and increased heat will
increase soil instability.

Sinkholes Low Low Low N/A No sink hole hazard
identified
Earthquakes Medium Medium Medium N/A Outside scope
Extreme Heat 0 days HI >90 0.2 days
HI>90
1 day HI>90 Impact for outdoor workers.

Change in days with
heat index >90 will go
from 0 to 1.

Hot Days 67 Annual
Max
. +4.5°F to

5.8°F . +5.6°F to 8.8°F
Additional condensate in
sanitary system. In extreme
conditions, more energy
demand for AC, resulting in
taxed electric grid.

Hot day is considered HI
> 77
Source: First Street
Extreme Cold Low Low Low
A freeze, especially a
consecutive days below
freezing could damage pipes
Freezing temps are
reached occasionally on
winter nights. Average
low temp in winter is 39
degrees.

Snow Events 0 0 0
Extreme Wind Medium Medium Medium
Damage to wastewater
infrastructure Power Supply.

Spread wildfires
Trends are unknown.

Strongest winds occur
along coastline.

Tornadoes Low Low Low N/A N/A
Wildfires High Critical Critical
Damage to Pump Station
and Pump Station/ WWTP
power supply
Only south of the Noyo
River
Lightning Low Low Medium
Disruption or damage to monitoring and control
equipment.

Not directly a concern,
but can ignite fuel
during droughts and
cause wildfires.

Flooding
Extreme
Tempera
ture
Other
Geo
Hazards
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CHAPTER 3.0 CLIMATE RESILIENCE

ASSESSMENT

3.1 Approach
The Climate Resilience Assessment (CRA) approach is based on existing conditions and aligns with best practices adapted to Fort Bragg’s unique context. Preliminary findings reflect the City’s priorities in assessing risk and identifying key actions. The CRVA process includes three steps: first, assessing exposure to potential climate risks; second, evaluating vulnerability based on asset sensitivity and adaptive capacity; and third, conducting a risk assessment that considers the consequences of asset failure and the likelihood of climate threats. These steps (Figure 18) guide the prioritization of critical assets and inform the development of a resilience implementation plan.

Figure 18 – Illustration of Steps for Developing a Climate Resilience Assessment (CRA) (Source: HDR)
Vulnerability is a function of exposure, sensitivity, and adaptive capacity. • Exposure determines which assets are exposed to climate risks using the best available information. For the purposes of this study, exposure is considered for the primary climate parameters as identified within the scope and resources of climate analysis in Section 2. • Sensitivity is the degree to which an asset can be affected by a hazard. For this initial assessment, it is assumed that all assets exposed to a hazard are sensitive to it. • Adaptive Capacity is assessed based on whether assets had technological or operational protections in place and system-wide redundancy to help mitigate or cope with the impacts of exposure.

For this high-level assessment, vulnerability (Figure 19) has been assessed by exposure defining sensitivity.

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Figure 19 – Vulnerability Matrix
(Source: HDR, Adapted from ICLEI)
Risk is a function of consequences (of an asset failing) and the likelihood/probability it will occur (e.g., observed or projected) as illustrated in Figure 20. Likelihood was scored as either “High” or “Highest” (as informed by the exposure to the identified climate scenarios) while consequence of failure could be scored as “Low,” “Medium,” or “High” per anticipating possible consequences.

Figure 20 – Risk Matrix
(Source: HDR, Adapted from ICLEI)
Prioritization is the last step in risk and vulnerability assessment. Prioritization takes in all the information gathered related to vulnerability and risk and allows for a final assessment of infrastructure or assets that may or may not be a priority for focus. The prioritization of critical assets and infrastructure can then lead to better guidelines for climate-related issues and can focus an action plan on assets that are a higher priority, and, therefore, introduce changes to help assets become more resilient.

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3.2 Interdependency CRA
The purpose of the Interdependency CRA is to identify regional infrastructure critical to supporting Wastewater Collection System operations and to highlight vulnerable communities at greater risk in the event of system failure.

3.2.1 Overview
Risks and vulnerabilities were assessed for the following interdependent asset categories:
• Transportation Systems: Transportation networks are essential for accessing Wastewater Collection System assets to conduct timely repairs, maintenance, and operations. • Energy and Electrical Systems: Reliable and safe power delivery is required to support pump station operations as well as leak detection, monitoring equipment, and other electrically dependent infrastructure.
• Interconnected Water Infrastructure: The performance of the wastewater system is closely linked to potable water intake and treatment facilities, as well as stormwater management infrastructure. Ensuring the reliability of these upstream systems is critical for maintaining safe and continuous service.
• Telecommunication/IT Systems: Many Wastewater System assets and operational procedures rely on stable telecommunication and data connectivity for monitoring, control, and emergency response.
• Critical Facilities: Emergency response, public safety, and other essential facilities play a key role in stabilizing service disruptions and restoring community functions. These facilities must be identified and prioritized for protection.
• Serviced Communities: Customer demographics influence adaptive capacity and vulnerability. Low-Income and Disadvantaged Communities (LIDACs) within the service area should be specifically identified due to potentially heightened sensitivity to failures and service interruptions.
• Natural Systems: Wastewater discharge enters the Pacific Ocean just off the coastline.

Marine environments provide ecosystem services to Fort Bragg and beyond. Their health and integrity must be protected. . Natural land cover, riparian ecosystems, and urban tree canopies also provide essential ecological functions such as flood mitigation, water quality enhancement, wind breaks, and air purification.

Figures 21 through 24 illustrate key components of the Interdependency Climate Risk Assessment (CRA) that rely on or support the Wastewater System. Figure 21 shows the boundaries of the assessment, encompassing the Fort Bragg Wastewater Collection System and extending to interconnected systems at a larger scale. Figure 22 depicts areas of flooding risk within the service region, highlighting potential impacts on water infrastructure and access routes. Figure 23 presents landslide and erosion risk zones, which may affect source water reliability and system integrity.

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Figure 21 – Regional Critical Assets
(Source: HDR GIS Fort Bragg)
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Figure 22 – Regional Asset Map and Flooding Risk
(Source: HDR GIS based on Fort Bragg database; FEMA 2022) Resiliency and Climate Risks
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Figure 23 – Regional Asset Map of Existing Landslide and Coastal Erosion Risk (After CGS Map 58, 2011)
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Figure 24 illustrates the relationship between identified interdependent assets and wildfires.

Figure 24 – Regional Asset Map of Existing Wildfire Risk (Source: HDR GIS based on Fort Bragg database; CA Department of Forestry 2022)

3.2.2 CRA Per Category

TRANSPORTATION
Reliable access routes are essential for timely repair, maintenance, and operation of wastewater collection and conveyance infrastructure. Climate change stressors such as increased frequency of extreme precipitation events, landslides, and wildfire-related road closures can severely limit access during emergencies.
• The Noyo River Bridge is the single means for automobiles to cross the Noyo Basin and River. Erosion, landslides, and other acute or chronic conditions could result in premature bridge failure.
• Bridge closure can prevent access to Water System assets for repairs or maintenance. • The assets most at risk are those south of Noyo River; resources, staff, and equipment are primarily located on the north side.

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3.2.3 Energy and Electrical
Energy and Electrical systems are critical to the continuous operation of Fort Bragg’s wastewater collection and treatment processes. Reliable power ensures functionality of pump stations, disinfection systems, and monitoring equipment. Any disruption to these systems can result in significant service interruptions and public health risks. Identified at risk:
• Single Point of Dependency: Fort Bragg relies on one electrical substation to power all community assets, including the South Harbor Drive pump station and the Water Treatment Plant’s on-site sodium hypochlorite generation (OSHG) system, which requires continuous electricity for disinfection.
• Substation Risk: Based on current information, the substation itself is not considered at risk. • Transmission Line Vulnerability: Transmission lines feeding the substation are highly vulnerable to wildfire because they are primarily wooden and traverse forested corridors.

Damage to these lines could result in a complete loss of power for all water system operations.
• Distribution Line Risk: While distribution lines were not assessed in this study, there is an elevated risk of outages between the substation, pump station, and treatment facility.

3.2.4 Telecommunications
SCADA systems, remote sensors, and automated controls require stable telecommunication connectivity for real-time monitoring and operational decision-making. Wildfires and severe storms can disrupt communication networks, compromising system reliability. No dedicated telecommunication assets are currently associated with the Water System infrastructure. However, if remote system management is implemented in the future, reliance on telecommunications will increase.
• While telecom assets themselves are not considered at risk, their dependence on the electrical grid—which may be vulnerable to climate-related disruptions such as wildfires or extreme weather—introduces an indirect risk that should be evaluated.

3.2.5 Critical Infrastructure
Emergency operations centers, fire protection systems, and health facilities must be prioritized for water service continuity. Wildfire poses a major threat to these facilities, increasing demand for water during fire suppression and recovery efforts. For this study, critical infrastructure includes support emergency infrastructure and schools:
• Fire station: There are three fire stations. The two facilities north of Noyo River are not at risk, as informed by our current available information. The facility south of Noyo River (Fort Bragg Fire Station 2) is at risk of wildfire. Because the facility is at the furthest limits of the Water System the water pressure may be low. Additionally, the water main does not appear to be looped, thus reducing capacity for fire protection. • Hospital: There is one hospital serving Fort Bragg. This facility is not at risk, as informed by our current available information.

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• Schools: There are six schools served by the Water System – five north of Noyo River, and one south. These facilities are not at risk, as informed by our current available information.

3.2.6 Impacted Communities
The CalEnviroScreen was used as a proxy to assess socio-economic vulnerability in Fort Bragg. It shows the city has a higher vulnerability score (>50–60) compared to surrounding areas (0–10), with slightly elevated social vulnerability east of Main Street and south of Oak Street. Key Vulnerability:
• Higher CalEnviroScreen scores indicate Fort Bragg is more susceptible to environmental and socio-economic stressors than neighboring regions.
• Variability in adaptive capacity among low-income and disadvantaged communities increases risk during climate-related events (e.g., droughts, heat waves, wildfire evacuations).

Refined data sources will be needed to better identify and prioritize Environmental Justice (EJ) communities for targeted resilience strategies.

3.2.7 Natural Systems
Fort Bragg’s comprehensive water system and hydrology rely on three primary surface sources:

Waterfall Gulch (tributary to Hare Creek), the Noyo River, and the Summers Lane Reservoir. While the collection system operates somewhat independently, its failure could significantly impact Fort Bragg’s water distribution supply. Key Vulnerabilities:
• Collection system failure can disrupt natural hydrology, increase erosion, damage marine, and aquatic ecosystems; all of which are critical for long-term resilience. • Collection system failure could also lead to contamination of surface water sources (e.g., Noyo River, Waterfall Gulch, Summers Lane Reservoir). The City maintains a Sewer System Management Plan (SSMP) and an SSO Emergency Response Plan to mitigate this risk through proactive maintenance, monitoring, containment, and rapid response. • Increasing variability of drought and extreme precipitation events threatens substrate and bank integrity.
• Sea-level rise and salinity intrusion currently pose minimal risk.

3.2.8 Key Findings
Table 2. Interdependency CRA, highlights critical vulnerabilities across transportation, energy, water, telecommunications, and community systems. Fort Bragg’s reliance on single points of failure — such as the Noyo River Bridge and electrical substation—creates significant risk during extreme events. Climate stressors like flooding, wildfire, and drought threaten infrastructure integrity, access routes, and water reliability. Socio-economic vulnerability amplifies these risks, underscoring the need for targeted resilience strategies and integrated planning to maintain service continuity and protect public health.

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Table 2 - Interdependency CRA – Summary Table
Category Key Risks Impacts
Transportation Noyo River Bridge failure;
landslides; wildfire closures
Loss of access for repairs;
isolation of assets south of river
Energy & Electrical Single substation dependency;
wildfire risk to transmission lines
Complete power loss halts
pumping and disinfection
Water/Wastewater Bluff erosion; drought; saltwater
intrusion
Wastewater plant damage;
reduced raw water availability
Telecommunications Wildfire/storm disruptions;
indirect grid dependency
Compromised remote
monitoring and control
Critical Facilities Fire Station 2 at wildfire risk; low water pressure
Reduced fire suppression and
emergency response
Communities High socio-economic
vulnerability; low adaptive
capacity
Greater hardship during climate
events
Natural Systems Drought variability; extreme
precipitation; erosion
Reduced water supply
resilience; watershed
degradation
It is important to note that this interdependency risk assessment was conducted at a qualitative, high-level scale and does not represent a detailed quantitative analysis.

3.3 Wastewater Collection System CRA
This Climate Resilience Assessment (CRA) for the specific assets of the Collection System evaluates their vulnerability under existing climate risks and projected scenarios outlined in Section

2. The goal is to identify potential weaknesses that will inform resilience strategies for enhancing system resilience.

3.3.1 Overview
The Climate Risk Assessment (CRA) evaluates the risk for each asset group within the wastewater collection system, using the same methodology applied in the interdependency analysis but tailored to key assets in this system. The assessment incorporates sensitivity and adaptive capacity specific to each asset.

Assets included in the CRA are:
• Sanitary sewer mains.
• Manholes and junction boxes.
• Outfalls.
• Sanitary pump stations.
• SCADA systems.

The wastewater treatment plant is outside the scope of this project; however, a high-level risk assessment—limited to its parcel boundaries—has been conducted due to its critical role in overall system operations.

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The following wastewater collection system assets were not included in this initial high-level assessment:
• Service laterals.
• Bends and fittings.
• Water quality sensors.
• Illegal stormwater connections.

Although these assets may still be vulnerable to identified climate hazards, their associated risk is assumed to be lower than that of the assets included in the CRA.

Figure 25 identifies key assets included in the collection system risk assessment.

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Figure 25 – Wastewater Collection Assets Map
(Source: HDR GIS based on Fort Bragg database)
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3.3.2 CRA per Assets
The Risk and Vulnerability Assessment was conducted for assets within the geographic boundaries shown inwhile Figure 26 illustrates exposure between wastewater collection system assets and flooding/SLR. Figure 27 shows the relationship between wastewater collection system assets and coastal erosion.

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Figure 26 – Wastewater Collection Assets Map and Flooding Risk (Source: HDR GIS based on Fort Bragg database; NOAA 2023; FEMA 2022) Resiliency and Climate Risks
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Figure 27 – Wastewater Collection Assets Map and Erosion and Landslide Risk (Source: HDR GIS based of Fort Bragg database; CA Department of Conservation 2011; CoSMoS 2022) Figure 28 illustrates the relationship between Wastewater Collection System assets and wildfires.

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Figure 28 – Wastewater Collection Assets Map and Wildfire Risk (Source: HDR GIS based on Fort Bragg database; CA Department of Forestry 2022) Resiliency and Climate Risks
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SANITARY SEWER MAINS
Wastewater collection mains include gravity-fed lines and low-pressure lines pumped from lift stations near the Noyo River and Pudding Creek. Sanitary mains adjacent to the Noyo River are vulnerable to bank erosion and landslides. Exposed pipe can be compromised and cause effluent discharge into the Noyo River and contaminate groundwater. Pipes in the lower-lying areas—namely the valleys of the Noyo River and Pudding Creek—are vulnerable to flotation and premature corrosion as sea levels rise, raising groundwater levels.

Vulnerability identified in two specific locations:
• Noyo River: One force main cross under the Noyo River. While assumed properly encased and not directly vulnerable to sea-level rise or erosion, flooding can generate substantial inflow, overwhelming lift stations and causing pressure surges. This line is one of the lowest points in the system, increasing rupture risk during surge events. • Pudding Creek: Another force main crosses under Pudding Creek with similar conditions and risks to the Noyo River crossing.

Assessment of Main Risks are:
• Bank Erosion & Landslides.
o Adjacent mains susceptible to exposure and structural compromise. o Exposed pipe can discharge effluent into surface water and groundwater. • Sea-Level Rise & Groundwater Rise:
o Low-lying pipes are vulnerable to flotation and accelerated corrosion. • Flooding & Hydraulic Surge:
o Force mains assumed encased, direct erosion risk minimal. o Flood-induced inflow can overwhelm lift stations, causing pressure surges and water hammering.
o Lowest hydraulic grade line points increase rupture risk during surge events.

MANHOLES AND JUNCTION BOXES
Distributed across the network within the service area, these allow for access and maintenance and combine flow from multiple lines. Several manholes and junction boxes are within the 100- and 500- year floodplain of the Noyo River. These are vulnerable to inflow during heavy precipitation events, which can surcharge the system and cause overflows or pipe ruptures. • Flooding:
o Located within mapped floodplains.
o Susceptible to inflow during heavy precipitation, leading to system surcharge, overflow, and potential pipe failure.

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OUTFALL
The only outfall within the scope of this study is the discharge outfall to the wastewater treatment plant. The sanitary sewer outfall to the wastewater treatment plant is not at risk as informed by best available information.

SANITARY LIFT STATIONS
Six lift stations are located within the collection system network:
• Pudding Creek Pump Station
• Elm Street Pump Station
• North Noyo Pump Station
• Noyo Heights Pump Station
• Noyo Point Pump Station
• South Noyo Pump Station
The Noyo Heights pump station is moderately at risk of wildfire. The South & North Noyo pump stations and the Pudding Creek pump stations are just outside the mapped Sea-Level Rise (SLR) + Mean Higher-High Water Mark. No layer could be identified that accounted for SLR + 100-year flood; however, it is likely these two lift stations would fall within that compounded hazard zone. Lastly, all lift stations are at risk of power failure during an outage (see Interdependency section for associated electrical system hazards).

Vulnerability in Specific Locations:
• Noyo Heights pump station: Moderate wildfire exposure. • South & North Noyo pump stations, and Pudding Creek pump station: Just outside SLR + Mean Higher-High Water Mark; likely within SLR + 100-year flood hazard zone. • All Lift Stations: Vulnerable to power failure during outages.

Assessment of Main Risks are:
• Wildfire.
o Noyo Heights pump station exhibits moderate exposure. • Sea-Level Rise + Flooding.
o Two stations are likely within compounded hazard zone (SLR + 100-year flood). • Power Failure.
o All stations are at risk during outages.

SCADA SYSTEMS
Intelligent monitoring and control systems (SCADA) are connected to all six lift stations. These systems require a continuous electricity supply for proper operation. SCADA is typically housed inside lift stations, making it susceptible to hazards affecting those stations.

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Vulnerability in Specific Locations:
• All SCADA Systems: Dependent on uninterrupted electricity; power outages disrupt monitoring and control.
• Three Lift Stations with Hazard Exposure: SCADA components within stations exposed to flooding or wildfire can be damaged or impaired.

Assessment of Main Risks:
• Power Outage
o SCADA requires continuous electricity; outages disrupt monitoring and control functions.
• Flooding & Wildfire
o SCADA is housed within lift stations; exposure can damage components and impair functionality.

3.3.3 CRA Operations and Maintenance
Although detailed analysis of CRA operations and maintenance was outside the primary scope of this high-level assessment, it is important to consider risks inherent to the current emergency response plan and incorporate human factors related to staff safety during potential climate-driven events.

EMERGENCY RESPONSE
The current emergency response framework is strong, with at least one generator per pump station and additional units for redundancy. However, all generators are stored at the wastewater treatment plant (WWTP), which is in a flood-prone area.
• Risk: During a major flood event, access to backup power could be compromised, reducing system resilience.

STAFF SAFETY
Personnel face risks related to communication and mobility during extreme events. Limited real-time communication systems may fail to prevent staff from traveling under hazardous conditions such as flooding, landslides, erosion, or wildfire.
• Risk: Increased exposure to physical danger and operational delays.

3.3.4 Key Findings
The vulnerability and risk assessment identifies which key infrastructure elements are most at risk of being impacted by climate change events, consequently placing the wastewater collection system at risk.

Table 3 synthesizes the key findings of this section by summarizing asset vulnerability across categories. Vulnerability is assessed based on exposure to climate hazards, sensitivity to stressors Resiliency and Climate Risks
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such as flooding or landslides, and adaptive capacity, including system redundancy. The analysis indicates that lift stations are the most vulnerable assets, while sanitary sewer lines also exhibit high vulnerability.

Vulnerability ranges from low to critical, with assets shifting along this scale based on their combined exposure, sensitivity, and adaptive capacity. “Low” indicates minimal expected impact and strong coping capacity; “Medium” reflects moderate sensitivity with impacts that are manageable; while “High” to “Critical” signals limited resilience and the potential for severe system disruption.

Table 3 - Vulnerability Per Asset Type
Table 4 shows the recommended prioritization of asset types, informed by vulnerability and risk determined by the likelihood and consequences of an asset type failing. Likelihood is based on climate scenarios, while consequences are assessed through expert judgment for this high-level evaluation. Prioritization is determined by the higher of the two factors—risk or vulnerability. Key findings include:
• Sanitary lines should be a priority for resilience improvements primarily because of risk:
flooding is highly probable under climate scenarios, and consequences could be severe for critical facilities and underserved communities. Severe Drought Localized Flooding Extreme Heat Sea Level Rise Wildfire Landslide Strong Winds Erosion Lightning Risk
Collection System RVA
C
H
L
H
SCADA systems M
Likelihood + Consequence
Sanitary Lines
Manholes and junction boxes
Outfalls

3. Monitoring and Control

2. Pumping and Treatment

1. Conveyance Infrastructure
Lift stations
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• Lift stations are also critical, mainly due to their high vulnerability—exposure to flooding and lack of adaptive capacity—and the cascading impact their failure would have on the entire collection system.

As outlined in Section 3.1 (Approach), vulnerability is characterized as the combined effect of an asset’s exposure, sensitivity, and adaptive capacity. Risk builds on this by evaluating both the consequences of asset failure and the likelihood that such failure will occur. The prioritization process then integrates all vulnerability and risk findings, providing a clear basis for identifying which assets or infrastructure elements should be considered priorities for further attention or action.

Table 4 - Prioritization Per Asset Type
Vulnerability Risk Prioritization*
Collection System RVA

1. Conveyance Infrastructure
Sanitary Lines H C Critical
Manholes and junction boxes M H High
Outfalls L L Low

2. Pumping and Treatment
Lift stations C H Critical

3. Monitoring and Control
SCADA systems M M Moderate
* Prioritization is determined as the higher of the two factors, Risk and Vulnerability Resiliency and Climate Risks
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CHAPTER 4.0 RECOMMENDATIONS
This section focuses on strategies to strengthen the wastewater collection system, informed by a Climate Risk Assessment (CRA) and supported by regional measures where relevant.

4.1 Regional Recommendations
The table below summarizes key hazards, associated risks, and recommended resilience strategies for infrastructure systems that indirectly support the operations and functioning of the wastewater collection system, as well as critical equipment that relies on it. These strategies aim to reduce single points of failure, enhance redundancy, and strengthen adaptive capacity across interconnected systems. By addressing vulnerabilities holistically—rather than in isolation, Fort Bragg can maintain service continuity, safeguard critical assets, and protect community well-being during extreme events.

Some strategies may involve collaboration with other agencies or entities to ensure regional benefits and shared resilience outcomes.

Table 5 - Resilience Strategies for Interdependencies

4.2 Wastewater Collection System Recommendations
The following tables provide for high-level strategies developed for critical assets within the wastewater collection system, prioritized by risk associated with specific hazards and exposures.

These strategies were derived from a technical climate resilience assessment focused primarily on infrastructure vulnerabilities.

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Table 6 - Resilience Strategies for Sanitary Sewer Lines Table 7 - Resilience Strategies for Manholes and Junction Boxes Risk Sanitary Sewer Lines
Severe Drought Moderate
Localized
Flooding
High Prevent illegal stormwater interconnects. Ensure pressure relief for lines crossing under Noho River and Pudding Creek.

Extreme Heat
Line or replace sewer mains exposed to saline groundwater as sea levels rise.

Pipe Anchoring & Corrosion Protection: Install anti-flotation devices and apply advanced coatings or cathodic protection in low-lying areas.

Surge Mitigation: Incorporate surge relief valves and pressure monitoring at critical low points.

Wildfire
Landslide Critical Harden steep slopes with engineered stabilization measures.

Strong Winds
Erosion Moderate
Lightning
Sea Level Rise Critical
Hazard Risk Manholes and Junction boxes
Severe Drought Low
Prevent illegal stormwater interconnects. Ensure pressure relief for lines crossing under Noho River and Pudding Creek.

Floodproofing: Elevate or seal manhole covers; install watertight gaskets to reduce inflow.

Inflow/Infiltration Control: Deploy check valves and improve drainage grading around structures.

Extreme Heat Low
Sea Level Rise
High Line or replace sewer mains exposed to saline groundwater as sea levels rise.

Wildfire
Landslide High Harden steep slopes with engineered stabilization measures.

Strong Winds
Erosion Moderate
Lightning
High
Localized
Flooding
Hazard
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Table 8 - Resilience Strategies for Lift Stations
Table 9 - Resilience Strategies for SCADA
Risk Lift Stations
Severe Drought Moderate
Localized
Flooding
High Have back-up generators located nearby, but not on site. Seal the structure's openings. Stock pile sand bags for rapid deployment Extreme Heat Low
Have back-up generators(generators, battery storage) located nearby, but not on site, and automatic transfer switches.

Flood Adaptation: Elevate electrical components and SCADA panels; consider submersible pumps for stations in hazard zones.

Wildfire Low
Landslide Moderate
Strong Winds Low
Erosion Low
Lightning Moderate
Sea Level Rise Critical
Hazard Risk SCADA
Severe Drought
Localized
Flooding
Moderate
Extreme Heat Moderate
Elevate equipment in the lift station. Have back up power source.

Redundant Communication & Power: Integrate backup power and remote monitoring capability.

Wildfire Moderate
Landslide
Strong Winds Low
Erosion
Lightning Moderate
Sea Level Rise High
Hazard
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4.3 Next Steps/Further Studies
Although operations and maintenance were not included in this technical assessment, they are recognized as critical for ensuring continuity of services during and after disruptive events.

Therefore, complementary operational strategies should be identified to strengthen emergency response and staff safety, bridging the gap between physical resilience and organizational preparedness. Below are examples that could be developed as part an integrated water system master plan:
• Enhancing protocols for remote coordination and situational awareness. • Investing in robust communication systems and staff training.

Further analysis may be required to refine and better operationalize strategies. Below are examples of detailed analyses that could be conducted as part of an integrated water system master plan:
• Developing improved flooding scenarios.
• Evaluating land subsidence, particularly as it relates to decreasing soil moisture caused by droughts.
• Conducting wildfire risk assessments for the Water Treatment Plant and Fire Station #2 • Forecasting salinity levels at intake points along the Noyo River, Waterfall Gulch, and Newman Gulch.

While the scope of this project focuses on the Wastewater Collection System, it is important to emphasize that this system is part of an interconnected and interdependent network of infrastructure, economics, community, ecology, and hydrology, which must perform and adapt to sustainably serve Fort Bragg. Some systems are more critical than others, and their interdependence must be considered in future planning.

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CHAPTER 5.0 REFERENCES
California Air Resources Board (CARB), 2023. Wildfires and Climate Change. Website:
https://ww2.arb.ca.gov/wildfires-climate-change
Jensen, M.N., 2016. How Climate Change Will Affect Western Groundwater. University of Arizona.

Website: https://news.arizona.edu/story/how-climate-change-will-affectwesterngroundwater#:~:text=Groundwater%20already%20is%20being%20withdrawn,those %20aquifers%2C%20the%20researchers%20report.

IPCC, 2022: Climate Change 2022: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M.

Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)]. Cambridge Univ University Press. Cambridge University Press, Cambridge, UK and New York, NY, USA, 3056 pp., doi:10.1017/9781009325844.

Cal-Adapt database. (as of 09-2023). https://cal-adapt.org/about/ CalEnviroScreen, 4.0 Tool (September 2023) Maps & Data - CalEnviroScreen - OEHHA - CA.gov Critical Infrastructure at Risk: Sea Level Rise Planning Guidance for California’s Coastal Zone.

California Coastal Commission. (2021)https://www.coastal.ca.gov/climate/slr/vulnerabilityadaptation/infrastructure/ California Adopts Level Rise Guidance. California Ocean Protection Council (OPC). (2018). https://www.opc.ca.gov/webmaster/ftp/pdf/agenda_items/20180314/Item3_ExhibitA_OPC_SLR_Guidance-rd3.pdf U.S. Climate Resilience Toolkit Climate Explorer (CRTCE), 2023. Observed and Future Climate Projections for Fort Bragg, CA. Website: Fort Bragg | Climate Resilience Toolkit Climate Explorer. National Environmental Modeling and Analysis Center (NEMAC), University of North Carolina Asheville.

National Centers for Environmental Information (NCEI), 2023. Daily Observational Data, Fort Bragg 5 N, CA US. Website: NCEI Daily Observations. NCEI GIS Team, Asheville, NC.

Drought Resilience Plan, Mendocino County. May 2025
(https://www.mendocinocounty.gov/departments/water-agency/drought-waterconservation/drought-resilience-plan ) Multi-Jurisdictional Hazard Mitigation Plan; Mendocino County. Volume 1 and Volume 2. 2021. ( https://mendoready.org/oes-documents/ )
i
City of Fort Bragg
Fort Bragg Wastewater Collection System Master Plan
August 1, 2026 | I-1
Appendix I. Desktop Geotechnical Assessment
Geotechnical Evaluation
of City of Fort Bragg
Seismic Safety Elements
Related to Water
Distribution Facilities
Fort Bragg Distribution System
Master Plan
City of Fort Bragg
April 1, 2025
City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
2365 Iron Point Road, Suite 300, Folsom, CA 95630-8709
(916) 817-4700
hdrinc.com
i
Table of Contents
1 Executive Summary ................................................................................................................... 1

1.1 Scope................................................................................................................................... 1

1.2 Topography and Geology..................................................................................................... 1

1.3 Emergency Access .............................................................................................................. 2

1.4 Risks to Water Supply and Distribution ................................................................................ 2

1.5 Geologic Hazards................................................................................................................. 3

1.6 Other Geologic Related Concerns ....................................................................................... 4

1.7 Non-Geologic Hazards......................................................................................................... 5

1.8 Areas of Concern for Rehabilitation of Water Distribution Facilities ..................................... 6

1.9 Recommended Future Actions............................................................................................. 6 2 Introduction ................................................................................................................................ 8 3 Approach.................................................................................................................................... 8 4 Background................................................................................................................................ 9 5 Topography and Geology......................................................................................................... 11

5.1 Mapped Units ..................................................................................................................... 12 6 Emergency Access .................................................................................................................. 17 7 Water Supply and Distribution.................................................................................................. 17 8 Geotechnical Conditions Assessments.................................................................................... 18

8.1 Geologic Hazards............................................................................................................... 20

8.2 Other Geologic Related Concerns ..................................................................................... 26 9 Areas of Concern for Rehabilitation of Water Distribution Facilities ......................................... 30

9.1 Densification and Liquefaction ........................................................................................... 31

9.2 Corrosivity .......................................................................................................................... 31

9.3 Groundwater ...................................................................................................................... 32

9.4 Seismic Response ............................................................................................................. 32

9.5 Bluff Erosion....................................................................................................................... 32 10 Recommended Future Actions................................................................................................. 32 11 Limitations................................................................................................................................ 34 12 References............................................................................................................................... 34 Attachment A – Summary of Geotechnical Conditions Depicted by City-Provided Geotechnical Reports.............................................................................................................................................. 36 Attachment B – NCRS Soil Survey Map and Select Data ................................................................. 43 City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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ii
List of Figures
Figure 1 – City of Fort Bragg Water Distribution System Schematic (no scale) ................................ 10 Figure 2 – Area Topography ............................................................................................................. 11 Figure 3 – Excerpt Geologic Mapping by Durham, 1979................................................................... 14 Figure 4 and Figure 5 – Excerpt from Noyo Watershed Mapping Relative Landslide Potential with Geology and Geomorphic Features (Manson et Al. 2001) ................................................................ 15 Figure 6 – Postulates Path of Historical Drained Beneath the City (No Scale).................................. 16 Figure 7 – Location Map – Reference Geotechnical Investigations .................................................. 19 Figure 8 – Quaternary Fault Map (Source USGS.maps.arcgis.com/apps)........................................ 21 Figure 9 – Tsunami Hazard Area - Shaded (source Cal OES MyHazard)......................................... 22 Figure 10 - Relative Slope Instability in the Fort Bragg Area (After CGS Map 58, 2011) .................. 30 List of Tables
Table 1 – Geotechnical Reference Provided by City of Fort Bragg by Area...................................... 23 City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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Version History
Version Date Comments/Description
rev0 12/12/2023 Draft Submitted to City of Fort Bagg
rev1 04/01/2025 Revised Draft – City of Fort Bragg review comments addressed City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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1 1 Executive Summary

1.1 Scope
HDR has been retained by the City of Fort Bragg (City) to develop a water distribution system master plan. The purpose of this memorandum is to:
• Provide input on the geotechnical section of the Seismic Safety Components of the General Plan as they relate to the water distribution system,
• Develop a high-level summary description of geotechnical and geologic conditions within the City’s area of influence, and
Provide discussion regarding critical elements of the analysis of six geotechnical studies for City and private development projects, provided from the City representing subsurface conditions in different areas across the City, and geotechnical data available online related to the former Georgia-Pacific Lumber Company site closure. The study did not include an exhaustive investigation of applicable geotechnical reports that may be contained in City records and does not provide a site-specific seismic hazard analysis. This Executive Summary should not be referenced alone as it is a summary and does not contain specific discussions and details provided in the body of the report.

The data and discussion presented in this memorandum are organized as follows:
• Topography and Geology
• Emergency Access
• Water Supply and Distribution System
• Geotechnical Condition Assessment
• Geologic and Non-Geologic Hazards
• Areas of Concern for Rehabilitation of Water Distribution Facilities • Limitations
HDR’s review of the subsurface conditions as described in the provided reports is briefly summarized in Attachment A. Although some portions of this memorandum may include discussions on climate change, a separate report is being prepared by HDR addressing climate change implications.

Although the memorandum was prepared specifically as part of the water distribution master planning effort, it is applicable to other City agencies responsible for infrastructure such as the stormwater and sewer system.

1.2 Topography and Geology
The City is located on an uplifted terrace along the California Pacific North Coast. The uplifted terrace has created a coastal bluff that is approximately 50 feet tall at Soldier Point near the existing City’s Wastewater Treatment Plant and 85 feet tall at Pomo Bluffs State Park. Site grades slope gently upward towards the east to approximately El. 400 feet where the terrace meets the western edge of the Coastal Range Mountains. A high-level discussion of the City topography and mapped City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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2 geology is provided in the memorandum based on review of available published information. Review of other geotechnical studies contained in the City files could be a benefit to better understand subsurface conditions that could impact the water distribution (or other) system. Former creek channels may be present beneath the City that became obscured as the terraces were uplifted.

1.3 Emergency Access
Subsurface conditions and the response to strong seismic shaking or a large storm event can impact City features such as vehicle access. The main vehicle access (and emergency evacuation/access routes) into and out of the City is Highway 1, which includes bridges that cross Hare Creek, Noyo River, and Pudding Creek (from south to north). If these bridges were damaged during a seismic event or a large storm event, such as an intense storm washing out the bridge approaches or a tsunami damaging the bridge foundations, access would be limited. Highway 1 provides the main emergency access in and out of the City over bridges maintained by California Department of Transportation (Caltrans). Caltrans reports that the Noyo and Pudding Creek bridges have undergone seismic structure upgrades and plans to perform Hare Creek Bridge seismic structure upgrades in the future. In addition, the 2020 Medocino County Hazard Mitigation (MCHMP) plan identifies slope failure and wildfire risk as having highly likely and critical impact on the city of Fort Bragg while earthquake would be an extreme risk though it is a less likely hazard (see figure 2-2, City of Fort Bragg Risk Assessment, MCHMP Vol 2 2020), both briefly discussed in subsequent sections of this report.

1.4 Risks to Water Supply and Distribution
The City water supply system, described in the memorandum, consists of water collection points, treatment facilities and storage structures, and distribution system interconnected by pipelines. The water main line system connects the storage system to the end user and these pipelines likely have additional structural connections to a network of smaller diameter pipes forming the distribution system. Each part of the system is subject to geologic hazards including strong seismic shaking, seismic-induced differential movement at connections, seismically induced ground settlement and, potentially, ground failure. Also, soil chemistry can cause corrosion to steel and concrete materials.

Each needs to be evaluated based on site-specific conditions and in accordance with the appropriate design code.

Distribution piping itself can be at risk due to many geotechnical causes, such as:
• Corrosive soils that weaken the pipe itself
• Differential settlement or pipe lengthening due to land sliding, bluff retreat, soil densification, or liquefaction resulting in large magnitude settlements or lateral spreading, static settlement due to change of overburden or imposed loads, or hydro-compression due to changes in saturation
• Differential movement during earthquake, such as at service or distribution connections like large maintenance holes or bridge crossings
Also, the City fire hydrant system must be operational for small and large seismic events and wildfires.

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3 1.5 Geologic Hazards

1.5.1 Seismicity
The City of Fort Bragg is in an area that is known for seismic activity; however, the City is not within a currently established State of California Earthquake Fault Zone for surface fault rupture hazards and there are no known active fault traces in the immediate project vicinity. The following active faults are located within 60 miles of the City
• North San Andreas Faults System – 6.5 miles west
• Maacama Fault Zone – 21 miles east
• Mendocino Fault Zone – 60 miles north
The Pacific Star Fault is a recently identified potentially active fault located northeast of the City as is the Pudding Creek Fault. They are reported as being connected to the San Andreas Fault but have not been located in the State of California Special Studies Zone. USGS estimates that there is a

64.92% chance of an earthquake with a magnitude greater than 5 to occur in the next 50 years.

1.5.2 Fault Offset, Strong Ground Motion, Liquefaction and Tsunami Impacts The fault offset hazard in the City of Fort Bragg is very low. There are no Alquist Priolo Hazards Zones identified within or near the City (www.conservation.ca.gov). The City will be subject to strong ground shaking that could induce densification of loose to medium dense terrace deposits, and slope movement within the steeply incised river and creek channels and along the coastal bluff. Loose, saturated, cohesionless soils are susceptible to liquefaction, including sediments that have accumulated within and at the mouth of the coastal, river, and creek channels and potentially in eolian (windblown) derived terrace deposits that become saturated due to groundwater.

The State of California Office of Emergency Services online MyHazard maps (myhazards.caloes.ca.gov) does not identify Fort Bragg as having a mapped liquefaction zone; however, the risk of liquefaction is judged to be moderate in the terraces and high in the river and creek channels and could occur in the event of strong ground shaking.

Tsunamis would impact the coastal areas, the Noyo Harbor, and upstream areas of Noyo River, Pudding Creek, and Hare Creek. The Pacific Institute has prepared a graphic showing the effects of a 55-inch sea level rise and the effect combined with a tsunami. Sea level rise would raise river levels in Noyo River and Hare Creek to above the 100-year flood level. Sea level rise combined with a tsunami would impact all three river/creeks and cause saltwater intrusion to the existing raw water intake on the Noyo River. Recent high tides have also caused saltwater intrusion and impacted the raw water intake.

1.5.3 Non-seismic Hazards
Non-seismic hazards include presence of unstable soils on steep slopes, continued bluff retreat, and presence of weak and/or unstable soils.
• The presences and mitigation, if required, would be determined on a project-specific investigation/basis. It would be beneficial to document the past performance of the water distribution system (Geographical information System [GIS], mapping, and tabular format), City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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4 including areas of past pipe repairs/leak/breaks and areas of known surface (street pavement and hardscape) distress to identify areas that may be underlain by weaker soils.

A more detailed description of the regional geology and the near-surface geology and surface conditions is included in the body of this document. Of particular importance is that groundwater conditions documented in the reference reports represent conditions observed at the time of investigation and are generally poorly understood. Groundwater (at depth) and near-surface perched groundwater are two different groundwater occurrences and both have been reported. Additional groundwater investigations would be required to better understand the current temporal variations in groundwater at a specific site within the City’s area of influence. The assumptions related to groundwater levels have a significant impact on the occurrence of liquefaction induced by strong ground shaking and the values reported in the different documents should not be relied on for future projects.

The Georgia-Pacific Site cleanup documentation provides detailed maps showing groundwater conditions west of Highway 1 in the central portion of the City Coastal Area. The City of Fort Bragg has recently began to track shallow groundwater condition for the stormwater and water projects in the city.

1.6 Other Geologic Related Concerns

1.6.1 Mineral Resources
The Fort Bragg General Plan does not identify any locally important mineral resource recovery sites or sites being utilized for Surface Mining and Reclamation Act (SMARA) activities.

1.6.2 Corrosion
Limited studies have identified that the terrace deposits are acidic and have cation exchange capacity, being more acidic closer to the ocean.

The terrace deposit soils should be considered corrosive to steel and slightly corrosive to concrete unless specific testing is performed or the performance of buried structures can be determined from visual inspection. A testing standard should be developed for all corrosion testing so that a “Zone” database can be developed by the City to aid in their management of the water system.

1.6.3 Erosion
Removal of vegetation and redirection of surface water could induce erosion on any area of the City.

Care must be taken to restore disturbance to reduce the risk of developing areas of concentrated surface water flow that could induce erosion. Care must be taken to install trench dams along lengthy pipelines and in elevation transitions so that the pipeline trench does not act as collection, drawing and redirecting concentrated seepage to the trench outlet causing ground saturation and potential slope failure and erosion.

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5 1.7 Non-Geologic Hazards

1.7.1 Flooding
Flooding hazard is typically determined for a 100-year flood level for insurance purposes using maps developed by the Federal Emergency Management Agency (FEMA). The FEMA updated flood maps for the Fort Bragg area are dated as being published in 2017 and show larger 100-year flood hazard than shown in the Coastal General Plan Map. The Inland Zone General Plan includes Map SF-3 Tsunami Inundation Map and Map SF-4 100-year Sea Level Rise Inundation Area, which is the Pacific Institute map previously referred to as an additional source document for this memorandum.

The most recent FEMA Flood Mapping and the Pacific Institute mapping of sea level rise are recommended as references for assessing flooding impacts.

1.7.2 Fire
The City’s fire hydrant system is critical infrastructure for public safety. Significant fires have occurred in Northern California in the last few years and the ability to protect the City from structure fires and wildfire is important. The fire hydrant system is also critical after a large seismic event.

In 2022, California Department of Forestry and Fire Protection (CALFIRE) published maps depicting Fire Hazard Severity Zones for Mendocino County as part of the Fire and Resource Assessment Program. The City is outside the jurisdiction of CALFIRE and the City itself is zoned as a local responsibility area (LRA). The Fire Hazard Zone Severity Viewer is no longer available online . The MCHMP does include earlier viersions of these maps that show the area south and east of the Noyo River zoned as Very High risk and the area north and east of the City as Moderate risk. High risk zones are located east of the City on the north side of the Noyo River and east of the north Coastal Area. The south Coastal Area is located in a Moderate risk zone west of Highway 1 and in the lower elevations east of Highway 1.

1.7.3 Extreme Weather Events
In February 2023, the United States Department of Agriculture USDA) declared Mendocino County a Disaster Area due to severe winter storms and flooding. The occurrence of heavy storms and storm events characterized as Atmospheric Rivers, defined by National Oceanic and Atmospheric Administration (NOAA) as long narrow regions in the atmosphere that transport most of the water vapor out of the tropics that have an equivalent flow at the mouth of the Mississippi River and exceptionally strong events can have 15 times that amount. The Pineapple Express is a strong atmospheric river bringing moisture from the tropics near Hawaii to the west coast. The rain events can induce slope instability and rapid slope movement and debris flows.

The ranking of deep-seated landslide susceptibility is presented on California Geological Survey (CGS) Sheet 58 that show the areas to the east and along the incised channel banks having the highest potential for slope instability and deep-seated sliding. The susceptibility of landslides impacting the City water supply and distribution system or evacuation routes directly or from debris flows should be evaluated on a case-by-case basis. It should be noted that climate change may increase the risk of slope instability.

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6 1.7.4 Chemically Impacted Sites
A review of the DTSC GeoTracker website showed the locations of numerous identified chemically impacted sites that range from small underground storage tanks to large facility clean-up activity.

Many of the sites are identified as having closed files, meaning that the sites have been remediated to meet cleanup goals set forward by regulatory agencies. It should be noted that there may be residual chemically impacted soils at these sites that did not require removal but, should they be excavated, may require special testing and handling to determine material reuse or disposal. The GeoTracker site and associated data should be checked as part future system upgrade or rehabilitation projects to be aware of potential impacted sites.

1.8 Areas of Concern for Rehabilitation of Water Distribution Facilities The following geotechnical factors should be considered when addressing water distribution design or rehabilitation.
• Densification and Liquefaction
• Corrosivity
• Seismic Response
• Bluff Erosion

1.9 Recommended Future Actions
To better understand geologic risk to specific portions of the water distribution system, a more detailed understanding is needed at the location of critical components of the system. Specifically, the following should be determined:
• The peak ground acceleration based on current code requirements, typically expressed as the design earthquake return period. Depending on the age of the facility, the current design code may be different than what was used at the time the component was designed and constructed.
• The thickness of fill and/or terrace deposits at the site, the depth to bedrock and an understanding of the groundwater depth and seasonal fluctuation. Past geotechnical investigations associated with the original design of the component/facility, or a report prepared for an adjacent property combined with review of the as-built grading plans would typically provide data regarding the site soil stratigraphy and depth to bedrock.

Understanding groundwater conditions below the site would likely require additional study, discussed below. This information is required as input into a seismic vulnerability assessment for understanding the potential for seismic densification or vertical or lateral deformation because of liquefaction, if potentially liquefiable soils are present at the specific site.
• Mapping of areas of slope instability along pipeline corridors and within 300 feet of a component or facility at a local scale will provide the input to assess the current hazards slope instability pose to the facility as well as allow comparison for changes in the risk, specifically after major storms/flood events or a large seismic event. Each specific area of concern should be mapped at a scale of 1 inch = 50 feet and fixed reference points set, such as rebar hubs setback (above) the area of instability in readily accessible areas that can be City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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7 used to easily identify changes visually and hand measurement. Each location will need to be assessed on a case-by-case basis to establish the limits of mapping and location and number of reference points. Use of fixed features such as a fence, fire hydrant, or street curb may not be sufficient as they can be modified or damaged over time.

The depth to bedrock could be evaluated by performing limited geophysical surveys (seismic refraction) that is a non-invasive and lower cost method of field investigation. The geophysical surveys, in combination with other geotechnical or environmental investigation reports that the City has, could provide the level of detail required without the expense of drilling soil borings.

Understanding the depth of groundwater and fluctuation over time could require installation of a strategically placed monitoring well or wells to understand the source and direction of groundwater flow and the effects of rainwater and irrigation infiltration. An initial widely spaced grid of wells could be established and monitored semi-annually to quarterly to develop an understanding of groundwater behavior. The wells could be supplemented if an areas data seems erratic of if additional detail is desired.

Planning for such a study should be proceeded by a desktop study reviewing available data contained in City files and interviewing local civil/geotechnical and geological consultants familiar with area soil and geologic conditions that may bring specific knowledge from past experience within the City limits. All the groundwater, soil, and bedrock depth and slope instability data can then be collected in a geographic information system (GIS) and reviewed to determine where more detailed study would be warranted. The information would need to be reviewed and updated to provide a living document that can be used by all City departments for planning and risk assessment.

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8 2 Introduction
HDR has been retained by the City of Fort Bragg (City) to develop a water distribution system master plan. The purpose of this evaluation is to:
• Provide input on the geotechnical section of the Seismic Safety Components of the general plan as it relates to the water distribution system,
• Develop a high-level summary description of geotechnical and geologic conditions within the City’s area of influence, and
• Provide discussion regarding critical elements of the water supply system that should be considered as part of master planning and future distribution system maintenance/rehabilitation efforts.

This study is limited to review of the City’s existing general plans for the Inland and Coastal Zones, review of available published geotechnical and geologic information, review of six geotechnical studies for City and private development projects provided from the City representing subsurface conditions in different areas across the City, and geotechnical related data available online related to the former Georgia-Pacific Lumber Company site closure. This is not an extensive review of all potentially available geotechnical reports or related documents that may be contained in the City’s records or from local consultants, which is beyond the scope of this study. This evaluation also does not provide specific geotechnical hazards assessments for the specific components of the water distribution system. The scope of site-specific hazards assessments would need to be developed after a detailed review of each specific component which has not been performed for this evaluation. 3 Approach
The data and discussion presented in this evaluation are organized as follows:
• Topography and Geology
• Emergency Access
• Water Supply and Distribution System
• Geotechnical Conditions Assessment
o Geologic and Non-Geologic Hazards
• Areas of Concern for Rehabilitation of Water Distribution Facilities • Recommended Future Actions
• Limitations
HDR’s review of the subsurface conditions as described in the provided reports is briefly summarized in Attachment A. Although some portions of this evaluation may include discussions on climate change, a separate report is being prepared by HDR addressing climate change implications.

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9 4 Background
The City is located along the coast of Mendocino County. The City is approximately 2.92 square miles in size and includes five island areas (non-contiguous land) totaling 0.15 square miles in size and comprised of city-owned property that was annexed on April 7, 1997.

While Fort Bragg is a small community, it is the largest city on the coast between San Francisco and Eureka and is a popular tourist and recreational destination. Commercial land uses in the City are located along the California State Route 1 (Highway 1) and Franklin Street corridors. The Central Business District, located between Oak Street and Pine Street, is the historic, civic, and cultural core of the community. Industrial lands are located on the Georgia-Pacific Mill property located west of Highway 1 on North Franklin Street, immediately north of the Central Business District, and on Highway 1 north of Pudding Creek. Residential neighborhoods are located east of the commercial core and in the west Fort Bragg area.

For planning purposes, the City is divided into the Coastal Zone as described in Coastal Act Section 30150 (July 2008 Land Use Element Fort Bragg Coast General Plan) and the Inland Zone for areas within the City influence but outside of the Coastal Zone (bounded by the City limits on the north and east, and the coastal zone to the south [Walnut Street] and west [Highway 1]). These zones are shown on Map LU-1, Land Use Designations and LU-2 City Boundary and Sphere of Influence, both contained in the updated 2012 Inland General Plan. The Coastal zone includes a specific plan area in the Timber Resources Industrial Land Use Designation (former Georgia-Pacific Properties) between Walnut Street to the South and Elm Street to the North and Highway 1 on the east.

Figure 1 presents a graphic showing the existing City water distribution system that consists of a network of pipes within the central portion of the City, primarily in the Inland Zone with supply provided to the south of the Noyo River in the Pomo Bluffs area north of Hare Creek, and to the north across Pudding Creek to the Fort Bragg Airport area. The coastal area west of Highway 1 and the main part of the City was previously occupied by the now closed Georgia-Pacific Mill with limited connection to the water distribution system.

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10 Figure 1 – City of Fort Bragg Water Distribution System Schematic (no scale) City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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11 5 Topography and Geology
The City is located on an uplifted terrace along the California Pacific North Coast. The uplifted terrace has created a coastal bluff that is approximately 50 feet tall at Soldier Point near the existing City’s wastewater treatment plant and 85 feet tall at Pomo Bluffs State Park. Site grades slope gently upwards towards the east to approximately El. 400 feet where the terrace meets the western edge of the Coastal Range Mountains. A topographic terrain map of the region is provided below.

Figure 2 – Area Topography
Source: www.topozone.com
The elevations used in this study are relative to the 1929 National Geodetic Vertical Datum (NGVD 1929) which is sufficient for the general purposes of this discussion. Coastal Area elevations range on the east boundary from El. 78 feet (Main Street at Pine Street) to El 82 feet (Simpson Lane at Highway 1). Inland areas rise in elevation to about El. 200 feet (Marsben Lane at Sherwood Road).

The terrace is incised by the Noyo River, Pudding Creek, and Hare Creek. Pudding Creek and the Noyo River have incised at least 160 feet into the terrace where the California Western Railroad once crossed these creeks and enters a now collapsed tunnel beneath Sherwood Road. United States Geologic Survey Benchmark at Noyo Harbor is listed as El. 11.73 feet. The mouth of Pudding Creek and Hare Creek are at or slightly above sea level where beaches have formed (El. 0 feet).

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12 Noyo Harbor has been dredged to provide access to the Noyo Basin Marina. The most recent nautical charts should be reviewed to determine the depth of the dredged channel.

There is limited published geologic mapping of the City vicinity. The most detailed mapping was prepared as part of the Noyo River Watershed program in 2025 that includes preliminary mapping performed by Durham for the Department of Forestry in 1979. A portion of the Durham 1979 map and maps from the Noyo Watershed mapping are presented in Figure 3, Figure 4, and Figure 5.

These figures are provided for illustrative purposes and are not presented to scale. The actual maps should be referenced for more specific information.

The primary units mapped by Durham are quaternary aged Terrace Deposits (Qtm) and tertiary aged Franciscan bedrock. These units are further differentiated and described by Manson as Pleistocene aged Marine Terrace Deposits Undifferentiated (Qmts) and tertiary - cretaceous aged Coastal Belt Franciscan (TKfs). Manson also maps an additional unit Older Dunes (Qods), briefly described as follows and shown in Figure 4.

5.1 Mapped Units
• Older Dunes (Qods) – Well-sorted, semi-consolidated, fine- to medium grained overlying various marine terrace deposits (Qtmts)
• Marine Terrace Deposits Undifferentiated (Qmts) Deposits generally consist of well sorted sand with minor gravel and have courser textures near major drainages, may include some dune sand.
• Coastal Belt Franciscan (TKfs) – Broken formation consisting of light colors, well-cemented to deeply weathered and sheared, clastic sedimentary rock (sandstone, conglomerate, shale).

Durham mapped a number of active landslides along the incised slopes of Pudding Creek, Hare Creek, and the Noyo River identified with the letter “A” and an arrow showing the direction of movement. Mapping by Mason et. al for the Noyo River (Figure 5) also includes shading depicting the relative risk of landslide in areas that were also mapped by Durham and show a correlation between the risk of landslide and slope inclination. Review of current Map SF-1 Geologic Hazards contained in both the Coastal and Inland General Plans include identification of landslide hazards in the City’s sphere of influence and references mapping by the State of California dated 1983.

These figures are in general agreement with the Manson landslide mapping. As the data for the General Plan maps is approximately 40 years old, a site reconnaissance by a registered engineering geologist should be considered to update the general plan Map SF-1. The State of California has prepared a map of deep landslide susceptibility originally published in 2011 as California Geologic Service Map Sheet 58 (CGS 2011). This map ranks landslide susceptibility to underlying bedrock strength and slope inclination. This map does not present the location of mapped/identified landslide and is discussed in more detail in the Geologic Hazard Section.

Mapped instability identified in Figure 5 are areas of surficial instability in the immediate City limits as points and the actual mapping of large deep-seated sliding are shown a distance approximately 2.5 miles east of the Noyo River Bridge along the Noyo river south Bank. Deep-seated landslides are more abundant within the State of California Jackson Demonstration Forest located to the east and southeast of the City with the closest slides located about 3.5 miles east of the Noyo River Bridge.

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13 Additional insight into the surficial geology is provided from the review of mapped conditions within the City north of the Noyo River as depicted by the NCRS Soil Survey and review of the geotechnical report performed for the Aquatic Center near the intersection of Maple Street and South Lincoln Street. The 2003 geotechnical study (see Table 1) did not include a location plan for their borings; however, NCRS Soil Survey reports the material to the east of this site as fluvial marine derived deposits.

The 2003 SHN report identified the presence of soft soils and a layer of peat at a depth of 15.5 to 22 feet in Boring B-3. Boring B-2 found a gravel strata at a deeper depth. The study found the site contained fill to a depth of 4.5 feet along the north side of the site, underlain by dense sandy deposits to a depth of 18.5 feet. Boring B-3 depicts slightly different conditions suggesting that the terrace deposits mantled the bedrock and state that “the data indicates potentially variable or erratic soil conditions.”
However, an alternate interpretation may be that the boring data suggests that the Noyo River or Pudding Creek may once have crossed the site and later shifted as the underlying bedrock was tectonically uplifted. The former drainage may have connected to the Soldier Bay cove at the coast, located to the west of Fort Bragg – Sherwood Road (Sherwood Road) shown in Figure 6. Studies performed for the restoration of the former mill pond document that Alder and Maple Creeks do cross the City and discharge into Soldier Bay that was dammed to form the mill pond (Arcadis 2011).

The creeks were later placed in culverts and buried. The drainage could indicate more variable subsurface conditions and effect groundwater conditions beneath the main portion of the City (see https://www.fortbragghistory.org/?page_id=1071 for the 1873 map). The location of the postulated drainage roughly corresponds to the west end of the Noyo Anticline (geologic ridge formed by tectonic movement) shown on the geologic map in Figure 3. The anticline is an extension of the anticline mapped on the adjacent geologic map, the Geologic Map of the Comptche Quadrangle prepared by the State of California Department of Forestry also by Durham, 1979. If present, the drainage feature may follow a less resistant bedrock zone along the north side of the mapped anticline.

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14 Figure 3 – Excerpt Geologic Mapping by Durham, 1979
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15 Figure 4 and Figure 5 – Excerpt from Noyo Watershed Mapping Relative Landslide Potential with Geology and Geomorphic Features (Manson et Al. 2001)
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16 Figure 6 – Postulates Path of Historical Drained Beneath the City (No Scale) City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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17 6 Emergency Access
Subsurface conditions can impact City features such as vehicle access. The main vehicle access (and emergency evacuation/access routes) into and out of the City is Highway 1, which includes bridges that cross Hare Creek, Noyo River and Pudding Creek (from north to south). If these bridges were damaged during a seismic event or a large storm event, such as an intense storm washing out the bridge approaches or a tsunami damaging the bridge foundations, access would be limited.

The conditions of the logging roads that would be traveled to reach these points have not been evaluated as part of this study and do cross areas with high landslide susceptibility. Pedestrian access to the north from central Fort Bragg could be provided over the train trestle that crosses Pudding Creek west of the Highway 1 Bridge. The bridges are under the jurisdiction of the California Department of Transportation (Caltrans). The Noyo River Bridge replacement was completed in 2005. The previous bridge was replaced due to the seismic vulnerability. Pudding Creek Bridge was seismically retrofitted in 1998 and is currently being widened by Caltrans (2023). The Hare Creek Bridge is to be widened and retrofitted by Caltrans in the future.

It should be noted that Caltrans has its own design standards for bridges that is different than other codes such as the California Amendments to the International building Code (IBC) that govern design of occupied structures and American Water Works Association (AWWA) that govern design of water treatment, storage, and distribution systems.
7 Water Supply and Distribution
The following description of the water supply and distribution system is taken from Section 3 Public Facility Element included in the Inland General Plan.

The City's current water supply system consists of the Newman Reservoir, the Simpson (Waterfall Gulch) diversion, and a direct diversion in the Noyo River (which includes a wet well in the Noyo River, a pump station at the Noyo River, and various conveyances to the water treatment plant.

The City currently obtains about 50 percent of its water from the Noyo River. Under its existing temporary license, the City is entitled to draw up to 1,500 acre feet of water per year from the Noyo River so long as withdrawals do not exceed 3.0 cubic feet per second and specified amounts are maintained in the river to meet the needs of the fish population. The City's Water Permit limits how much water can be pumped from the Noyo River during drought conditions. These limits were established by the State Department of Health Services because it concluded that the City must ensure sufficient flows within the river necessary to support the fish population. To comply with these Permit conditions, the City requires that new development implement measures that limit new water demand. Additionally, the City is developing new water storage facilities to ensure adequate water during severe drought years and to meet the needs of future development in both the Inland Area and the Coastal Zone.

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18 Since the Inland General Plan was last updated, the City constructed a new 45-acre-foot lined water storage reservoir and then purchased 580 acres of land south and east of the city limits on Summer Lane for future reservoirs. The City is also in the process of designing and replacing raw water pipelines connecting to the water treatment facility on Cedar Street that includes two older abovegrade welded steel storage reservoirs (tanks) and one above-grade welded steel reservoir. The city also has a tall above grade welded steel reservoir at the corner of Highway 20 and Babcock Lane.

As the treated water steel reservoirs will be subject to strong ground shaking during an earthquake the design and maintenance of the reservoirs are governed by AWWA D-100 for welded steel tanks and D103 for bolted steel tanks, including requirements for having retrained foundations. Steel structures require inspection and maintenance and may require seismic upgrades as design codes evolve. Geotechnical reports related to these tanks have not been provided for review and comments regarding the design of the reservoirs is beyond the scope of this report.

Pipeline connections to these reservoirs present a seismic vulnerability as the structure and the pipe connection movement can cause localized stresses and cause failures. Flexible/articulating connections are usually provided to connect the reservoir to pumping to accommodate differential movement.

Distribution piping itself can be at risk due to many geotechnical causes, such as:
• Corrosive soils that weaken the pipe itself
• Differential settlement or pipe lengthening due to land sliding, bluff retreat, soil densification, or liquefaction resulting in large magnitude settlements or lateral spreading, static settlement due to change of overburden or imposed loads, or hydro-compression due to changes in saturation
• Differential movement during earthquake such as at service or distribution connections such as large manhole or bridge crossings
The fire hydrant network is also critical infrastructure for the City. The hydrant system needs to remain operational for small and large events such as wildfire and after a large seismic event.

The following sections discuss the different geotechnical conditions that are present within the City of Fort Bragg and its areas of influence.
8 Geotechnical Conditions Assessments
The City of Fort Bragg provided eight geotechnical reports from their files to provide a background of near surface soils conditions listed in Table 1 below and the location of the investigations are shown on Figure 7. Geotechnical information provided in these reports and in other information reviewed include the following topics, to some degree:
• Review of existing data
• Geologic setting
• Site conditions
• Site geology
• Subsurface conditions
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19 • Groundwater
• Soil corrosivity
• Geologic hazard including:
o Seismicity and strong ground motion
o Soil liquefaction
o Expansive soils
o Bluff retreat
General geotechnical subsurface conditions within the coastal and inland areas of Fort Bragg are discussed in the following sections referencing the eight reports provided for review. Each report is identified in the specific area it is located. All the reports include a very limited review of existing data and typically limited review of available published geology and other historical investigations that were performed at the site being investigated.

Figure 7 – Location Map – Reference Geotechnical Investigations Other sources of data that were reviewed for this evaluation and may be of interest are cited below to provide additional insight in the geotechnical conditions and geologic hazards within the City’s area of influence.
• California Department of Conservation, Mendocino County Tsunami Hazard Areas https://www.conservation.ca.gov/cgs/tsunami/maps/mendocino • California Department of Conservation - Alquist-Priolo Earthquake Fault Zones (ca.gov) • California Geological Survey (CGS) 2011, Sheet 58, Deep Seated Landslide Susceptibility • California Office of Emergency Services online MyHazard Maps myhazards.caloes.gov City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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20 • Geotracker - Environmental Clean-up Areas within and in the Vicinity of Fort Bragg https://geotracker.waterboards.ca.gov/map/?CMD=runreport&myaddress=Fort+Bragg+Ca • Coastal Conservancy – Projects and Land Acquisitions the Coastal Conservancy is s supporting along the coastline in Fort Bragg -
http://websites.greeninfo.org/mapcollaborator/sccpv/prod/# • Mendocino County Hazard Management Plan (2020)
https://mitigatehazards.com/mendocino-county/final-mjhmp/ • Office of the State Fire Marshal – Fire Hazard Severity Zones Pacific Institute – California Flood Risk: Sea Level Rise, For Bragg Quadrangle
https://pacinst.org/reports/sea_level_rise/hazmaps/Fort_Bragg.pdf (Link not active in 2025) • TRC, 2004, Phase II Environmental Site Report, Georgia-Pacific California Wood Product Manufacturing Division, 90 Fort Bragg Avenue, Fort Bragg, California, May (EnviroStor. ca.gov))
• United Stated Department of Agriculture Web Soil Survey https://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx • United States Geological Survey Quaternary fault map - USGS.maps.arcgis.com/apps

8.1 Geologic Hazards

8.1.1 Seismicity
The City of Fort Bragg is located in an area that is known for seismic activity; however, the City is not within a currently established State of California Earthquake Fault Zone for surface fault rupture hazards and there are no known active fault traces in the immediate project vicinity. The nearest Alquist-Priolo Earthquake Fault Zone to the project site is associated with the North San Andreas Fault system and located approximately 6.5 miles west of the site, which is the most likely source of earth shaking. The Maacama Fault zone is approximately 21 miles to the east of the City; the Mendocino Fracture Zone is approximately 60 miles to the northwest (Figure 8). The recently identified, potentially active, Pacific Star Fault is located to the northeast between the towns of Fort Bragg and Westport. All the faults could potentially cause earth shaking activity. Potential hazards associated with earthquakes includes rupture of the ground surface by displacement along faults, shaking of the ground caused by the passage of seismic waves through the earth, ground failure induced by shaking, such as landslides, liquefaction and subsidence of unstable ground, and tsunamis. The Pacific Star and Pudding Creek Faults were identified in 2006 and are reported as connecting to the San Andreas fault paralleling the Pacific Coast though they are not located within a special fault study zone.

The 1977 5.2 magnitude earthquake near Willits is the largest magnitude earthquake in the vicinity of the City, approximately 28 miles east of the City. Fort Bragg reported severe losses after the 1906 earthquake due to structure damage and fire. A 7.0 magnitude earthquake offshore Cape Mendocino occurred on December 12, 2024, approximately 90 miles northwest of Fort Bragg, with little damage report in the City as a result. Strong ground shaking is likely for a large earthquake event along the North California Coast region on the Maacama fault zone east of the city, the San Andreas Fault west of the City, and the Mendocino Fracture Zone/Cascadia Thrust Zone off the Pacific Coast near Eureka, California. USGS estimates that there is a 64.92% chance of an earthquake with a magnitude greater than 5 to occur in the next 50 years.

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21 Figure 8 – Quaternary Fault Map (Source USGS.maps.arcgis.com/apps)

8.1.2 Fault Offset, Strong Ground Shaking, Liquefaction and Tsunami Impacts The fault offset hazard in the City is very low. There are no Alquist Priolo Hazards Zones identified within or near the City (www.conservation.ca.gov). The City will be subject to strong ground shaking that could induce densification of loose to medium dense terrace deposits and slope movement within the steeply incised river and creek channels and along the coastal bluff. Loose, saturated cohesionless soils are susceptible to liquefaction, including sediments that have accumulated within and at the mouth of the coastal, river, and creek channels and potentially in eolian (windblown) derived terrace deposits that become saturated due to groundwater.

The State of California Office of Emergency Services online MyHazard maps (myhazards.caloes.gov) does not identify Fort Bragg as having a mapped liquefaction zone; however, the risk of liquefaction is judged to be moderate in the terraces and high in the river and creek channels and could occur in the event of strong ground shaking.

Fort Bragg
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22 Tsunamis would impact the coastal areas, the Noyo Harbor and upstream areas of Noyo River Pudding Creek and Hare Creek (Figure 9). The Pacific Institute presents the effect of 55 inches of sea level rise on their Sea Level Rise Map of the Fort Bragg Quadrangle referenced above. The map shows that sea level rise will exceed the 100-year flood level within the Noyo River and Pudding Creek. The occurrence of tsunami(s) combined with sea level rise would impact the areas shown effected by sea level rise within the limits of Pudding Creek, Hare Creek, and the Noyo River including impacting existing raw water intakes along the Noyo River with salt water. The intakes have been impacted in the past with saltwater intrusion from high tides, and beginning in 2021 the City began using a desalination system to treat high salinity raw water from the Noyo River (Water Boards Media Release October 12, 2021).

Figure 9 – Tsunami Hazard Area - Shaded (source Cal OES MyHazard) City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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23 Table 1 – Geotechnical Reference Provided by City of Fort Bragg by Area Date Area Author Address Rock
Depth
Bluff
Erosion
Estimated
Dynamic
Densification Liquefaction Lateral Spreading
Tsunami
Risk
2022
Inland
Crawford
Segment
2 NE NA Low Low ND ND
Inland * Segment
3 NE NA low Low ND ND
Inland * Segment
4 NE NA Low Low ND ND
Inland * Segment
5 NE NA Low Low ND ND
2018 South
Coastal
Salem 1151
South
Main
Street
>20 ft
NA Yes Low Low Low
2016 Central
Coastal
HDR 101
Cypress
Street

11.5 to
18 No Yes No No NA
2016 Central
Coastal
Brunsing 101
Cypress
Street
ND
Yes
(14.75 ft/75
years)

NA NA NA NA
2015 North
Coastal
Brunsing 1201
North
Main
Street
10 to16
ft Yes (31.25
ft /75 yrs)
Yes Yes (0.4g
shallow
GW)
Yes Low
2011 South
Coastal
Caltrans Highway
1 (ADA
Project)
10 to
11 ft NA ND ND ND ND
2007 Inland
(outside
City
Limits)
Curry
Group
Summers
Lane NE NA Yes
Yes (0.65g
and GW at
ground
surface)
Yes NA
2003 Inland SHN Green
Memorial
Field/Star
r State
Park

11.5 to

38.5 ft NA Low Low ND ND
Note: * - Outside of City Limits
ND – Not Determined
NA – Not Analyzed
NE – Not Encountered
Low, No, Yes – Individual Report Author’s Opinion

8.1.3 Non-Seismic Hazard
Non-seismic geologic hazards include the presence of unstable soils on steep slopes and expansive soils which, in the presence of moisture, will swell and shrink when returning to a dry condition, and compressible soils. Map SF-1: Geologic Hazards identifies areas of potential landslides and is discussed in more detail in the Section of Topography and Geology earlier in this evaluation.

Bluff retreat (erosion) is estimated for two locations in the provided reports, and is discussed in more detail in the following sections. The Pacific Institute has provided graphical estimates of bluff retreat by the year 2100 on their Sea Level Rise Map of the Fort Bragg Quadrangle referenced above. It is City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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24 unlikely that bluff retreat will impact the City’s water distribution system unless there are existing distribution pipelines or connections within that zone.

The presence of loose and/or weak compressible soils has been noted in the reference geotechnical reports. The presence and mitigation, if required, would be determined on a project-specific investigation/basis. It would be beneficial to document the past performance of the water distribution system (Geographic Information System [GIS], mapping and tabular format) including areas of past pipe repairs/leak/breaks and areas of known surface (street pavement and hardscape) distress to identify areas that may be underlain by weaker soils.

8.1.4 Regional Geology
The bedrock of this part of the Mendocino coast is comprised of well-consolidated sedimentary rocks of the Cretaceous-Tertiary Period coastal belt Franciscan Complex, such as sandstone and shale.

The bluff-top property occupies a near-level marine terrace underlain by the Franciscan Complex bedrock. The terrace was formed during the Pleistocene Epoch, when periods of glaciation caused sea level fluctuations, which created a series of steps, or terraces, cut into the coastal bedrock by wave erosion. Shallow marine sediments (Pleistocene terrace deposits) were deposited on the wave-cut, bedrock platforms while they were submerged beneath the ocean during interglacial sealevel high stands. Some of these marine deposits have been locally eroded as the terraces began to emerge from the ocean due to uplift associated with the San Andreas Fault Zone during the middle and late Pleistocene. Present sea levels are believed to have been achieved about 5,000 to 7,000 years ago.

8.1.5 Near-Surface Geology and Surface Condition
The following descriptions of site near-surface geotechnical conditions are excerpted from the geotechnical reports provided by the City separated by zone, Coastal (North, Central and South) and Inland zones, and by report author to provide a basis to understand the variability of subsurface geotechnical and groundwater conditions of the terrace deposits that mantle the bedrock within the city. It should be noted that the geotechnical reports have been developed to different standards based on their age and their primary purpose. However, the reports provide insight into the variable subsurface conditions across the city, particularly the thickness of fill materials and terrace deposits.

The identification of Zones is based on the City of Fort Bragg Inland and Coast General Plans (City of Fort Bragg 2012 and 2008) The Inland Zone is identified as a generally a westward project extending from the intersection of Walnut Street and Highway 1, projecting east to the top of the Noyo River north bank and to the north from the intersection of Walnut Street and Highway 1, following Highway 1 north to beyond Virgin Creek, as shown on Map LU-1, Land Use Designation.

The Coastal Zone is all areas west and south of the Inland Zone, including the intersection of Highway 1 and Highway 20, for areas within the City boundary and sphere of influence as shown on Figure LU-1 Land Use Designations. The Noyo River has been included in the Coastal Zone. For this document, Pudding Creek and the Noyo River have been selected to divide the Coastal Zone into the North, Central and Southern zones. Therefore, historical investigations that extend or are located south of the Noyo River north top of bank are included in the southern Coastal Zone.

A summary of the conditions reported at each of the eight reports are provided in attachment A.

Included is a comparison to the data available from the NCRS Soil Survey data regarding the City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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25 composition of new surface soil composition. The NCRS Soil Survey Data is provided in an online map of soil conditions for depths on the order of 6 feet. A map of the units overlain on an aerial map for the City and surrounding area is provided as Attachment B as well as tabular list data of typical engineering and chemical properties contained in the NCRS database organized by soil unit number. The tabulated values are developed focused on agricultural uses but can provide insight into the soil texture and chemical nature of the soil. This data can be used for a preliminary highlevel assessment of near surface site conditions in areas within a specific zone but not explicitly investigated. More detailed investigations may be warranted depending on the project under consideration.

It is particularly important to note that groundwater conditions documented in the reference reports represent conditions observed at the time of investigation and are generally poorly understood.

Groundwater (at depth) and near surface perched groundwater are two different groundwater occurrences and both have been reported. Additional groundwater investigations would be required to better understand the current temporal variations in groundwater at a specific site with the City’s area of influence. The assumptions related to groundwater levels have a significant impact on the occurrence of liquefaction induced by strong ground shaking and the values reported in the different documents should not be relied on for future project.

Documents related to the environmental cleanup of the Georgia-Pacific site (Central Coastal Zone) are available through the California Department of Toxic Substances (DTSC) using the Envirostor system (https://www.envirostor.dtsc.ca.gov). Groundwater in the central portion of the Coastal Zone is depicted in a series of monitoring reports that show a groundwater depression in the vicinity of Soldier Bay. The 2004 Phase 1 study described this area as a natural low spot and groundwater at the eastern edge of the zone was measured at El. 65 feet.

Fill – All Reports
Variable thickness of fill is present throughout the City due to historical grading and development. Fill is likely locally derived and can be highly variable. Fill material may contain significant organics (such as topsoil) and can have little to no compaction efforts. Suitability for reuse of fill will need to be determined on a case-by-case basis.

Marine Terrace Deposit – Coastal (five report sources)
The Coastal Zone generally consists of sand with variable amounts of gravel, silt and in some instance s clay. It is listed as being eolian (windblown) origin by NCRS, is under consolidated and can be susceptible to liquefaction due to strong ground shaking depending on the level of groundwater. Where estimated, the liquefaction hazard is generally low and liquefaction induced settlement has been calculated based on conservative (elevated) groundwater levels. The liquefiable soils are also susceptible to lateral spreading.

The depth of bedrock is variable. Bedrock was not encountered in the southern coastal zone. In the Coastal Central Zone, depth to bedrock varies from to within 2 feet of the ground surface to a depth of 9.5 feet at the City WWTP and 20 to 30 feet at the Georgia-Pacific facility in the topographic low point at Soldier Point. In the Coastal Northern Zone the depth of bedrock varied from 7 to 15 feet.

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26 The depth to groundwater has been reported to occur at a depth of 7 to 8 feet in Georgia-Pacific monitoring wells. Groundwater encountered at the time of drilling in the north and south area was reported between 2 and 7 feet and are expected to vary seasonally.

Marine Terrace Deposits – Inland (two report sources)
The Inland Zone is likely comprised of both eolian and fluvial terrace deposits depending on the distance east from Highway 1. The terrace deposits transition to fluvial derived deposits that have higher clay and silt contents up to materials being classified as clay. These have been identified at the Aquatic Center and along the raw water pipeline alignment. The transition between the two types of terrace deposits are not defined but, for a first estimate, may be located along the El. 160-foot contour.

A potential buried drainage (bedrock depression) may be located beneath the Aquatic Center and may extend to the west towards the bay north of Soldier Point. The buried drainage would have thicker terrace deposits than the adjacent areas that could increase the risk of differential settlements due to seismic densification liquefaction. Bedrock was only encountered by the 2003 Aquatic Center investigation at depths of 5 to 10 feet but was below a depth of 22 feet at one location. A compressible peat layer was found at depths of 22 feet.

Shallow groundwater was encountered during the 2003 investigation.

Colluvium – Incised River and Creeks Slopes
Colluvium is mapped as being along slopes that have moderate to high risk for landslides. The thickness of the colluvium is not defined but is estimated in one report as being on the order of 5 feet.

Alluvium and Beach Deposits
Alluvium and beach deposits have accumulated along the river and creek channels. The Noyo River is maintained by the United Stated Corps of Engineers that periodically dredge the channel. Beach deposits are located at the mouth of Hare and Pudding creeks. Alluvium derived from erosion of adjacent areas has accumulated in the stream bottoms and likely varies from sand bars to siltation within the channel that are likely saturated and loose (granular deposits) and soft and weak (cohesive deposits). Targeted geotechnical studies would need to be performed to assess the conditions that existing for projects that are located across these deposits.

8.2 Other Geologic Related Concerns

8.2.1 Mineral Resources
According to a 2019 Initial Study and Mitigated Negative Declaration, the City does not have any identified locally important mineral resources recovery sites delineated in the general plan, specific plan, or other land use. The City has also not been utilized for Surface Mining and Reclamation Act (SMARA) activities, as noted in the City of Fort Bragg General Plan Amendment 1-19 (GPA 1-19), Inland General Plan Amendment – Housing Element Update (2019).

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27 8.2.2 Corrosivity (Chemical Analysis)
As stated in the previous sections, the near-surface soil blanketing the site is acidic and has a low cation exchange capacity being more acidic closer to the ocean. Corrosivity analyses were only available from two of the eight studies reviewed, reported as follows.

South Coastal Zone (Salem 2018)
Soluble Sulfate - 100 mg/kg
Soluble Chloride - 36 to 37 mg/kg
pH – 7.1
The water-soluble chloride concentration detected in saturation extract from the soil samples was 37 mg/kg.

The reports states that this level of chloride concentration is considered slightly corrosive.

Inland – (Crawford 2022)
Pipeline Segment 4 – two samples depths 2.0 to 3.0 feet.

Minimum Resistivity (Ohm-CM) - 4,290 and 10,990
Sulfate Content (ppm) - 3.1 and 15.1
pH - 3.99 and 4.26
The report states that in accordance with Caltrans Standards, the soil tests indicate corrosive to structural steel materials and non-corrosive to structural concrete materials. The Crawford results correlate with NCRS data for pH.

The terrace deposits soils should be considered corrosive to steel and slightly corrosive to concrete unless specific testing is performed or the performance of buried structures can be determined from visual inspection. A testing standard should be developed for all corrosion testing so that a “Zone” database can be developed by the city to aid in their management of the water system.

8.2.3 Erosion
For the steeper slopes, Crawford (2022) stated the following for the proposed pipelines:

The proposed pipeline alignment meanders through steep slopes with a few areas mapped as inner gorge which are prone to landslides, erosion, and creeping. Based on our review of the project plans, the slopes are shown to range from 1H:1V to 4H:1V along the pipeline alignment. Observations along the proposed alignment showed the existing slopes are performing adequately and consist of heavily established vegetation. Following the completion of construction, overly steepened areas (such as between Station 125+00 through 126+60 and Station 130+00 through 132+00) where vegetation is being removed will be susceptible to erosion and may require periodic maintenance while the vegetation is reestablished.

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28 Removal of vegetation and redirection of surface water could induce erosion on any area of the City.

Care must be taken to restore disturbance to reduce the risk of developing areas of concentrated surface water flow that could induce erosion. Care must be also taken to install trench dams along long lengths of pipeline in and in areas of elevation transitions so that the pipeline trench does not act as collection drawings redirecting and concentrated seepage to the trench outlet, which could lead to ground saturation and potential slope failure and erosion.

8.2.4 Non-Geotechnical Hazards

8.2.4.1 Flooding
Flooding Hazard is typically determined for a 100-year flood level for insurance purposes using maps developed by the Federal Emergency Management Agency (FEMA). As described in the Inland General Plan:
“FEMA … requires the City to establish development standards for construction in the 100-year floodplain. Typically the standards developed by a city or county can range from limits on the intensity of development to requirements to raise the "habitable floor" of the structure to at least one foot above the 100-year flood peak elevation. Most of the City, over 99% of the land area, is situated above both the 100-year and the 500-year floodplains. The only areas in the Inland Area located within the 100-year flood plain are along the Noyo River and Pudding Creek. The presence of riparian habitat and excessive slopes in this area prohibits development within the 100-year flood plain.”
And,
“Portions of the City have areas subject to potential flooding during severe storms.

Because of the generally flat terrain in the Fort Bragg area, a 100-year storm could exceed the ability of the City's infrastructure to move runoff water from the City to outfalls into natural drainages and the ocean. This drainage overload may result in standing water in low areas. High tides and severe storms may also cause flooding in low-lying areas near creeks and drainages.”
The Coastal Zone Map SF-2 references flood mapping dated 1992 while the Inland Zone map references mapping stated in 2011. The FEMA updated flood maps for Fort Bragg area are dated as being published in 2017 that show larger 100-year flood hazard than shown in the Coastal General Plan Map. The Inland Zone General Plan includes Map SF-3 Tsunami Inundation Map and Map SF4 100-year Sea Level Rise Inundation Area, which is the Pacific Institute map previously referred as an additional source document for this evaluation. The most recent FEMA flood mapping and the Pacific Institute mapping of sea level rise is recommended as references for assessing flooding impacts.

8.2.5 Fire Hazard
The City’s fire hydrant system is critical infrastructure for public safety. Significant fires have occurred in Northern California in the last few years and the ability to protect the City from structure fires and wildfire is important. The fire hydrant system is also critical after a large seismic event.

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29 In 2022, the California Department of Forestry and Fire Protection (CAL FIRE) published large-scale maps depicting Fire Hazard Severity Zones for Mendocino County as part of the Fire and Resource Assessment Program
(https://osfm.fire.ca.gov/media/loqhpr10/fhsz_county_sra_e_2022_mendocino_ada.pdf).

Zones north and south of the City are zoned as having a high severity and the east is zoned as moderate severity. The City is outside the jurisdiction of CAL FIRE and the City itself is zoned as a local responsibility area (LRA). The Fire Hazard Zone Severity Viewer is located at https://egis.fire.ca.gov/FHSZ/. The viewer shows the area south and east of the Noyo River zoned as very high and the area north and east of the City as moderate. High risk zones are located east of the City on the north back of the Noyo River and east of the north Coastal Area. The south Coastal area is located in a moderate risk zone west of Highway 1 and in the lower elevations east of Highway 1.

8.2.6 Extreme Weather Events
In February 2023, the United States Department of Agriculture (USDA) declared Mendocino County a Disaster Area due to severe winter storms and flooding. The occurrence of heavy storms and storm events, characterized as atmospheric rivers, are defined by National Oceanic and Atmospheric Administration (NOAA) as long narrow regions in the atmosphere that transport most of the water vapor out of the tropics that have an equivalent flow at the mouth of the Mississippi River and exceptionally strong events can have 15 times that amount. The Pineapple Express is a strong atmospheric river bringing moisture from the tropics near Hawaii to the west coast. The rain events can induce slope instability and rapid slope movement and debris flows. One such event happened to the community of Rio Nido along the Russian River in 1998 and have also been attributed to coastal landslides in 1962.

Figure 10 presents a ranking of the potential deep-seated landslide occurrence-based on rock strength and slope inclination from CGS Map Sheet 58. The darker the color red indicates the higher potential risk. Rock strength in Mendocino County is generally ranked as moderate; therefore; the instability is a function of slope inclination ranging from 3 degrees to over 40 degrees, with rocks inclined 15 to 20 degrees or greater having the highest susceptibility (approximately equivalent to a 27 percent grade or higher). Therefore, the susceptibility of landslides impacting the City water supply and distribution system or evacuation routes directly or from debris flows should be evaluated on a case-by-case basis. It should be noted that climate change may increase the risk of slope instability.

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30 Figure 10 - Relative Slope Instability in the Fort Bragg Area (After CGS Map 58, 2011)

8.2.7 Chemically Impacted Sites
A review of the DTSC GeoTracker website provides the locations of numerous identified chemically impacted sites that range from small underground storage tanks to large facility clean-up activity.

Many of the sites are identified as having closed files, meaning that the sites have been remediated to meet cleanup goals s set forward by regulatory agencies. It should be noted that there may be residual chemically impacted soils at these sites that did not require removal but, should they be excavated, may require special testing and handling to determine material reuse or disposal. The GeoTracker site and associated data should be checked as part of a future system upgrade or rehabilitation projects to be aware of potential impacted sites. 9 Areas of Concern for Rehabilitation of Water
Distribution Facilities
The following geotechnical factors should be considered when addressing water distribution design or rehabilitation.

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31 9.1 Densification and Liquefaction
The City will experience strong ground shaking that could induce seismically densification and/or liquefaction in saturated, loose granular soil. Liquefaction can also induce lateral spreading.

Differential movement both vertically and laterally can damage water distribution facilities such as when connected to structures founded on rock or connected to bridges. The magnitude of movement will dictate the appropriate measures to include in a repair or rehabilitation of the system including use of articulating joints for entering rigid structures and the use Earthquake Resistant Ductile Iron Pipe (ERDIP) if the anticipated movements are significant and would damage standard pipe systems, such as those being implemented by the Los Angeles Department of Water and Power (LADWP) to provide greater resilience to their distribution system. ERDIP allows for the pipeline to extend, accommodating seismic deformations limiting failures for pipelines failing at joint. The amount of movement that can be accommodated is a function of the length of ERDIP installed.

LADWP limits use of ERDIP to sites that are deemed critical to the function of the entire water system in the event of a major earthquake and are typically located in areas that are calculated to have widespread lateral spreading and large fault offset. For more information, see https://www.hdrinc.com/sites/default/files/2017-05/hdr-seismic-considerations-for-waterdistribution.pdf (link not active in 2025). and https://scag.ca.gov/sites/main/files/fileattachments/srpwebinar_orourkepresentation.pdf?1603219825 ) The American Lifeline Alliance is a public/private alliance between FEMA and the National Institute of Building Sciences. In 2005, they published Seismic Guidelines for Water Pipelines that provides extensive guidance for the design of water pipelines in the seismic environment. (https://www.americanlifelinesalliance.com/pdf/SeismicGuidelines_WaterPipelines_Comm.pdf.

There are also numerous articles published in AWWA and ASCE conference proceedings, including work by O’Rourke. In the 1970s, asbestos concrete pipe (ACP) was used for water distribution systems. As these pipes age the pipes can become brittle and fail catastrophically with no warning.

ACP also poses an environmental hazard. Therefore, the pipelines can be lined with a drinking water compatible resin cured-in-place pipe (CIPP) line technology that, when the resin hardens, forms a new ductile and deformation resistant pipe within the ACP. CIPP can also be applied to ductile iron pipes.

Seismic shaking itself can induce differential movement between structures and pipeline causing damage to connections, such as connections to vaults, steel reservoirs, or bridge crossings. Large, out-of-phase movement can cause damage to connections to structures. To improve resiliency flexible connections should be provided. The City will likely be subject to strong ground shaking due to earthquakes occurring on nearby faults. Existing and new connections should be evaluated by the appropriate design standards.

9.2 Corrosivity
Based on the limited amount of the data, the soils in and around Fort Bragg should be considered corrosive to iron and mildly corrosive to concrete. Site Specific testing should be performed and compiled to confirm the corrosivity of the soils. Testing should include:

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32 • As-received and saturated electrical resistivity per ASTM G-187 and pH per ASTM G-51; and • Chemical analysis for Major anions and cations per ASTM 6919, ASTM 4327 and AWWA 4110B

9.3 Groundwater
Groundwater levels are reported as varying seasonally, rising to near the ground surface in some instances. Long reaches of pipelines can interconnect areas of high groundwater and transmit water to other areas along the trench bedding or pipe zone material. This can be exacerbated by pipelines that run from higher elevations to lower elevations in the city. Trench dams should be included wherever expected or known groundwater is encountered during construction and spaced at the midpoint of each line segment, and where future construction access will be required. Trench dams consist of low permeability material (soil or Controlled Low Density Fill, manufactured materials that are slipped over the pipe at the time of installation).

9.4 Seismic Response
In addition to dynamic densification and liquefaction effects, pipe connections to structures, such as vaults, steel reservoirs or bridge crossing may experience differential movements based on the response of the ground compared to the response (shaking) of the structure. Out-of-phase movement can cause damage to connections to structures. To improve resiliency flexible connections should be provided. The City will likely be subject to strong ground shaking due to earthquakes occurring on nearby faults. Existing and new connection should be evaluated by the appropriate design standards.

9.5 Bluff Erosion
The bluffs along the coastline are actively eroding, which is referred to as bluff retreat or bluff erosion. Estimates of bluff erosion have been provided in two referenced geotechnical reports (Table 1) and from the Pacific Institute. Placement of distribution systems within the limits of future bluff retreat is not recommended.
10Recommended Future Actions
To better understand specific geologic risk to specific portions of the water distribution system, a more detailed understanding is needed at the location of critical components of the system.

Specifically, the following should be determined:
• The peak ground acceleration based on current code requirements, typically expressed as the design earthquake return period. Depending on the age of the facility the current design, the code may be different from what was used at the time the component was designed and constructed.
• The thickness of fill and/or terrace deposits at the site, the depth to bedrock and an understanding of the groundwater depth and seasonal fluctuation. Past geotechnical investigations associated with the original design of the component/facility or a report prepared for an adjacent property combined with review of the as-built grading plans would City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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33 typically provide data regarding the site soil stratigraphy and depth to bedrock.

Understanding groundwater conditions below the site would likely require additional study, as discussed below. This information is required as input into a seismic vulnerability assessment for understanding the potential for seismic densification or vertical or lateral deformation as a result of liquefaction, if potentially liquefiable soils are present at the specific site.
• Mapping of areas of slope instability along pipeline corridors and within 300 feet of a component or facility at a local scale will provide the input to assess the current hazard that slope instability poses to the facility as well as allow comparison for changes in the risk, specifically after major storms/flood events or a large seismic event. Each specific area of concern should be mapped at a scale of 1”=50 feet and fixed reference points set, such as rebar hubs setback (above) the area of instability in readily accessible areas that can be used to easily identify changes visually and hand measurement. Each location will need to be assessed on a case-by-case basis to establish the limits of mapping and location and number of reference points. Use of fixed features such as a fence, fire hydrant, or street curb may not be sufficient as they can be modified or damaged over time.

The depth to bedrock could be evaluated by performing limited geophysical surveys (Seismic Refraction) that is a non-invasive and lower cost method of field investigation. The geophysical surveys in combination with other geotechnical or environmental investigation reports available from the City could provide the level of detail required without the expense of drilling soil borings.

Understanding the depth of groundwater and fluctuation over time could require installation of strategically placed monitoring well(s) to understand the source and direction of groundwater flow and the effects of rainwater and irrigation infiltration. An initial widely spaced grid of wells could be established and monitored semi-annually to quarterly to develop an understanding of groundwater behavior. The wells could be supplemented if an area’s data seems erratic or if addition detail is desired.

Planning for such a study should be preceded by a desktop study reviewing available data contained in City files and interviewing local civil/geotechnical and geological consultants familiar with the Fort Bragg’s soil and geologic conditions that may offer specific knowledge from past experience within the City. All the groundwater, soil, and bedrock depth and slope instability data can then be collected through GIS and reviewed to determine where more detailed study would be warranted. The information would need to be reviewed and updated to provide a living document that can be used by all departments of the City for planning and risk assessment. HDR understands that they City is documenting the presence of shallow groundwater as part of ongoing maintenance work (unpublished).

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34 11Limitations
This report was developed by HDR for the client’s sole and exclusive use on this project for the purposes described in this report and within the scope of work, and in accordance with contract conditions. This report is not for the benefit of any third party and may not be distributed to, disclosed in any form to, used by, or relied upon by any third party without prior written consent of HDR.

Consent may be withheld by HDR at its sole discretion. Use of this work product by others is at their own risk and the user assumes all liability for its use. This report must be read as a whole; individual sections should not be considered or interpreted on a stand-alone basis. The content included in this report is correct to the best of HDR’s knowledge and has been developed in accordance with the standard of care that is customarily followed by a practitioner in this industry reviewing and reporting existing data. The scope of this project did not include collection and analysis of data and for calculations or modeling in support of this report.

The information provided in this report was developed or provided by others. Except as specifically identified in this report, HDR has not performed independent validation or verification of exploration data, modeling data, or other analysis data provided by others. HDR has used qualified and diligent staff to prepare this report and has assumed that third-party or client data are accurate, complete, reliable, and current. Depth to groundwater levels recorded on boring logs in these studies is subject to many variables and may not be indicative of long-term equilibrium conditions. These variables include water introduced during drilling operations, surface infiltration, puncture of perched horizons, build-up of mud against the walls of the boring (which can reduce infiltration), and inadequate time for equilibration of groundwater pressure.

HDR has not performed a site-specific seismic evaluation of ground shaking intensity or duration.

Recommendations in this report are based on published mapping prepared by others and standard practices for the area.
12 References
American Lifeline Alliance (2005) Seismic Guidelines for Water Pipelines(https://www.americanlifelinesalliance.com/pdf/SeismicGuidelines_WaterPipelines_Co mm.pdf.

Arcadis (2011) Draft Conceptual Design, Mill Pond Complex Restoration, Former Georgia Pacific Wood Products Facility (Text only) June (source savenoyoheadlands.org ) California Department of Conservation, Mendocino County Tsunami Hazard Areas https://www.conservation.ca.gov/cgs/tsunami/maps/mendocino California Department of Conservation - Alquist-Priolo Earthquake Fault Zones (ca.gov) California Geological Survey (CGS) 2011, Sheet 58, Deep Seated Landslide Susceptibility California Office of Emergency Services online MyHazard Maps myhazards.caloes.gov City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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35 Coastal Conservancy – Projects and Land Acquisitions the Coastal Conservancy is s supporting along the coastline in Fort Bragg - http://websites.greeninfo.org/mapcollaborator/sccpv/prod/# Durham, J.B., 1979, Title II Geologic Compilation Project, Ukiah and Santa Rosa Map Sheets:

California Department of Forestry, unpublished 15-minute quadrangle maps, scale 1:62,500 Fort Bragg (2008) Coastal General Plan, July
Fort Bragg (2012) Inland General Plan, November
Fort Bragg Mendocino Coast Historical Society – 1873 Coastal Survey Map, 18723/2023 Slider Maphttps://www.fortbragghistory.org/?page_id=1071
Geotracker - Environmental Clean-up Areas within and in the Vicinity of Fort Bragg https://geotracker.waterboards.ca.gov/map/?CMD=runreport&myaddress=Fort+Bragg+CaHDR 2017, Seismic Considerations for Water Distribution
https://www.hdrinc.com/sites/default/files/2017-05/hdr-seismic-considerations-for-waterdistribution.pdf. (link no longer active as of 3/2025)Manson, M.W., Sowma-Bawcom, J.A., and Parker, T.K. (2001) Geologic and geomorphic features related to landsliding, Noyo River watershed, Mendocino County, California, California Division of Mines and Geology. Publication DMG CD 2001-03
Office of the State Fire Marshal – Fire Hazard Severity Zones https://osfm.fire.ca.gov/divisions/community-wildfire-preparedness-and-mitigation/wildfirepreparedness/fire-hazard-severity-zones/fire-hazard-severity-zones-map/ O’Rourke, T.O. (Undated) Seismic Resilient Pipelines, Webinar Slides, Seismic Resilient Pipelines with Cornell Professor Thomas O’Rourke (ca.gov) Pacific Institute – California Flood Risk: Sea Level Rise, For Bragg Quadrangle https://pacinst.org/reports/sea_level_rise/hazmaps/Fort_Bragg.pdf TRC, 2004, Phase II Environmental Site Report, Georgia-Pacific California Wood Product Manufacturing Division, 90 Fort Bragg Avenue, Fort Bragg, California, May (EnviroStor.dtsc. ca.gov))
United Stated Department of Agriculture Web Soil Survey https://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx United States Geological Survey Quaternary fault map - USGS.maps.arcgis.com/apps USGS Publication Warehouse – Simon, R.B, Pampeyan, E.H. and Stover C.W. (1978) The Willits, California, magnitude-4.8 earthquake of November 22, 1977 https://pubs.usgs.gov/publication/ofr781075
USGS Earthquake Hazards Program M7.0- 2024 Offshore Cape Mendocino, California Earthquake - https://earthquake.usgs.gov/earthquakes/eventpage/nc75095651/executive City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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36 Attachment A – Summary of Geotechnical Conditions
Depicted by City-Provided Geotechnical Reports
The thickness of soil layers described below will likely vary across the project site. Borings indicate the depth across the site, but these elevations (or depths) may be somewhat higher/lower/greater between the borings.

The reports state that the materials encountered in exploratory borings were continuously logged in the field by an engineering geologist/geological engineer. The unconsolidated materials (soil) were visually classified using the Unified Soils Classification System (USCS), according to ASTM D-2487.

However, the quality of the observations, visual logging, and quantity supporting laboratory testing vary between the reports. HDR has not performed independent validation or verification of exploration data, modeling data, or other analysis data provided by others. HDR has used qualified and diligent staff to prepare this report and has assumed that third-party or client data are accurate, complete, reliable, and current.

The reports reviewed are:
• Brunsing and Associates (2015), Geotechnical Investigation, The Avalon Inn, 1201 North Main Street, Fort Bragg, December 4
• Brunsing and Associates (2016), Engineering Geologic and Geotechnical Reconnaissance, Blufftop Biological Treatment Facility, Fort Bragg Wastewater treatment Plan, 101 Cypress Street, Fort Bragg, California, September 12
• Caltrans (2011), Memorandum, Geotechnical Design Report, Fort Bragg ADA project October 31
• Crawford and Associates (2022), Final Geotechnical Report, City of Fort Bragg Raw Water Pipeline Replacement, Segment 2 – 5, Fort Bragg, California, March • Curry Group (CGI, INC) (2007), Geotechnical Study, 45-acre-foot Line Reservoir, Fort Bragg California, January 9
• HDR 2016 Fort Bragg Wastewater Treatment Plan Upgrade Project, Fort Bragg, California, February 19
• Salem Engineering Group, Inc. (2018), Geotechnical Engineering Investigation, Proposed AutoZone Retail Store, 1151 South Main Street, Fort Bragg, California, March 6 • SHN Consulting Engineers & Associates (2003) Revised Geotechnical Report, Proposed Recreation Building Green Memorial Field, Fort Bragg, California, August The identification of Zones is based on the City of Fort Bragg Inland and Coast General Plans (City of Fort Bragg 2012 and 2008) The Inland Zone is identified as a generally a westward project extending from the intersection of Walnut Street and Highway 1, projecting east to the top of the Noyo River north bank and to the north from the intersection of Walnut Street and Highway 1, following Highway 1 north to beyond Virgin Creek, as shown on Map LU-1, Land Use Designation.

The Coastal Zone is all areas west and south of the Inland Zone, including the intersection of Highway 1 and Highway 20, for areas within the City boundary and sphere of influence as shown on Figure LU-1 Land Use Designations. The Noyo River has been included in the Coastal Zone. For this document, Pudding Creek and the Noyo River have been selected to divide the Coastal Zone City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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37 into the North, Central and Southern zones. Therefore, historical investigations that extend or are located south of the Noyo River north top of bank are included in the southern Coastal Zone.

North Coastal Zone
Brunsing 2015
The report by Brunsing (2015) is located in the North Coastal Area along the west side of Highway 1 just south of the intersection of Airport Road. The report states:
• Surface soils depicted by the exploratory borings generally consist of about one to 2.5 feet of brown silty sand topsoil that is very loose to medium dense and porous. • Beneath the topsoil, the site is typically mantled by poorly-consolidated marine terrace deposits.
• The terrace deposits consist of beach or shallow marine sediments that are typically comprised of sands with some silt, gravel, and clay, along with incorporated rock fragments eroded from the underlying bedrock platform.
• The terrace materials were deposited in lenses that are generally flat, with local undulations caused by the variable-energy nature of the depositional environment and are mostly comprised of loose to medium dense, saturated sands. Clayey or silty sands were observed in some of the borings, generally just under the topsoil, but most of the terrace deposits encountered are relatively devoid of fines (silt- and clay-sized particles). • The terrace deposits generally extend to between 7.5 and 15 feet below the ground surface (bgs), and appear to generally thicken toward the east. • The terrace deposits we observed within the bluff face west of the property, up to about 10 feet thick, consisting of reddish brown silty sands interbedded with silty sandy gravels. • Bedrock was encountered at depths ranging from approximately 7.5 to 15 feet. The encountered bedrock generally consists of dark gray sandstone that is moderately to intensely fractured, moderately hard to very hard, and deeply- to little-weathered. • Practical drilling refusal was generally encountered after about one to three feet of penetration into the bedrock.

Unstabilized ground water levels were observed at the time the exploration was performed between about 2.5 and 7 feet below the ground surface. The report state states that shallow ground water can temporarily occur during, and immediately following wet weather periods.

The US Department of Agriculture provides maps of soil conditions depths on the order of 6 feet. A map of the units for the City and surrounding and typical engineering and chemical properties are provided in Attachment A. The units for this are (117, 161, and 214) are consistent with the Brunsing report’s description of near surface conditions.

The results of tests evaluating the corrosion protection of the soil on steel and concrete were not performed by the Author of the report. According to the available soil survey data the marine terrace deposits are acidic (pH range of 2 to 5.5) and have a low cation exchange capacity. Discussion of corrosivity testing results presented in other geotechnical report is discussed in the section entitled Other Geologic Related Concerns.

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38 Central Coastal Zone
HDR 2016
HDR performed a focused geotechnical investigation of the City’s Waste Water Treatment Plant (WWTP) Expansion in 2016. The plant is located on Noyo Point Road to the south west of the former Georgia-Pacific Lumber southern processing mill site, on the southside of the site. Other geotechnical investigation have been performed in the historical past related to the WWTP and are included within this report. This document reports near surface geotechnical conditions consisted of:
• Pleistocene age marine terrace deposits that overlie marine sedimentary bedrock consisting of sandstone, shale, and conglomerate.
• Past borings by others and borings for the current study indicate that fill generally overlies bedrock at the WWTP site except shallow bedrock was encountered for two structures. • Fill was reported as extending to depths of about 8 to 9½ feet, and the report states “generally consists of dark brown to black, loose to medium dense silty sand with varying amounts of gravel.
• Beneath the fill, brown-yellow loose to medium poorly-graded fine sand with silt was encountered.
• The sand deposits are consistent with descriptions of marine terrace deposits mapped by Kilbourne (1983). The sand deposits extend to depths of about 11½ feet (Elevation 38½ feet) in Boring K-2, 13 feet in Boring B-02 (Elevation 35 feet), and 18 feet in Boring B-01 (Elevation 30 feet), where bedrock was encountered suggesting that the depth to bedrock generally increases to the north and west.
• The bedrock encountered generally consists of slightly weathered to decomposed, weak to moderately strong sandstone and interbedded shale and sandstone and extended to the maximum depth explored of about 24 feet.

The units for the northern area just south of Pudding Creek are reported as the same as for the North Coast Area (117, 161, and 214). The unit for the majority of the Central Coast Zone and the Inland Zone of Fort Bragg is Unit 219 – Urban Land with little soil descriptions other that the material source is fluvial marine.

The results of tests evaluating the corrosion protection of the soil on steel and concrete were not performed by the Author of the report. According to the available soil survey data the marine terrace deposits are acidic (pH range of 2 to 5.5) and have a low cation exchange capacity. Discussion of corrosivity testing results presented in other geotechnical report is discussed in the section entitled Other Geologic Related Concerns.

Two boring (B-03 and B-04) were drilled in an area of shallow bedrock with near surface conditions reported as the upper approximately ½-foot to 1.5 foot silty sand fill and underlain by bedrock generally consisting of slightly weathered, moderately strong sandstone that extended to the depth explored of about 15 feet.

The report states that monitoring well data from studies performed in the surrounding area associated with the adjacent Georgia-Pacific operations were available online (Arcadis, 2010). “From a review of these data and what was encountered in the WWTP borings, … “true” groundwater may City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
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39 exist in the bedrock at depths below the bottom elevation of the proposed structures (Elevation 28 feet).”
The report concluded that the reported groundwater in the past WWTP borings is perched water from near surface sources. Fluctuations in the groundwater level could occur due to changes in seasons, variations in rainfall, and other factors.

South Coastal Zone, Salem 2018 and Caltrans 2011
Salem (2018) - West of Highway 1
Salem performed a geotechnical investigation for a commercial development to be located at 1151 South Main Street northwest of the intersection of Highway 1 and Ocean View Street. The document reports:
• The soils encountered in the test borings drilled as part of this investigation generally consisted of silty and clayey sands with gravel underlain by interbedded layers of sandy silty clay, sand with silt, silty sands, and sandy silts to the maximum depth explored of 20.5 feet. • The upper 5 feet were noted to be loose to medium dense. Below 5 feet the soils were generally described as dense to very dense, however one boring encountered loose soils at 15 feet.
• The borings were checked for the presence of groundwater during and after the drilling operations. Free groundwater was not encountered within the borings excavated for this investigation. However, perched groundwater was encountered in two borings at depths of about 11 feet below ground surface.

Caltrans 2011 - East of Highway 1 on the North Side of Highway 20 Caltrans performed an investigation for a sidewalk/retaining structure at the intersection of Highway 20 and Boatyard Drive. Subsurface Material Consist of Terrace Deposits underlay by decomposed sandstone. Weathering progresses from decomposed to intensely weathered between depths of 10 to 12 feet.

Groundwater was encountered at about 9 feet below ground surface in one boring and not encountered in other borings.

The NCRS units for this area lying north of Hare Creek are Units 106 and 161 and south of Hare Creek 212. These units are windblown terrace deposits (Eolian) consistent with the conditions provided in the two reports. Within Hare creek and the incised drainage, it is Units 131 and 139 alluvial sediments derived from bedrock.

The results of tests evaluating the corrosion protection of the soil on steel and concrete were not performed by the Author of the report. According to the available soil survey data the marine terrace deposits are acidic (pH range of 2 to 5.5) and have a low cation exchange capacity. Discussion of corrosivity testing results presented in other geotechnical report is discussed in the section entitled Other Geologic Related Concerns. The Caltrans report states that corrosion testing of soils was ongoing and would be provided at a later date.

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40 Inland Zone – South (Outside City Limits)
CGI 2007 – Summer Lane Reservoir
The Summer Lane reservoir is located at the north end of Summer Lane north of Highway 20, located is outside of the City Limits and Inland of Southern Coastal Area. The report states the near surface conditions as:

The project site is located on an emergent marine terrace that is locally covered with older dune sands. According to Kilbourne (1983), the Fern Creek marine terrace deposits underlie the majority of the site and are exposed in Newman Gulch that projects north of the project. The Fern Creek marine terrace in the project area is composed predominantly of interbedded silty sand with intermittent sandy silt, clayey sand, and sandy clay. Minor fine to medium, subangular to subrounded gravels were observed in test pits and local cobbles might be encountered within these terrace deposits; however, cobbles were not observed during this study. The Fern Creek terrace is approximately 70 to 90 feet thick and is underlain by the Coastal Belt of the Franciscan Formation bedrock. Older dune sands were mapped by Kilbourne (1983) overlying the terrace deposits in the southwesterly corner of the site. The presence of these dune sands was not observed during this study.

Bedrock was not encountered within explorations made during this study. Regional geotechnical studies have encountered Franciscan Formation sandstone, siltstone, and shale at depths ranging from:
• 12 to 35 feet on the Boddy property located about 3,000 west of the project site (Wahler, 1994b);
• 25 to 32 feet at a site downstream of the existing Newman Reservoir (Wahler, 1994b); • 26 to 55 feet at GP-2 and GP-3, located about 5,000 feet east if the site (Wahler, 1994a and 1994b).

The report notes that groundwater was encountered at depths of 10 to 18 feet.

Crawford 2022
Crawford investigated near surface soil conditions for construction of a replacement pipeline that included 7 test pits excavated to a depth of 6 to 9 feet and 31 hand augers to depths of 3 to 5 feet.

The pipeline segments are located along the eastern edge of the City extending from the water treatment facility located at the intersection of Sherwood Road and Monsen Way, extending about 2,500 lineal feet south to Chestnut Street (Segment 2 discussed in the previous section), then about 5,000 lineal across the Noyo River and then to the southeast to the Summer Lane Reservoir (Segment 3). Two additional segments are located from Benson Lane water storage facility and progress to the south side of Hare Creek (Segment 4) to a hilltop above and to the south of Hare Creek Segment 5. Segments 4 and 5 have a straight-line distance of 4,500 feet. Bedrock was only encountered in one exploration at a depth of 3.5 feet and not encountered in the remainder of the explorations. Refusal was encountered in 16 of the 31 hand augers between 2 to 4.5 feet. No estimates of stiffness or consistency were provided on the log of borings. The report states for Segments 3,4 and 5:

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41 • Segment 3 and 4 – Encountered conditions: silty to clayey sand with interbedded silt and clay. Poorly graded sand was encountered along Dwyer Lane. Auger refusal ranged from 2 to 4 feet.
• Segment 5 – Encountered Conditions clayey sand, sandy silt and sandy lean clay. Auger refusal at a depth 4.0 to 5 feet along the alignment.

Groundwater was not encountered in the explorations. However, the report states that groundwater will likely fluctuate with the river and stream elevations in Hare Creek (Segment 5) and the Noyo River (Segment 3).

The units, as shown on Attachment B – NCRS Soil Survey Map, for Inland Zone are 122, 174 and 214 for the Segment 3 Noyo Creek crossing to the Summer Lane Reservoir. The soil unit for Segment 4 is primarily unit 122, and until 135 where it crosses hare Creek. Unit 5 is in Unit 157. Unit 122 is derived from salt affected marine terrace deposits with no reported depth to bedrock, Unit 214 are fluvial marine deposits with depth of bedrock in excess for 6 feet and Units 135 and 174 are colluvium derived material with bedrock at a depth of 5 feet or greater.

The units for the Inland Zone (south) is 196 and in the adjacent areas as 108, 122, 148, 149, 195, 199 and 214. These units are all described as marine terrace deposits derived from sandstone with the western units (122, 148, 149) comprised of Eolian Terrace Deposits that would be subsurface conditions similar to the Southern Coastal Area.

The results of tests evaluating the corrosion protection of the soil on steel and concrete were not performed by the Author of the report. According to the available soil survey data the marine terrace deposits are acidic (pH range of 4.5 to 5.5) and have a low cation exchange capacity. Discussion of corrosivity testing results presented in other geotechnical report is discussed in the section entitled Other Geologic Related Concerns.

Inland
SHN 2003
This report was prepared for the design and construction of the aquatic facility located at the intersection of South Lincoln Street and Maple Street. The report states that site soils include compressible upper deposits to depths of at least 6 feet, some minor layers of loose to moderately dense sandy soils below that depth and are variable (erratic), with low density Peat, or silty/clayey layers, extending as deep as 22 feet in some locations. The density of the sand layers below 155 feet was estimated as dense to very dense in one boring. Sand Heaving occurred in other borings resulting in lower density estimates and are not representative. Dense materials were encountered between 5 to 10 feet of the ground surface at the southern 2/3 building area (Location unknown). A compressible clay layer was encountered in three explorations between 11 and 15 feet. It is not clear if the dense sand below 15 feet is completely weathered sandstone.

Groundwater was monitored by what is described as installing a well screen at a depth of 20 feet then sealing the borehole. Groundwater reportedly rose to a depth of 3 feet below the ground surface. Other groundwater investigations are to be performed per the report. Log of borings report water at a depth of 6.5 to 7.5 ft at the time of drilling (October 28, 1998) City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
Draft Technical Memorandum
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42 Crawford (2022)
As previously stated, Crawford investigated near surface soil conditions for construction of a replacement pipeline that included 7 test pits excavated to a depth of 6 to 9 feet and 31 hand augers to depths of 3 to 5 feet. Crawford performed a near surface geotechnical investigation for 4 segments of pipeline (Segments 2 through 5) that extends from the inland (segment 2) area to the south inlead area (Segments 3, 4 and 5). Segment 2 is located along the eastern edge of the City extending from the water treatment facility located at the intersection of Sherwood Road and Monsen Way, extending about 2,500 lineal feet south to Chestnut Street. Bedrock was only encountered in one exploration at a depth of 3.5 feet and not encountered in the remainder of the explorations. Refusal was encountered in 16 of the 31 hand augers between 2 to 4.5 feet. No estimates of stiffness or consistency were provided on the log of borings. The report states for Segment 2:
• Segment 2 – Encountered conditions: clayey sand to lean clay over slightly weathered sedimentary rock
Groundwater was not encountered in the explorations.

The units for the Inland Zone is 195 for the majority of the city (Urban Land) and 141, 199, 214 along the eastern edge of the city with and 136 and 174 along the north slope of the Noyo River incised channel. Units 199, and 214 are thick fluvial marine in origin derived from sedimentary rock and Unit 141 is comprised of Marine deposits. Units 136 and 174 are colluvial deposits.

The results of tests evaluating the corrosion protection of the soil on steel and concrete were not performed by the Author of the report. According to the available soil survey data the Unit 141 marine terrace deposits are acidic (pH range of 3.5 to 5.5) and have a low cation exchange capacity (5 to 50 meq/100g). Unit 199 upper soils are reported as having similar to Unit 141 while no data is provided for Unit 214. Colluvial units are report as being less acidic (Ph 5.6 to 6.5) and have a slightly higher cation exchange capacity. Discussion of corrosivity testing results presented in other geotechnical report is discussed in the section entitled Other Geologic Related Concerns.

City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
Draft Technical Memorandum
2365 Iron Point Road, Suite 300, Folsom, CA 95630-8709
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43 Attachment B – NCRS Soil Survey Map and Select
Data
Figure B-1 NCRS Map of Soil Units
City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
Draft Technical Memorandum
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44 NCRS Engineering Properties by Unit (See Figure B-1 for Unit Numbers) City of Fort Bragg | Geotechnical Evaluation of City of Fort Bragg Seismic Safety Elements related to Water Distribution Facilities
Draft Technical Memorandum
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45 NCRS Chemical Properties by Unit (See Figure B-1 for Unit Numbers) Engineering Properties
This table gives the engineering classifications and the range of engineering properties for the layers of each soil in the survey area.

Hydrologic soil group is a group of soils having similar runoff potential under similar storm and cover conditions. The criteria for determining Hydrologic soil group is found in the National Engineering Handbook, Chapter 7 issued May 2007(http://directives.sc.egov.usda.gov/OpenNonWebContent.aspx? content=17757.wba). Listing HSGs by soil map unit component and not by soil series is a new concept for the engineers. Past engineering references contained lists of HSGs by soil series. Soil series are continually being defined and redefined, and the list of soil series names changes so frequently as to make the task of maintaining a single national list virtually impossible. Therefore, the criteria is now used to calculate the HSG using the component soil properties and no such national series lists will be maintained. All such references are obsolete and their use should be discontinued. Soil properties that influence runoff potential are those that influence the minimum rate of infiltration for a bare soil after prolonged wetting and when not frozen. These properties are depth to a seasonal high water table, saturated hydraulic conductivity after prolonged wetting, and depth to a layer with a very slow water transmission rate. Changes in soil properties caused by land management or climate changes also cause the hydrologic soil group to change. The influence of ground cover is treated independently. There are four hydrologic soil groups, A, B, C, and D, and three dual groups, A/D, B/D, and C/D. In the dual groups, the first letter is for drained areas and the second letter is for undrained areas.

The four hydrologic soil groups are described in the following paragraphs:

Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission.

Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture.

These soils have a moderate rate of water transmission.

Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission.

Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission.

Depth to the upper and lower boundaries of each layer is indicated.

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Texture is given in the standard terms used by the U.S. Department of Agriculture. These terms are defined according to percentages of sand, silt, and clay in the fraction of the soil that is less than 2 millimeters in diameter. "Loam," for example, is soil that is 7 to 27 percent clay, 28 to 50 percent silt, and less than 52 percent sand. If the content of particles coarser than sand is 15 percent or more, an appropriate modifier is added, for example, "gravelly." Classification of the soils is determined according to the Unified soil classification system (ASTM, 2005) and the system adopted by the American Association of State Highway and Transportation Officials (AASHTO, 2004).

The Unified system classifies soils according to properties that affect their use as construction material. Soils are classified according to particle-size distribution of the fraction less than 3 inches in diameter and according to plasticity index, liquid limit, and organic matter content. Sandy and gravelly soils are identified as GW, GP, GM, GC, SW, SP, SM, and SC; silty and clayey soils as ML, CL, OL, MH, CH, and OH; and highly organic soils as PT. Soils exhibiting engineering properties of two groups can have a dual classification, for example, CL-ML.

The AASHTO system classifies soils according to those properties that affect roadway construction and maintenance. In this system, the fraction of a mineral soil that is less than 3 inches in diameter is classified in one of seven groups from A-1 through A-7 on the basis of particle-size distribution, liquid limit, and plasticity index. Soils in group A-1 are coarse grained and low in content of fines (silt and clay). At the other extreme, soils in group A-7 are fine grained. Highly organic soils are classified in group A-8 on the basis of visual inspection.

If laboratory data are available, the A-1, A-2, and A-7 groups are further classified as A-1-a, A-1-b, A-2-4, A-2-5, A-2-6, A-2-7, A-7-5, or A-7-6. As an additional refinement, the suitability of a soil as subgrade material can be indicated by a group index number. Group index numbers range from 0 for the best subgrade material to 20 or higher for the poorest.

Percentage of rock fragments larger than 10 inches in diameter and 3 to 10 inches in diameter are indicated as a percentage of the total soil on a dry-weight basis. The percentages are estimates determined mainly by converting volume percentage in the field to weight percentage. Three values are provided to identify the expected Low (L), Representative Value (R), and High (H).

Percentage (of soil particles) passing designated sieves is the percentage of the soil fraction less than 3 inches in diameter based on an ovendry weight. The sieves, numbers 4, 10, 40, and 200 (USA Standard Series), have openings of

4.76, 2.00, 0.420, and 0.074 millimeters, respectively. Estimates are based on laboratory tests of soils sampled in the survey area and in nearby areas and on estimates made in the field. Three values are provided to identify the expected Low (L), Representative Value (R), and High (H).

Liquid limit and plasticity index (Atterberg limits) indicate the plasticity characteristics of a soil. The estimates are based on test data from the survey area or from nearby areas and on field examination. Three values are provided to identify the expected Low (L), Representative Value (R), and High (H).

References:

American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition.

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American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00.

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Report—Engineering Properties
Absence of an entry indicates that the data were not estimated. The asterisk '*' denotes the representative texture; other possible textures follow the dash. The criteria for determining the hydrologic soil group for individual soil components is found in the National Engineering Handbook, Chapter 7 issued May 2007(http://directives.sc.egov.usda.gov/ OpenNonWebContent.aspx?content=17757.wba). Three values are provided to identify the expected Low (L), Representative Value (R), and High (H).

Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
106—Biaggi loam, 5
to 15 percent slopes
Biaggi 80 C 0-23 Loam ML A-4 0- 0- 0 0- 0- 0 80-90-1
00 75-88-1
00 70-78-
85 50-55-
60 25-30
-35
NP-5
-10
23-27 Unweathered
bedrock
— — — — — — — — — —
107—Bigriver loamy
sand, 0 to 5 percent
slopes
Bigriver 80 A 0-6 Loamy sand SM A-2 0- 0- 0 0- 0- 0 100-100 -100
100-100
-100
50-63-
75 15-23-
30 — NP
6-63 Stratified loamy
sand to silt loam
SM A-2, A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
60-68-
75 25-38-
50 15-20
-25
NP-3 -5
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Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
108—Blacklock and
Aborigine soils, 0 to
5 percent slopes
Blacklock 42 D 0-7 Loamy sand SM A-2 0- 0- 0 0- 0- 0 100-100 -100
100-100
-100
50-63-
75 15-23-
30 0-7 -14 NP
7-14 Sandy loam, loamy
sand
SM A-2, A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
50-63-
75 15-28-
40 20-23
-25
NP-3 -5
14-61 Cemented SP-SM,
SM
A-2 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
60-73-
85 5-18- 30 0-7 -14 NP
61-64 Loamy sand, sand,
loamy fine sand
SP-SM,
SM
A-2 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
60-73-
85 5-18- 30 0-7 -14 NP
Aborigine 38 D 0-6 Sandy loam SC-SM,
SM
A-2-4, A-4 0- 0- 0 0- 0- 0 95-97-1
00 90-93-1
00 65-71-
80 30-35-
43 18-22
-25
2-4 -6
6-13 Loam CL A-6 0- 0- 0 0- 0- 0 95-97-1
00 90-93-1
00 76-83-
93 53-60-
71 25-30
-35
9-13-17
13-61 Sandy clay, clay,
clay loam
CH, CL A-7-6 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
81-85-
93 51-57-
68 42-52
-62
24-32-4
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Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
117—Cabrillo-Heeser
complex, 0 to 5
percent slopes
Cabrillo 50 B 0-26 Sandy loam SM A-4 0- 0- 0 0- 0- 0 100-100 -100
100-100
-100
65-73-
80 35-43-
50 20-25
-30
NP-3 -5
26-35 Sandy clay loam SC A-6 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
80-85-
90 35-43-
50 30-35
-40
10-15-2
0 35-50 Sandy clay loam,
sandy clay
SC A-6, A-7 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
80-85-
90 35-43-
50 30-38
-45
10-15-2
0 50-60 Sandy loam, loamy
sand
SM A-2 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
50-60-
70 10-23-
35 20-25
-30
NP-3 -5
Heeser 30 A 0-34 Sandy loam SM A-2, A-4 0- 0- 0 0- 0- 0 100-100 -100
95-98-1
00 60-70-
80 30-35-
40 20-25
-30
NP-3 -5
34-65 Sandy loam, loamy
sand, sand
SM A-2 0- 0- 0 0- 0- 0 100-100
-100
95-98-1
00 50-65-
80 15-25-
35 — NP
122—Caspar sandy
loam, 2 to 9 percent
slopes
Caspar 80 B 0-16 Sandy loam SM A-4 0- 0- 0 0- 0- 0 100-100 -100
95-98-1
00 60-68-
75 35-43-
50 20-25
-30
NP-3 -5
16-37 Sandy loam, loam,
sandy clay loam
SC-SM,
SC
A-4, A-6 0- 0- 0 0- 0- 0 85-93-1
00 75-88-1
00 50-68-
85 35-43-
50 25-30
-35
5-10-15
37-48 Sandy clay loam,
clay loam, sandy
clay
CL, SC A-6, A-7 0- 0- 0 0- 0- 0 85-93-1
00 75-88-1
00 65-78-
90 35-48-
60 30-38
-45
10-15-2
0 48-62 Sandy loam, loamy
sand
SM A-2 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
50-60-
70 20-28-
35 20-25
-30
NP-3 -5
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Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
123—CasparQuinliven complex,
30 to 50 percent
slopes
Caspar 50 B 0-16 Sandy loam SM A-4 0- 0- 0 0- 0- 0 100-100 -100
95-98-1
00 60-68-
75 35-43-
50 20-25
-30
NP-3 -5
16-37 Sandy loam, loam,
sandy clay loam
SC-SM,
SC
A-4, A-6 0- 0- 0 0- 0- 0 85-93-1
00 75-88-1
00 50-68-
85 35-43-
50 25-30
-35
5-10-15
37-48 Sandy clay loam,
clay loam, sandy
clay
CL, SC A-6, A-7 0- 0- 0 0- 0- 0 85-93-1
00 75-88-1
00 65-78-
90 35-48-
60 30-38
-45
10-15-2
0 48-62 Sandy loam, loamy
sand
SM A-2 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
50-60-
70 20-28-
35 20-25
-30
NP-3 -5
Quinliven 35 C 0-4 Sandy loam SM A-2, A-4 0- 0- 0 0- 0- 0 100-100 -100
100-100
-100
60-65-
70 30-38-
45 20-25
-30
NP-3 -5
4-11 Sandy loam, loam CL-ML,
SC-SM,
ML, SM
A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
65-78-
90 35-48-
60 25-30
-35
5-8 -10
11-18 Loam, sandy clay
loam, clay loam
CL, SC A-6 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
80-88-
95 45-60-
75 25-33
-40
10-15-2
0 18-51 Clay, sandy clay MH, ML A-7 0- 0- 0 0- 0- 0 100-100 -100
100-100
-100
85-93-1
00 50-73-
95 40-50
-60
10-18-2
5 51-60 Sandy clay loam,
clay loam
CL, SC A-6 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
80-90-1
00 40-60-
80 30-35
-40
10-15-2
0 60-64 Loamy sand, sandy
loam
SM A-2, A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
50-63-
75 20-30-
40 20-25
-30
NP-3 -5
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Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
124—CasparQuinliven-Ferncreek
complex, 9 to 30
percent slopes
Caspar 37 B 0-16 Sandy loam SM A-4 0- 0- 0 0- 0- 0 100-100 -100
95-98-1
00 60-68-
75 35-43-
50 20-25
-30
NP-3 -5
16-37 Sandy loam, loam,
sandy clay loam
SC-SM,
SC
A-4, A-6 0- 0- 0 0- 0- 0 85-93-1
00 75-88-1
00 50-68-
85 35-43-
50 25-30
-35
5-10-15
37-48 Sandy clay loam,
clay loam, sandy
clay
CL, SC A-6, A-7 0- 0- 0 0- 0- 0 85-93-1
00 75-88-1
00 65-78-
90 35-48-
60 30-38
-45
10-15-2
0 48-62 Sandy loam, loamy
sand
SM A-2 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
50-60-
70 20-28-
35 20-25
-30
NP-3 -5
Quinliven 33 C 0-4 Sandy loam SM A-2, A-4 0- 0- 0 0- 0- 0 100-100 -100
100-100
-100
60-65-
70 30-38-
45 20-25
-30
NP-3 -5
4-11 Sandy loam, loam CL-ML,
SC-SM,
ML, SM
A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
65-78-
90 35-48-
60 25-30
-35
5-8 -10
11-18 Loam, sandy clay
loam, clay loam
CL, SC A-6 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
80-88-
95 45-60-
75 25-33
-40
10-15-2
0 18-51 Clay, sandy clay MH, ML A-7 0- 0- 0 0- 0- 0 100-100 -100
100-100
-100
85-93-1
00 50-73-
95 40-50
-60
10-18-2
5 51-60 Sandy clay loam,
clay loam
CL, SC A-6 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
80-90-1
00 40-60-
80 30-35
-40
10-15-2
0 60-64 Loamy sand, sandy
loam
SM A-2, A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
50-63-
75 20-30-
40 20-25
-30
NP-3 -5
Ferncreek 15 D 0-7 Sandy loam SM A-4 0- 0- 0 0- 0- 0 80-90-1 00 75-88-1
00 65-70-
75 35-43-
50 20-25
-30
NP-3 -5
7-33 Clay, clay loam MH, ML A-7 0- 0- 0 0- 0- 0 80-90-1 00 75-88-1
00 70-80-
90 50-63-
75 40-50
-60
10-18-2
5 Engineering Properties---Mendocino County, Western Part, California Natural Resources
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Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
33-43 Sandy clay loam SC-SM,
SC
A-4, A-6 0- 0- 0 0- 0- 0 80-90-1
00 75-88-1
00 65-73-
80 35-43-
50 25-33
-40
5-10-15
43-61 Sandy loam, sandy
clay loam
SC-SM,
SC
A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
60-68-
75 35-43-
50 20-25
-30
5-8 -10
131—Cottoneva loam,
0 to 2 percent
slopes
Cottoneva 90 C 0-12 Loam CL-ML,
ML
A-4 0- 0- 0 0- 0- 0 100-100
-100
95-98-1
00 85-90-
95 50-63-
75 20-25
-30
NP-5
-10
12-43 Stratified sandy
loam to very fine
sandy loam
SM A-4 0- 0- 0 0- 0- 0 100-100
-100
95-98-1
00 60-73-
85 35-43-
50 15-20
-25
NP-3 -5
43-63 Stratified loam to
clay loam
CL-ML,
CL
A-4, A-6 0- 0- 0 0- 0- 0 100-100
-100
95-98-1
00 80-88-
95 55-65-
75 25-33
-40
5-10-15
Engineering Properties---Mendocino County, Western Part, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/22/2023

Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
135—Dehaven-Hotel
complex, 50 to 75
percent slopes
Dehaven 45 B 0-17 Gravelly loam GC-GM,
SC-SM,
GM, SM
A-4 0- 0- 0 0- 0- 0 60-70-
80 50-63-
75 45-58-
70 35-43-
50 25-30
-35
5-8 -10
17-34 Very gravelly sandy
clay loam, very
gravelly clay loam
GC A-2 0- 0- 0 0-13- 25 30-45-
60 25-38-
50 25-35-
45 15-25-
35 25-33
-40
10-15-2
0 34-52 Extremely gravelly
sandy clay loam,
extremely gravelly
clay loam
GP-GC,
GC
A-2 0- 0- 0 0-13- 25 25-28-
30 15-20-
25 10-18-
25 5-13- 20 25-33
-40
10-15-2
0 52-56 Unweathered
bedrock
— — — — — — — — — —
Hotel 35 C 0-8 Very gravelly loam GC-GM,
GM
A-2 0- 0- 0 0- 3- 5 40-48-
55 35-43-
50 30-38-
45 25-30-
35 25-30
-35
5-8 -10
8-35 Very gravelly clay
loam, very
gravelly sandy
clay loam,
extremely gravelly
clay loam
GP-GC,
GC
A-2 0- 0- 0 0- 8- 15 20-40-
60 15-35-
55 10-28-
45 5-20- 35 30-35
-40
10-15-2
0 35-39 Unweathered
bedrock
— — — — — — — — — —
Engineering Properties---Mendocino County, Western Part, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/22/2023

Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
136—Dehaven-Hotel
complex, 75 to 99
percent slopes
Dehaven 42 B 0-17 Gravelly loam GC-GM,
SC-SM,
GM, SM
A-4 0- 0- 0 0- 0- 0 60-70-
80 50-63-
75 45-58-
70 35-43-
50 25-30
-35
5-8 -10
17-34 Very gravelly sandy
clay loam, very
gravelly clay loam
GC A-2 0- 0- 0 0-13- 25 30-45-
60 25-38-
50 25-35-
45 15-25-
35 25-33
-40
10-15-2
0 34-52 Extremely gravelly
sandy clay loam,
extremely gravelly
clay loam
GP-GC,
GC
A-2 0- 0- 0 0-13- 25 25-28-
30 15-20-
25 10-18-
25 5-13- 20 25-33
-40
10-15-2
0 52-56 Unweathered
bedrock
— — — — — — — — — —
Hotel 38 C 0-8 Very gravelly loam GC-GM,
GM
A-2 0- 0- 0 0- 3- 5 40-48-
55 35-43-
50 30-38-
45 25-30-
35 25-30
-35
5-8 -10
8-35 Very gravelly clay
loam, very
gravelly sandy
clay loam,
extremely gravelly
clay loam
GP-GC,
GC
A-2 0- 0- 0 0- 8- 15 20-40-
60 15-35-
55 10-28-
45 5-20- 35 30-35
-40
10-15-2
0 35-39 Unweathered
bedrock
— — — — — — — — — —
Engineering Properties---Mendocino County, Western Part, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/22/2023

Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
141—Ferncreek
sandy loam, 2 to 9
percent slopes
Ferncreek 80 D 0-7 Sandy loam SM A-4 0- 0- 0 0- 0- 0 80-90-1 00 75-88-1
00 65-70-
75 35-43-
50 20-25
-30
NP-3 -5
7-33 Clay loam, clay MH, ML A-7 0- 0- 0 0- 0- 0 80-90-1 00 75-88-1
00 70-80-
90 50-63-
75 40-50
-60
10-18-2
5 33-43 Sandy clay loam SC-SM,
SC
A-4, A-6 0- 0- 0 0- 0- 0 80-90-1
00 75-88-1
00 65-73-
80 35-43-
50 25-33
-40
5-10-15
43-61 Sandy clay loam,
sandy loam
SC-SM,
SC
A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
60-68-
75 35-43-
50 20-25
-30
5-8 -10
148—Gibwell loamy
sand, 2 to 9 percent
slopes
Gibwell 75 C 0-12 Loamy sand SM A-2 0- 0- 0 0- 0- 0 100-100 -100
100-100
-100
50-63-
75 15-23-
30 — NP
12-18 Sandy clay loam,
clay loam
CL, SC A-6 0- 0- 0 0- 0- 0 95-98-1
00 90-95-1
00 80-88-
95 40-55-
70 30-35
-40
10-13-1
5 18-26 Sandy clay, clay MH, ML A-7 0- 0- 0 0- 0- 0 95-98-1 00 90-95-1
00 85-90-
95 50-65-
80 40-50
-60
10-18-2
5 26-42 Sandy clay loam SC A-6 0- 0- 0 0- 0- 0 95-98-1
00 90-95-1
00 75-83-
90 35-43-
50 30-35
-40
10-13-1
5 42-65 Sandy loam, loamy
sand, sand
SM A-2 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
50-63-
75 10-20-
30 — NP
Engineering Properties---Mendocino County, Western Part, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/22/2023

Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
149—Gibwell loamy
sand, 9 to 15
percent slopes
Gibwell 75 C 0-12 Loamy sand SM A-2 0- 0- 0 0- 0- 0 100-100 -100
100-100
-100
50-63-
75 15-23-
30 — NP
12-18 Clay loam, sandy
clay loam
CL, SC A-6 0- 0- 0 0- 0- 0 95-98-1
00 90-95-1
00 80-88-
95 40-55-
70 30-35
-40
10-13-1
5 18-26 Sandy clay, clay MH, ML A-7 0- 0- 0 0- 0- 0 95-98-1 00 90-95-1
00 85-90-
95 50-65-
80 40-50
-60
10-18-2
5 26-42 Sandy clay loam SC A-6 0- 0- 0 0- 0- 0 95-98-1
00 90-95-1
00 75-83-
90 35-43-
50 30-35
-40
10-13-1
5 42-65 Sandy loam, loamy
sand, sand
SM A-2 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
50-63-
75 10-20-
30 — NP
157—Harecreek
sandy loam, 2 to 9
percent slopes
Harecreek 85 A 0-2 Slightly
decomposed plant
material
PT A-8 0- 0- 0 0- 0- 0 — — — — — —
2-10 Sandy loam SM A-2-4, A-4 0- 0- 0 0- 0- 0 95-97-1
00 85-91-1
00 62-70-
81 30-35-
43 20-25
-30
—
10-18 Sandy loam SM A-4 0- 0- 0 0- 0- 0 95-97-1
00 85-91-1
00 62-70-
81 30-36-
43 20-25
-30
—
18-45 Sandy loam, sandy
clay loam
SC-SM,
SC, SM
A-2-4, A-4 0- 0- 0 0- 0- 0 95-97-1
00 85-92-1
00 68-79-
88 34-42-
48 25-30
-35
5-8 -10
45-65 Sand, loamy sand,
sandy loam
— — 0- 0- 0 0- 0- 0 95-97-1
00 86-92-1
00 66-74-
84 9-13- 19 — —
Engineering Properties---Mendocino County, Western Part, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/22/2023

Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
161—Heeser sandy
loam, 2 to 15
percent slopes
Heeser 85 A 0-34 Sandy loam SM A-4 0- 0- 0 0- 0- 0 100-100 -100
95-97-1
00 69-75-
82 33-38-
46 20-25
-30
—
34-65 Sandy loam, loamy
sand, sand
— — 0- 0- 0 0- 0- 0 100-100
-100
96-97-1
00 69-74-
83 29-37-
43 — —
Engineering Properties---Mendocino County, Western Part, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/22/2023

Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
173—IrmulcoTramway complex,
30 to 50 percent
slopes
Irmulco 70 B 0-1 Slightly
decomposed plant
material
PT A-8 0- 0- 0 0- 0- 0 — — — — — —
1-7 Loam SC-SM,
CL, ML
A-4 0- 0- 0 0- 0- 0 90-95-1
00 76-86-1
00 65-80-
96 45-57-
72 25-30
-35
5-8 -10
7-42 Loam, clay loam,
gravelly loam
SC-SM,
CL, SC
A-2-4,
A-4, A-6
0- 0- 0 0- 0- 0 76-86-1
00 49-69-1
00 43-64-
98 31-49-
78 25-33
-40
5-10-15
42-62 Clay loam, gravelly
clay loam
CH, SC A-2-4,
A-6,
A-7-6
0- 0- 0 0- 0- 0 76-86-1
00 48-68-1
00 41-63-1
00 30-49-
81 30-40
-50
10-18-2
5 62-72 Bedrock — — — — — — — — — —
Tramway 16 C 0-2 Slightly
decomposed plant
material
PT A-8 0- 0- 0 0- 0- 0 — — — — — —
2-9 Loam SC-SM,
CL, ML
A-4 0- 0- 0 0- 0- 0 91-95-1
00 77-87-1
00 66-77-
91 47-56-
66 25-30
-35
5-8 -10
9-14 Loam CL-ML,
CL
A-4, A-6 0- 0- 0 0- 0- 0 91-95-1
00 78-87-1
00 67-78-
93 50-59-
71 25-33
-40
5-10-15
14-30 Clay loam, gravelly
clay loam
CL, SC A-2-4,
A-6,
A-7-6
0- 0- 0 0- 0- 0 76-85-1
00 48-68-1
00 40-62-
98 31-48-
78 30-38
-45
10-15-2
0 30-43 Bedrock — — — — — — — — — —
Engineering Properties---Mendocino County, Western Part, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/22/2023

Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
174—IrmulcoTramway complex,
50 to 75 percent
slopes
Irmulco 45 B 0-6 Loam CL-ML,
ML
A-4 0- 0- 0 0- 0- 0 90-95-1
00 85-93-1
00 75-85-
95 55-63-
70 25-30
-35
5-8 -10
6-61 Loam, clay loam,
gravelly loam
CL-ML,
GCGM,
CL, GC
A-4, A-6 0- 0- 0 0- 0- 0 65-83-1
00 60-80-1
00 50-70-
90 40-58-
75 25-33
-40
5-10-15
61-65 Weathered bedrock — — — — — — — — — —
Tramway 35 C 0-7 Loam CL-ML,
ML
A-4 0- 0- 0 0- 0- 0 90-95-1
00 85-93-1
00 65-80-
95 50-63-
75 25-30
-35
5-8 -10
7-12 Loam CL-ML,
CL
A-4, A-6 0- 0- 0 0- 0- 0 90-95-1
00 85-93-1
00 65-80-
95 50-63-
75 25-33
-40
5-10-15
12-28 Clay loam, gravelly
clay loam

CL, GC,
SC
A-6, A-7 0- 0- 0 0- 0- 0 65-83-1
00 60-80-1
00 55-75-
95 40-60-
80 30-38
-45
10-15-2
0 28-32 Weathered bedrock — — — — — — — — — —
Engineering Properties---Mendocino County, Western Part, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/22/2023

Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
196—QuinlivenFerncreek complex,
2 to 15 percent
slopes
Quinliven 60 C 0-5 Slightly
decomposed plant
material
PT A-8 0- 0- 0 0- 0- 0 — — — — — —
5-9 Sandy loam SM A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
72-77-
83 34-40-
46 20-25
-30
—
9-16 Loam, sandy loam SC-SM,
ML, SC
A-2-4, A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
69-77-
85 32-40-
50 25-30
-35
5-8 -10
16-23 Loam, sandy clay
loam, clay loam
CL A-6 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
83-91-
96 59-69-
76 25-33
-40
10-15-2
0 23-56 Clay, sandy clay MH, ML A-7-5 0- 0- 0 0- 0- 0 100-100 -100
100-100
-100
84-92-1
00 67-80-
89 40-50
-60
10-18-2
5 56-65 Sandy clay loam,
clay loam
CL, SC A-6 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
79-87-
95 42-51-
60 30-35
-40
10-15-2
0 65-75 Loamy sand, sandy
loam
SM A-2-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
75-82-
89 18-22-
33 20-25
-30
—
Ferncreek 25 C 0-2 Slightly
decomposed plant
material
PT A-8 0- 0- 0 0- 0- 0 — — — — — —
2-9 Sandy loam SM A-2-4, A-4 0- 0- 0 0- 0- 0 85-91-1
00 67-80-1
00 49-61-
84 24-31-
48 20-25
-30
—
9-35 Clay loam, clay MH, SM A-7-5 0- 0- 0 0- 0- 0 85-90-1 00 65-78-1
00 57-75-1
00 44-61-
91 40-50
-60
10-18-2
5 35-45 Sandy clay loam SC-SM,
CL, SC
A-2-4,
A-4, A-6
0- 0- 0 0- 0- 0 85-90-1
00 66-79-1
00 54-69-
92 30-39-
54 25-33
-40
5-10-15
45-63 Sandy loam, sandy
clay loam
SC-SM,
SC
A-2-4, A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
71-77-
84 34-40-
48 20-25
-30
5-8 -10
Engineering Properties---Mendocino County, Western Part, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/22/2023

Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
199—ShinglemillGibney complex, 2
to 9 percent slopes
Shinglemill 45 C/D 0-2 Slightly
decomposed plant
material
PT A-8 0- 0- 0 0- 0- 0 — — — — — —
2-10 Loam ML, SM A-4 0- 0- 0 0- 0- 0 84-88-
95 68-78-
95 55-69-
89 38-49-
65 25-30
-35
—
10-17 Sandy clay loam,
loam
CL, SC A-6 0- 0- 0 0- 0- 0 85-90-1
00 66-79-1
00 56-71-
91 42-54-
69 30-35
-40
10-13-1
5 17-27 Clay, clay loam MH, ML A-7-5 0- 0- 0 0- 0- 0 85-90-1 00 65-78-1
00 60-74-1
00 51-62-1
00 40-53
-65
10-18-2
5 27-65 Sandy clay, clay MH, SM A-2-7,
A-7-5
0- 0- 0 0- 0- 0 85-90-1
00 65-78-1
00 48-66-
91 30-44-
63 45-55
-65
15-20-2
5 Gibney 35 C 0-9 Loam SC-SM,
ML, SC
A-4 0- 0- 0 0- 0- 0 83-90-1
00 62-78-1
00 51-68-
91 36-48-
66 25-30
-35
5-8 -10
9-29 Sandy clay loam,
clay loam
CL, SC A-2-4, A-6 0- 0- 0 0- 0- 0 84-90-1
00 63-79-1
00 51-68-
92 31-42-
59 30-35
-40
10-15-2
0 29-55 Clay MH, SM A-7-5 0- 0- 0 0- 0- 0 83-90-1
00 62-78-1
00 51-72-1
00 44-63-
91 40-50
-60
10-18-2
5 55-63 Sandy clay loam,
sandy clay
CH, SC A-2-4,
A-6,
A-7-6
0- 0- 0 0- 0- 0 84-90-1
00 63-79-1
00 49-69-
98 30-45-
67 30-40
-50
10-18-2
5 Engineering Properties---Mendocino County, Western Part, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/22/2023

Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
212—TregoningCleone complex, 0
to 5 percent slopes
Tregoning 60 B/D 0-2 Slightly
decomposed plant
material
PT A-8 0- 0- 0 0- 0- 0 — — — — — —
2-11 Sandy loam SM A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
72-77-
81 33-39-
45 20-25
-30
—
11-25 Loamy sand, sandy
loam
SM A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
70-76-
82 30-38-
46 20-25
-30
—
25-64 Sand — — 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
78-80-
83 11-14-
16 — —
Cleone 20 B 0-3 Loamy sand — — 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
76-80-
85 19-23-
28 — —
3-7 Sandy loam SM A-2-4, A-4 0- 0- 0 0- 0- 0 87-92-1
00 70-83-1
00 52-63-
79 25-31-
41 20-25
-30
—
7-13 Gravelly sandy
loam, gravelly
loamy sand
SC-SM,
SC
A-2-4, A-4 0- 0- 0 0- 0- 0 76-81-
86 57-70-
86 41-54-
70 19-27-
37 20-25
-30
—
13-40 Sandy loam, loamy
sand
SC-SM,
SC
A-2-4, A-4 0- 0- 0 0- 0- 0 95-97-1
00 86-92-1
00 61-70-
82 29-35-
44 20-25
-30
—
40-62 Loamy sand, sand — — 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
77-80-
84 19-23-
26 — —
Engineering Properties---Mendocino County, Western Part, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/22/2023

Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
213—TregoningCleone complex, 5
to 15 percent slopes
Tregoning 55 B/D 0-2 Slightly
decomposed plant
material
PT A-8 0- 0- 0 0- 0- 0 — — — — — —
2-11 Sandy loam SM A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
72-77-
81 33-39-
45 20-25
-30
—
11-25 Loamy sand, sandy
loam
SM A-4 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
70-76-
82 30-38-
46 20-25
-30
—
25-64 Sand — — 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
78-80-
83 11-14-
16 — —
Cleone 25 B 0-3 Loamy sand — — 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
76-80-
85 19-23-
28 — —
3-7 Sandy loam SM A-2-4, A-4 0- 0- 0 0- 0- 0 87-92-1
00 70-83-1
00 52-63-
79 25-31-
41 20-25
-30
—
7-13 Gravelly sandy
loam, gravelly
loamy sand
SC-SM,
SC
A-2-4, A-4 0- 0- 0 0- 0- 0 76-81-
86 57-70-
86 41-54-
70 19-27-
37 20-25
-30
—
13-40 Loamy sand, sandy
loam
SC-SM,
SC
A-2-4, A-4 0- 0- 0 0- 0- 0 95-97-1
00 86-92-1
00 61-70-
82 29-35-
44 20-25
-30
—
40-62 Loamy sand, sand — — 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
77-80-
84 19-23-
26 — —
221—Vandamme
loam, 9 to 30
percent slopes
Vandamme 85 C 0-9 Loam CL-ML,
ML
A-4 0- 0- 0 0- 0- 0 95-98-1
00 85-90-
95 70-78-
85 55-63-
70 25-30
-35
5-8 -10
9-42 Clay, clay loam CH, MH A-7 0- 0- 0 0- 0- 0 95-98-1 00 85-90-
95 80-85-
90 75-80-
85 50-55
-60
20-25-3
0 42-46 Bedrock — — — — — — — — — —
Engineering Properties---Mendocino County, Western Part, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/22/2023

Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
222—VandammeCaspar complex, 2
to 15 percent slopes
Vandamme 50 C 0-9 Sandy loam SM A-4 0- 0- 0 0- 0- 0 100-100 -100
100-100
-100
60-65-
70 35-43-
50 20-25
-30
NP-3 -5
9-42 Clay, clay loam CH, MH A-7 0- 0- 0 0- 0- 0 95-98-1 00 85-90-
95 80-85-
90 75-80-
85 50-55
-60
20-25-3
0 42-46 Weathered bedrock — — — — — — — — — —
Caspar 35 B 0-16 Sandy loam SM A-4 0- 0- 0 0- 0- 0 100-100 -100
95-98-1
00 60-68-
75 35-43-
50 20-25
-30
NP-3 -5
16-37 Sandy loam, loam,
sandy clay loam
SC-SM,
SC
A-4, A-6 0- 0- 0 0- 0- 0 85-93-1
00 75-88-1
00 50-68-
85 35-43-
50 25-30
-35
5-10-15
37-48 Sandy clay loam,
clay loam, sandy
clay
CL, SC A-6, A-7 0- 0- 0 0- 0- 0 85-93-1
00 75-88-1
00 65-78-
90 35-48-
60 30-38
-45
10-15-2
0 48-62 Sandy loam, loamy
sand
SM A-2 0- 0- 0 0- 0- 0 100-100
-100
100-100
-100
50-60-
70 20-28-
35 20-25
-30
NP-3 -5
Engineering Properties---Mendocino County, Western Part, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/22/2023

Engineering Properties–Mendocino County, Western Part, California Map unit symbol and
soil name
Pct. of
map
unit
Hydrolo
gic
group
Depth USDA texture Classification Pct Fragments Percentage passing sieve number— Liquid limit
Plasticit
y index
Unified AASHTO >10
inches
3-10
inches
4 10 40 200
In L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H L-R-H
224—VandammeIrmulco-Tramway
complex, 50 to 75
percent slopes
Vandamme 32 C 0-9 Loam CL-ML,
ML
A-4 0- 0- 0 0- 0- 0 95-98-1
00 85-90-
95 70-78-
85 55-63-
70 25-30
-35
5-8 -10
9-42 Clay, clay loam CH, MH A-7 0- 0- 0 0- 0- 0 95-98-1 00 85-90-
95 80-85-
90 75-80-
85 50-55
-60
20-25-3
0 42-46 Weathered bedrock — — — — — — — — — —
Irmulco 28 B 0-6 Loam CL-ML,
ML
A-4 0- 0- 0 0- 0- 0 90-95-1
00 85-93-1
00 75-85-
95 55-63-
70 25-30
-35
5-8 -10
6-61 Loam, clay loam,
gravelly loam
CL-ML,
GCGM,
CL, GC
A-4, A-6 0- 0- 0 0- 0- 0 65-83-1
00 60-80-1
00 50-70-
90 40-58-
75 25-33
-40
5-10-15
61-65 Weathered bedrock — — — — — — — — — —
Tramway 15 C 0-7 Loam CL-ML,
ML
A-4 0- 0- 0 0- 0- 0 90-95-1
00 85-93-1
00 65-80-
95 50-63-
75 25-30
-35
5-8 -10
7-12 Loam CL-ML,
CL
A-4, A-6 0- 0- 0 0- 0- 0 90-95-1
00 85-93-1
00 65-80-
95 50-63-
75 25-33
-40
5-10-15
12-28 Clay loam, gravelly
clay loam

CL, GC,
SC
A-6, A-7 0- 0- 0 0- 0- 0 65-83-1
00 60-80-1
00 55-75-
95 40-60-
80 30-38
-45
10-15-2
0 28-32 Weathered bedrock — — — — — — — — — —
Data Source Information
Soil Survey Area: Mendocino County, Western Part, California Survey Area Data: Version 18, Sep 7, 2022
Engineering Properties---Mendocino County, Western Part, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
5/22/2023

City of Fort Bragg
Fort Bragg Wastewater Collection System Master Plan
August 1, 2026 | J-1
Appendix J. Preliminary Engineering Reports
Improvement Name: Chief Celeri Dr Sewer Main Replacement Project ID: P-01
CIP Year: 2027
Description: Replace approximately 1,408 LF of existing 18” main and 474 LF of existing 24” main to 36” Ductile Iron (DI) pipe. The project area extends from the terminus of
the existing 18” main at W Alder Street east of N Main
Street to the existing 30” main at Maple Street and S
Main Street. The depth of the existing water mains is
approximately 7.5’ throughout. Utility conflicts will
need to be identified during pre-design.

Purpose: The main purpose of this project is to address condition and structural deficiencies in this line and
to accommodate expected increased capacity needs
as needed upstream improvements are addressed.

Hydraulic Model Results During the 10-year storm event, the existing main does not experience any capacity deficiencies.

However, as capacity deficiencies upstream of the
main are addressed, flows downstream increase. This
results in capacity issues in the existing main. These
resulting capacity deficiencies are eliminated with the system improvement, with max d/D reduced to 0.71.

Alternatives Analysis Pipeline replacement projects have a limited alternative alignment and associated alternatives
analysis; however, there is always a “no project”
alternative that can be considered. The “no project”
alternative for P-01 results in increasing risk of
structural collapse and deficiencies in capacity
during the 10-year storm.

Project Trigger: The primary project triggers for P-1 are the material, condition, and location of the line. It is Corrugated
Metal Pipe, which is no longer considered an
appropriate material for sanitary sewer gravity mains.

According to City staff, corrosion damage to the line
is probable. Portions of the line also run under storage structures at the Meno Mill lumber yard, and there is a danger that damage to the line could affect ground
stability near those structures. A secondary trigger is a moderately high risk score for the northern portion
of the line.

Expected Environmental
Compliance:

This project may qualify as categorically exempt.

However, the increased size to support future growth
may trigger an Initial Study (IS). If the IS identifies no significant impact, the project may adopt a Negative
Declaration and proceed with implementation. If the
IS identifies significant impacts, but the impacts can
be reduced to a less than significant level through
mitigation, then the project may adopt a Mitigated
Negative Declaration (MND) and proceed. Projects
with significant impacts that cannot be mitigated to
less than significant levels must be evaluated in an
Environmental Impact Report (EIR).

OPCC (2027 dollars): $2,853,000
Funding Opportunities: Funding would need to be evaluated further. WIFIA funding may be an option but requires a $5 million
project minimum. However, projects can be
combined to reach the minimum project size. Fort
Bragg qualifies as a small and rural community based
on the USDA’s eligibility criteria of providing loans to populations of 10,000 or less and USDA loans may be
available at a lower than market interest rate. A cost- benefit analysis should be used to evaluate if a USDA
loan would be worth applying for when compared to
water revenue bonds. To qualify, Fort Bragg must
propose projects that expand services to very small,
rural parts of the town. Eligible activities include legal and engineering fees, acquisitions, start-up
operations and maintenance, interest incurred during
construction, and the purchase of facilities to expand
service.

Improvement Name: WWTP Inflow Sewer Main Replacement
Project ID: P-02
CIP Year: 2027
Description: Replace approximately 2,300 LF of existing 30” main to a 42” Ductile Iron (DI) pipe. The project area
extends from the terminus of the existing 30” main at
South Main Street and Maple Street to the
Wastewater Treatment Plant (WWTP) intake. The
depth of the existing water mains areis approximately
12’ throughout. Utility conflicts will need to be
identified during pre-design.

Purpose: The main purpose of this project is to address condition and structural deficiencies in this line and
to accommodate expected increased capacity needs
as needed upstream improvements are addressed.

Hydraulic Model Results During the 10-year storm event, the existing main does not see any capacity deficiencies. However, as
capacity deficiencies upstream of the main are
addressed, flows downstream increase. This results
in capacity issues in the existing main. These resulting capacity deficiencies are eliminated with the system
improvement, with max d/D reduced to 0.68.

Alternatives Analysis Pipeline replacement projects have a limited alternative alignment and associated alternatives
analysis; however, there is always a “no project”
alternative that can be considered. The “no project”
alternative for P-02 results in increasing risks of
structural collapse and deficiencies in capacity
during the 10-year storm.

Project Trigger: P-1has multiple triggers. First is the known condition of the pipeline. City staff are aware of the poor
condition of the line, including large voids in the
bottom of the pipe in some areas, along with
corrosion damage. A second trigger is a high risk
score for the pipe, mainly driven by its age, material, and criticality.

Expected Environmental
Compliance:

This project may qualify as categorically exempt.

However, the increased size to support future growth
may trigger an Initial Study (IS). If the IS identifies no significant impact, the project may adopt a Negative
Declaration and proceed with implementation. If the
IS identifies significant impacts, but the impacts can
be reduced to a less than significant level through
mitigation, then the project may adopt a Mitigated
Negative Declaration (MND) and proceed. Projects
with significant impacts that cannot be mitigated to
less than significant levels must be evaluated in an
Environmental Impact Report (EIR).

OPCC (2027 dollars): $6,103,000
Funding Opportunities: Funding would need to be evaluated further. WIFIA funding may be an option, but requires a $5 million
project minimum. However, projects can be
combined to reach the minimum project size. Fort
Bragg qualifies as a small and rural community based
on the USDA’s eligibility criteria of providing loans to populations of 10,000 or less and USDA loans may be
available at a lower than market interest rate. A costbenefit analysis should be used to evaluate if a USDA loan would be worth applying for when compared to
water revenue bonds. To qualify, Fort Bragg must
propose projects that expand services to very small,
rural parts of the town. Eligible activities include legal and engineering fees, acquisitions, start-up
operations and maintenance, interest incurred during
construction, and the purchase of facilities to expand
service.

Improvement Name: E Oak St Replacement IV
Project ID: P-16
CIP Year: 2027
Description: Replace 146 LF of existing 8” main to a 10” PVC SDR 35 pipe. Replace 1,203 LF of existing 8" main to a 12”
PVC SDR 35 pipe. Replace 303 LF of existing 6" main
to a 16” PVC SDR 35 pipe. Replace 319 LF of existing
6” main to a to 18” PVC SDR 35 pipe. The project area
extends along E. Oak Street from the existing 8” main
at Dennison Lane to the existing 6” at Sanderson
Way. The depth of the existing water mains is
approximately 7’ throughout. Utility conflicts will need to be identified during pre-design.

Purpose: The main purpose of this project is to address capacity issues in the existing system under existing
10-year storm conditions.

Hydraulic Model Results During the 10-year storm event, the existing main is over capacity with a max d/D of 1, with moderate
overflows expected on three manholes. This capacity
deficiency is eliminated with the system
improvement, with max d/D reduced to 0.74.

Alternatives Analysis Pipeline replacement projects have a limited alternative alignment and associated alternatives
analysis; however, there is always a “no project”
alternative that can be considered. The “no project”
alternative for P-16 results in deficiencies in capacity during the 10-year storm.

Project Trigger: There are multiple project triggers for P-16. The primary drivers are the full pipe flow and manhole
overflows of these gravity mains during the 10-year
design storm, along with their moderately high risk
score. A secondary driver is the pipe segments
proximity to a planned paving and storm drain
improvement project that is currently scheduled in
the City’s existing CIP program. These pipe segments
can be replaced at the same time as the other CIP
work eliminating the need to open the pavement
again.

Expected Environmental
Compliance:

This project may qualify as categorically exempt.

However, the increased size to support future growth
may trigger an Initial Study (IS). If the IS identifies no significant impact, the project may adopt a Negative
Declaration and proceed with implementation. If the
IS identifies significant impacts, but the impacts can
be reduced to a less than significant level through
mitigation, then the project may adopt a Mitigated
Negative Declaration (MND) and proceed. Projects
with significant impacts that cannot be mitigated to
less than significant levels must be evaluated in an
Environmental Impact Report (EIR).

OPCC (2027 dollars): $724,000
Funding Opportunities: Funding would need to be evaluated further. WIFIA funding may be an option, however, there is a $5
million project minimum. But projects can be
combined to reach the minimum project size. Fort
Bragg qualifies as a small and rural community based
on the USDA’s eligibility criteria of providing loans to populations of 10,000 or less and USDA loans may be
available at a lower than market interest rate. A costbenefit analysis should be used to evaluate if a USDA loan would be worth applying for when compared to
water revenue bonds. To qualify, Fort Bragg must
propose projects that expand services to very small,
rural parts of the town. Eligible activities include legal and engineering fees, acquisitions, start-up
operations and maintenance, interest incurred during
construction, and the purchase of facilities to expand
service.

Improvement Name: E Oak St Replacement IV – Buildout Option Project ID: P-16
CIP Year: 2027
Description: Replace 146 LF of existing 8” main to 18” PVC SDR 35 pipe. Replace 1,203 LF of existing 8" main to 18” PVC
SDR 35 pipe. Replace 303 LF of existing 6" main to 18”
PVC SDR 35 pipe. Replace 319 LF of existing 6” main
to a to 18” PVC SDR 35 pipe. The project area extends
along E. Oak Street from the existing 8” main at
Dennison Lane to the existing 6” at Sanderson Way.

The depth of the existing water mains are
approximately 7’ throughout. Utility conflicts will need to be identified during pre-design.

Purpose: The main purpose of this project is to address capacity issues in the existing system under 10-year
storm conditions with anticipated future buildout.

Hydraulic Model Results During the 10-year storm event and future buildout conditions, the main is over capacity with a max d/D
of 1, with moderate overflows expected on three
manholes. This capacity deficiency is eliminated with
the system improvement, with max d/D reduced to

0.74. Alternatives Analysis Pipeline replacement projects have a limited alternative alignment and associated alternatives
analysis; however, there is always a “no project”
alternative that can be considered. The “no project”
alternative for P-16 results in deficiencies in capacity during the 10-year storm and future buildout
conditions.

Project Trigger: There are multiple project triggers for P-16. The primary drivers are the full pipe flow and manhole
overflows of these gravity mains during the 10-year
design storm, along with their moderately high risk
score. A secondary driver is the pipe segments
proximity to a planned paving and storm drain
improvement project that is currently scheduled in
the City’s existing CIP program. These pipe segments
can be replaced at the same time as the other CIP
work eliminating the need to open the pavement
again.

Expected Environmental
Compliance:

This project may qualify as categorically exempt.

However, the increased size to support future growth
may trigger an Initial Study (IS). If the IS identifies no significant impact, the project may adopt a Negative
Declaration and proceed with implementation. If the
IS identifies significant impacts, but the impacts can
be reduced to a less than significant level through
mitigation, then the project may adopt a Mitigated
Negative Declaration (MND) and proceed. Projects
with significant impacts that cannot be mitigated to
less than significant levels must be evaluated in an
Environmental Impact Report (EIR).

OPCC (2027 dollars): $866,000
Funding Opportunities: Funding would need to be evaluated further. WIFIA funding may be an option, however, there is a $5
million project minimum. But projects can be
combined to reach the minimum project size. Fort
Bragg qualifies as a small and rural community based
on the USDA’s eligibility criteria of providing loans to populations of 10,000 or less and USDA loans may be
available at a lower than market interest rate. A costbenefit analysis should be used to evaluate if a USDA loan would be worth applying for when compared to
water revenue bonds. To qualify, Fort Bragg must
propose projects that expand services to very small,
rural parts of the town. Eligible activities include legal and engineering fees, acquisitions, start-up
operations and maintenance, interest incurred during
construction, and the purchase of facilities to expand
service.

City of Fort Bragg
Fort Bragg Wastewater Collection System Master Plan
August 1, 2026 | K-1
Appendix K. CIP Projects
Table K-1 - CIP Projects
Time
Frame
(years)
Priority RankingCIP ID
Project Name Category
Pipe Count
Total Pipe
Footage
(FT) Project Description Buildout Project Alternative Description Associated Projects Escalated Existing
Project Cost
Escalated Buildout
Project Cost
0-5 yrs 1 P-01
Chief Celeri Dr
Sewer Main
Replacement
Capacity 3 1,408 Replace 1408 FT of 18-inch pipe with 36-inch.

Replace 474 FT of 24-inch pipe with 36-inch.

P-10: Chief Celeri Dr
Water Main
Replacement
(0-5 yrs)
$2,853,000
0-5 yrs 2 F-01 Elm Street Force
Main CIPP Lining Renewal 2 2,293 CIPP lining of 2293 FT force main $1,053,000 0-5 yrs 3 P-02 WWTP Inflow Sewer
Main Replacement Capacity 9 2,305 Replace 2305 FT of 30-inch pipe with 42-inch P-3: Noyo Center
Water Line
(0-5 yrs)
$6,103,000
0-5 yrs 4 P-03 E Alder St Sewer
Main Replacement Capacity 6 797
Replace 174 FT of 18-inch pipe with 24-inch.

Replace 187 FT of 18-inch pipe with 30-inch.

Replace 231 FT of 18-inch pipe with 24-inch.

Replace 205 FT of 18-inch pipe with 30-inch.

P-10: Chief Celeri Dr
Water Main
Replacement
(0-5 yrs)
$892,000
0-5 yrs 5 P-16
E Oak St Sewer
Main Replacement
IV
Capacity 8 1,970
Replace 303 FT of 6-inch pipe with 16-inch.

Replace 319 FT of 6-inch pipe with 18-inch.

Replace 146 FT of 8-inch pipe with 10-inch.

Replace 1203 FT of 8-inch pipe with 12-inch.

Replace 303 FT of 6-inch pipe with 18-inch.

Replace 319 FT of 6-inch pipe with 18-inch.

Replace 146 FT of 8-inch pipe with 18-inch.

Replace 1203 FT of 8-inch pipe with 18-inch.

Paving Plan
(0-5 yrs) $724,000 $866,000
0-5 yrs 6 P-10 S Franklin St Sewer
Main Replacement Capacity 2 633 Replace 633 FT of 8-inch pipe with 24-inch. $351,000 0-5 yrs 7 P-11 S Harrison St Sewer
Main Replacement Capacity 1 662 Replace 662 FT of 6-inch pipe with 18-inch. $291,000 0-5 yrs 8 P-06
E Oak St Sewer
Main Replacement
III
Capacity 6 989 Replace 167 FT of 6-inch pipe with 10-inch.

Replace 822 FT of 6-inch pipe with 16-inch.

V-1: Oak St. Valves
(0-5 yrs) $377,000
0-5 yrs 9 P-34
North Fort Bragg
Sewer Main
Extension
Build-out 2 1,970 Install new 1970 FT of 8 inch pipe diameter.

P-2: N Fort Bragg
Water Main Extension
(0-5 yrs)
$471,000
0-5 yrs 10 P-35
GP Mill Sewer Main
Extension I (Noyo
Center)
Build-out
1 1,074
Install new 1074 FT of 16-inch pipe diameter.

P-3: Noyo Center
Water Line
(0-5 yrs)
$471,000
Time
Frame
(years)
Priority RankingCIP ID
Project Name Category
Pipe Count
Total Pipe
Footage
(FT) Project Description Buildout Project Alternative Description Associated Projects Escalated Existing
Project Cost
Escalated Buildout
Project Cost
0-5 yrs 11 R-01 CCTV Condition
Inspection Renewal Placeholder for CCTV Condition Inspection of gravity mains. $500,000 0-5 yrs 12 R-02 Lift Station
Rehabilitation Renewal
Consolidated electrical, mechanical, and
structural upgrades at multiple lift stations,
coordinated as a single capital project to
maintain operations and minimize outages during
rehabilitation.
$442,000
0-5 yrs 13 R-03 0-5 yr CIPP Lining
Projects Renewal Targeted CIPP lining projects based on known pipe condition. $500,000 0-5 yrs 14 O-01 Capital Plan Update Other 10-year capital plan update $110,000 0-5 Yr Subtotal $14,196,000 $15,280,000
6-10
yrs
15 P-05 E Oak St Sewer
Main Replacement II Capacity 8 2,893
Replace 715 FT of 10-inch pipe with 16-inch.

Replace 1462 FT of 10-inch pipe with 18-inch.

Replace 716 FT of 6-inch pipe with 16-inch.

V-1: Oak St. Valves
(0-5 yrs) $1,399,000
6-10
yrs
16 P-13 Cedar St
Replacement I Capacity 12 2,172
Replace 919 FT of 6-inch pipe with 8-inch.

Replace 11 FT of 6-inch pipe with 18-inch.

Replace 1241 FT of 8-inch pipe with 18-inch.

Replace 11 FT of 6-inch pipe with 12-inch.

Replace 906 FT of 6-inch pipe with 16-inch.

Replace 11 FT of 6-inch pipe with 24-inch.

Replace 1241 FT of 8-inch pipe with 24-inch.

P-1: Cedar St Water
Line Replacement
(0-5 yrs)
$961,000 $1,224,000
6-10
yrs
17 P-18 E Laurel St Sewer
Main Replacement Capacity 2 783 Replace 783 FT of 8-inch pipe with 18-inch. Replace 783 FT of 8-inch pipe with 24-inch. $399,000 $504,000 6-10
yrs
18 P-26 E Chestnut St Sewer
Main Replacement II Capacity 15 3,958
Replace 176 FT of 6-inch pipe with 10-inch.

Replace 1734 FT of 6-inch pipe with 12-inch.

Replace 143 FT of 6-inch pipe with 8-inch.

Replace 384 FT of 8-inch pipe with 10-inch.

Replace 1180 FT of 8-inch pipe with 12-inch.

Replace 176 FT of 6-inch pipe with 12-inch.

Replace 748 FT of 6-inch pipe with 12-inch.

Replace 986 FT of 6-inch pipe diameter to 16-
inch.

Replace 143 FT of 6-inch pipe with 10-inch.

Replace 384 FT of 8-inch pipe with 12-inch.

Replace 1180 FT of 8-inch pipe with 16-inch.

Replace 342 FT of 12-inch pipe with 16-inch.

P-9: East Chestnut
Street Water Main
Replacement
(6-10 yrs)
$1,567,000 $1,725,000
Time
Frame
(years)
Priority RankingCIP ID
Project Name Category
Pipe Count
Total Pipe
Footage
(FT) Project Description Buildout Project Alternative Description Associated Projects Escalated Existing
Project Cost
Escalated Buildout
Project Cost
6-10
yrs
19 P-29 Maple St Sewer
Main Replacement Capacity 1 180 Replace 180 FT of 6-inch pipe with 10-inch.

P-8: Maple St Water
Main Loop
(6-10 yrs)
$66,000
6-10
yrs
20 P-31
South Harold St
Sewer Main
Replacement
Capacity 2 902 Replace 902 FT of 6-inch pipe with 12-inch.

P-8: Maple St Water
Main Loop
(6-10 yrs)
$364,000
6-10
yrs
21 P-24
N Sanderson Way
Sewer Main
Replacement
Capacity 4 647 Replace 647 FT of 6-inch pipe with 18-inch. Replace 647 FT of 6-inch pipe with 24-inch.

P-1: Cedar St Water
Line Replacement
(0-5 yrs)
$330,000 $416,000
6-10
yrs
22 P-23
N McPherson St
Sewer Main
Replacement
Capacity 5 909
Replace 225 FT of 18-inch pipe with 24-inch.

Replace 410 FT of 6-inch pipe with 10-inch.

Replace 42 FT of 6-inch pipe with 12-inch.

Replace 231 FT of 8-inch pipe with 18-inch.

Replace 225 FT of 18-inch pipe with 30-inch.

Replace 410 FT of 6-inch pipe with 10-inch.

Replace 42 FT of 6-inch pipe with 16-inch.

Replace 231 FT of 8-inch pipe with 30-inch.
$429,000 $1,068,000
6-10
yrs
23 P-15 Dennison Ln Sewer
Main Replacement Capacity 3 1,151 Replace 331 FT of 6-inch pipe with 10-inch.Replace 325 FT of 8-inch pipe with 10-inch.

Replace 331 FT of 6-inch pipe with 16-inch.

Replace 325 FT of 8-inch pipe with 16-inch.

Replace 494 FT of 6-inch pipe with 8-inch.

P-1: Cedar St Water
Line Replacement
(0-5 yrs)
$239,000 $526,000
6-10
yrs
24 P-33
Georgia-Pacific-Haul
Rd Sewer Main
Replacement
Capacity 3 874 Replace 681 FT of 8-inch pipe with 10-inch.

Replace 193 FT of 8-inch pipe with 12-inch. $326,000
6-10
yrs
25 P-28
S Sanderson Way
Sewer Main
Replacement
Capacity 3 613 Replace 613 FT of 6-inch pipe with 8-inch. $216,000 6-10
yrs
26 P-27
Minnseota Ave
Sewer Main
Replacement
Capacity 1 700 Replace 700 FT of 6-inch pipe with 8-inch. $246,000 6-10
yrs
27 P-20
E Redwood Ave
Sewer Main
Replacement
Capacity 2 703 Replace 703 FT of 8-inch pipe with 18-inch. Replace 703 FT of 8-inch pipe with 24-inch.

P-1: Cedar St Water
Line Replacement
(0-5 yrs)
$359,000 $452,000
6-10
yrs
28 P-32 Cypress St Sewer
Main Replacement Capacity 2 674 Replace 674 FT of 8-inch pipe with 10-inch. $245,000 6-10
yrs
29 P-30 Park St Sewer Main
Replacement Capacity 1 250 Replace 250 FT of 6-inch pipe with 10-inch.

P-8: Maple St Water
Main Loop
(6-10 yrs)
$91,000
Time
Frame
(years)
Priority RankingCIP ID
Project Name Category
Pipe Count
Total Pipe
Footage
(FT) Project Description Buildout Project Alternative Description Associated Projects Escalated Existing
Project Cost
Escalated Buildout
Project Cost
6-10
yrs
30 P-04 E Oak St Sewer
Main Replacement I Capacity 1 316 Replace 316 FT of 6-inch pipe with 8-inch.

P-13: E. Alder St Water
Main Replacement
(6-10 yrs)
$112,000
6-10
yrs
31 P-08 E Chestnut St Sewer
Main Replacement Capacity 2 703 Replace 363 FT of 12-inch pipe with 18-inch. Replace 340 FT of 8-inch pipe with 18-inch.

P-3: Noyo Center
Water Line
(0-5 yrs)
$359,000
6-10
yrs
32 P-21 N Harold St Sewer
Main Replacement Capacity 1 433 Replace 433 FT of 8-inch pipe with 18-inch. Replace 433 FT of 8-inch pipe with 24-inch. $221,000 $279,000 6-10
yrs
33 P-25 N Whipple St Sewer
Main Replacement Capacity 1 439 Replace 439 FT of 10-inch pipe with 18-inch. Replace 439 FT of 10-inch pipe with 24-inch. $224,000 $282,000 6-10
yrs
34 P-14 Cedar St
Replacement II Capacity 1 399 Replace 399 FT of 6-inch pipe with 10-inch.

P-1: Cedar St Water
Line Replacement
(0-5 yrs)
$145,000
6-10
yrs
35 P-07 N Franklin St Sewer
Main Replacement Capacity 4 472 Replace 130 FT of 12-inch pipe with 18-inch.Replace 342 FT of 12-inch pipe with 24-inch.

P-13: E. Alder St Water
Main Replacement $286,000
6-10
yrs
36 P-19 E Pine St Sewer
Main Replacement Capacity 2 745 Replace 375 FT of 15-inch pipe with 18-inch.Replace 370 FT of 15-inch pipe with 18-inch.

Replace 375 FT of 15-inch pipe with 24-inch.

Replace 370 FT of 15-inch pipe with 30-inch. $380,000 $971,000 6-10
yrs
37 P-17 E Fir St Sewer Main
Replacement Capacity 7 1,140 Replace 196 FT of 8-inch pipe with 12-inch.Replace 944 FT of 18-inch pipe with 24-inch.

Replace 196 FT of 8-inch pipe with 16-inch.

Replace 944 FT of 18-inch pipe with 30-inch. $686,000 $1,951,000 6-10
yrs
38 P-12 S Main St Sewer
Main Replacement II Capacity 3 671 Replace 66 FT of 12-inch pipe with 24-inch. $432,000 6-10
yrs
39 P-22 N Main St Sewer
Main Replacement Capacity 7 1,829 Replace 1829 FT of 21-inch pipe with 24-inch. Replace 1829 FT of 21-inch pipe with 30-inch. $1,176,000 $3,605,000 6-10
yrs
40 P-09 Hazel St Sewer
Main Replacement Capacity 1 357 Replace 357 FT of 12-inch pipe with 24-inch. $230,000 41 P-36 S Main St Sewer
Main Extension
BuildOut 3 2,334 Install new 2334 FT of 8-inch pipe diameter. $647,000
6-10
yrs
42 R-04 CCTV Condition
Inspection Renewal Placeholder for CCTV Condition Inspection of gravity mains. $634,000 6-10
yrs
43 R-05 6-10 yr CIPP Lining
Projects Renewal Placeholder for CIPP lining projects to be identified through condition assessment $761,000 6-10
yrs
44 O-02 Capital Plan Update Other 10-year capital plan update $127,000 Time
Frame
(years)
Priority RankingCIP ID
Project Name Category
Pipe Count
Total Pipe
Footage
(FT) Project Description Buildout Project Alternative Description Associated Projects Escalated Existing
Project Cost
Escalated Buildout
Project Cost
6-10 Yr Subtotal $13,010,000 $19,689,000
Total $27,206,000 $34,969,000
>10 yr 45 P-53 Basin St Sewer Main
Replacement Build-Out 10 1767.20043
Increase 235 FT of 10-inch pipe diameter to 12-
inch. Increase 1160 FT of 8-inch pipe diameter
to 10-inch. Increase 372 FT of 8-inch pipe
diameter to 12-inch.
$728,000
>10 yr 46 P-40 Cedar St Sewer
Main Extension I Build-Out 3 694.40313 Install new 694 FT of 12-inch pipe diameter.

P-1: Cedar St Water
Line Replacement
(0-5 yr)
$250,000
>10 yr 47 P-45 Cedar St Sewer
Main Extension I Build-Out 3 2182.4855 Install new 2182 FT of 8-inch pipe diameter.

P-1: Cedar St Water
Line Replacement
(0-5 yr)
$661,000
>10 yr 48 P-46 Cedar St Sewer
Main Extension III Build-Out 4 2838.60887 Install new 2839 FT of 8-inch pipe diameter.

P-1: Cedar St Water
Line Replacement
(0-5 yr)
$859,000
>10 yr 49 P-43 Dennison Ln Sewer
Main Extension Build-Out 7 3670.97975 Install new 3439 FT of 12-inch pipe diameter. Install new 232 FT of 16-inch pipe diameter.

P-1: Cedar St Water
Line Replacement
(0-5 yr)
$1,332,000
>10 yr 50 P-49 E Chestnut St Sewer
Main Extension Build-Out 3 2987.56034 Install new 2988 FT of 10-inch pipe diameter. $942,000 >10 yr 51 P-44 Fawn Ln Sewer
Main Extension Build-Out 1 1335.32525 Install new 1335 FT of 12-inch pipe diameter.

P-1: Cedar St Water
Line Replacement
(0-5 yr)
$480,000
>10 yr 52 P-47
Fort Bragg
Sherwood Rd Sewer
Main Extension
Build-Out 4 3659.062 Install new 1613 FT of 12-inch pipe diameter.

Install new 2046 FT of 18-inch pipe diameter.
$1,552,000
>10 yr 53 P-50
Georgia-Pacific-Haul
Rd Sewer Main
Extension
Build-Out 13 5385.31259
Install new 852 FT of 12-inch pipe diameter.

Install new 4301 FT of 16-inch pipe diameter.

Install new 232 FT of 8-inch pipe diameter.

Install proposed lift station with 80 GPM
capacity.
$2,786,000
>10 yr 54 P-37 GP Mill Sewer Main
Extension II Build-Out 4 2782.22572 Install new 2360 FT of 10-inch pipe diameter. Install new 422 FT of 18-inch pipe diameter. $945,000
>10 yr 55 P-38 GP Mill Sewer Main
Extension III Build-Out 8 5954.50522 Install new 2348 FT of 10-inch pipe diameter. Install new 3606 FT of 12-inch pipe diameter. $2,036,000
>10 yr 56 P-39 GP Mill Sewer Main
Extension IV Build-Out 8 7199.21355
Install new 3261 FT of 10-inch pipe diameter.

Install new 3939 FT of 8-inch pipe diameter.

Install proposed lift station with 80 GPM
capacity
P-10: Chief Celeri Dr
Water Main
Replacement (6-10 yr)
$2,808,000
>10 yr 57 P-55 Highway 20 Sewer
Main Extension Build-Out 5 729.304155 Install new 729 FT of 12-inch pipe diameter. $262,000 Time
Frame
(years)
Priority RankingCIP ID
Project Name Category
Pipe Count
Total Pipe
Footage
(FT) Project Description Buildout Project Alternative Description Associated Projects Escalated Existing
Project Cost
Escalated Buildout
Project Cost
>10 yr 58 P-51 Jacobsen Ln Sewer
Main Extension I Build-Out 1 620.20626 Install new 620 FT of 4-inch pipe diameter. $116,000 >10 yr 59 P-52 Jacobsen Ln Sewer
Main Extension II Build-Out 2 482.705068 Install new 483 FT of 8-inch pipe diameter. $147,000 >10 yr 60 P-48 Lyta Way Sewer
Main Extension Build-Out 4 5186.15799 Install new 5186 FT of 12-inch pipe diameter. $1,863,000 >10 yr 61 P-54 N Harbor Dr Sewer
Main Replacement Build-Out 2 280.248742
Increase 30 FT of 12-inch pipe diameter to 24-
inch. Increase 251 FT of 8-inch pipe diameter to
24-inch.
$197,000
>10 yr 62 P-41
Nurnberger Ln
Sewer Main
Extension
Build-Out 2 3058.77951 Install new 3059 FT of 12-inch pipe diameter.

P-1: Cedar St Water
Line Replacement
(0-5 yr)
$1,099,000
>10 yr 63 P-56 Ocean View Sewer
Main Extension Build-Out 34 23052.9975 Install new 23053 FT of 8-inch pipe diameter. $6,974,000 >10 yr 64 P-42 Peterson Ln Sewer
Main Extension Build-Out 1 1653.71432 Install new 1654 FT of 12-inch pipe diameter.

P-1: Cedar St Water
Line Replacement
(0-5 yr)
$594,000
>10 yr 65 LS-1
South Noyo LS
Improvement Build-Out N/A N/A Increase South Noyo LS capacity from 920 GPM to 1,500 GPM. $7,337,000
>10 Yr Subtotal $0 $33,968,000
Total $27,206,000 $68,937,000
Figure K-1. - 0-5 Yr Capital Projects
Figure K-2. 6-10 yr Capital Projects
Figure K-3. >10 Yr Capital Projects