Repetitive Loss Analysis
On May 3, 2016, the City of Sacramento’s Repetitive Loss Area Analysis (RLAA) was adopted by City Council as part of the City of Sacramento’s Comprehensive Flood Management Plan (CFMP).
Since its initial adoption, additional investigations have been performed in the City’s repetitive loss areas. This report reflects all current and past findings.
The City of Sacramento is using the ISO repetitive loss list and AW-501s dated December 2021, and a follow-up list dated December 2022 as the basis for this RLAA. This is the last officially sanctioned Community Rating System (CRS) repetitive loss data set issued to the City. According to the list, the City of Sacramento has 59 repetitive loss properties; 23 are mitigated, 23 are unmitigated, and 13 are misidentified and are pending removal. See Attachment 1 for details of the Repetitive Loss List. Area analyses are not required to be completed for mitigated properties.
Four properties have been added to the list since the 2016 analysisthat are analyzed herein. These are Region 3-Area 12 and Region 6-Areas 19 and 20.
The City is seeking mitigated status approval for one property; this property is included in the area analyses provided in this RLAA.
Repetitive Loss Area Analysis Process
The RLAA planning process incorporated requirements from Section 510 of the 2017 CRS Coordinator’s Manual. The planning process also incorporated requirements from the following guidance documents:
• Federal Emergency Management Agency (FEMA) publication Reducing Damage from Localized Flooding: A Guide for Communities, Part III Chapter 7; • CRS publication Mapping Repetitive Loss Areas dated August 15, 2008; and • Center for Hazards Assessment Response and Technology, University of New Orleans draft publication The Guidebook to Conducting Repetitive Loss Area Analyses.
Most specifically, this RLAA included all five planning steps included in the 2017 CRS Coordinator’s Manual:
Step 1. Advise all properties in the repetitive loss areas that the analysis will be conducted and request their input on the hazard and recommendation actions.
Step 2. Contact agencies or organizations that may have plans or studies that could affect the cause or impacts of the flooding. The agencies and organizations must be identified in the analysis report.
Step 3. Visit each building and collect basic data.
Step 4. Review alternative approaches and determine whether any property protection measures or drainage improvements are feasible.
Step 5. Document the findings. A separate analysis report must be prepared for each area.
Beyond the five planning steps, additional credit criteria must be met:
• The community must have at least one repetitive loss area delineated in accordance with the criteria in Section 503.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
• The repetitive loss area must be mapped as described in Section 503.a. A Category “C” community must prepare analyses for all of its repetitive loss areas if it wants to use the RLAA to meet its repetitive loss planning prerequisite. • The RLAA report(s) must be submitted to the community’s governing body and made available to the media and the public. The complete RLAA report(s) must be adopted by the community’s governing body or by an office that has been delegated approval authority by the community’s governing body.
• The community must prepare an annual progress report for its area analysis. • The community must update its RLAA in time for each CRS cycle verification visit.
The majority of the repetitive loss areas experience the same cause of flooding, that of local drainage problems; however, each region has unique characteristics that impact the property protection measures that are most effective in promoting flood protection. Therefore, data collected and analyzed in steps three, four, and five have been organized by region.
1. Step 1. Advise all Property Owners
RLAA Step 1 (2017 CRS Coordinator’s Manual Section 512.b) requires notification that an analysis is being conducted to all properties in the repetitive loss areas, with a request for input on the hazard and recommended actions. The City of Sacramento sends an annual notice to all repetitive loss area properties with information on the potential flood hazard and recommended mitigation activities.
Before fieldwork began on the current RLAA, individual letters were mailed to property owners within all six repetitive loss areas (Figure 1). Letters were mailed to all properties within each area, including repetitive loss properties, and additional properties with similar flooding conditions but which have no known claims paid against the NFIP. In total, 438 notification letters were mailed to property owners. The letters were sent out on January 17, 2023. Copies of the addresses are maintained on file with the City of Sacramento, Department of Utilities. In accordance with the privacy act of 1974, the letters will not be shared with the general public.
For this process, the City also developed a questionnaire (Figure 2), which allowed homeowners to share important information about flooding in their neighborhoods. The questionnaire included an explanation of what a repetitive loss area was, and requested historical information on the properties’ flood history.
Prior to the field visit, a second targeted outreach letter and questionnaire were mailed in March 2023. This mailing included properties recently added to the City’s repetitive loss list. A copy of this targeted letter is included as Figure 3.
1.1. Mailed Questionnaire and Online Survey
The questionnaire wasincluded with each letter mailed to building owners, and was also available online, through an online link as well as a QR code. The questionnaire asks about the type of foundation and if the building has a basement, if the building has experienced any type of flooding, the cause of the flooding, flood protection measures and whether the owner has flood CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
insurance. A copy of the entire mailing, including the property notification letter, survey, and “Protect Your Home from Flooding” FEMA brochure, is included in Attachment 2.
Of the 438 mailed notification letters and questionnaires, the City of Sacramento received 14 responses. A compilation of the responses can be found in Attachment 4.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
FIGURE 1.EXAMPLE RLAAPROPERTY NOTIFICATION LETTER (JANUARY MAILING) CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
FIGURE 2.QUESTIONNAIRE SENT WITH MAILING,AND AVAILABLE ONLINE CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
FIGURE 3.TARGETED PROPERTY NOTIFICATION LETTER MAILED IN ADVANCE OF FIELD VISIT (MARCH MAILING) CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
2. Step 2. Contact Agencies and Organizations
The City reached out to external agencies and internal departments to access plans and studies that could affect or help determine the causes or impacts of flooding within the repetitive loss area. The following reports could help determine future problems and potentially assist in mitigation measures for the property owners.
• City of Sacramento
o Comprehensive Flood Management Plan
o Sacramento Rescue and Flood Evacuation Maps: Levee & Folsom Dam Breach o Capital Improvement Plan and Utilities Drainage Master Plans o Urban Design Guidelines
o Historical flood data
• County of Sacramento
o Sacramento County Local Hazard Mitigation Plan
• California Department of Water Resources (DWR)
o FloodSAFE
o Levee Flood Protection Zone Map (LFPZ)
o Best Available Maps
o California Data Exchange Center (CDEC)
• Sacramento Area Flood Control Agency (SAFCA)
• US Army Corps of Engineers
o Sacramento District Levee Systems Inspection Status
• FEMA
o Repetitive Loss & Flood Insurance Claims Data
o FEMA Flood Insurance Studies/Flood Insurance Rate Maps o NFIP Coordinators Manual
• National Oceanic and Atmospheric Administration California Nevada River Forecast Center • GEI Consultants, Inc.
o Technical Memorandum: Repetitive Flood Loss Investigation
2.1.Summary of Studies and Reports
City of Sacramento Comprehensive Flood Management Plan
The purpose of this plan is to identify, assess, and mitigate flood hazards and flood risk in the City using nonstructural and structural measures. This plan analyzes improving floodplain management through land use planning and development, levee security, outreach, internal drainage, structural measures, and emergency management. The plan also develops strategies and action items on how the City will mitigate flood hazards and vulnerabilities.
Sacramento Rescue and Evacuation Maps
The maps show the results of hypothetical levee and dam failures at different locations within the City and County of Sacramento for the 100-year and 200-year flood events. The maps show evacuation routes and water depths over time.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
City of Sacramento Proposed Capital Improvement Program, 2023-2028 The 2023-2028 Capital Improvement Plan is a five-year plan for the funding and construction or repair of City buildings and facilities such as streets, roads, storm drains, traffic signals, parks, and community centers. The total planned Capital Improvement Plan budget for fiscal years 2023-2028 is $465 million.
The FY2023/24 budget for the City Utilities Program totals $47.3 million for 37 projects or programs. The five-year plan totals $235.7 million for 42 projects or programs. A total of $9 million is designated for storm drainage projects.
Sacramento County Local Hazard Mitigation Plan
The purpose of hazard mitigation is to reduce or eliminate long-term risk to people and property from hazards. The communities within Sacramento County developed this Local Hazard Mitigation Plan (LHMP) update to make its residents less vulnerable to future hazard events. This plan was prepared pursuant to the requirements of the Disaster Mitigation Act of 2000 so that Sacramento County would be eligible for FEMA’s Pre-Disaster Mitigation and Hazard Mitigation Grant programs.
The communities followed a planning process prescribed by FEMA, which began with the formation of a hazard mitigation planning committee comprising key representatives and other regional stakeholders.
The committee conducted a risk assessment that identified and profiled hazards that pose a risk within the County, assessed the County’s vulnerability to these hazards, and examined the capabilities in place to mitigate them. The County is vulnerable to several hazards that are identified, profiled, and analyzed in this plan. Floods, levee failures, wildfires, and severe weather are among the hazards that can have a significant impact on the County.
The 2021 LHMP update serves to update the 2016 FEMA approved Sacramento County LHMP. Annex F details the hazard mitigation planning elements specific to the City of Sacramento. The Comprehensive Flood Management Plan and RLAA from 2016 are those most recently used for reference.
FloodSAFE, Levee Flood Protection Zone Map, and Best Available Maps The FloodSAFE program is a sustainable integrated flood management and emergency response system throughout California where steps are taken to manage flood risk. Multiple types of maps have been prepared as part of this program. LFPZ maps were prepared for the Lower Sacramento Valley Region as part of the FloodSAFE initiative. The LFPZ maps identify the areas that are protected by a project levee.
The LFPZ maps are also used as part of the DWR’s levee risk notification program. The DWR has the Best Available Maps to display the latest floodplains in a web viewer located at http://gis.bam.water.ca.gov/bam. With this viewer, the DWR has expanded the floodplains to cover all counties in the State and to include 500-year floodplains. The 100-, 200-, and 500-year floodplains can be selected for display using this viewer. The web viewer allows users to view a particular area, identify their potential flood hazards, and print a floodplain map.
Sacramento District Levee Systems Inspection Status
The levee inspections show any unacceptable items within the levees that may have affected the repetitive loss area properties in the past and future projects. These unacceptable items include items CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
such as encroachments, slope stability issues, animal burrowing, and erosion. The State of California also provides levee inspection reports.
California Data Exchange Center
The CDEC installs, maintains, and operates an extensive hydrologic data collection network, including automatic precipitation and river stage sensors for the flood forecasting program through a centralized location online. The CDEC stores and processed real-time hydrologic information gathered by various cooperators throughout the State; it then disseminates this information to support forecasting and flood operations activities and to meet the data reporting needs of various cooperators, public and private agencies, the news media, and the public.
The CDEC includes the ALERT gauges maintained by the City and County of Sacramento. ALERT is an acronym which stands for Automated Local Evaluation in Real Time. The Sacramento City and County's ALERT system consists of two base stations and approximately 50 gauging stations.
FEMA Flood Insurance Studies (FIS)
FEMA’s FIS for the City of Sacramento are dated August 16, 2012, and June 16, 2015. The FIS revises and updates information on the existence and severity of flood hazards within the City. The FIS also includes part of the revised digital Flood Insurance Rate Maps (FIRMs), which delineate updated Special Flood Hazard Areas and flood zones for the City.
In 2022, FIS Number 06067CV001E was developed that affected Sacramento County (CID 060262) and Citrus Heights (CID 060765). FEMA is revising the FIRMs and FIS for Arcade Creek in Sacramento County.
The revision will enlarge the floodplain and increase the 100-year flood elevations by up to more than 2 feet. A number of properties in the County of Sacramento are being added to the floodplain for the first time and property owners may be required to obtain flood insurance by their mortgage companies. The 100-year flood elevations will also increase for properties already in the floodplain and these properties may see the cost of flood insurance increase. It is expected that the revised FIRM will become effective sometime in mid-2023.
Repetitive Loss and Flood Insurance Claims Data
The data received on the repetitive loss file such as the date(s), amount(s), and frequency of past flood insurance claims was used to analyze the cause of flooding. The Privacy Act of 1974 (5 U.S Code 522a) restricts the release of flood insurance policy and claims data to the public. This information can only be released to state and local governments for the use in floodplain management related activities.
Therefore, all claims data in this report are only discussed in general terms, but the data was used internally.
California Nevada River Forecast Center
The California Nevada River Forecast Center provides weather, water, and climate data. The City of Sacramento utilized this source to help in the analysis and explanation of claims that occurred during heavy precipitation events.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Technical Memorandum: Repetitive Flood Loss Investigation GEI Consultants and Michael Baker International provided assistance to the City of Sacramento, Department of Utilities in determining why seven repetitive loss areas flooded. Site visits, investigations and review of the local drainage system and the topographic/field survey contributed in determining the proposed mitigation efforts for each property. These analyses are included herein in Step 5. Analysis of Individual Repetitive Loss Areas.
Regional Reports
Many methods were utilized to collect data for the RLAA. During field investigation work for the 2016 RLAA, while delivering flood protection questionnaires, staff conducted field surveys for all structures in the 18 repetitive loss areas. Elevation data was collected from the Sacramento County Assessor’s Office, as well as through some on-site surveying. Staff reviewed all available Drainage Master Plans for the affected areas. These studies provided drainage capacity information and potential mitigation strategies.
Flood management plans were analyzed to help determine the community’s current mitigation activities and provided hazard information. Lastly, past insurance claim information was analyzed for each repetitive loss area to identify patterns in flooding issues.
The repetitive loss properties are vastly spread throughout the City of Sacramento. The majority of the structures flooded during the winter storms of 1995 and 1997 due to undersized drainage conveyance systems, power outages at the pump stations, and low-lying properties within their respective neighborhood. For reporting purposes, the 23 repetitive loss properties have been categorized into six regions which are then broken down into individually selected areas/neighborhoods where the properties are located. At no point is the repetitive loss property specifically identified in this report. All structures within a repetitive loss area are susceptible to the same flooding conditions; however, they may not have experienced flood losses.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Table 1 details the percentage of each repetitive loss area that falls within the 100-year, 500-year or Unshaded Zone-X flood zone, while Table 2 details the number of properties in each flood zone.
TABLE 1.PERCENTAGE OF REPETITIVE LOSS PROPERTIES IN EACH FLOOD ZONE RL Area Zone AE
100-yr
Zone X
Unshaded
Zone X
(Levee)
Zone
A99 Shaded X
1 33% 67%
2 100%
3 17% 83%
4 100%
5 100%
6 33% 33% 33%
TABLE 2.NUMBER OF RLPROPERTIES BY FLOOD ZONE (TOTAL 23) RL Area
Zone
AE
100-yr
Zone X
Unshaded
Zone X
(Levee)
Zone
A99 Shaded X
1 1 2
2 2
3 1 5
4 1
5 8
6 1 1 1
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
3. Step 3. Building Data Collection
The on-site field survey for the current analysis was conducted March 16 and 17, 2023. In addition to building-specific data collection, multiple photographs were taken of each structure on the properties, to the extent the structures were visible from the street.1 Photos were taken of current drainage features and mitigation and flood-proofing measures if evident from street or parking lot views. The following information was recorded for each property:
• Existing mitigation observed
• Type and condition of the structure and foundation
• Number of stories
• Height above street grade and height above site grade • Presence and type of appurtenant structures
• Likely areas and severity of damage on property
• Presence of any HVAC units that would be vulnerable
Data was also gathered, when possible, through conversations with property owners/and or residents.
These conversations provided detail on the extent of flooding, potential cause of flooding, and recollections from past flood events, which help to understand flooding issues for these areas. Data was also incorporated from off-site research, including a review of FEMA FIRMs and the location of the repetitive loss areas in relation to FEMA flood zones.
TABLE 3.TYPE OF FLOODING AFFECTING RLAAPROPERTIES ADDED IN 2022 Region Area No. Properties Type of Flooding
3 12 1 Localized/Stormwater Flooding
6 19 2 Overbank Flooding
6 20 1 Localized/Stormwater Flooding
Many of the properties are located outside of a Special Flood Hazard Area. This is consistent with the majority of the City of Sacramento classified as an X Zone whether it is due to minimal flood hazard or reduced risk due to levees. Exceptions include Region 1 where the area is classified mostly as an A99 Zone, with only a small fraction listed as an AE Zone. The AE Zone is found on the Garden Highway, which runs along the Sacramento River where a small amount of development was built on the waterside of the levee. Another localized AE Zone is along Arcade Creek. Based on this information, traditional flood zones are not a contributing factor in determining repetitive loss areas within the City. It also reinforces the findings that many of the repetitive loss areas are affected by on-site grading and draining issues during heavy, long duration storms.
1 Some structures were not visible due to fences around the entire structure or trees.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
4. Step 4. Review Alternative Approaches
Although this report presents separate analyses for each identified repetitive loss area in the City of Sacramento, the list of potential measures to address repetitive flooding problems is similar for each area.
This chapter summarizes the alternatives that were identified for consideration. These alternatives can be implemented by the City, the homeowner, or other entities. The selection of suitable alternatives for each at-risk property in the repetitive loss areas is described in the chapters presenting individual RLAAs.
Many types of flood hazard mitigation exist, and there is no single mitigation measure that fits every case or even most cases. Successful mitigation often requires multiple strategies. The 2017 CRS Coordinator’s Manual breaks the primary types of mitigation down as follows:
Preventive activities keep flood problems from getting worse. The use and development of floodprone areas are limited through planning, land acquisition, or regulation. These activities are usually administered by building, zoning, planning, and/or code enforcement offices.
Property protection activities are usually undertaken by property owners on a building-bybuilding or parcel basis.
Natural resource protection activities preserve or restore natural areas or the natural functions of floodplain and watershed areas. These activities are implemented by a variety of agencies, primarily parks, recreation, or conservation agencies or organizations.
Emergency services are measures taken during an emergency to minimize its impact. These measures are usually the responsibility of city or county emergency management staff and the owners or operators of major or critical facilities.
Structural projects keep floodwaters away from an area with a levee, reservoir, or other flood control measure. They are usually designed by engineers and managed or maintained by public works staff.
Public information and outreach activities advise property owners, potential property owners, and visitors about hazards and ways to protect people and property from them, as well as the natural and beneficial functions of local floodplains. They are usually implemented by a public information office.
TABLE 4.STRUCTURAL AND NONSTRUCTURAL POTENTIALMITIGATION MEASURES Structural Alternatives Nonstructural Alternatives
Dry flood-proofing. Commercial structures and even residential structures are eligible for dry flood-proofing; however, in many instances this requires human intervention to complete the measure and ensure success. For example, installing watertight shields over doors or windows requires timely action by the homeowner, especially in a heavy rainfall event.
Provide public education through posting
information about local flood hazards on City
websites, posting signs at various locations in
neighborhoods or discussing flood protection
measures at local neighborhood association
meetings.
Wet flood-proofing. Wet flood-proofing a structure involves making the uninhabited portions of the structure resistant to flood damage and allowing water to enter during flooding. For example, in a basement or crawl space, mechanical equipment and ductwork would not be damaged.
Implement volume control and runoff reduction
measures in the City's Stormwater Management
Ordinance.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Structural Alternatives Nonstructural Alternatives
For basements, especially with combined storm sewer and sewer systems, backflow preventer valves can prevent storm water and sewer from entering crawl spaces and basements.
Relocate internal supplies, products/goods
above the flooding depth.
Acquire and/or relocate properties/target abandoned
properties.
Promote the purchase of flood insurance.
Elevate structures and damage-prone components, such as the furnace or air conditioning unit, above the base flood elevation.
Continue to enforce the City's floodplain and
zoning ordinances.
Construct engineered structural barriers, berms, and floodwalls (Note: Assuming lot has required space for a structural addition).
Increase road elevations above the base flood elevation of the 100-year floodplain.
Implement drainage improvements such as increasing capacity in the system (up-sizing pipes), providing additional inlets or larger inlets to receive more stormwater, or constructing detention basins where space allows.
Promote stormwater system maintenance program to ensure inlets and channels are free of clogging debris.
4.1. Preventive
The City of Sacramento regulates residential and commercial development through its building code, planning and zoning requirements, stormwater management regulations and floodplain management ordinances. The City of Sacramento has adopted building codes and procedures designed to protect lives and property in the event of a 100-year flood. Specific floodplain management regulations and building codes are enforced to regulate construction in at-risk areas throughout the city. Construction certificate and hold harmless agreement requirements for each flood zone are shown in Table 5.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
TABLE 5.CITY OF SACRAMENTO CONSTRUCTION REQUIREMENTS FOR FLOOD ZONES
4.2. Property Protection
Property protection is essential to mitigating repetitive loss properties and reducing future flood losses.
There are many ways to protect a property from flood damage. Property protection measures recognized in the 2017 CRS Coordinator’s Manual include relocation, acquisition, building elevation, retrofitting, sewer backup protection, and insurance. Different measures are appropriate for different flood hazards, building types and building conditions. Table 6 lists typical property protection measures.
TABLE 6.TYPICAL PRIVATE PROPERTY PROTECTION MEASURES
Demolish the building or relocate it out of harm’s way.
Elevate the building above the flood level.
Elevate damage-prone components, such as the furnace or air conditioning unit.
Dry flood-proof the building so water cannot get into it.
Wet flood-proof portions of the building so water won’t cause damage.
Construct a berm or redirect drainage away from the building.
Maintain nearby streams, ditches, and storm drains so debris does not obstruct them.
Correct sewer backup problems.
Source: 2017 CRS Coordinators Manual.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
These measures are generally performed by property owners or their agents. FEMA has published numerous manuals that help a property owner determine which property protection measures are appropriate for particular situations.
4.2.1. Flood Insurance
Insurance is included as a property protection activity although it does not mitigate or prevent damage caused by a flood. However, flood insurance does help the owner repair and rebuild their property after a flood, and it can enable the owner to afford incorporating other property protection measures in that process. Flood insurance provides funding to repair flood-damaged property without the need to draw down savings and/or take on debt. As long as a policy is in force, insurance offers the advantage of protecting the property without requiring human intervention for the measure to work.
TABLE 7. ADVANTAGES AND DISADVANTAGES OF FLOOD INSURANCE Advantages Disadvantages
Provides protection outside of what is
covered by a homeowners’ insurance policy
Cost may be prohibitive
Can help to fund other property protection
measures after a flood through increased
cost of compliance coverage
Policyholders may have trouble
understanding policy and filing claims
Provides protection for both structure and
contents
Does not prevent or mitigate damage
Can be purchased anywhere in a
community, including outside of a flood
zone
4.2.2. Dry Flood-Proofing
Dry flood-proofing consists of completely sealing around the exterior of the building so that water cannot enter the building. Making the structure watertight involves sealing the walls with waterproof coatings, impermeable membranes, or a supplemental layer of masonry or concrete; installing watertight shields over windows and doors; and installing measures to prevent sewer backup. Due to the potential damage to a building as a result of hydrostatic pressure and/or hydrodynamic forces, dry flood-proofing is not a good option for areas where floodwater is deep or flows quickly. Dry flood-proofing can be a good option in areas that have minimal velocity and low depth.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
TABLE 8.ADVANTAGES AND DISADVANTAGES OF DRY FLOOD-PROOFING Advantages Disadvantages
Often less costly than other retrofitting
methods
Requires human intervention and adequate
warning to install protective measures
Does not require additional land Does not minimize the potential damage from highvelocity flood flow and wave action May be funded by a FEMA mitigation grant
program
May not be aesthetically pleasing
4.2.3. Wet Flood-Proofing
Wet flood-proofing consists of modifying uninhabited portions of a home (crawl space, garage, or unfinished basement) to allow floodwaters to enter or exit the structure without causing damage.
Openings must be large enough for the water to flow through the structure such that the elevation of the water in the structure is equal to the elevation of the water outside of the structure in order to prevent damage to structural walls as a result of hydrostatic pressure.
TABLE 9.ADVANTAGES AND DISADVANTAGES OF WET FLOOD-PROOFING Advantages Disadvantages
Often less costly than other mitigation
measures
Extensive cleanup may be necessary if the
structure becomes wet inside and possibly
contaminated by sewage, chemicals and other
materials borne by floodwaters
Allows internal and external hydrostatic
pressures to equalize, lessening the loads on
walls and floors
Pumping floodwaters out of a basement too soon
after a flood may lead to structural damage
Does not minimize the potential damage from a
high-velocity flood flow and wave action
4.2.4. Direct Drainage Away from the Building
Structures are sometimes built at the bottom of a hill or in a natural drainage way or storage area, such that water naturally flows toward them. Within zones AH, AO, and AR/AH, adequate drainage paths on slopes shall be required to guide floodwaters around and away from proposed structures. It may be necessary to regrade a yard if water flows toward the building; a new swale or wall can direct the flow to the street or a drainage way. Simple improvements can made on a property to keep floodwaters away from a structure.
4.2.5. Drainage Maintenance
Internal drainage creates a considerable risk in the City for shallow flooding. Internal storm drainage creates flood issues for many buildings because of the flat nature of terrain and runoff which is pumped through levees to a creek or river. If drainage inlets are clogged or pump stations fail, there is a potential for damage to properties. Part of the problem can be attributed to a combined drainage and sanitary CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
sewer system. Over 7,500 acres of the City is subject to a combined system. City Code states that no person shall dump any materials in any water or waterway, or upon the levees or banks adjacent thereto.
Residents are encouraged to report drainage discharges at 916-808-5454.
TABLE 10.ADVANTAGES AND DISADVANTAGES OF DRAINAGE IMPROVEMENTS Advantages Disadvantages
Could increase channel carrying capacity through
overflow channels, channel straightening,
crossing replacements, or runoff volume storage
May help one area but create new problems
upstream or downstream
Minor projects may be fundable under FEMA
mitigation grant programs
Channel straightening increases the capacity to
accumulate and carry sediment
May require property owner cooperation and
right-of-way acquisition
4.2.6. Sewer Improvements
Heavy rains can saturate the soil and infiltrate the sanitary sewer system through leaky joints or cracks in the pipes. The inflow of stormwater floods the sanitary sewer system causing water to back up into the home through lower-level plumbing fixtures. This occurrence can be prevented by installing a sewer backflow preventer, which would allow the sanitary sewer water to flow freely from the home to the sewer, but restrict the reverse flow. Backflow preventers do require maintenance and can fail if debris in the sewer prevents the valve seating properly.
4.2.7. Barriers
Several types of temporary barriers are available to address typical flooding problems. They work to direct drainage away from structures with the same principles as permanent barriers such as floodwalls or levees, but can be removed, stored, and reused in subsequent flood events. Lower-cost solutions include sandbags, inflatable barriers, and barriers that self-activate with the pressure of the floodwaters. A flood protection barrier is usually an earthen levee/berm or a concrete retaining wall. While levees and retaining walls can be large, spanning miles along a river, they can also be constructed on a much smaller scale to protect a single home or group of homes.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
TABLE 11.ADVANTAGES AND DISADVANTAGES OF BARRIERS
Advantages Disadvantages
Relative cost of mitigation is less expensive than
other alternatives
Property is still located within the floodplain and
has potential to be damaged by flood if barrier fails
or waters overtop it
No alterations to the actual structure or
foundation are required
Solution is only practical for flooding depths less
than 3 feet
Homeowners can typically construct their own
barriers that will complement the style and
functionality of their house and yard
Barriers cannot be used in areas with soils that
have high infiltration rates
The cost of constructing a barrier will depend on the type of barrier and the size required to provide adequate protection. An earthen berm will generally be less expensive compared to an equivalent concrete barrier primarily due to the cost of the materials. Another consideration is space; an earthen barrier requires a lot of additional width per height of structure compared to a concrete barrier to ensure proper stability. Key items to consider for barriers:
• There needs to be adequate room on the lot.
• A pump is required to remove water that either falls or seeps onto the protected side of the barrier.
• Human intervention will be required to sandbag or otherwise close any openings in the barrier during the entire flood event.
4.3. Natural Resource Protection
Care should be taken to maintain the streams, wetlands and other natural resources within a floodplain or repetitive loss area. Removing debris from streams and channels prevents obstructions. Preserving and restoring natural areas provides flood protection and natural habit, and preserves water quality.
4.4. Emergency Services
Emergency management is a critical risk reduction tool in the arsenal of any municipality. The role of city government in a disaster is to take all possible actions in order to protect life and property. To accomplish this task, the City has an aggressive emergency management system in place that includes comprehensive hazards planning. Utilities staff, City of Sacramento Office of Emergency Management, and the Sacramento Fire and Police departments work closely together to actively engage in the four phases of emergency management: preparedness/planning, response, recovery, and mitigation (or risk reduction).
These efforts are comprehensive in nature and cover an all-hazard approach, including emergencies involving flooding.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
The City also works closely with the Sacramento County’s Office of Emergency Services and the Sacramento Area Flood Control Agency during major flood events which impact both jurisdictions, demanding an integrated response prior to, during and following an emergency. This coordination provides consistent emergency management service to the Sacramento community.
4.5. Structural Projects
Structural projects keep floodwaters away from an area with a levee, reservoir, or other flood control measure. The majority of Sacramento is protected by dams and levees. While these dams and levees provide residents with excellent protection, they are still subject to failure and the City remains at risk of flooding.
The City of Sacramento is highly vulnerable to localized flooding. The City’s local drainage system services approximately 100 square miles and is handled by a combination of gravity and lift stations for a total of approximately 140 storm drainage basins. Since the City is typically lower than the elevated rivers by as much as 5-25 feet, most of the local drainage must be pumped into the rivers. The City operates 105 sumps and pumps to keep the drainage pumped down. Detention basins have been planned and, in many areas, constructed to help mitigate flooding in the region.
Improving the stormwater drainage system and storage capacity throughout the City can eliminate some building damage and road closures in these areas. Similarly, improving drainage outfalls can reduce stormwater flooding from heavy rains. These structural methods require large capital expenditures and cooperation from private property owners. The City’s websites,social media, email distribution lists, press releases and variable message boards can help get these messages out to business owners and residents.
4.6. Public Information and Outreach
Over the years, the City of Sacramento, through many departments and in coordination with various stakeholder groups and outside agencies, has prepared multiple independent outreach messages to educate the public on the hazards associated with flooding. Sacramento developed a Program for Public Information (PPI) in an ongoing effort to prepare, implement, and monitor a range of public information activities best suited for a community’s flood problems. The objective of the PPI is to provide additional credit for information programs that are designed to meet local needs and that are monitored, evaluated, and revised to improve their effectiveness.
With advances in technology and a greater familiarity with web-based services, Sacramento has realized that mailing information directly to property owners may not be the most effective method. The PPI process now grants communities the ability to decide how to best deliver messages to various groups throughout the City.
Social and economic factors were considered by the PPI Committee in ensuring that the right messages, tools and resources were used to reach all target audiences. The PPI Committee identified six target audiences who need special messages on flood protection:
Target Audience #1: Businesses, Homeowners, and Renters (entire City) Target Audience #2: School Children
Target Audience #3: Real Estate, Lending and Insurance Companies CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Target Audience #4: Vulnerable Populations (Special Needs, Elderly, etc.) Target Audience #5: Political Leaders
Target Audience #6: Language Barriers
In order to develop an effective local outreach program that raises public awareness about flood-related issues, the PPI identified the entire City of Sacramento as flood-prone, and for the entire City to be the target area for outreach within the community. The PPI Committee concluded that outreach projects should be directed to all properties (residential, commercial, and public). The entire City and all flood zones, including the X zone, are subject to flooding, and the PPI should strive to reach all residents and businesses within the City with a variety of messages for flood protection and flood safety.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
5. Step 5. Analysis of Individual Repetitive Loss Areas This section includes a review of the repetitive loss properties, and alternative approaches to determine whether any property protection measures or drainage improvements are feasible. It is organized by Repetitive Loss Regions 1 through 6.
5.1.Region 1 – South Natomas
The greater Natomas Basin is 55,000 acres in size and extends into the northwest portion of Sacramento County running south. The Basin is north of downtown at the American River Parkway (3 miles from downtown). Within the City, the area of the Natomas Basin is approximately 12,500 acres and is surrounded by levees. Natomas is in a FEMA A99 zone, meaning that levee construction is more than 50 percent complete to reach 100-year flood protection among other requirements. In addition to riverine flooding and potential levee breach, the Natomas Basin has interior levees and canals, so it is also at risk to internal drainage issues. The Natomas area is divided into North Natomas and South Natomas. The focus of the RLAA is in South Natomas where three repetitive loss areas were analyzed.
FIGURE 4.REPETITIVE LOSS AREA REGIONS MAP – REGION 1
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 1 – Area 1
Location: West of Northgate Blvd,
Binghampton Dr and Larchwood Dr
Number of Properties in Defined Area: 12
Number of RL Properties in Area: 1
Flood Zone: A99
Dates of RL Flooding: 1/10/1995, 1/24/2000
Source of RL Flooding: This area is in Drainage
Basin 141, which is prone to street flooding due
to increased development in the area. Also,
some properties are more prone to structural
damage due to the addition of fill to their
property. The changes in grading causes water
to pool and seep into a portion of the structure
that is built below or at grade.
Mitigation Recommendations: For the area, flooding can be reduced by the addition of a detention basin, increase in pumping capacity, and pipe improvements. These projects are identified in the Drainage Master Plan for Basin 141. As new development is constructed, drainage improvements will be funded and built. For individual property protection, residents are encouraged to ensure proper grading on the property to allow runoff to reach street drains. Other options, including installation of a drain or diversion, elevating the portion of the structure that is built below or at grade, and sandbagging, can provide additional protection from localized flooding.
FIGURE 5.EXAMPLE OF DIFFERENT FRONT YARD GRADING FOUND WITHIN THE NEIGHBORHOOD CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 1 – Area 2
Location: East of Truxel Road, Oak Nob Way,
Woodside Glen Way and Stonecreek Dr
Number of Properties in Defined Area: 28
Number of RL Properties in Area: 1
Flood Zone: A99
Dates of RL Flooding: 1/05/1997, 2/04/1998
Source of RL Flooding: Flooding occurred during
heavy winter storms. The source of the flooding is
runoff from adjacent properties graded to a higher
elevation.
Mitigation Recommendations: On-site grading on property to redirect the flow of water, installation of drains to divert pooling water, construction of a floodwall, or sandbags.
FIGURE 6.EXAMPLE OF THE CHANGE IN GROUND ELEVATION
BETWEEN ADJACENT PROPERTIES
FIGURE 7.DIVERSION WAS CREATED TO DIRECT
WATER AWAY FROM STRUCTURES
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 1 – Area 3
Location: Garden Highway, North of Sacramento
River
Number of Properties in Defined Area: 3
Number of RL Properties in Area: 1
Flood Zone: AE
Dates of RL Flooding: 1/09/1995, 1/01/1997
Source of RL Flooding: During winter storms, this
strip of commercial development will experience a
large amount of water draining down into the parking
structures and overflow from the Sacramento River.
Flooding has occurred when the pump system located in the parking structures fail.
Mitigation Recommendations: Improvement or replacement of sump system. Based on information provided by occupants of this area, improvements have been made to the pump systems and no additional failures have occurred. Also, the repetitive loss area is located adjacent to natural functions and open space areas. Care should be given to preserve the natural quality of its surrounding to promote natural flood control qualities found near the river.
FIGURE 8.PARKING GARAGE LOCATED NEAR THE EDGE
OF THE SACRAMENTO RIVER
FIGURE 9.ENTRANCE TO PARKING GARAGES BELOW
MAIN STRUCTURES
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Region 1 – Field Visits
Attachment C – Property Visit Documentation provides field visit information collected for all structures in Region 1’s repetitive loss areas. Questionnaires were left at each building and City staff talked with residents and tenants in the area after a large storm in January and February of 2017 to help further understand flooding patterns in the area.
Region 1 – Mitigation and Action Items
Various mitigation activities were considered when analyzing Region 1’s hazard assessment. Table 12 lists all considered mitigation activities and identifies appropriate mitigation activities for each repetitive loss area.
TABLE 12.REGION 1REVIEW OF ALTERNATIVE APPROACHES
Mitigation Activity Region 1
Area 1 Area 2 Area 3
Prevention
Continue Enforcement of Stormwater Regulations X X X
Continue Drainage System Maintenance X X X
Continue Enforcement of Floodplain Management Regulations X Property Protection
Building Elevation X
Relocation
Improvement or Installation of Private Sumps X
Sewer Backup Protection
Flood-proofing
Flood Insurance X X X
Grading X X
Sandbags X X
Elevate Utilities
Natural Resource Protection
Natural Area Preservation X
Natural Area Restoration
Structural Projects
Floodwalls X
Diversions X X
Conveyance System Improvements(Structural)
Detention Basin X
Increased Pumping Capacity X
Pipe Improvements X
Public Information
Outreach Projects X X X
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Mitigation Activity Region 1
Area 1 Area 2 Area 3
Map Information X X X
Technical Assistance X X X
Emergency Services
Hazard Threat Recognition X X X
Hazard Warnings X X X
Health and Safety Maintenance X
Based on the complete analysis of this region, the following action items were identified. These action items were selected based on community feedback, funding, current City activities, and data reports.
TABLE 13.REGION 1ACTION ITEMS
Action Item Responsible Office Schedule Potential Funding Elevate structuresthat are built at
or below grade
Department of
Utilities, Floodplain
Management
Dependent on
property owner
interest and grant
opportunities
Grants and private
funding
Flood/map information
hotline
Ongoing Department funding
Technical assistance visits
Enforcement of floodplain
management regulations
Promotion of flood
insurance
Inform residents of location of
sandbag supplies in their area
Department of
Utilities, Operations &
Maintenance
(supplies only);
Property Owner
During flood event Department funding
(supplies
only)
Improvement and maintenance of
private sumps
Property Owner Ongoing Private funding
On-site grading to divert waterto
city conveyance system
Dependent on
property owner
interest
Private funding or grants
Diversions to direct
stormwater to City conveyance
system
Hazard threat recognition
system
Department of
Utilities
Ongoing Department funding
Develop sandbag locations closer
to repetitive loss area
Ongoing Department funding
Hazard warnings Department of
Utilities; Emergency
Services; Public
Information Office
During flood event Department funding
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Action Item Responsible Office Schedule Potential Funding Conveyance system
improvements identified in
Drainage Master Plan for Basin
141
Department of
Utilities, Wastewater
& Stormwater
Engineering Program
Long-Term Capital Improvement
Program
Enforcement of stormwater
regulations
Department of
Utilities,
Environmental
& Regulatory
Compliance
Ongoing Department funding
Drainage system
maintenance
Department of
Utilities, Operations &
Maintenance
Ongoing Department funding
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
5.2. Region 2 – Downtown East
The three repetitive loss areas in Region 2 are located in the neighborhoods of River Park, McKinley Park, and Coloma Terrace. These are older areas of the City that are vulnerable to overbanking, erosion, and seepage from the American River levees nearby and have other risks such as interior drainage issues (i.e., undersized and aged pipes).
FIGURE 10.REPETITIVE LOSS AREA REGIONS MAP – REGION 2
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 2 – Area 5
Location: 45th St and C St, East of Elvas Avenue
in Coloma Terrace Neighborhood
Number of Properties in Defined Area: 15
Number of RL Properties in Area: 1
Flood Zone: Shaded-X Zone
Dates of RL Flooding: 4/08/1995, 2/04/1998
Source of RL Flooding: Flooding occurs during
heavy storms that overwhelmed the undersized
drainage system in the area. The structures
included in the repetitive loss are located in a
low-lying area of the neighborhood, so they are
more dramatically affected by street flooding.
Mitigation Recommendations: Based on the Basin 10 Drainage Master Plan, improvements have been identified. Recommends critical pipes in the system be enlarged and a detention basin be constructed to provide adequate flood protection for the basin. These improvements would mitigate the repetitive loss properties in Area 5. Individual property owners can mitigate flood losses by using sandbags, keeping street drains clear of debris, constructing floodwalls on their property, installing sump pumps, and elevating utilities.
FIGURE 11.RESIDENTS USE SANDBAGS TO PROTECT
GARAGES FROM STREET FLOODING DURING
JANUARY 2017 STORMS
FIGURE 12.DEBRIS COLLECTING ON A STORM DRAIN AT THE
CORNER OF 45TH AND CSTREETS
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 2 – Area 6
Location: McKinley Park, Park Way and Santa
Ynez Way
Number of Properties in Defined Area: 12
Number of RL Properties in Area: 1
Flood Zone: Shaded-X Zone
Dates of RL Flooding: 1/29/1995, 1/25/1997
Source of RL Flooding: This area is located in a
basin with an undersized drainage conveyance
system. This area is also impacted by overflows
from the Combined Sewer System. During large
storms, water pools in the streets and yards of
the surrounding properties. Most flood loss is due
to water seeping into garages, basements and entryways located at grade level.
Mitigation Recommendations: The McKinley Water Vault project was completed in 2021. An AW-501, the NFIP Repetitive Loss Update Worksheet is in process to change the property status to “Mitigated” on the Repetitive Loss list.
FIGURE 13.STREET FLOODING FROM FEBRUARY 2017
STORM.OVERWHELMED CONVEYANCE SYSTEM
FIGURE 14.EXAMPLE OF THE CITY’S WARNING THAT THE AREA
MAY CONTAIN SEWAGE
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
FIGURE 15.SOME HOMES IN THIS AREA HAVE BASEMENTS AND DOORWAYS LOCATED AT GRADE LEVEL Region 2 – Field Visits
Attachment C – Property Visit Documentation provides field visit information collected for all structures located in Region 2’s repetitive loss areas. Questionnaires were left at each building and City staff talked with residents and tenants in the area after a large storm in January and February of 2017 to help further understand flooding patterns in the area.
Region 2 – Mitigation and Action Items
The following mitigation activities were considered to address the hazards found in Region 2. Table 14 lists all considered mitigation activities and identifies appropriate mitigation activities for each repetitive loss area.
TABLE 14.REGION 2 REVIEW OF ALTERNATIVE APPROACHES
Mitigation Activity Region 2
Area 5 Area 6
Prevention
Continue Enforcement of Stormwater Regulations X X
Continue Drainage System Maintenance X X
Continue Enforcement of Floodplain Management
Regulations X X
Property Protection
Building Elevation X
Relocation
Improvement or Installation of Private Sumps X
Sewer Backup Protection X
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Mitigation Activity Region 2
Flood-proofing
Flood Insurance X X
Grading
Sandbags X X
Elevate Utilities X X
Natural Resource Protection
Natural Area Preservation
Natural Area Restoration
Structural Projects
Floodwalls X
Diversions
Conveyance System Improvements (Structural)
Detention Basin/Vault X X
Increased Pumping Capacity X
Pipe Improvements X X
Public Information
Outreach Projects X X
Map Information X X
Technical Assistance X X
Emergency Services
Hazard Threat Recognition X X
Hazard Warnings X X
Health and Safety Maintenance X
Mitigation Activity
Based on the complete analysis of this region the following action items were identified. These action items were selected based on community feedback, funding, current City activities, and data reports.
TABLE 15.REGION 2 ACTION ITEMS
Action Item Responsible Office Schedule Potential
Funding
Elevate structures that are built at
or below grade
Department of Utilities,
Floodplain Management
Dependent of
property owner
interest and grant
opportunities
Grants
and
private
funding
Develop grant proposal for Summer 2018 Department
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Action Item Responsible Office Schedule Potential
Funding
installation of sumps to protect
garages and basements
funding
Enforcement of floodplain
management regulations
Ongoing
Promotion of flood insurance
Flood/map information hotline
Technical assistance visits
Provide neighborhood with
storm/flood ready information -
include emergency alert
information
Annual
Improvement and maintenance of
private sumps
Property Owner Ongoing Private
funding
Sewer backup protection system Dependent on
property owner
interest
Private
funding or
grants
Construction of a floodwall
Conveyance system
improvements identified in
Drainage Master Plan for Basin 31
Department of Utilities Complete Capital
Improvement
Program
McKinley Water Vault Protect 2021 Complete
Enlarge critical pipes and
construct detention basin in
Drainage Basin 10
Dependent on
funding
Hazard threat recognition system Ongoing Department
funding
Inform residents of location of
sandbag supplies in their area
Department of Utilities,
Operations & Maintenance
(supply only); Property
Owner
During flood event Departme
nt funding
(supply
only)
Health and safety warnings and
inspection of Combined Sewer
System area
Department of Utilities,
Operations & Maintenance
During/after
flood event
Department
funding
Drainage system maintenance Ongoing Department
funding
Enforcement ofstormwater
regulations
Department of Utilities,
Environmental & Regulatory
Compliance
Ongoing Department
funding
Hazard warnings Department of Utilities;
Emergency Services; Public
Information Office
During flood event Department
funding
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
5.3. Region 3 – Downtown West
Region 3 of the City of Sacramento’s RLAA is the western portion of Downtown Sacramento located just east of the Sacramento River. This area consists of several commercial buildings and high-rises as well as housing. The repetitive loss properties in this region are residential and the primary source of flooding in this area occurs due to an undersized Combined Sewer System that gets overwhelmed during large storms.
FIGURE 16.REPETITIVE LOSS AREA REGIONS MAP – REGION 3
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 3 – Area 7
Location: 23rd St and X St
Number of Properties in Defined Area: 8
Number of RL Properties in Area: 1
Flood Zone: X-Zone
Dates of RL Flooding: 12/12/1995, 1/22/1997,
9/19/2004
Source of RL Flooding: During moderately intense
storms, flooding occurs in Area 7 due to the
undersized conveyance system. Also, during times
of high-level ground saturation ponding, uneven
grading, and seepage cause additional flooding in
resident’s yards, garages, and basements.
Mitigation Recommendations: Improvement of Combined Sewer System, flood-proof basements, installation of sump pumps, sewer system backup protection, basement fill-in, property grading, on-site drainage to flow into main system, sandbags, utilities elevation, outreach on storm/flood preparedness, and flood insurance.
FIGURE 17.ON-SITE DRAINAGE ADDED TO AID
IN STORMWATER DRAINAGE
FIGURE 18.AFRACTURED BASEMENT WALL CAUSED BY
HYDROSTATIC PRESSURE;CRACKS HAVE LED TO WATER
SEEPING INTO THE BASEMENT
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 3 – Area 8
Location: 14th St. & Broadway
Number of Properties in Defined Area: 33
Number of RL Properties in Area: 1
Flood Zone: X-Zone
Dates of RL Flooding: 1/10/1995, 9/19/2004
Source of RL Flooding: During long duration storms,
flooding occurs due to an undersized conveyance
system. Many residents experience flooding in their
yards, garages, and basements. Because of hills in the
areas, there are garages located below grade that can
be inundated by water during large storms.
Mitigation Recommendations: Improvement of Combined Sewer System, flood-proof basements, installation of sumps, sewer system backup protection, sandbags, elevate utilities, outreach on storm/flood preparedness, and flood insurance.
FIGURE 19.EXAMPLE OF DEBRIS IN THE STORM DRAIN.
LEAF PILES ARE ALLOWED TO BE LEFT ON STREETS FOR
CITY PICKUP AFTER CURBSIDE BINS ARE FULL; MANY
TIMES,THESE LEAVES CAN CLOGTHE STORM DRAIN
FIGURE 20.EXAMPLE OF A TYPICAL HOME IN THIS AREA
THAT WOULDN’T FLOOD; ELEVATED ON A CRAWLSPACE AND
THE GARAGE LOCATED IN THE BACK OF THE PROPERTY.
SOME HOMES HAVE BASEMENTS
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 3 – Area 9
Location: 28th St and N St
Number of Properties in Defined Area: 5
Number of RL Properties in Area: 1
Flood Zone: X - Zone
Dates of RL Flooding: 1/10/1995, 1/25/1997,
9/19/2004
Source of RL Flooding: During long duration
storms, flooding occurs due to an undersized
conveyance system. This is a commercial area
and many of the business entryways are not
elevated. If street flooding overtops the curbs,
water can flow into the structure causing
structural damage.
Mitigation Recommendations: Improvement of Combined Sewer System, sewer system backup protection, sandbags, elevate utilities, elevate buildings, outreach on storm/flood preparedness, and flood insurance.
FIGURE 21.THE MAJORITY OF THE BUILDINGS IN AREA 9 DO NOT HAVE ELEVATED ENTRYWAYS CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 3 – Area 10
Location: 6th St and Q St
Number of Properties in Defined Area: 3
Number of RL Properties in Area: 1
Flood Zone: X-Zone
Dates of RL Flooding: 3/02/1995, 1/25/1997,
9/19/2004
Source of RL Flooding: During long duration
storms, flooding occurs due to an undersized
conveyance system. This is an area that is
commercial and residential. Only some of the
structures are elevated. If street flooding overtops
the curb, water can flow into the structure. There are also garages that are located below grade that can be inundated by water during large storms.
Mitigation Recommendations: The Drainage Master Plan for Basin 52 recommends an alternative analysis be done. A 2D model is recommended to determine problem areas. For individual property mitigation, using sandbags, installation of a temporary floodwall, elevate buildings are recommended. Outreach on storm/flood preparedness, and flood insurance should continue.
FIGURE 22.BASEMENT WINDOWS AND ENTRY DOOR
ARE NOT ELEVATED.
FIGURE 23.GARAGES ARE LOCATED BELOW GRADE.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 3 – Area 11
Location: 12th St and L St
Number of Properties in Defined Area: 3
Number of RL Properties in Area: 1
Flood Zone: X-Zone
Dates of RL Flooding: 1/09/1995, 1/01/1997
Source of RL Flooding: During moderately intense
storms, flooding occurs when stormwater flows
into the underground parking structures. Some of
structures are now equipped with temporary
floodwalls and sumps.
Mitigation Recommendations: Installation of
temporary floodwalls, sumps, and sandbags.
FIGURE 24.AREA 11IS LOCATED IN THE MIDDLE OF DOWNTOWN SACRAMENTO.
MANY OF THE ENTRYWAYS ARE ELEVATED,BUTTHE PARKING STRUCTURES ARE BELOW GROUND CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 3 – Area 12
Location: J St and 3rd St
Number of Properties in Defined Area: 10
Number of RL Properties in Area: 1
Flood Zone: X
Dates of RL Flooding: 1/26/1997, 9/19/2004
Source of RL Flooding: During storm events, the
street will continue draining runoff to the gutter
until the capacity of the gutter is exceeded, and as
a result water could potentially flow from the street
downhill to the property. However, rainfall directly on the entire block (5 acres) can accumulate at the lowest point of the block, near the bottom floor of this building. Little availability for infiltration of rainfall.
Directly beneath the RL property there are banks of large (6-foot dia) culverts that may be a component of a large-scale, regional sump or drainage system but that information is currently unknown. The building’s mechanical equipment is elevated about 18 inches above the bottom floor (ground) level.
Mitigation Recommendations: 2D model analysis to determine if future development at the nearby Railyards could help this area. Other recommendations include improvement of Combined Sewer System, sewer system backup protection, sandbags, elevate utilities, elevate buildings, outreach on storm/flood preparedness, and flood insurance.
FIGURE 25.CURB AND GUTTER AT BASE OF RAMP
TO STREET ABOVE
FIGURE 26.BANKS OF 6-FOOT DIA CULVERTS
UNDER BUILDING
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
FIGURE 27.TRENCH DRAINS ALONG SOUTH SIDE
OF LOWEST FLOOR
FIGURE 28.UTILITIES ELEVATED
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Region 3 – Field Visits
Attachment C – Property Visit Documentation provides field visit information collected for all structures located in Region 3’s repetitive loss areas. Questionnaires were left at each building and City staff talked with residents and tenants in the area after a large storm in January and February of 2017 to help further understand flooding patterns in the area. Staff visited Area 12 in March 2023 to understand flooding patterns in this area.
Region 3 – Mitigation and Action Items
The following mitigation activities were considered to address the hazards found in Region 3. Table 16 lists the considered mitigation activities and identifies appropriate mitigation activities for each repetitive loss area.
TABLE 16.REGION 3 RECOMMENDED MITIGATION ACTIONS
Mitigation Activity Region 3
Area 7 Area 8 Area 9 Area 10 Area 11 Area 12
Prevention
Continue Enforcement of Stormwater Regulations X X X X X X Continue Drainage System Maintenance X X X X X X
Continue Enforcement of Floodplain Management
Regulations
X X X X X X
Property Protection
Building Elevation X X
Relocation
Improvement or Installation of Private Sumps X X X
Sewer Backup Protection X X X X
Flood-proofing X X X
Flood Insurance X X X X X X
Grading
Sandbags X X X X X X
Elevate Utilities X X X X X
Natural Resource Protection
Natural Area Preservation
Natural Area Restoration
Emergency Services
Hazard Threat Recognition X X X X X X
Hazard Warnings X X X X X X
Health and Safety Maintenance X
Structural Projects
Floodwalls X X X
Diversions
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Mitigation Activity Region 3
Area 7 Area 8 Area 9 Area 10 Area 11 Area 12
Conveyance System Improvements(Structural)
Detention Basin/Vault X
Increased Pumping Capacity X X X X X
Pipe Improvements X X X X
Public Information
Outreach Projects X X X X
Map Information X X X X X
Technical Assistance X X X X X
Based on the complete analysis of this region the following action items were identified. These action items were selected based on community feedback, funding, current City activities, and data reports.
TABLE 17.REGION 3 ACTION ITEMS
Action Item Responsible Office Schedule Potential Funding Elevate structures and utilities that
are built at or below grade
Department of Utilities,
Floodplain Management
Dependent on property
owner interest and
grant opportunities
Grants and private funding
Floodproofing
Provide neighborhoods with
storm/flood ready information -
include emergency alert information
Annual
Enforcement of floodplain
management regulations
Ongoing
Promotion of flood insurance
Flood/map information hotline
Technical assistance visits
Improvement and maintenance of
private sumps
Property Owner Ongoing Private funding
Prohibit occupancy of lowest level Short-term; Dependent on property owner
interest
Private
Sewer backup protection system Dependent on property
owner interest
Private funding or grants
Hazard threat recognition system Department of Utilities Ongoing Department funding CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Action Item Responsible Office Schedule Potential Funding Acquisition by City Long-term Grant/department funding
Inform residents of location of
sandbag supplies in their area
Department of Utilities,
Operations &
Maintenance (supply
only); Property Owner
During flood event Department funding
(supply only)
Health and safety warnings and
inspection of combined sewer
system area
Department of Utilities,
Operations &
Maintenance
During flood event Department funding
Drainage system maintenance Ongoing
Improvements identified in the
Combined Sewer System
Improvement Plan Update
Department of Utilities,
Wastewater &
Stormwater Engineering
Program
Long-Term Capital Improvement
Program
Conveyance system improvements
identified in Drainage Master Plan
for Basin
Enforcement of stormwater
regulations
Department of Utilities,
Environmental &
Regulatory Compliance
Ongoing Department funding
Hazard warnings Department of Utilities;
Emergency Services;
Public Information Office
During flood event Department funding
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
5.4. Region 4 – Southeast Sacramento
Region 4 of the RLAA is located in the southeast portion of Sacramento’s city limits. This entire region is composed of residential properties located between 65th Avenue and Power Inn Road. There are two repetitive loss properties located in this region that have flooded mainly due to poor grading. Water from higher adjacent properties flows into low-lying areas causing some homes to flood. A drainage study of Basin 96 concluded that limitations were discovered during observed flooding such as overland flow from one property to another and constraints such as fences and landscape features.
FIGURE 29.REPETITIVE LOSS AREA REGIONS MAP – REGION 4
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 4 –Area 13
Location: 37th Ave and 66th St
Number of Properties in Defined Area: 12
Number of RL Properties in area: 1
Flood Zone: X-Zone
Dates of RL Flooding:
1/10/1995, 1/22/1997, 12/31/2005
Source of RL Flooding: Flooding occurs during heavy,
long duration storms. The source of the flooding is
from open land adjacent to the properties.
Mitigation Recommendations: Grading on the
property to redirect the flow of water, installation of drains to divert water, construct floodwall, sandbags, flood insurance, and outreach on storm/flood preparedness.
FIGURE 30.STRUCTURE BUILT ON A CRAWLSPACE AND
HVACUNIT IS ELEVATED AS A FLOOD-PROOFING
MEASURE
FIGURE 31.PONDING CAUSED BY LANDSCAPING
OBSTRUCTIONS
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Region 4 – Field Visits
Attachment C – Property Visit Documentation provides field visit information collected for all structures located in Region 4’s repetitive loss areas. Questionnaires were left at each building and City staff talked with residents and tenants in the area after a large storm in January and February of 2017 to help further understand flooding patterns in the area.
Region 4 – Mitigation and Action Items
The following mitigation activities were considered to address the hazards found in Region 4. Table 18 lists the considered mitigation activities and identifies appropriate mitigation activities for each repetitive loss area.
TABLE 18.REGION 4 REVIEW OF ALTERNATIVE APPROACHES
Mitigation Activity Region 4
Area 13
Prevention
Continued Enforcement of Stormwater Regulations X
Continue Drainage System Maintenance X
Continued Enforcement of Floodplain Management Regulations X Property Protection
Building Elevation X
Relocation
Improvement or Installation of Private Sumps
Sewer Backup Protection
Flood-proofing
Flood Insurance X
Grading
Sandbags X
Elevate Utilities X
Natural Resource Protection
Natural Area Preservation
Natural Area Restoration
Emergency Services
Hazard Threat Recognition X
Hazard Warnings X
Health and Safety Maintenance
Structural Projects
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Mitigation Activity Region 4
Area 13
Floodwalls
Diversions
Conveyance System Improvements (Structural)
Detention Basin/Vault X
Increased Pumping Capacity
Pipe Improvements
Public Information
Outreach Projects X
Map Information X
Technical Assistance X
Based on the complete analysis of this region the following action items were identified. These action items were selected based on community feedback, funding, current City activities, and data reports.
TABLE 19.REGION 4 ACTION ITEMS
Action Item Responsible Office Schedule Potential
Funding
Elevate structures that are built at or
below grade
Department of Utilities,
Floodplain Management
Dependent on
property owner
interest and grant
opportunities
Grants
and
private
funding
Flood/map information hotline Ongoing Departm
ent
funding
Technical assistance visits
Enforcement of floodplain
management regulations
Promotion of flood insurance
Elevate utilities that are at or below
grade
Property Owner Dependent on
property owner
interest
Privat
e
fundi
ng
Grading or diversion to redirect the
flow of stormwater to drainage
system
Inform residents of location of
sandbag supplies in their area
Department of Utilities,
Operations &
Maintenance; Property
Owner
During flood event Department
funding
Hazard threat recognition system Department of Utilities Ongoing Department funding
Drainage system maintenance Department of Utilities,
Operations &
Maintenance
Ongoing Department
funding
Enforcement of stormwater Department of Utilities, Ongoing Department CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Action Item Responsible Office Schedule Potential
Funding
regulations Environmental &
Regulatory Compliance
funding
Conveyance system improvements
identified in Drainage Master Plan
for Basin 96
Department of Utilities,
Wastewater &
Stormwater Engineering
Program
Long-Term Capital
Improvement
Program
Hazard warnings Department of Utilities;
Emergency Services; Public
Information Office
During flood event Department
funding
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
5.5. Region 5 – Sutterville/Meadowview
Region 5 of the RLAA stretches from Sutterville Road down south to Meadowview Road. The majority of this area is residential; however, it does consist of a few shopping/corporate centers, Bing Maloney Gold Course, and the Sacramento Executive Airport. This entire region is classified by FEMA as Zone X with a low risk of flooding due to surrounding levees.
FIGURE 32.REPETITIVE LOSS AREA REGIONS MAP – REGION 5
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 5 – Area 14
Location: 24th St and 69th Ave
Number of Properties in Defined Area: 10
Number of RL Properties in Area: 1
Flood Zone: X-Zone
Dates of RL Flooding: 2/23/20002, 12/31/2005
Source of RL Flooding:
Based on the investigation performed by GEI
Consultants, it was discovered that flooding likely
occurred due to undersized drainage system during
long duration storm events. Discussions with the
property owners confirmed this conclusion.
Mitigation Recommendations: Based on Drainage
Master Plan of Basin 33 and the technical analysis performed by GEI, on-site private property protection should be implemented. This area is a localized low spot. Private property actions including drainage and grading of the property, sandbags, or elevation of the finished floor would be effective mitigation actions.
FIGURE 33.DRAINS INSTALLED AFTER FLOODING TO DIVERT
WATER BACK TO THE MAIN DRAINAGE SYSTEM
FIGURE 34.FRONT YARDS INUNDATED BY STREET
FLOODING; PICTURES TAKEN TWO DAYS AFTER
A LARGE STORM
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 5 – Area 15
Location: 20th Ave and Freeport Blvd
Number of Properties in Defined Area: 13
Number of RL Properties in Area: 4
Flood Zone: X-Zone
Dates of RL Flooding:
Property 1: 1/10/1995, 2/07/1996
1/22/1997
Property 2: 1/10/1995, 1/22/1997
Property 3: 1/10/1995 1/22/1997
Property 4: 3/25/1989 1/12/1990 1/13/1993
1/09/1995 1/20/1996 1/22/1997
Source of RL Flooding: This area is located in a
low-lying area with an undersized drainage
conveyance system. Flooding occurs during
moderate and long duration storms.
Mitigation Recommendations: A master plan will need to be prepared for this area to look for alternatives to mitigate this area. Pipeline replacement and upsizing should be performed at the end of the pipe’s useful life. For individual property protection, flood insurance, sandbags, diversions, and elevation of utilities will provide additional flood protection.
FIGURE 35.EXAMPLES OF FLOODPROOFING MEASURE SUCH AS A CRAWLSPACE (LEFT)
AND ADDITIONAL ON-SITE DRAINAGE PIPE (RIGHT)
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 5 – Area 16
Location: Alcedo Dr and Winnett Way,
West of Franklin Blvd
Number of Properties in Defined Area: 5
Number of RL Properties in Area: 1
Flood Zone: X-Zone
Dates of RL Flooding: 1/10/1995,
1/27/1997
Source of RL Flooding: This area is in a lowlying area with an undersized drainage conveyance system. Flooding occurs during
moderately intense and long duration
storms.
Mitigation Recommendations: Elevate garages, ensure proper on-site drainage to allow water to flow to storm drains, elevate utilities, sandbags, storm readiness outreach, and flood insurance.
FIGURE 36.CRAWLSPACE UTILIZED AS A FLOODPROOFING
MEASURE TO PREVENT FLOODING IN THE STRUCTURE
FIGURE 37.STANDING WATER AFTER A LARGE
JANUARY STORM UNABLE TO CONVEY FLOWS
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 5 – Area 17
Location: 68th Ave and 21st St
Number of Properties in Defined Area: 13
Number of RL Properties in Area: 1
Flood Zone: X-Zone
Dates of RL Flooding: 1/10/1995, 2/26/2000
Source of RL Flooding: Based on GEI
Consultants’ investigation, the most logical
reason for flooding is unique to specific
property drainage within the area. It is
believed that an addition of a patio structure
in the back of the property reduced the ability
of the property to drain properly.
Mitigation Recommendations: For area flood protection, Drainage Master Plan for Basin 108 does not show property damage in this area. Some pipe upsizing recommendations to mitigate street flooding. Also suggest updating the model for alternative recommendations. Residents can add diversion(s) to promote the flow of water to the main drainage system, purchase flood insurance, and use sandbags to mitigate flooding.
FIGURE 38.ELEVATED HOME WITHLANDSCAPING
ASSISTING IN ON-SITE DRAINAGE
FIGURE 39.ELEVATED STRUCTURE WITH A CRAWLSPACE
BELOW AS A FLOOD PROTECTION METHOD
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 5 – Area 18
Location: Golf View Dr and 48th Ave
Number of Properties in Defined Area: 14
Number of RL Properties in Area: 1
Flood Zone: X-Zone
Dates of RL Flooding: 1/25/1997, 12/23/2004
Source of RL Flooding:
Based on GEI Consultants’ investigation, the
flooding in this area is caused by undersized
drain pipes that are overwhelmed during long
duration storms. Street flooding can overtop the
curbs and begin to flood yards and garages.
Mitigation Recommendations: The Drainage Master Plan for Basin 22 to be completed. Old master plan did not show property damage in this area. Some pipe upsizing improvements to mitigate street flooding.
Also suggest updating the model. Other mitigation options are flood preparedness education, elevate utilities, flood insurance, and sandbags.
FIGURE 40.EXAMPLE OF FLOODED YARD FROM
JANUARY 2017 STORMS
FIGURE 41.EXAMPLE OF UTILITIES LOCATED ON THE ROOF;
MANY OF THE HOMES IN THIS AREA HAVE HVACUNIT
LOCATED ONTHE ROOF
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Region 5 – Field Visit
Attachment C – Property Visit Documentation provides field visit information collected for all structures in Region 5’s repetitive loss areas. Questionnaires were left at each building and City staff talked with residents and tenants in the area after a large storm in January and February of 2017 to help further understand flooding patterns in the area.
Region 5 – Mitigation and Action Items
The following mitigation activities were considered to address the hazards found in Region 5. Table 21 lists the considered mitigation activities and identifies appropriate mitigation activities for each repetitive loss area.
TABLE 20.REGION 5 MITIGATION ALTERNATIVE APPROACHES
Mitigation Activity Region 5
Area 14 Area 15 Area 16 Area 17 Area 18
Prevention
Continue Enforcement of Stormwater
Regulations X X X X X
Continue Drainage System Maintenance X X X X X
Continue Enforcement of Floodplain
Management Regulations X X X X X
Property Protection
Building Elevation X X
Relocation
Improvement or Installation of Private
Sumps
Sewer Backup Protection
Flood-proofing
Flood Insurance X X X X X
Grading X X X
Sandbags X X X X X
Elevate Utilities X X X X
Natural Resource Protection
Natural Area Preservation
Natural Area Restoration
Emergency Services
Hazard Threat Recognition X X X X X
Hazard Warnings X X X X X
Health and Safety Maintenance
Structural Projects
Floodwalls X
Diversions X X X X
Conveyance System Improvements (Structural)
Detention Basin/Vault X X
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Based on the complete analysis of this region the following action items were identified. These action items were selected based on community feedback, funding, current City activities, and data reports.
TABLE 21.REGION 5 MITIGATION ALTERNATIVES
Action Item Responsible Office Schedule Potential
Funding
Provide neighborhoods with storm/flood
ready information - include emergency alert
information
Department of Utilities,
Floodplain Management
Annual Department
funding
Elevate structures that are built at or below
grade
Dependent on
property owner
interest and grant
opportunities
Grants and
private funding
Drainage system maintenance Ongoing Department
Enforcement of floodplain management funding
regulations
Promotion of flood insurance
Flood/map information hotline
Technical assistance visits
Grading or diversion to redirect the flow of
stormwater to drainage system
Property Owner Dependent on
property owner
interest
Private funding
Elevate utilities that are at or below grade
Construction of a floodwall Dependent on
property owner
interest
Private funding or
grants
Hazard threat recognition system Department of Utilities Ongoing Department funding
Conveyance system improvements
identified in Drainage Master Plan for Basin
33 Department of Utilities,
Wastewater &
Stormwater Engineering
Program
Long-Term Capital
Improvement
Program
Diversion identified in Drainage Master Plan
for Basin 108
Mitigation Activity Region 5
Area 14 Area 15 Area 16 Area 17 Area 18
Increased Pumping Capacity
Pipe Improvements X X X X
Public Information
Outreach Projects X X X X X
Map Information X X X X X
Technical Assistance X X X X X
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Action Item Responsible Office Schedule Potential
Funding
Conveyance system improvements
identified in Drainage Master Plan for Basin
22 Conveyance system improvements
identified in- Drainage Master Plan for Basin
108
Inform residents of location of sandbag
supplies in their area
Department of Utilities,
Operations &
Maintenance; Property
Owner
During flood event Department
funding
Enforcement of stormwater regulations Department of Utilities, Environmental &
Regulatory Compliance
Ongoing Department
funding
Hazard warnings Department of Utilities;
Emergency Services;
Public Information Office
During flood event Department
funding
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
5.6. Region 6 – Arcade Creek
Region 6 of the RLAA stretches from Watt Avenue, through Haggin Oaks Golf Course, and west to Steelhead Creek. The majority of this area is residential. The flooding in this region is due to overbank flooding due to severe storm events. The region includes Zone AE.
FIGURE 42.REPETITIVE LOSS AREA REGIONS MAP – REGION 6
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 6 – Area 19
Location: Arcade Creek Blvd and Marysville
Blvd to Verano St
Number of Properties in Defined Area: 71
Number of RL Properties in Area: 2
Flood Zone: AE
Dates of RL Flooding 1: 1/4/1982, 1/10/1995
Dates of RL Flooding 2: 2/17/1986, 1/10/1995
Source of RL Flooding: This area is located
along Arcade Creek, directly west of the
publicly owned Haggin Oaks Golf Course. A
record high stage reading of 80.9 feet was
recorded at Arcade Creek on January 10, 1995. This suggests that the overtopping of the creek was probably the cause of the damage at the properties along Arcade Creek on that date. Properties along Palmer Street are additionally at a lower grade than Palmer itself; therefore at this location there is the potential for runoff from Arcade Blvd. as well as adjacent streets. Many properties have out-buildings at the back of the property that are even more directly adjacent to Arcade Creek that may have received the damage.
East side: A visit was made to the area during regional flooding on January 5, 2023. Properties that flooded are directly adjacent to the large, partially concrete-lined channel that is the bed of Arcade Creek through this area. These homes sit at a lower finished floor elevation than the adjacent road. Water also pools on Verano Bridge and along the streets during high storm events and due to poor drainage in the area.
West side: During the January site visit, water had accumulated at the intersection of Palmer St and Arcade Blvd to a depth of about 8 inches. Farther down the street on Palmer, accumulation of tree leaves, debris, and branches had clogged up the only two drainage inlets on the north and the south ends of the street.
Properties on the north end of Palmer are at the lowest point of the street, which leads runoff to travel down north alongside the two gutter pans to the undersized drainage inlet at the end of the street.
Without proper maintenance or drainage inlet upsizing, water will keep accumulating in this location and could cause flooding to the adjacent properties.
Mitigation Recommendations: Properties’ finished floor elevations are low. Regional improvements could include detention storage in the golf course to provide adequate flood protection to the area, regional stormwater improvements to street drainage, and maintenance of the partially concrete-lined channel that is Arcade Creek. Ensure all upstream stormwater collection and conveyance infrastructure is cleaned and maintained before and during large events. On-property mitigation efforts should include raising mechanical equipment, raising of the structures themselves, relocating the structures, and sandbags or a floodwall to divert or direct water away from the structures.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
FIGURE 43.VIEW NORTH ON PALMER TOWARD END OF THE
STREET AND RLPROPERTY
FIGURE 44.CLOGGED DRAINAGE INLET ON PALMER
ST AND ARCADE BLVD
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
FIGURE 45.ARCADE CREEK LOOKING WEST FROM VERANO
BRIDGE (CULVERT OUTLET AT RED ARROW)(STAGE 35 FT AT
MARYSVILLE BLVD (CITY)(47403);MARCH 16
FIGURE 46.ARCADE CREEK LOOKING WEST FROM
VERANO BRIDGE (STAGE 40-42 FT AT MARYSVILLE BLVD
(CITY)(47403);JANUARY 5
FIGURE 47.ARCADE CREEK LOOKING WEST FROM
VERANO BRIDGE
FIGURE 48.VERANO BRIDGE WATER PONDING
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
RLAA Region 6 – Area 20
Location: Gillespie St and Fairbanks Ave
Number of Properties in Defined Area: 12
Number of RL Properties in Area: 1
Flood Zone: X
Dates of RL Flooding: 12/23/2012, 1/7/2017,
3/1/2018
Source of RL Flooding: Previous communications
with homeowner indicated that the foundation is
weak from the 1986 flood, resulting in water
entering the home through the foundation. The
main area of flooding was in a lower level room and
patio. Resident uses sandbags and boards to keep
water out; however, the cracks in the foundation continue to let it seep through the floor.
Mitigation Recommendations: Structural improvements to house/foundation, use sandbags to prevent damage to the house, grading on the property to redirect the flow of water, installation of drains to divert water, construct floodwall, sandbags, flood insurance, and outreach on storm/flood preparedness.
FIGURE 49.SUMP 158 NEAR GILLESPIE STREET FIGURE 50.SUMP 158 POND CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
FIGURE 51.TYPICAL NEIGHBORHOOD HOME BUILT UP FROM STREET Region 6 – Field Visits
Attachment C – Property Visit Documentation provides field visit information collected for all structures located in Region 6’s repetitive loss areas. Targeted outreach letters and questionnaires were mailed to residents prior to the visit. Local residents responded to the outreach and provided anecdotal information on the local flooding.
Region 6 – Mitigation and Action Items
The following mitigation activities were considered to address the hazards found in Region 6.
Table 22 lists all considered mitigation activities and identifies appropriate mitigation activities for each repetitive loss area.
TABLE 22.REGION 6 REVIEW OF ALTERNATIVE APPROACHES
Mitigation Activity Area 19 Area 20
Prevention
Continue Enforcement of Stormwater Regulations X X
Continue Drainage System Maintenance X X
Continue Enforcement of Floodplain Management Regulations X X Property Protection
Building elevation X X
Relocation X
Improvement or Installation of Private Sump
Sewer Backup Protection
Flood-proofing X
Flood insurance X
Grading
Sandbags X X
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
TABLE 23.REGION 6 ACTION ITEMS
Action Item Responsible
Office
Schedule Potential
Funding
Promote flood insurance Department of
Utilities, Floodplain
Management
Ongoing Department
funding
Brochures, specific outreach
Continue to enforce local
floodplain development
ordinance
Inform residents of location of
sandbag supplies in their area
Prior to flood event
Investigate grant funding Long-term Department
funding, HMGP
funding
Elevate the structure Property owner Depends on interest of owner
Rebuild foundation/structural
improvements
Long-term
Investigate Capital
Improvement Plan for regional
stormwater infrastructure
Department of
Utilities
Long-term Department
funding, HMGP
funding
Acquisition by City Grant/department
funding
Mitigation Activity Area 19 Area 20
Elevate Utilities X X
Structural Improvements X
Natural Resource Protection
Natural Area Preservation
Natural Area Restoration X
Emergency Services
Hazard Threat Recognition
Hazard Warnings
Health and Safety Maintenance
Structural Projects
Floodwalls X
Diversions
Conveyance System Improvements (Structural)
Detention Basin X
Increased Pumping Capacity
Pipe Improvements
Public Information
Outreach Projects X x
Map Information
Technical Assistance
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
6. Repetitive Loss Area Analysis Summary
The City of Sacramento is highly vulnerable to localized flooding. The City’s local drainage system services approximately 100 square miles and is handled by a combination of gravity and lift stations for a total of approximately 140 storm drainage basins. Since the City is typically lower than the elevated rivers by as much as 5-25 feet, the majority of the local drainage must be pumped into the rivers. The City operates 105 sumps and pumps to keep the drainage pumped down.
It is conceivable that extremely heavy local rainstorms can result in badly flooded streets and flooding of homes in some areas. It is estimated that such situations would be brought about by a slow-moving highintensity rainstorm over several hours reaching a peak intensity of one-half inch per hour later in the storm event. Any higher intensity storm event will cause localized flooding problems. The majority of the structures in the City’s repetitive loss areas are impacted by local drainage flooding. The identified structural projects related to drainage improvements will result in long-term flood protection for affected areas. However, most of these projects must wait for funding to proceed.
It is recommended that property owners prepare themselves at the beginning of each rainy season, typically October. The City suggests having sandbag materials on hand, clear debris of storm drains on a regular basis, and have backup generators for sumps. The City’s mitigation activities recommended in this report include increased outreach on hazard awareness and warning, with additional efforts in repetitive loss area to ensure flood preparedness. Finally, the development of an ongoing program to match residents who would like to move forward with a structural or property protection mitigation activities with possible grant funding.
Through the collaborative efforts of the City and residents, the repetitive loss areas within Sacramento can become better prepared, more protected, and resilient to localized flooding.
6.1.Current Mitigation Projects
6.1.1. Capital Improvements Plan Drainage Improvements
The FY2023/24 budget for the City Utilities Program totals $47.3 million. At the current time, drainage improvements identified by the Utilities Department for implementation are under review and will be prioritized upon funding approval.
6.1.2. Acquisition and Demolition
The City of Sacramento has not identified any properties on its repetitive loss list that would be candidates for acquisition or demolition of the structures.
6.1.3. Advantages and Disadvantages of Mitigation Measures Seven primary mitigation measures are discussed here: acquisition, relocation, barriers, floodproofing, drainage, elevation, and insurance. In general, the cost of acquisition and relocation will be higher than other mitigation measures but can completely mitigate the risk of any future flood damage. Building small barriers to protect single structures is a lower cost solution, but it may not be able to offer complete protection from large flood events and may impact flood risk on other properties. Where CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
drainage issues are the source of repetitive flooding, drainage improvements can provide flood mitigation benefits to multiple properties. Each of these solutions is discussed in greater detail below.
Insurance differs from other property protection activities in that it does not mitigate or prevent damage caused by a flood. However, flood insurance does help the owner repair and rebuild their property after a flood, and it can enable the owner to afford incorporating other property protection measures in that process. Insurance offers the advantage of protecting the property, as long as the policy is in force, without requiring human intervention for the measure to work.
7. Conclusion and Recommendations
Conclusion and Recommendations
Based on the field survey and collection of data, the analysis of existing studies and reports, and the evaluation of various structural and nonstructural mitigation measures, the City of Sacramento has identified various mitigation measures that can be implemented by homeowners or identified for possible regional stormwater or drainage improvements that will be evaluated by City staff.
The City will encourage property owners to use flood-proofing measures to help protect lower levels of their property. Outreach and education will continue to be a priority, not only citywide but to individually affected residents, in order to minimize future flood risk through increased public education efforts to increase awareness of flood preparedness and flood protection measures such as moving valuable items to above the flood elevation and permanently elevating vulnerable HVAC units. At the same time, the City will work with property owners, citizens, the State and other regional and federal agencies to implement capital improvement projects, which will help to eliminate flooding in the repetitive loss areas.
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Attachment 1 - Repetitive Loss List
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Status Total
Count Item Count RL# Mitigated? Flood Zone NFIP Insured Approved AW-501
1 1 302953 NO A99 NO
2 2 83750 NO A07 NO
3 3 76416 NO A99 YES
4 4 14959 NO X NO
5 5 304401 NO X NO
6 6 80810 NO X NO
Pending AW-501
7 7 74636 YES A99 NO
8 8 49291 YES AE YES
9 9 28436 NO AE NO
10 10 54735 NO AE NO
11 11 162939 NO AE NO
12 12 81320 NO A99 YES
13 13 48021 NO A NO
Unmitigated
14 1 158498 NO X YES
15 2 89651 NO AE YES
16 3 91177 NO A99 YES
17 4 108339 NO X NO
18 5 138956 NO X NO
19 6 83634 NO X NO
20 7 83635 NO X NO
21 8 83636 NO X NO
22 9 69776 NO X NO
23 10 78107 NO X NO
24 11 84233 NO X NO
25 12 136519 NO X YES
26 13 134126 NO X NO
27 14 302890 NO AE NO
28 15 257133 NO X NO
29 16 90285 NO X NO
30 17 300958 NO X NO
31 18 107964 NO A99 YES
32 19 91108 NO X NO
33 20 84247 NO X NO
34 21 80791 NO X NO
35 22 90378 NO X NO
36 23 158876 NO X NO
Mitigated
37 1 89648 YES A99 NO
38 2 49650 YES A NO
39 3 86119 YES A99 NO
40 4 76417 YES A99 NO
41 5 72548 YES A99 NO
42 6 86111 YES A99 NO
43 7 82068 YES X NO
44 8 89658 YES C NO
45 9 57940 YES A99 NO
46 10 80886 YES A99 YES
47 11 88303 YES A99 YES
48 12 85945 YES A99 NO
49 13 70855 YES A99 NO
50 14 94362 YES A99 NO
51 15 86120 YES A99 NO
52 16 1144 YES X NO
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Status Total
Count Item Count RL# Mitigated? Flood Zone NFIP Insured 53 17 57936 YES X NO
54 18 82390 YES A99 NO
55 19 81318 YES A99 NO
56 20 71120 YES A99 NO
57 21 84257 YES C NO
58 22 88789 YES A99 NO
59 23 88811 YES NO
CITY OF SACRAMENTO – Comprehensive Floodplain Management Plan Repetitive Loss Area Analysis July 2023
Attachment 2 – Outreach Mailing Materials