Portland Metro Levee System New Start Feasibility Study

U.S. Army Corps of Engineers,
CENWP-PM
ATTN: Laura Hicks
P.O. Box 2946
Portland, OR 97208-2946

PMLS-Feasibility@usace.army.mil

 

Feasibility Study Chronology

The Draft Integrated Feasibility Report and Environmental Assessment is posted below in the Related Documents and Resources section. *This document is large and may take a moment to fully load.*

The U.S. Army Corps of Engineers has initiated a Feasibility Study focusing on Flood Risk Management of the Portland Metro Levee System in partnership with the Columbia Corridor Drainage Districts (CCDD) Joint Contracting Authority. CCDD consists of four drainage districts: Peninsula Drainage District #1, Peninsula Drainage District #2, Multnomah County Drainage District and the Sandy Drainage Improvement Company. The study area includes 27 miles of levees along the lower Columbia River within the Portland Metropolitan Area, running from Sauvie Island to the Sandy River.

The levee system is experiencing significant signs of structural vulnerabilities during high water, including sloughing, boils, and seepage. The three-year federal feasibility study process will lead to a recommendation to Congress for federal investment in addressing the problem areas in the Portland metropolitan area levee and drainage system.

The study will focus on developing an integrated plan to address potential system failures, meeting current levee safety standards, and identifying potential impacts from future changes including system consolidation, changing water flow conditions and potential operational changes to the Columbia River System.

The Non-Federal Sponsor on the project is the Multnomah County Drainage District (MCDD), which has been granted decision authority to act on behalf of the four drainage districts. The feasibility study is authorized in Section 216 of the Flood Control Act of 1970.

Public involvement

The U.S. Army Corps of Engineers, in partnership with Levee Ready Columbia, has been hosting ongoing informational meetings on the Portland Metro Levee System feasibility study. The events are open to the public and provide updates on the feasibility study including refinement of alternatives, technical information and analysis conducted to date, and the next steps in the feasibility study process. Past public meetings occurred in August, October and December of 2019. The presentations shown at those meetings are posted below in the Related Documents and Resources section.

NEIGHBORHOOD ALIGNMENT WALKS

Bridgeton Road Map (2.3MB pdf)
Date: Tuesday, February 25, 2020
Time: 8 a.m.
Meeting Location: Western end of Bridgeton Road at Blue Frogs Landing (Marina)
Video: Corps and MCDD discuss alignment options (Youtube)

East Columbia Neighborhood & Yacht Club Map (1.4MB pdf)
Date: Wednesday, March 4, 2020
Time: 8:30 a.m.
Meeting Location: Portland Yacht Club

Heron Lakes Golf Course
Date: Wednesday, July 8, 2020
Time: 2:00 p.m.
Meeting Location: Virtual

Peninsula Terminal Co.
Date: Tuesday, May 19, 2020
Time: 12:30 p.m.
Meeting Location: Virtual

Riverside Golf Course
Date: Thursday, September 24, 2020
Time: 10:00 a.m.
Meeting Location: Virtual

Virtual
Date: Wednesday, October 28, 2020
Time: 5:30-7:00 p.m.
Meeting Location: Virtual

Public input is critical to the development of this feasibility plan. The Corps wants to hear the concerns and ideas of community members regarding the Columbia River corridor levee system and managed floodplain. The draft report is posted below in the Related Documents and Resources section.

Past public engagement: The Corps and MCDD held two scoping meetings in December 2018 to engage community members in discussing the study process, study milestones, and the development of preliminary alternative strategies for the reduction of flood risk in the Portland metropolitan area. Discussion also focused on modernization of the levees, flows and flood risk, geotechnical studies of the levees, and the economic risk and consequences posed by various flooding scenarios, as well as the effects on natural and cultural resources of alternatives considered.

In addition, The Corps and MCDD held informational public meetings in January 2020 in the Oregon cities of Fairview and Portland.

Our goals

  • Reduce flood damages, in particular critical infrastructure, in the Portland Metro Levee system over the period of analysis
  • Reduce threats to life safety from flooding and increase awareness of flood risk in the Portland Metro Levee system over the period of analysis
  • Increase resiliency of the flood management system over the planning period of analysis
  • Increase reliability of the flood management system over the planning period of analysis
  • To the extent practicable, provide opportunities for recreation, natural resources, and cultural resources
  • Improve operability of the flood management system and decrease flood response and recovery time

Understanding flood risk

Cross section of a river, a levee, and a building protected by the levee show the elements that make up flood risk: hazard, performance, exposure, vulnerability,

The primary goal of the feasibility study is to reduce the risk of flood damages to the Portland metropolitan area, thereby reducing threats to life and safety.

Flood risk is made up of a variety of factors, beyond exclusively the condition of the levees themselves. These factors include: the hazard, system performance, exposure, vulnerability, and consequences.

The essential questions in determining flood risk are:

  • What possible loading events could occur?
  • How well will the levee system perform when the event occurs?
  • What are the consequences if the levee does not perform as expected? What loss of life could occur?

In even simpler terms, flood risk is the probability of a flood multiplied by the consequences of that flood.

Clarification of concerns we have heard

On October 28, 2020 the four drainage districts hosted a virtual community update meeting. Approximately 77 people joined the meeting.  MCDD presented information on “why the study matters” and the role of the Drainage Boards in the decision-making process for the study. The Corps presented updates on refinements since the Tentatively Selected Plan. Participants’ questions were captured through a chat. Several questions were addressed during the allotted meeting time, all the questions with responses are displayed below.

Q: Which of the original options meet the new FEMA standards for flood insurance certification?
A: This Corps Feasibility Study is focused on a complete assessment of flood risks to the entire levee system versus FEMA’s approach of focusing on a single design flood event Any improvements to the levee system that are constructed by the Corps will meet FEMA standards, but the drainage districts  will need to take some actions outside of this study to meet all of FEMA’s certification standards. For instance, the gate tower drainage connection between MCDD and SDIC will likely need to be addressed to obtain FEMA certification. The Corps determined this is an operations and maintenance issue that needs to be addressed by the non-federal sponsor.  FEMA certification and accreditation is not within the Corps’ primary mission thus obtaining certification of the levee systems to maintain FEMA accreditation is not a study objective.

Local sponsor perspective:
The US Army Corps of Engineers (Corps) and the Federal Emergency Management Agency (FEMA) have different yet complementary missions. FEMA administers the National Flood Insurance Program and evaluates flood risk in order to set flood insurance rates throughout the country. The Corps takes a more holistic view of flood risk when evaluating levees, including evaluating life safety and a wider range of potential flood scenarios. The drainage districts must pay attention to the requirements of both agencies.  The four drainage districts are technically responsible for maintaining the levees to the Corps’ standards, while the cities and county within the managed floodplain are the FEMA-designated floodplain “mapholders“ and share responsibility with the drainage districts to ensure the levee system can be certified. Losing FEMA accreditation and having the area behind the levees designated as a Special Flood Hazard Area under the National Flood Insurance Program, would have profound impacts on landowners and the region. There are eight projects that need to be addressed to meet certification standards. The preferred plan in the Feasibility Study addresses four of them. Levee Ready Columbia, a collaborative partnership of the local cities, drainage districts, Port of Portland, Metro, Multnomah County, and others, is focused on addressing the remaining projects.

Q: How much community support do you need to move forward?
A:  Community involvement and input is critical in helping to identify areas of concern related to various proposals and to evaluate tradeoffs. Overall, reducing flood risk in the region is important to the community, local landowners, and the private and public sector. With this support, the study has progressed to the final phase of completion and making a recommendation for Congressional Authorization. The opinions and support of the community are very important to your Drainage District Board Members. The Drainage District Board Members will need to make the decisions about endorsing the preferred plan in the Feasibility Study and ultimately committing to the cost sharing requirements.

Local sponsor perspective:
The Drainage District boards will evaluate numerous issues before determining endorsement of the final Feasibility Study, including community input and support. The Drainage Districts have worked hard to maintain the local flood safety infrastructure system while the land use around us has continued to change.  This is no longer an agricultural area. The levee system now reduces the risk of flooding for nearly 8,000 residents, 60,000 jobs, the Portland International Airport, and so much more. This Feasibility Study represents the potential to secure federal support for the work needed to bolster the levee system. As we look out at the future, one thing remains clear: these levees are going to continue to protect vital assets for our region, state, and nation. As the districts continue to operate and maintain the systems, it is also important to consider how to modernize it into the future. Your feedback is important as we face these important decisions. If you wish to share any comments on the Feasibility Study with the Drainage District Boards, please use the form on MCDD’s website.

Q: What level of protection (e.g., 500-yr) is currently and planned to be provided?
A: The final estimates of flooding probability will be included in the feasibility report. After improvements are made, the probability of flooding is projected to be about five times less likely than the existing condition. Currently, the system has greater than a 1% (1 in 100) chance of failing in any given year. The proposed improvements reduce the chance of flooding to less than 1 in 500.

Q: What role did the recent Amazon warehouse construction have on this process?
A:
The increased impervious area resulting from the Amazon warehouse development was included in the pump station assessment. The addition of paved areas increases demand on the pump station, since less rainwater is able to infiltrate into the ground and instead moves downstream to the pump station. The Amazon warehouse is also accounted for in the inventory of buildings and structures in the system, which affects the economic benefits of the project.

Q: Can you specify details regarding the remaining HTRW site? location? type of contamination?
A: Details on the remaining hazardous, toxic, and radioactive waste (HTRW) site will be included in the final feasibility study report. A more detailed investigation, including soil samples, will be conducted in a later phase, subject to federal authorization. This information will be given to the local sponsors for their use. As stated during the presentation, the alignment has been refined to avoid known or potential areas of contamination and this sampling will reduce uncertainty at this site.

Q: How about green infrastructure approaches?
A: The focus of this study is on the existing flood risk system and infrastructure already in place to reduce risks to lives and properties protected by the levee system. Non-structural measures were considered throughout the alternatives development process and are included in the preferred Alternative 5.

Local sponsor perspective:
The drainage districts recognize that interior drainage and stormwater attenuation can greatly benefit from green infrastructure, including on-site swales, meandering stream channels, and similar designs. This infrastructure improvements may be incorporated as a part of the capital program of the Urban Flood Safety & Water Quality District (UFSWQD). Improvements to return the watershed to a more natural hydrology (slowing the speed at which water reaches our pumps) is important to the function of the internal conveyance system, but such changes require a comprehensive watershed plan and are out of the scope of the Feasibility Study.

Q: How does 38' downstream at Pen1 mean to Pen2? is that 38' as well?
A: The design levee height tracks the elevation of the Columbia River as it moves upstream. The top of levee at the upstream end of PEN 2 (perpendicular to the Peninsula Drainage Canal) is about a half-foot higher than the downstream elevation of PEN 1. In the Bridgeton Road area, the top of the proposed levee is a few inches higher than 38’, as shown in the PowerPoint presentation. The slope of the levee in this area can also be seen in the PowerPoint presentation.

Q: Remind us how does the 38 feet height compare to Vanport flood? 1996 flood?
A: At the I-5 bridge, the 1996 flood reached an elevation of approximately 32.5 feet NAVD88*, and the 1948 Vanport flood reached an elevation of approximately 36.3 feet NAVD88*. While it would take a large flood to generate river levels higher than 38 feet, the consequences of levee failure are very high and justify the levee improvement. For context, the 1894 flood crested at 39.7 feet NAVD88, though this was before upstream reservoirs had been constructed. *NAVD88 is a vertical datum that provides a common reference point for height measurements. Elevations in NAVD88 are 5.3 ft higher than elevations in the Vancouver Gauge datum, which is the datum that the average river user commonly references.

Q: Potential flooding in this micro-region will be a result of the greater Columbia River flooding - what has the Army Corp of Engineers learned from the results of their previous flood outcomes in New Orleans, etc. and have they consulted with the unique approaches Netherlands are taking in water infringement and flooding?
A: Flooding from Hurricane Katrina caused the Corps to re-evaluate the levee safety program. There have been multiple revisions to the engineering design requirements since Hurricane Katrina, which are accounted for in this study. For instance, one of the issues during Hurricane Katrina was the failure of I-Walls. An I-Wall is a series of steel-reinforced concrete panels shaped like an “I”.  These floodwalls keep floodwaters from entering interior areas. As a direct response to the findings from Hurricane Katrina, Portland District performed detailed inspections and analysis of the local I-walls that run along the Columbia River and Marine Drive from N Portland Road to just west of N Force Avenue in PEN 1. This investigation found that the I-Walls in PEN 1 are in suitable condition to withstand modeled flood scenarios, which are most often generated from high flows on the Columbia and Willamette Rivers. This is one of many examples of how the Corps has applied lessons learned from Katrina. Enhancements to the Corps levee safety program have also included collaboration with approaches taken in the Netherlands.

Q: We have a longitudinal section of elevations along Bridgeton Road but no idea of the current height on the unpaved levee west of the road - in the NW corner of Pen2 in front of condos and apartments. What is current height along that section?
A: Existing top of levee elevations in the northwest corner of PEN 2 near the condos, apartments, and hotels range from around 37 feet NAVD88 to 38.5 feet NAVD88. As noted in the PowerPoint presentation, the levee would be raised up to a foot in this area. The elevations in this area do not reflect the elevation of the levee for the remainder of PEN 2. In order to provide a consistent height, the levee will need to be raised by different amounts in other locations.

Q: How many trees are scheduled for removal at the railroad embankment?
A:   The exact tree count has not yet been surveyed but the impact will be considerably less than previously anticipated based on the concept in the Draft Feasibility Report (Jan 2020) due to reduction in the levee footprint. Vegetation, including trees, removed during construction will be replaced. Additional information on vegetation will be included in the Final Report.

Q: Is the Pen 1 railroad embankment where the Vanport flood breached?
A: Yes, the PEN 1 railroad embankment is where the 1948 Vanport floodwaters first breached. The railroad embankment was never designed to perform as a levee, and there is low confidence it would withstand another flood as large as Vanport. During the Vanport flood, subsequent breaches occurred at the southern section of the Denver Avenue cross-levee between PEN 1 and PEN 2 and the MCDD levee near the MCDD Headquarters.

Q: Are the closure structures hydraulic or manual?
A: The closure structures in the Portland Metro Levee System are manual, and no automated equipment is proposed. High water conditions can be forecasted well in advance of a flood, so there is adequate time to dispatch crews to erect the closure structures.

Q: Will you be working with property owners on size of closure structures to access their property?
A: Yes, the Corps and the Drainage Districts will reach out to property owners affected by new closure structures when more detailed designs of the closure structures are available, which will occur in a later phase of design.

Q: Will the road drop back down at those two floodwall sections?
A: The concept shared at the community meeting included raising the levee under Marine Drive and Bridgeton Road and placing the road back on top. In several places, however, the use of a floodwall is recommended because there is not enough horizontal space to raise the levee. That is the case for the two short segments of floodwall proposed along Bridgeton Road. So, in those two locations, the road will stay at its existing height. As this project moves forward, Bridgeton Road will be designed and constructed to smoothly transition from the higher to the lower roadway elevations.

Q:  Which alternative north-to-south (1-6) will you propose for the floodwalls?
A: The two short sections of floodwalls are proposed to be on the north shoulder of Bridgeton Road. As mentioned above, the floodwalls are proposed in these two short sections because there is not enough horizontal space to raise the levee. The addition of a short floodwall should not impact visibility for the homes across the street. To get a rough idea of how high the floodwall would be, consider the grasses that often grow on the north side of the levee, which are often at the height of the proposed floodwalls or higher. Refer to the PowerPoint presentation for pictures of these areas.

Q: Why is the road-raise indicated as approx. one foot, but the flood wall indicated 2 feet?
A: The existing road elevations where the floodwall is proposed are currently lower than the road elevations to the east and west. Since the existing ground is lower, the floodwall must be slightly higher than the increase in height of the levee embankment.

Q: Is it possible to design it so that trees can be planted on the levee?
A: In general, it is not within Corps guidance to plant trees on levees. But as described in Chapter 4 of Engineer Pamphlet 1110-2-18 (current Corps vegetation guidance), planting berms are allowed next to a levee (Figure A-13) and planters (concrete plant containers) can be used in some areas. There is also possibility to use different types of plantings on a levee, including native grasses. Click here to access Corps policy on vegetation.

Local sponsor perspective:
This Feasibility Study was funded by Congress through the 2018 storm supplemental appropriations package in response to Hurricanes, Harvey, Marie and Irma (HIM). It has been authorized to evaluate flood safety improvements. The Levee Ready Columbia partnership and the Urban Flood Safety & Water Quality District (UFSWQD), however, may make investments in increased vegetation and other improvements, where the four remaining certification projects are located, and in other potential locations within the managed floodplain. The UFSWQD’s mission includes making contributions to water quality, habitat, landscape resilience, and floodplain restoration based upon available resources so they will be able to consider opportunities for habitat investments.  

Q: Given the amount of excavation for the sheet wall foundation to support a flood wall, how does cost compare between raising the road and the floodwall?
A: Elevating the levee and putting the road on top is projected to cost less than installing floodwall. While pavement will need to be removed and replaced, it is expected to be less costly than installing floodwalls, sheet piles, and re-routing utility connections in this area.

Q: There is significantly less work in the refined plan. How much less will it cost?
A: The cost estimate is still under development and will be included in the final report. The cost of this alternative will be lower in the final report than the draft report due to the revisions and refinements to the designs. 

Q: Lowering level of protection from 40 to 38 feet hints at a strong emphasis on reducing cost. How much will safety be compromised by reliance on early warning and non-structural alternatives?
A: Life safety is paramount to the Corps flood risk management studies. The analysis of life safety for this study shows a minimal difference between a levee elevation of 38 and 40 feet. Higher levees can provide a longer warning time for people to evacuate, but in the case of the Portland Metro Levee System, evacuation is triggered at river levels long before the levee is close to having water come over the top.  For instance, for the neighborhoods along the Columbia River in Portland, the City’s current plan calls for issuing evacuation notices at 28.3 ft in PEN 1 and 30.9 in PEN 2 with MCDD to follow shortly thereafter. At a minimum, evacuation warnings are expected to be issued at least a day before floodwaters reach the top of the levee. If residents heed the warning and evacuate when directed, this should be enough time for residents to evacuate to safety.

Q: The closure structures will require additional easements. Does the USACE pay for this or are these negotiations the responsibility of the Drainage Districts?
A: The roles and obligations of the Corps and the Drainage Districts will be defined in the Project Partnership Agreement (PPA), which is signed before the end of the Pre-Engineering & Design Phase (PED).  Upon authorization of the project, it is the responsibility of the Non-Federal Sponsor (NFS) – PEN 1, PEN 2, MCDD, and SDIC – to acquire the lands, easements, rights of way, relocations and disposal sites (LERRDS) necessary for the project. The Corps provides guidance and oversight to the drainage districts throughout the process.

Local sponsor perspective:
The Drainage Districts are working in coordination with the Corps on the real estate requirements, which includes the lands, easements, rights of way, relocations, and disposal sites (LERRDS) that need to be acquired to complete the project. As the Non-Federal Sponsors, the Districts are responsible for negotiating and acquiring all properties needed to initiate construction. The costs incurred by the districts for LERRDS are credited toward the 35% local cost-share requirement as long as the expenditures are made after the Project Partnership Agreement has been signed following the Pre-Engineering & Design (PED) phase. The real estate requirements are an important issue that the Drainage Districts will continue to evaluate carefully.

Q:  What about the size of the structures (measured in linear feet)?  Will you be working with property owners to ensure that the closure structures between floodwalls are wide enough to allow access for current industrial use?
A: Closure structures will be wide enough to allow access for current industrial use.  The Corps and the Drainage Districts will reach out to property owners affected by new closure structures. Currently, the study is at a feasibility-level of design, meaning only a general location of closure structures are included in the feasibility report. More detailed designs of closure structures and associated coordination will occur in a later phase of design.  

Q: Will the raised road also raise the parking in the overbuild?
A: Yes, the parking in the overbuild along Bridgeton Road will be elevated when the levee is raised. Parking areas will be restored in the condition they were prior to construction (either re-paved or re-graded with gravel).

Q: Will the design include sidewalks on the south side?
A: Yes, where existing sidewalks are impacted by construction, they will be replaced. The designs have not progressed far enough to determine whether sidewalks can be placed in areas where they do not currently exist.

Q:  When you move into the pre-engineering and design phase, would you anticipate all the projects going out to bid for engineering services at the same time? And would the Corps manage these as a single project or as multiple projects?
A: The Corps views this as one project spanning four Drainage Districts. During the Pre-construction Engineering and Design (PED) phase, it is envisioned that most of the work would be performed by the Corps, however, if additional engineering services are needed, the scope of the need will be decided and contracted for. Any engineering contracts would be managed by the Corps. The number of construction contracts to implement the project will depend upon when and how Federal appropriations are received. The Corps will administer and oversee the construction contracts.

Q: Would this project be part of a WRDA appropriation? Or separate funding?
A: For the project to move into construction, the Corps needs two Acts of Congress, first an authorization and secondly, construction appropriations. Congressional authorizations typically come in the Water Resource Development Act (WRDA). The Federal appropriations come through the annual federal budget passed by Congress.

Q: A statement was made requesting information on natural resources and environmental justice.
A: A full evaluation of natural resources can be found in the Draft Feasibility Report/Environmental Assessment (January 2020) and will be revised to reflect changes as a result of refining the various measures in the preferred alternative. In general, from project initiation and throughout alternatives development and refinement, the team has sought to avoid impacts to natural resources, particularly sensitive habitats and endangered species. For example, impacts to Endangered Species Act-listed salmon and their critical habitat were avoided by focusing improvements to the landward side of the levee system. The Corps continues to work with resource agencies, including formal consultation with National Marine Fisheries Service and US Fish and Wildlife Service under the Endangered Species Act process as well as the Fish and Wildlife Coordination Act.  Results of these consultations will be included in the final Feasibility Study Report. As was explained in the meeting, the overall footprint for levee improvements has been reduced. In PEN 1, at the railroad embankment area, the levee no longer extends into the environmentally sensitive/forested area in the NW corner, so natural resource impacts have been reduced, including keeping the work farther away from a known great blue heron rookery. A discussion of environmental justice communities was included in the January 2020 Draft Feasibility Report.  Certain populations in the districts fall within this category and stand to directly benefit from the system improvements. One of the key strategies for Alternative 5 was to provide a more equitable level of protection throughout the system; currently flood risks are higher in the lowest areas of PEN 1 and PEN 2 where environmental justice communities live and work. The proposed improvements reduce the impacts from flood risk on these community members.   

Q: With the significant investment in the stability and height of the levee, will FEMA insurance costs go down?
A: It is beyond the scope of this study to project how FEMA insurance costs will change. While flood insurance is an important item from a local perspective, FEMA would be a more appropriate party to respond to this question.

Local sponsor perspective:
As previously stated, USACE and FEMA have different yet complementary missions. There are currently eight projects that require completion to meet certification standards for FEMA. The preferred plan in the USACE Feasibility Study addresses four of those projects and Levee Ready Columbia is focused on how best to address the other four. As long as the system remains uncertified, FEMA could revoke accreditation of the levee system and remap the area as a Special Flood Hazard Area at any time. This would result in landowners behind the levees no longer being eligible for flood insurance through FEMA’s National Flood Insurance Program and mortgage holders would be required to purchase flood insurance at higher rates through the private market.  The drainage districts continue to keep FEMA apprised of the efforts to reduce the risk. For questions about flood insurance, please contact your insurance broker.

Q:  How are they addressing issues related to the FEMA Floodplain Biological Opinion in terms of mitigating for impacts to listed salmonids?
A:  The Corps is currently in consultation with the National Marine Fisheries Service regarding effects to endangered fish species under their jurisdiction, including salmonids, and has made efforts to avoid and minimize the footprint of the system improvements to salmonid habitat. This means that all work on the levees and pump stations has been sited on the landward side of the levees to avoid impacts below the ordinary high-water mark.


FAQ's

Q: I’m concerned that my property value has been been impacted by the PMLS feasibility study and will be impacted more in the future. What are you doing about this issue?
A: We are actively engaging community members to listen to their concerns. In the Spring of 2020, we walked the proposed floodwall alignments with some communities to capture site-based concerns, questions. . We have not made a decision on the final alignment of any floodwall evaluated in the draft integrated Feasibility Report and Environmental Assessment (FR/EA), nor have we confirmed our decision to construct a floodwall at this point. We had to layout conceptual floodwall alignments to evenly evaluate the cost and benefits of the different alternatives in the draft EA/FR.

The earliest construction would occur is 2025, pending approval and funding. We will spend the next year refining the recommended plan prior releasing the final FR/EA and final agency decision. We would then spend another 2-3 years further refining the design during Pre-construction Engineering and Design (PED). Thus, the final alignment of the floodwall will continue to evolve as the study and design of the plan progresses.

Q: If a 3-foot floodwall is built, would pilings need to be raised so floating homes stay attached during a flood? Aren’t floating home pilings required to be at least as high as the top of levee?
A: The proposed floodwall does not trigger any actions for floating homeowners under City of Portland code Section 28.06.040.D.1, which requires pilings be two feet above FEMA’s 100-year flood elevation, not the top of the levee.

For example, in the Bridgeton area, the FEMA 100-year flood is approximately 32 feet in the North American Vertical Datum of 1988 (NAVD88), therefore, the minimum piling height is approximately 34 feet NAVD88.

Even during an extreme flood larger than the FEMA 100-year event, the construction of the floodwall would have minimal effect on floating homes. An analysis of a 1000-year flood event, which has a 0.1% chance of occurring, as shown in Section 7.5 of Appendix A of the Draft Feasibility Report, was simulated with and without the floodwall. With the floodwall, water levels on the Columbia River were only about an inch higher. The floodwall has very little impact to water levels because the interior area is a relatively small volume compared to the volume of water in the Columbia River during an extreme flood. When the interior area fills with floodwaters, it produces very little change to water levels on the Columbia River.

While it may be prudent to extend the height of the pilings beyond minimum requirements to reduce risk, it is not required beyond two feet above the FEMA 100-year flood water level.

Q: The Tentatively Selected Plan does not adequately account for costs of cleaning up sites contaminated with hazardous wastes. This would be an additional burden on taxpayers.
A: Ideally, we could avoid areas contaminated by hazardous waste, but this isn’t always possible, especially in an urban environment. If we can’t avoid using a site that is contaminated, the non-federal sponsor is responsible for resolving the contamination issue in a manner that meets Environmental Protection Agency (EPA) and Oregon State Department of Environmental Quality (DEQ) standards. However, this does not mean that the non-federal sponsor must bear all the costs of cleanup activities, which are usually borne by the Potentially Responsible Party (PRP) responsible for creating the contamination. The non-federal sponsor may be able to recover clean-up costs or compel the PRP (or responsible third parties), to clean-up the site prior to the acquisition of the land. Before the final feasibility report is released, the local non-federal sponsor must commit either to accepting responsibility for the required response, or initiating procedures requiring the responsible parties to respond.

The draft feasibility report identified 25 potential sites with contamination concerns, but further investigation since the draft report was released shows three potential sites remain. It is anticipated that the number of sites with concerns will continue to decrease.

For the sites that cannot be avoided, an approximate preliminary cost estimate for Hazardous, Toxic, And Radioactive Waste (HTRW) response actions will be included in the final feasibility report. This estimate will be refined with more detail during Preconstruction Engineering and Design (PED).

Learn more about Hazardous, Toxic, And Radioactive Waste (HTRW) policies in Engineer Regulation 1165-2-132

Q: Is the Army Corps of Engineers complying with local and state regulations?
A: Compliance with state and local requirements is not a requirement for federal projects. However, state and local agencies are encouraged to provide their feedback to inform the Corps on the project’s conformance with state and local requirements. In addition, Federal projects require environmental coordination, evaluation and compliance with the appropriate federal agencies or state agencies administering federal laws (Water Quality Certification).