Appeal 33586

Title 24.

Title 24.50.060.F.8. Balanced Cut and Fill Required. In all Flood Management Areas of the City not addressed by Subsection 24.50.060 G, balanced cut and fill shall be required. All fill placed at or below the base flood elevation shall be balanced with at least an equal amount of soil material removal. Soil material removal shall be within the same flood hazard area identified in Subsections 24.50.050 A. through I.

a. Excavation shall not be counted as compensating for fill if such areas will be filled with water in non-storm winter conditions.

The intent of this appeal is to repurpose sediment material obtained from hydraulic suction dredging of the Tomahawk Bay Marina to create a berm to protect the marina basin from future shoaling. In addition, dredge sand will be placed on the eastern shore of Ricky Point to nourish the beach and protect against further erosion, which could lead to bank failure.

The dredged sand is obtained from the marina where shoaling, which has occurred in successive high-water events, has rendered large sections of the marina unusable and destroyed three rows of docks (188 boat slips). The extracted material is utilized below ordinary high water (OHW) to partially enclose the east entrance of Tomahawk Bay to prevent reoccurrence.

Substantial volumes of sand will be placed on the eastern side of Ricky Point to create a continuous streamline that directs water flows past the marina entrance. This fill will create a shallower slope which will reduce the velocity of river currents and protect the berm from scouring. The interventions are also designed to reduce the eddy effect that occurs at higher water levels in the current configuration.

The grading project also includes beach nourishment below OHW and the planting of willow species where erosion has occurred due to acute scouring that is undercutting the bank.

All the grading work will occur below OHW and well-below FEMA base flood elevation for the subject location. The project is intended to significantly improve the resilience of the marina to high water events and flooding.

The disturbance area in which both dredge and fill will occur is limited to the east entrance of Tomahawk Bay, Ricky Point, and the eastern area of the marina basin, which has been rendered unusable due to severe shoaling.

Section 24.50.060.F.8, Subsection A excludes the extraction of material from submerged areas as compensatory volumes. This is intended to close a loophole whereby conventional on-land projects that absorb flood storage capacity in flood hazard areas could satisfy the balanced cut and fill requirements by, for instance, removing sediment from rivers or lakes. The drafting of the Section did not contemplate a project in which both extraction and fill occur in submerged areas.

As proposed, material sourced from the river will be re-deposited in the river area below OHW and will have no impact on terrestrial water surface elevation in a flood. The project thus fulfills the intent of flood storage preservation.

Dredging and disposal activities occurring below OHW are regulated by Oregon DSL and USACE, among other state and federal agencies from which authorizations have been obtained. DSL Permit 63312-RF and USACE Permit NWP-2021-412 require all fill for the Tomahawk Bay project to be excavated from the river and placed in the designated disposal areas below OHW. DSL mandates extensive pre- and post- project reporting and performs rigorous surveillance of dredging activities. The agency scrupulously reviews bathymetric surveys and other topographical studies to validate compliance.

WEST Consultants, Inc, performed a hydraulic study on the Tomahawk project, applying standard engineering practices and the FEMA No-Rise criteria. They conclude, “the proposed development will not cause an increase in water surface elevations during the occurrence of the 1% annual chance flood event.”

The proposed fill placement is below OHW and balanced by compensating excavation that also occurs below OHW, therefore there is no effect on upland flood absorption capacity.

Responses to Variance Questionnaire:

1. The danger that materials may be swept into other lands to the injury of others;

This river sand is placed at low elevation in an area below OHW and therefore will not impact adjacent upland property. Downriver sand transport will be no greater than if the material remained at its present location, which is also in the river, or if the Applicant carried out in-water disposal as authorized under the its DSL (64474GP) and USACE (NWP-2010-141-6) maintenance dredge permits. The project involves placement of river sand which does not pose risk of injury.

1. The danger to life and property due to flooding or erosion damage;

The project’s purpose is to reduce the risk of shoaling and erosion from flooding and high-water events. Flooding will result in the loss of the functional use of the marina, destruction of docks and marine infrastructure, and eventually bank failure from continued scouring of Ricky Point if no action is taken.

1. The susceptibility of the proposed facility and its contents to flood damage and the effect of such damage on the individual owner;

No enclosed structure is proposed. The only adjacent installations are floating structures which rise and fall with the water level. As stated, the project purpose is to reduce the susceptibility of the marina and nearby habitat to high water events.

1. The importance of the services provided by the proposed facility to the City;

The marina offers year-round moorage for the public to enjoy Oregon’s riverways. Active recreation on the river, including sailing, kayaking, motorboating etc. cultivates appreciation for the natural beauty of our waterways and their environs, and is integral to the lives of many boaters in the Pacific Northwest. Clean, well-maintained marinas are critical to the health of our rivers, aquatic species, and shoreline habitat.

1. The necessity to the facility of a waterfront location, where applicable;

Marinas must be on navigable waterways. The project restores full operational use of the marina and protects the basin from sedimentation and erosion risks.

1. The availability of alternative locations, not subject to flooding or erosion damage;

This project is, by its nature, site-specific, and no alternative location fulfills the objectives of protecting the marina from further shoaling or Ricky Point from bank failure.

1. The compatibility of the proposed use with existing anticipated development;

The Applicant has obtained land use approval (LU 23-006494 EN) to replace docks damaged by shoaling with new docks that meet current standards. The proposed grading will protect the new dock and its occupants from property damage and loss of navigation due to shoaling. The replacement dock would likely be rendered unusable one again without intervention.

1. The relationship of the proposed use to the Comprehensive Plan and Floodplain Management Program for that area;

No change of use is proposed. The current use as a marina is permitted under the site’s base code and comprehensive plan zoning. The use has been authorized since the original construction of Tomahawk Bay Marina, and has been affirmed in repeated land use decisions, including LU 23-006494 EN, which confirmed the proposed project’s compatibility with the Comprehensive Plan.
The berm and other interventions protect the marina from flooding and high-water events that would cause property destruction. The Resource Enhancement on Ricky Point is intended to reduce the risk of erosion. Property protection and erosion control are fundamental objectives of the Floodplain Management Program.

1. The safety of access to the property in times of flood for ordinary and emergency vehicles;

No vehicle access is permitted as per LU 23-006494 EN. The area in which the proposed grading will be done is not currently accessible to vehicles.

1. The expected heights, velocity, duration, rate of rise, and sediment transport of the floodwaters and the effects of wave action, if applicable, expected at the site;

A site-specific HEC-RAS was performed for this project by WEST Consultants. The certified FEMA No-Rise analysis confirmed “no impact” on the expected base flood elevations (BFE). Therefore, the project does not impact these parameters, and thus, values correspond to the initial conditions. These values are shown in the FEMA No-Rise analysis.

1. The costs of providing governmental services during and after flood conditions including maintenance and repair of public utilities and facilities such as sewer, gas, electrical, and water systems, and streets and bridges.

This site on which the proposed grading will occur is not served by any public or private utility services.