MCDD projects

	Capital Projects for Multnomah County Drainage District No. 1

	Completed

	City Canal Levee Improvements - This project was a joint project between MCDD and PEN 2. In 2007 the US Army Corps of Engineers (USACE), inspected the levees for recertification, the USACE determined the levee on the east side of the Peninsula Canal was deficient because of the established trees on top of the levee. The trees had to be removed in order for the levee to be eligible for recertification. MCDD and PEN 2, agreed the levee on the east side of the Peninsula Canal would be the legal cross levee between the two districts because the levee on the west side of the Peninsula Canal had been removed from the USACE levee program several years before for building and tree encroachments into the levee. In the fall of 2007 485 trees and root wads were removed during the month of August and the levee was roughly shaped with a maintenance bench and then hydro-seeded before the winter months arrived. Some of the trees, at the direction of the Oregon Department of Fish and Wildlife, were placed into the slough for use as turtle habitat. Project cost to remove the trees and root wades $164,000. The levee still needs additional work to accommodate a maintenance bench which will be completed in the near future.

	NE 33rd Base Flood Plan Elevation (BFE) - An area east and west of NE 33rd Avenue has been reclassified with its own sub-basin BFE. The BFE for MCDD is 14 feet NGVD, which means that any structure must have a finished floor at 15 ft. NGVD if it is to be permitted.At the request of the City of Portland the District, submitted hydraulics and hydrology documentation to FEMA to reduce the BFE in the NE 33rd basin to 10 ft NGVD. FEMA approved the request through a LOMR.

	USACE 1135 Project - In 2008 the District completed the dredging of 6.3 miles and construction of 6.5 acres of emergent wetlands in the middle Columbia slough.

	Sleeving the 142nd Street Pipe. One of the culverts under 142nd cross levee had partially separated causing soil above it to be sucked in and distributed downstream. In 2007, divers went in to find the problem and proceeded to install an HDP sleeve and grout around it. This was much less expensive than the alternatives. In 2008, the debris was removed from the 2nd pipe and new grates were installed in front of both pipes.

	223rd Cross Levee. The USACE observed during their certification evaluation that a pond had developed at the toe of the cross levee. The District, placed a total of 14,000 cubic yards of soil in the low area and regraded the slope to prevent future ponding at the toe of the slope. The District cost was about $2,500.00. Now NACCO Material Handling, the property owner, installed a fence to keep recreational vehicles off the levee and their property.

	On Going Projects

	NE Marine Dr. Levee Resurfacing - Resurfacing the Levee. The Marine Drive levee from the 42nd Street boat launch to 185th needs to have its landward face resurfaced with a fresh overlay of dirt. The levee is built of sand with an overlay of soil into which grass is seeded. Over the years the soil overlay have been eroded by some vehicle and pedestrian traffic, but mostly by the winds that blow down the gorge from the east. In 2007, the first section beginning at the boat launch was stripped of vegetation and a soil overlay put into place and hydro-seeded. As funds are available, the project will continue heading east each year until it is completed.

	Future Projects

	Levee Seepage Investigation - During high river levee when the levees become saturated the District will use some form of infrared or ground penetration radar to detect areas in the levee that are abnormally saturated or identify potential conduits for high level seepage of boils.

	Investigate Levee Toe Drains - Majority of the levee systems have a toe drainage system which drains the water away from the levee during high river levels so the levee does not become overly saturated at the base of the levee. Over time the toe drainage system may become plugged or damaged. The investigation will identify any deficiencies that need to be corrected.

	SW Quad Conveyance System - The drainage basin on the west end of the Portland Airport drainage to a District pump station located on NE Elrod Dr. (PS#2). As this area develops PS#2 will not be able to handle the increased stormwater flows. The district and the Port of Portland are working together to realign the drainage system to take a large portion of the future flows to the Broadmoor pump station which has been designed with greater pumping capacity than PS#2.

	Lower Columbia Slough Levee Improvement - The District is performing a slope stability analysis along the lower Columbia Slough levees to identify slopes that may need to be repaired or rebuilt to meet USACE levee design standards.

	MCDD Shallow Water Restoration Project - The District and the USACE is performing a feasibility study to potentially dredge the Columbia River on the east and west sides of the I-205 bridge and to deposit the dredged sands along the toe of the levee on the east end of the I-205 bridge to create a 50 foot wide by 7000 feet long restoration project supporting trees and wetland plants. The feasibility study is estimated to cost $250,000 with a completion date in late 2011.

	Trash Raking Systems for Secondary Pump Stations - As water quality improve in our ditch system the aquatic weed becomes an increasing issue with plugging the intakes to the pump stations. In order to prevent the pumps from cycling continuously because of the weed build up the District has designed a trash raking system to remove the weed from the grate automatically. The trash raking system cost between $90,000 and $130,000 per pump station. As soon as the district can budget for the improvement the trash raking systems will be installed.

	Coordinate with Utilities to get a Secondary power grid to Pump Station - The District is working with the electrical utilities to install a secondary power source from a secondary sub-station to all of our pump stations to establish a redundant and reliable power source to the pump stations.

	NE 223rd Columbia River Levee Relocation - The NE 223rd levee toe has eroded taking a large portion of the maintenance bench with it. In order to rebuild the eroded slope the District would have fill into the Columbia River which requires mitigation for the fill in the river. The district has determined it will be less costly to relocate the levee to the south within existing levee easement to avoid the river impact.