South Platte River Notes

By Bryan Kohlenberg, P.E., Senior Project Engineer

In 2006 the South Platte River Program officially joined forces with the District’s Design and Construction Program and the Maintenance Program.  The newly formed mega program, aptly named the Design, Construction and Maintenance Program, now consists of a project engineer, a construction manager, and a student intern assigned to each county and the 41 miles of the South Platte River.

We continue to work with the cities, counties, special districts, utility owners, and property owners along the South Platte River to help preserve the corridor, improve conditions and habitat of the river, and assist with the maintenance of this valuable natural resource downstream of Chatfield Reservoir. 

Capital Projects
Globeville Project
The final construction phase of Denver’s project to remove approximately 200 acres of highly urbanized lands in north Denver from the 100-year floodplain continues.  Lawrence Construction is the general contractor.  Under an agreement with the District, Love and Associates and their sub-consultant team are providing construction management services for Denver.  Construction is expected to be complete in the spring of 2008.

Zuni/Sun Valley Reach Project
This year, Denver and the District selected Matrix Design Group, Inc. to provide final engineering design of this channel improvement/environmental enhancement project between 8th Avenue and Lower Colfax Avenue.  The design team is now actively pursuing project real estate and utility relocation needs along this reach of the South Platte River.  Construction is expected to begin in early 2008.

Maintenance Activities
Routine Maintenance
In 2006, South Platte River routine maintenance efforts included:

• 198 river miles (equivalent) of trash and debris pickup and removal

• 3.6 acres of string-trim mowing at access ramps and rest areas

• 79 miles (equivalent) of recreation/maintenance trail edge mowing

• 9.1 miles of tree pruning and trimming along the trail

• Removal of dead trees and other large items from the river

• Participation in annual NIMBY ("Not In My Backyard") FEST volunteer trash cleanup event

This year over $210,000 was spent to perform these services along the 41 miles of river between C-470 and the Adams/Weld County Line.  Colorado Total Maintenance (CTM), Inc. was selected again to perform these services.  The routine maintenance also included efforts to re-vegetate various areas along the South Platte River.  These efforts included reseeding, with native grasses, as well as the installation of various native trees and shrubs.

The complete South Platte River routine maintenance contract documents, including scalable aerial photos of the 41-mile river corridor are downloadable from our web site (www.udfcd.org).

Noxious Weed Management
We continue to be aggressive in controlling many varieties of invasive vegetation, including both noxious weeds and trees, along the river.  Local governments consistently ask for our assistance in removing weeds such as Purple Loosestrife, Thistle, and Knapweed.

Before and After (prior to revegetation) of West Bank at Adams County South Platte Fishing Lakes

We have also removed Tamarisk (a.k.a. salt cedar), Russian Olive, and Chinese/Siberian Elms by cutting, and selective and careful application of herbicides, when needed.  Removal is followed by the planting of native Plains Cottonwood, Sandbar Willow, shrubs and various native dry land grasses.

The Northeast Colorado Tamarisk Task Force (NoCoTTF) has been a great resource for effective Tamarisk control measures.  For more information about the NoCoTTF, contact Kelly Uhing, Adams County Weed Specialist, at (303) 637-8115 or KUhing@co.adams.co.us.

Restoration Maintenance
In 2006, the following restoration maintenance projects were completed:

• Restoration and stabilization of 1100 feet of highly erosive west riverbank near 164th Avenue extended in Brighton.
• Lowered and restored west riverbank at the new Adams County South Platte Fishing Lakes & Open Space just north of 104th Avenue.
• Buried and vegetated over 2000 feet of exposed riprap bank in Thornton.  Excess excavation from the above project was hauled and placed at this location.
• Repaired two failing bank revetments within the Army Corps of Engineer's channelized reach between Coal Mine Road and Hampden Avenue.  More specifically, along the east bank adjacent to the Englewood Golf Course and 1200 feet upstream of Oxford Avenue.
• Repaired a damaged boat chute below Union Avenue with grouted boulders.
• Constructed 1000 feet of east riverbank restoration/stabilization adjacent to the new Ken Mitchell Lakes facility currently being constructed by the City of Brighton.  This project was in response to on-going lateral river migration that threatened to bypass the Brighton Ditch diversion structure.
• Replaced severely cracked or heaved concrete recreation/maintenance trail sections in Denver.

Several restoration maintenance projects that are planned for construction next year include: 

• Repair of several riverbank stabilization and wildlife habitat rehabilitation structures within South Platte Park in Littleton.
• Repair or replace badly deteriorated wooden retaining walls and wooden bridges along the South Platte River trail within Denver.
• Construction of at least two bank stabilization/restoration projects adjacent to existing sand and gravel mines in Adams County.

Cooperative Projects
Cooperative projects are constructed on flowage and maintenance access easements dedicated to the District by private property owners adjacent to the river in exchange for river restoration work.  The District can participate financially up to 75 percent of the total project cost.  To date over 740 acres of such easements have been dedicated, resulting in over 35 bank stabilization and/or river grade control and riparian revegetation projects since 1987. 

Boat Chute Repair Below Union Ave

Three new cooperative projects were completed this year:

• McIntosh Farm Coop - West bank of the river south of 120th Avenue.  Left Hand Excavating installed buried riprap along the bank in order to help protect the adjacent dairy farm operations.  Thirty-one acres of riparian area were dedicated to the District.
• Stagecoach Stop Pit Coop - Naranjo Civil Constructors completed 700 feet of east riverbank restoration/stabilization on property owned by LaFarge Inc. north of 124th Avenue.  Six acres of riparian area were dedicated to the District.
• Worthing Pit Coop – Left Hand Excavating completed over 1400 feet of east riverbank restoration/stabilization on property owned by Henderson Aggregates Inc. (Albert Frei and Sons) just south of 132nd Avenue.  Forty-four acres of riparian area were dedicated to the District.

Next year we hope to have the following cooperative projects under construction:

• Hazeltine Reservoir Coop - East riverbank restoration/stabilization adjacent to a sand and gravel mine just north of 104th Avenue on property owned by Aggregate Industries.
• Lindgren Property Coop - East riverbank restoration/stabilization on property owned by the Lindgren family just north of 124th Avenue.
• Brighton Mine Coop - West riverbank restoration/stabilization adjacent to a sand and gravel mine north of E-470 on property owned by Aggregate Industries.