Maintenance
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Maintenance Program Activities

by
Mark R. Hunter, P.E., Chief, Maintenance Program

STATUS OF MAINTENANCE REHABILITATION PROJECTS

Project Jurisdiction

Cost

Status
ADAMS COUNTY
Little Dry Ck., Shaw Heights. - South Westminster Design

65,000

50%
   of 80th. Repair bank erosion, partic. Const.

400,000

0%
Sand Creek -confluence w/ S. Platte R. Commerce City Design

14,600

25%
   Repair bank erosion, participation Const.

next year

0%
Niver Creek – S.Platte to Steele St. Adams County Design

by others

100%
   Replace pipes,repair channel, partic. Const.

272,500

100%
ARAPAHOE COUNTY
Cherry Creek – west of Colorado Blvd. Glendale Design

$10,000

5%
   Repairs to outlet of tributary. Const.

next year

0%
East Toll Gate Trb. - Along Uravan Av Aurora Design

29,610

50%
   Drops and channel repair Const.

next year

0%
Little Dry Ck. – east of Holly at Arap. Arapahoe County Design

41,800

40%
   Sediment trap and park repairs, partic. Const

next year

0%
Little Dry Ck – north of Belleview Ave Cherry Hills Village Design

29,744

100%
   Repair several erosion sites, partic. Const

76,989

100%
Piney Creek Tribs-north of Orchard Rd Arapahoe County Design

by others

100%
   Repair 2 regional detention ponds Const.

61,764

100%
S.J.C.D. North – East of Sheridan Bvd. Arapahoe County Design

34,387

40%
   Repair low flow channel and drops. Const.

next year

0%
Willow Creek – s. of Dry Creek Road Arapahoe County Design

29,600

100%
   Sediment trap Const.

211,496

100%
Willow Creek, Jamison Trib. - Dry Ck Arapahoe County Design

by others

100%
   Road. Repair drop structures. Const

329,888

30%
BOULDER COUNTY
City Pk Drainageway – w.of Hwy 287 Broomfield Design

by others

100%
   Replace low flow chan./drops, partic. Const.

50,000

100%
Coal Creek – west of Erie at r.r. tracks Erie Design

by others

75%
   Rebuild obliterated channel Const.

next year

0%
Fourmile Canyon Creek Boulder Design

46,192

100%
   West of Broadway at Lee Hill Const.

238,075

100%
Elmer’s Twomile Ck. – s. of Iris Ave. Boulder Design

by others

70%
   Rebuild detention pond and channel Const.

100,000

0%
DENVER COUNTY
Bear Creek – Raleigh to Sheridan Denver Design

$111,588

100%
   Repair bank and rebuild drop Const.

525,638

100%
Bear Creek – N. of Hampden at Lamar Denver Design

by others

100%
   Improve pedestrian bridge Const

82,078

100%
Cherry Creek – W. of Colorado Blvd. Denver Design

37,344

60%
   Repair drop structure Const

next year

0%
Cherry Creek – S.Platte R. to Delgany Denver Design

35,960

100%
   Low flow channel protection, partic. Const

323,640

100%
Cherry Ck, Babi Yar T.-Yale &Havana Denver Design

34,865

100%
   Drops, bank repair Const.

322,556

30%
Goldsmith Gulch – Cook Park Denver Design

94,564

100%
   Low flow channel repairs Const.

462,709

100%
Harvard Gulch – DeBoer Park Denver Design

39,845

30%
   Rebuild trickle channel Const

next year

0%
Lakewood Gulch – In Martinez Park Denver Design

by others

90%
   Trail repairs, participation Const

6,000

0%
Lakewood Gulch – Federal to Knox Denver Design

78,432

100%
   Channel erosion repair Const.

next year

0%-phase 3
South Platte River, Westside Trib. - Denver Design

43,868

95%
   N.E. of 6th and I-25. Install pipe. Const.

next year

0%
DOUGLAS COUNTY
Cherry Creek – S. of Arapahoe County Parker Design

by others

100%
   Trail construction, participation Const.

$39,481

100%
Marcy Gulch – N. of Highlands R. Pky Douglas County Design

by others

100%
   Build drops and channel work, partic. Const

205,705

100%
Sulphur Gulch – W. of Hwy #83. Parker Design

45,000

0%
   Rebuild drop structure Const.

next year

0%
Tallman Gulch – In Rowley Downs Parker Design

by others

85%
   Trail construction, participation Const

75,000

0%
JEFFERSON COUNTY
Dutch Ck – NE. of Pierce & Coal Mine Jefferson County Design

$76,558

95%
   Repair eroding channel Const.

next year

0%
Ralston Creek – west of Brooks Drive Arvada Design

48,237

100%
   Repair narrow eroding channel Const.

240,039

100%

Routine Maintenance
Through the routine maintenance program $679,000 was spent in 1999 for mowing and debris pickups. This work was done on approximately 210 different sections of drainageways within the District boundaries. This equates to a total of over 100 miles of drainageways in the Denver area on which we performed scheduled mowing and debris pickup maintenance.

For 1999 we continued with the increased level of mowing and debris pickups on many urban drainageways. Most of the more urban drainageways now receive four to five mowings and debris pickups per year. Three to four mowings per year was inadequate for effective weed control and for overall appearance.

Other drainageways we maintain are more rural in character. On portions of some of these drainageways we have taken the opportunity to reduce or eliminate our mowing activities. This has been done to encourage habitat and leave a more natural character in the drainageway corridor.

For the calendar year we awarded seven separate contracts for routine work. Four of those contracts were awarded through an internal review of proposals submitted by potential contractors. The remaining three were awarded through a direct competitive bid process.

Restoration Maintenance
In 1999 the restoration program completed $2,261,000 of work. Restoration projects typically address isolated drainage problems where the solution involves small-scale construction. Ninety individual activities were completed during the year. A major advantage of the restoration program is the opportunity to use it to react quickly to local drainage needs.

Nature dictates that as long as sediment is being carried by a stream some of that sediment will drop out when the stream expands into a quiescent pool. One of the on-going obligations created when detention ponds are built is to keep those ponds relatively free of accumulated sediment. We have removed sediment from two-dozen detention ponds over the last two years. It takes a continual effort to keep these flood protection facilities functioning as intended. We envision that it will be more difficult to carry out this type of regular maintenance in the future as the Clean Water Act regulations become more restrictive. We also repaired the trickle channels and outlet structures in three of those regional detention ponds.

Over the years the City of Boulder has built erosion prevention features on rural sections of Boulder Creek east of the City. Some of these improvements have recently been damaged. Our work will repair the damage and reinforce the improvements. An earlier project by a federal agency had straightened portions of the creek alignment. We will also return some local sinuosity to the creek.

In contrast to the work on rural Boulder Creek we are also doing repairs to the trapezoidal concrete channels in the Montbello Drainageways. There are nine miles of concrete channels in this portion of Denver. The concrete panels lining these urbanized drainageways tend to buckle from hydrostatic pressure or collapse as a result of being undermined. Ninety percent of these channels are squeezed into the median between the opposing traffic lanes. There is little room for creativity in repairing these confined linear channels.

On the banks of the valley where Harlan Street Outfall discharges into Clear Creek the City of Wheat Ridge is building some playfields. The lower three hundred feet of Harlan Street Outfall needed repair as the result of severe erosion. Our funds for the channel repair were combined with Wheat Ridge money to reconfigure the outfall to address the erosion and to provide more useable area for sports.

In a similar cooperative project we are combining funds with the City of Lakewood to accelerate improvements to McIntyre Gulch along Alameda Parkway. These channels currently have a longitudinal slope of about two- percent. Drop structures and erosion resistant materials will be used for these narrow channels.

Rehabilitation Maintenance
Thirty-one projects were at various stages of design or construction during 1999. Those projects are listed in the accompanying table titled "STATUS OF MAINTENANCE REHABILITATION PROJECTS". Rehabilitation projects usually take the form of consultant-designed repairs that are intended to address severe problems that have occurred on a previously improved urban drainageway. By the end of 1999 the District will have spent about $2,161,600 on rehabilitative design and construction for the year. A few of the unique projects are discussed below.

Over the past three years we have reported on our project on Niver Creek in Adams County near the South Platte River. Construction is now complete. The result is that the deteriorated pipes, the concrete-lined channel, and the eroded open channel were replaced by a new roadway bridge, a rehabilitated open channel with drop structures and a wetland bottom, and an expanded trailhead park.

Shaw Heights Tributary joins Little Dry Creek at Sheridan Boulevard and 76th Avenue in Westminster. Upstream from that point Shaw Heights Tributary passes through a small park. Above that it is compressed into a narrow corridor between a railroad track and residential backyards. Design is underway to contain the backyard erosion and to replace the temporary erosion control measures that were installed to protect the railroad and a nearby sewer line.

In last year’s Flood Hazard News we reported on the sediment trap that was being constructed on Willow Creek at Dry Creek Road in Arapahoe County. It was completed in early summer of 1999. Four months later we removed nearly 1000 cubic yards of accumulated sediment from the facility. We expect to need to clean it again in the summer of 2000. About a mile away a comparable sediment control facility is being designed for Little Dry Creek (not related to the Little Dry Creek mentioned above) at Arapahoe Road in Arapahoe County. This site is just upstream from the Holly Dam regional detention pond. The new sediment trap will serve as a forebay for the detention facility and is expected to simplify our sediment removal procedure.

Three large projects, which included significant revegetation efforts, were completed in 1999. Two of them were on Goldsmith Gulch in the City of Denver; one in Bible Park and the other in Cook Park. The third project was on Greenwood Gulch at Holly Street in Greenwood Village. All three projects were situated on parkland or open space and benefited from the design efforts of landscape architects. Our climate does not always agree with our revegetation schedule and our desire for quick re-establishment of plant life. On each of the three sites we have had to return with contractors to replant or reinforce the vegetation we originally installed. Clearly, part of the problem is the power that the stream has to wash away new seedlings. But, the more important factor is our semi-arid climate. Limited and sporadic moisture typically dictates that it will take three years to get the plant community re-established on a given project site.

South of Dry Creek Road in Arapahoe County the Jamison Tributary to Willow Creek flows through a naturally-contoured urban corridor. It is a small channel but the gradient is steep enough that several drop structures were originally built to control the grade. Five of the drop structures have been damaged or undermined by erosion. We are rebuilding the drops with grouted boulders and have designed a cutoff wall to be installed with each structure.

The town of Erie is northeast of the City of Boulder and has been experiencing a recent surge in population growth. A tributary to Coal Creek drains the new developments on the southwest side of Erie. It flows to the north until it encounters a railroad track where the water simply ponds until it can flow between the ties and rails of the track. For this project we will participate with Erie in the funding to channel the water to the east, parallel with the railroad tracks, to an appropriate connection with Coal Creek.

In the early to mid-1980s the Maintenance Program rehabilitated six drop structures on Cherry Creek between University Boulevard and Holly Street in Denver. We rebuilt all six of them as sloping riprap drop structures making use of the existing sheet pile as the cutoff wall for our new drops. Each of the rebuilt drops starting failing almost immediately. Areas of the riprap appeared to be undersized and, in general, riprap is only as strong as its weakest area. We have re-rebuilt four of them as grouted sloping boulder structures and will begin the fifth one in the spring of 2000.

The City of Parker has been active in extending its trails system. On Cherry Creek near the Arapahoe County line and on Sulphur Gulch in Rowley Downs trail connections are being built. The Maintenance Program was able to help fund these projects because the trails in both areas will provide maintenance access that otherwise would not exist.

Welcome to New Staff Member
Cindy Thrush has joined the District as a Project Engineer in the Maintenance Program. Cindy is a registered professional engineer with over 13 years experience working in the field of stormwater management, including the areas of water quality, floodplain management, capital improvement projects and maintenance projects. She received her BS in Civil Engineering from Oregon State University and has worked for both the public and private sectors. Most recently Cindy worked for Arapahoe County. She is an active member of the Colorado Association of Stormwater and Floodplain Managers and the American Society of Civil Engineers.

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