The Engineering Department recommends approval of Contract Modification No. 1 for the increase in the professional services agreement with Walter P. Moore and Associates, Inc., in the amount of $244,820, for the Indian Creek Tributary No. 13 Study and Shady Creek Circle Bank Stabilization project.

Contract Modification No. 1 includes additional improvements along Indian Creek Tributary No. 13 upstream of the current project site. An inspection upstream of the current project site was prompted by an adjacent resident. After inspecting the creek upstream, an additional five (5) sites were identified as having severe erosion and were recommended to be added to the project. This recommendation is based on the severity of the erosion, the economic impact to repair now rather than in later projects, and to minimize the amount of disturbance to the residents in this neighborhood. The five (5) additional site improvements include:

1. Protection of two existing retaining walls experiencing undermining of the toe and end of the wall erosion. A gabion mattress will be placed for the toe and end protection and the backfill will be replaced and protected by either turf reinforcing mat or gabion mattress.
2. Placement of a gabion wall along the outside bend of the channel near the southern end of the Shady Creek Circle cul-de-sac due to severe erosion creating a vertical bank threatening a residential property.
3. The City’s concrete trail is being threatened by channel erosion on the outside bend of the stream. This will be addressed by either relocation of the existing trail or construction of a new gabion wall to protect the trail.
4. An outside bend of the channel is experiencing erosion along the bottom half of the bank within erodible rock. This erosion within the rock bank may cause a loss of significant portion of streambank near the existing Indian Trail. This will be addressed by the protection of the bottom half of the erodible rock bank by installing a partial-height gabion wall structure.
5. An elevated section of the trail is threatened by erosion on the outside bend of the stream. After investigation, either the foundations for the elevated trail will be reconstructed to a deeper bearing, the trail will be relocated, or a longer span structure will be installed to completely span the problem area.

If this contract modification is not approved, additional erosion will continue to damage the streambanks of Indian Creek Tributary No. 13 creating loss of property, steep and unsafe slopes near homes, loss of soil/foundations along Parks trails, and possible failure/loss of Parks trails. The continued erosion may cause the closure of the Parks trail, create additional maintenance costs, additional disturbance to the residents, and develop a poor quality of life for local residents and trail users.

Funding for this item is available in the 2019-20 Municipal Drainage CIP and is planned for 2020-21, as well.  The first modification to the professional services contract, in the amount of $244,820, will leave a current year balance of $253,730 for future project expenditures.  

Approval of this item will support the City's Strategic Plan Critical Success Factors of being an Excellent, Innovative, and Accountable City Government that offers Safe, Vibrant Neighborhoods.

Funding for this item is available in the 2019-20 Municipal Drainage CIP and is planned for 2020-21, as well.  The first modification to the professional services contract, in the amount of $244,820, will leave a current year balance of $253,730 for future project expenditures.  

Approval of this item will support the City's Strategic Plan Critical Success Factors of being an Excellent, Innovative, and Accountable City Government that offers Safe, Vibrant Neighborhoods.