Item 07: Change Order Adding Dog Beach Maintenance Repairs

[COSM_Admin]

Consider approval of Resolution 2021-224R, authorizing a Change Order to the contract with Austin Filter Systems, Inc., for the addition of Dog Beach maintenance repairs in the amount of $148,896.00 and adding a contingency in the amount of $100,000.00 to be added to the Rio Vista Falls Maintenance Project; authorizing the City Manager or his designee to execute the documents necessary to implement the Change Order; and declaring an effective date.

 

[MBaker]

Are these fixes to the original construction and were they under any kind of warranty to be built to last "x years"? Will this new contract stipulate how long these newly engineered design will last? When would we anticipate these features require their next repairs, and will the work now mitigate the extent of future repairs in any way?

At what point do we consider this a flawed design/approach and consider something less grandiose but more sustainable?

 

[COSM_Admin]

Response to CM Baker, provided by Laurie Moyer, Director of engineering:
Are these fixes to the original construction and were they under any kind of warranty to be built to last "x years"? The maintenance repairs at Dog Beach are to the original construction. Typical construction warranties are for one year after construction is complete. The original construction is not under any warranty currently. The failures we are seeing at Dog Beach are due to the structure foundations not extending below the potential scour depth produced by river flow. Will this new contract stipulate how long these newly engineered design will last? . The design engineer has calculated the scour depth and the proposed maintenance repair will include deepening the foundation along the water’s edge and also adding a layer of rock rubble armament at the toe of the foundation on the riverbed to further protect against any scouring. When would we anticipate these features require their next repairs, and will the work now mitigate the extent of future repairs in any way? The design team believes that deepening the foundation and adding armament will be an effective strategy in providing a robust and long lasting structure.

At what point do we consider this a flawed design/approach and consider something less grandiose but more sustainable? The design approach is to use more natural materials and less invasive construction to work within the river’s natural framework vs. using “engineered” concrete structures. These locations are within a developed urban area and have experienced multiple significant flood events. Rivers are dynamic systems and because of human impacts already in place there will probably always be a need for intervention to maintain stability.