My Favorite Dams - Bar CCC

My Favorite Dams – Bar CCC, Parker, CO

David W. Harris, PhD, PE, F.SEI, F.ASCE

Bar CCC - Today - Ready for many more years of use

Earlier I wrote about being at Hoover Dam and the interesting work that would prove to be there.  Dynamic properties of concrete, properties of aged mass concrete, and later helping set up security protocols following 911.

So from a dam considered as an Engineering marvel, why a small dam (a bathtub dam) setup to contain a small holding reservoir in the Parker Water and Sanitation District?

Well, from a personal level it was my first embankment dam job after I set up my consulting business.  Over 35 years with US Bureau of Reclamation, now applying the knowledge gained.  So that was important to me.

For folks interested in dams, this is a good case study in aging and in good dam management.

Before - Wave erosion and embankment sliding

First, the aging process in embankment dams.  This is a small reservoir with a total length in the longest direction of about one half mile.  This direction is roughly in the north-south direction.  Waves in this small reservoir had slowly cut away at the toe of the dam washing away some of the dam and causing slides in the dam; in both cases reducing the cross section of the dam.  Remarkably, even with this small fetch, winter winds could be predicted to produce waves in the 1.5 foot range.  These were enough to do damage to the slopes protected only by plantings of thick grass.  I traveled there one blustery winter day and leaned into the ice cold winds at the water’s edge to confirm waves could lap over a 1 foot ruler.  That convinced me!

Remedial construction underway

So what to do? 

1.  1.    Reslope the dam back to its original design slopes with a material specifically graded for low permeability (figure to the left – foreground)

2.   2.  Add a two stage filter leading to rip rap to prevent embankment wash out (figure to the left placement)

3   3.  Add rip rap graded to withstand wave size (figure to the left – rock towards background of picture)

4.     

                      Designer - -me – inspecting placement and casting the shadow.

Dam Safety and Dam Management in Action

Parker Water and Sanitation District (PWSD) takes its role of public service and public safety seriously.  Working as their consultant (as a subcontractor to Bates Engineering) was a joy and honor.  Representing the owner with the construction contractor was all done with in a team atmosphere with “get the job done” professional cooperation from all parties.  Engineering design isn’t about cheapest, least money possible, but it also isn’t about budget be damned. 

Balance in design, balance in owner/team relations, balance in environmental considerations and any public disruption.  This is one of my favorites because this is how dam inspection; remedial design and construction; and getting a dam ready for more decades of use should be done.