Concerns over Milliken Dam
on the web at: http://sodacanyonroad.org/forum.php?p=1410
Chris Malan | Feb 14, 2017


Holes in Milliken Dam

NVR 2/14/17: Holes are the key to protecting concrete dam outside Napa

From: Chris Malan
Date: Mon, Feb 13, 2017 at 8:50 AM
Subject: Milliken Dam
To: Mary Luros, Juliana Inman, Peter Mott , Jill Techel, Keith Caldwell, Alfredo Pedroza, Brad Wagenknecht, Diane Dillon, Ryan Gregory, Belia Ramos, Scott Sedgley

Orville Dam failure reminds us of our own aging Milliken Dam and itís lack of full structural integrity since 1924.

Several years ago, the State Division of Dams and Safety (SDDS) ordered the owner of Milliken Dam, the City of Napa, to lower the water surface level in the reservoir such that the pressure against the dam would be reduced due to unacceptable long term Ďcracking' in the damís concrete structure.

It took many years for the engineers to come up with a design remedy short of lowering or removing the dam itself. The State engineers accepted the City of Napaís remedy to bore 5 holes in the face of dam in hopes of keeping the water surface level 16 feet below the rim of the dam.

Given the winter storms and the earthquake in Angwin a few days ago I have these questions about Milliken Dam:

  1. How long has the dam been spilling this year? If so, for how long? Do you expect the dam to spill if it hasnít yet? If so, when?
  2. Are the 5 holes bored in the dam efficiently keeping up with the volume of water coming into the reservoir such that the water surface elevation is kept the required 15 feet below the damís concrete rim to reach as required by the SDDS
  3. Are there any new structural failures of the dam? If so, what are they?
  4. When was the last time the Division of Dams and Safety inspected Milliken Dam? When was the last time new recommendations were made? If so, what were they?
  5. Who is the official at the SDDS that inspects Milliken Dam? When did SDDS last inspect the dam? Are the SDDSís monitoring reports available to the public? If so, please provide a link.

Above Milliken Reservoir
These questions should be answered in a publicly noticed town hall meeting or put on the Napa City Councilís regular agenda.

Not only is public safety of utmost concern, but there is unique and valuable aquatic habitat below the dam. Both interests must be protected ahead of any dam failure possibility.

Given climate change (deluge to drought), increased erosion and runoff from watershed degradation (vineyards in the hills above Milliken Dam), and the age of this defective Dam, I would like to request that this issue be put on the City Councilís agenda for full public disclosure about the status of Milliken Dam.

Please advise.

Thank You,
Chris Malan
Institute for Conservation Advocacy, Research and Education,
ICARE

Executive Director

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