by Andrew Craig
Each year MMWD’s Capital Improvement Program invests $15 million for replacement of aging water infrastructure and other improvements to ensure water is delivered to our customers reliably. These improvements include replacing and upgrading our aging water storage tanks. Did you know that MMWD has over one hundred potable water storage tanks throughout our system, with a total storage capacity of 82 million gallons?
Old redwood water storage tank in Glenwood area of San Rafael
The district still has 21 redwood storage tanks in service within our system, ranging in age from 23 to 52 years old, that we plan to replace over time. Originally redwood tanks were selected and installed because they were less expensive and were appropriate for smaller storage requirements within our service area. Redwood, however, naturally deteriorates over time, to the point of severely leaking, prompting the need to replace these tanks, such as one recently replaced in the Glenwood area of San Rafael. Additionally, these tanks are not able to withstand much ground movement and are subject to toppling over in the event of a moderate earthquake.
Since 1991, the district has replaced 50 redwood storage tanks, with two replacement tanks currently under construction. The replacement tanks are constructed of high-strength steel and are coated with a material that protects the steel from corrosion. This coating is either applied in a factory setting or out in the field, depending on the circumstances. Corrosion is also prevented with the installation of cathodic protection systems. New design criteria also require anchoring the tanks to a solid foundation for seismic stability.
The new Glenwood tank, constructed of high-strength steel
The district’s new steel tanks have piping arrangements that introduce water into them in such a way that it improves overall water quality. New water sampling assemblies enable us to ensure that the water is as pristine as it was when it originated from the source. Finally, new electrical and instrumentation controls enable us to operate our tanks with maximum efficiency and ensure that water delivery is as reliable as you have come to expect.
The next time you fill up your water glass, take a shower, or sip a cup of coffee, take a moment to ponder how water makes its way to your home or business. You can rest assured that MMWD’s engineering team is working diligently to implement the district’s Capital Improvement Program, making sure that the water flowing from your faucet is clean, tastes great, and is reliable for years to come.
Think Blue Marin 