Natomas Basin Construction Update – December 16, 2019 Update 

The million dollar question on everybody’s mind in Lower Natomas is…When is Garden Highway between Northgate Blvd and Natomas Park Dr going to reopen?
Our current schedule has Garden Highway fully open to traffic again by the end of January. Reopening by end of January is weather dependent, of course, but our contractor is working seven days a week (breaking only for Christmas Day and New Year’s Day) to get this work done and Garden Highway reopened.

Why is it taking so long, especially when it doesn’t seem like there’s any construction activity?
Underground construction always leaves unanswered questions about what lies beneath the surface until we start digging, and sometimes our best information isn’t always exactly right. When that’s the case, it requires changes…And many changes you may not see or expect. In this case, our designed connections for Sump 58 didn’t match up. So we had to change the design to meet the new conditions but it’s not as simple as you may think. Designs have to be approved, parts have to be fabricated and shipped, and then finally we get to install it. That process takes time, and has caused us to have to delay the reopening of the road as we work to finalize this necessary work.

Why couldn’t you re-open Garden Highway while you redesigned that part of work?
We could not reopen Garden Highway while we redesigned our sump 58 pipe connections because its discharge lines run across the road- way and there was an open trench. Safety is always our first consideration, and it simply didn’t make sense to sacrifice it in this case.

What’s happening under I-5?  When are you going to be done with that work?
We are constructing a seepage berm along Garden Highway under the Interstate 5 overpass to help prevent seepage from occurring through this section of levee. We cannot install a seepage cutoff wall here like the rest of the project because the I-5 overpass is too low for our construction vehicles to do the necessary work under the highway. So, rather than leaving a gap in our flood risk reduction project, which could allow water to sneak through and cause significant flooding in the Natomas Basin, we are using a different method here that bulks up the levee to help keep the water in the channel. This work is expected to wrap up by the end of the month.

Is it safe to still be doing this levee work when we’ve been getting so much rain recently?
Generally, our construction season ends on November 1 to make sure we are ready for the rainy season. Obviously we have gone past that deadline this year but there isn’t reason to worry. The seepage cutoff wall between Northgate Blvd and Natomas Park Dr is complete, and work continues under I-5 understanding that if major rains are forecasted before we wrap up the work we may have to button up the levee early and come back next summer to finish.

So after January, all the Garden Highway closures will be over?
Not quite. Next summer we will have to close a small section between Natomas Park Dr and Interstate 5 to complete the seepage cutoff wall and connect it to our new seepage berm. We will also have to close the intersection of Gateway Oaks for a short duration to complete similar work to the west of I-5. We appreciate the community’s continued patience as we complete these necessary upgrades for the Natomas Basin!

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