Culverts sometimes get plugged especially if there is not maintenance.  The “Urban interfaces” in the West are often prone to fire and wildfires can also play havoc with culvert crossings.  So, sometimes, in certain environments, it it best to reduce the reliance on culverts.  Gravel roads, secondary roads, access roads may be best designed without culverts – which greatly reduces cost, maintenance, and water quality problems.   How can reducing culverts lead to water quality? you ask.  The answer is in understanding that culverts concentrate water, therefore at the outlets there is often a hydraulic jumb ergo EROSION.

Well, an alternative to culvert crossings are low water crossings.  Concrete fords have been used for some time but they are difficult to build, forming and pouring concrete in a channel!  Building “hardened crossings” out of rock, that can withstand periodic flooding and high flows, can also be difficult.

One of the techniques we have been using lately is building low water crossings from Articulated Concrete Blocks (ACBs).  SWAG (Sacramento Watersheds Action Group), our non-profit, public benefit watershed restoration group, and Salix Applied Earthcare has designed and built several of the over the last few years.  We have built them using both Submar ACBs and ArmorLok ACBs (Contech). 

We have also been incorporating a Energy Transition System into our Low Water Crossing designs.  These transitions systems include a couple of new products, Scour Stop and Green Armor System.  These transition systems not only reduce erosion but they are often aesthetically pleasing and can be designed to increase infiltration.

The pictures below show Low Water Crossings built in our local watershed, as part of a 12-year, $1.2 million, grant-funded  Sulphur Creek Restoration Projects.  Also, Salix has been designing and building similar “crossings” for CA State Parks, Off Highway Vehicle Division to use in the SVRAs (State Vehicle Recreation Areas).

Articulated Concrete Blocks and Low Water Crossings are covered in much greater detail in our ‘ACB Episode’ – available at the WatchYourDirtStore (www.watchyourdirtstore.com).    

For more on this install, check out this previous WatchYourDirt Post.

Manhole covers gushed, streets swam and hillsides slid.

The sky just opened up as the most intense storm I have ever seen – hit my hometown – and most fortunately I was HOME.  I grabbed my camera(s) and ran down to Sulphur Creek.  I had a moment of pause though.  

Should I instead run out to Shasta College and see what the storm was doing at the ECTF (Erosion Control Training Facility) since we had JUST (three days prior) completed filming the Big Cover Up and Hydromulch episodes and the compost blankets, hydromulch, ECBs and everything else was also getting blasted?

I chose Sulphur Creek because it was close to home and the storm cell was really “doing it here”.  Also for the last 12 years our non-profit watershed restoration group, SWAG (Sacramento Watersheds Action Group) has been restoring the long-degraded, gold mined, turned upside down, urban salmon/steelhead stream.  We have put over $1.8 million in grant funding “on the ground” realigning and restoring over 2-miles of stream, doing road-to-trail conversions, and increasing riparian and stream function.  See www.watershedrestoration.org for more info.

The most recent work, completed 3 years ago was under a grant from CA DWR; SWAG partnered with the City of Redding.  Almost $400K was used to realign and restore floodplain along over 1 mile of creek.  This included sewer crossings camouflaged by Newbury rock riffles/rock vanes hybrids (David Derrick and I dubbed them “viffles”).  We also designed some fish passage step/pools at a Union Pacific Railroad Culvert (No fish have passed this point since construction – 1938).  

I was able to document the 1.8” / hour intensity rainfall.  WOW.  See how the Articulated Concrete Block (ACB) low water crossings faired.  Look at the before and during pix of the huge boulder step/pool viffles at the railroad.  During construction I was skeptical that such big rocks were necessary – but now I’m glad.  The orientation of the boulders was also critical as the viffle orientation provided much-needed stability.  Also, so grateful that David Derrick explained the importance of building riffles from the bottom up and “under compression”.

Well, that’s it for now.  But with Sulphur Creek I always have  more to say.  So stay tuned!!

-John

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Quick Update on our Low Water Crossing installation that was featured in our Articulated Concrete Block episode.

John snapped this pic of the very high, very erosive flows going over our l’il crossing.  Amazing stuff, when filming, I never imagined that it’d see this type of action.  But apparently it does.

The crossing is located in a valley, a valley that is pretty much a catch basin for a good portion of Redding, CA and surrounding areas.  When it rains, a heck of a lot of water gets diverted into a small channel that goes over the LWC and into Sulphur Creek.  Crazy flows.

So how is it holding up?  Well it’s been 3 seasons and everything is looking great!  No undercutting, no movement.  Some of the angular rock spread on top of the ACB has washed away – but, frankly, we expected that to happen to an extent.

All in all, it’s looking great.  I hope this one holds up just as well (from Salix’s Sacramento OHV Job)…