Drainage and flood control
Water is what takes roads and pads apart, and it does it slowly enough that nobody notices until the repair is structural. Most of the drainage work we do is somebody deciding not to do that a third time.
What we build
- Culvert installation and replacement, RCP, CMP, and HDPE
- Headwalls, wingwalls, flared end sections, and rock energy dissipators
- Roadside ditches, V-ditches, and lined channels
- Detention and retention basins, forebays, and outlet structures
- Levee, berm, and access road maintenance
- Agricultural drainage, tailwater returns, and pump pads
- Rock slope protection and bank stabilization
The culvert nobody sized
A great many culverts under North State roads and driveways were put in decades ago at whatever diameter was on the truck. They were adequate until the watershed above them was paved, or burned. A culvert that overtops takes the road with it, and the replacement costs many times what upsizing it would have.
We replace culverts to a size an engineer picked, with the headwall and the outlet protection that keeps the new one from scouring itself out. On a private road that is often a one-day job and the cheapest insurance on the property.
Basins and the drainage report
Detention basins get built to a volume and an outlet rating, both of which are in the drainage report. The two things that go wrong are the volume, if the basin is not built to the design cross section, and the outlet, if the orifice is not the diameter the report says. We build to the report and we shoot the as-built so it can be certified.
Burn scars and the first wet winter
After a fire, the ground above a road sheds water it used to absorb, and it sends ash, soil, and debris down with it. The first winter is the dangerous one. Work that pays for itself before that winter: cleaning and upsizing culverts, cutting and shaping ditches, armoring outlets, and building debris catchment where a channel narrows. We have done a lot of it in Butte County and we know which of it can be done in the window that is left.
What drainage runs
| Item | Range |
|---|---|
| 24 inch culvert, installed with headwalls | $4,500 to $14,000 each |
| Ditch cleaning and reshaping | $4 to $12 per LF |
| Detention basin excavation | $5 to $12 per CY |
| Rock slope protection, placed | $70 to $140 per ton |
| Outlet structure with orifice plate | $6,000 to $18,000 each |
| Levee or berm repair | Quoted per reach |
Unit ranges are what this kind of work has been going for in the Sacramento Valley, put here so you can sanity-check a budget. They are not a bid. Quantities, access, haul distance, and the spec move every one of them.
Questions we get
Almost certainly. Work in a stream bed typically needs a Fish and Wildlife streambed alteration agreement, and often an Army Corps and Regional Water Board permit too, and the agencies have work windows that keep you out of the channel during the wet season and during spawning. Those take months. Start early, and we will build to whatever the permit ends up saying.
Usually a day, sometimes two if the road has to stay open. The bigger question is whether the replacement should be the same size, and often it should not be.
Yes, around the water. Tell us the district's rotation and when the ditch is dry and we will schedule to it. That is normal for us.
No. We build to a civil engineer's design and we are happy to be brought in early to say what is buildable and what a given detail will cost. If you do not have an engineer, we will point you at one who does this work in this valley.
Photos are stand-ins until our own job photos are up: public domain images from the U.S. Army Corps of Engineers and the National Park Service, plus freely licensed photos from Wikimedia Commons (CC0 and CC BY-SA 4.0).
Request a bid: drainage and flood control
Scope, rough quantities, the town, and when the site is available. If there is a bid date on it, put the date and time in and we will confirm receipt the same day.
- The yard
- (530) 555-0142
- Bids and plan sets
- bids@northstateconstruction.com
- Where we work
- Butte, Glenn, Tehama, Colusa, Shasta, Sutter, and Yuba counties
- Yard at 4180 Midway, Chico, CA 95928
CSLB Class A General Engineering · license pending, expected June