Caltrans-Approved Erosion Control Stone for Bay Area Projects
 
Rip Rap RSP Boulders are large, angular quarry stone specifically produced for erosion control, slope protection, shoreline stabilization, and hydraulic applications. This material is commonly specified on Caltrans projects, public works infrastructure, creek restoration, bridge abutments, levees, and stormwater channels throughout Northern California.
 
At North Bay Materials, we supply Rip Rap RSP by the ton, sourced from regional quarries and delivered directly to job sites across Marin, Sonoma, Alameda, Contra Costa, San Francisco, and San Mateo Counties using dump-truck delivery suitable for both urban and remote locations.
Rip Rap RSP stone is durable, dense, and angular Granite or Basalt, designed to interlock when placed—providing long-term resistance against water flow, wave action, and soil displacement. Sizes range from Class I through Class VII and higher, allowing engineers and contractors to match material exactly to project specifications.
 
Common Caltrans & civil applications include:
Slope and embankment protection
Channel lining and drainage ways
Shoreline and creek bank stabilization
Bridge abutments and culvert outlets
Flood control and stormwater infrastructure
Roadway and highway erosion control
All Rip Rap RSP supplied meets typical Caltrans RSP gradation intent, with natural size variation inherent to quarried stone. Learn More
 
Rip Rap RSP Size Classes & Typical Uses
Rip Rap RSP is classified by stone size and weight to meet varying hydraulic and erosion-control requirements. North Bay Materials supplies the following commonly specified Caltrans RSP classes, sold per ton.
 
Available Rip Rap RSP Classes
#2 Backing RSP (~10-100 lbs. range)
6x12" Rip Rap
Smaller rip rap stone used for light erosion control, low-flow drainage channels, and slope protection where water velocity is minimal.
 
#1 Backing RSP (~30-200 lbs. range)
9x18" Rip Rap
Medium rip rap for moderate flow conditions, commonly used along roadside ditches, swales, and small channel linings.
 
Class III (Facing RSP ~1/4 ton)
Heavier stone for higher-velocity water, creek banks, culvert outlets, and slope protection requiring increased stability.
 
Class IV / V (~1/2-1 ton range)
Large, heavy rip rap used for major erosion control, bridge abutments, shoreline protection, and high-energy hydraulic environments.
 
Class VI / VII (and larger) (~1-2 ton range)
Extra-large rip rap boulders for severe erosion zones, flood control projects, levees, coastal protection, and critical infrastructure where maximum resistance is required.
 
Important Notes
Rip Rap RSP sizes are naturally variable due to quarry production
Material is angular for proper interlock and stability
Class selection should match project flow velocity and design intent
Engineers may specify higher classes or custom ranges depending on conditions
We work directly with contractors and project managers to help match the correct RSP class to Caltrans plans, municipal specs, and site conditions.
 
Delivery, Load Sizes & Jobsite Access
North Bay Materials offers dump-truck delivery of Rip Rap RSP Boulders by the ton throughout Marin, Sonoma, Alameda, Contra Costa, San Francisco, and San Mateo Counties. Our delivery-only model allows us to source the correct rip rap class and deliver directly from quarry to job site.
 
Dump Truck Delivery
Performed using dump trucks
Ideal for city streets, hillside roads, bridge approaches, and open access areas
Material is end-dumped in a safe, accessible location on site
Take caution when ordering heavy boulders can cause damage to the surface
 
Load Information
Sold by the ton
Typical dump truck payloads vary by truck size and site access
Multiple loads available for large-scale Caltrans and municipal projects
 
Important Delivery Considerations
A flat, stable dump area is required
Limited access, steep grades, or soft ground should be disclosed in advance
Delivery timing can be coordinated to match project schedules and inspections
 
Our team works closely with contractors and site managers to ensure proper material selection, efficient delivery, and jobsite compliance.
 
Rip Rap RSP Boulders – Frequently Asked Questions
Q. What is Rip Rap RSP?
Rip Rap RSP (Rock Slope Protection) is large, angular quarry stone used to protect slopes, channels, shorelines, and infrastructure from erosion caused by water flow, wave action, and runoff. It is commonly specified on Caltrans and public works projects.
 
Q. Is this material Caltrans approved?
Rip Rap RSP supplied by North Bay Materials is sourced from regional quarries that produce material meeting typical Caltrans RSP gradation intent. Final acceptance and class selection should always be verified against project plans and specifications.
 
Q. What Rip Rap classes do you offer?
We supply:
#3 Backing 3x6"
#2 Backing 6x12"
#1 Backing 9x18"
Class IV / V
Class VI / VII and larger
Availability may vary by quarry. We can help source higher classes or custom size ranges when required.
 
 
Q. How much area does a ton of rip rap cover?
Coverage varies by stone class, size distribution, and placement depth. Larger classes cover less surface area per ton due to void space. Engineers typically specify tonnage based on design thickness and slope geometry.
 
Q. How is the material delivered?
Rip Rap RSP is delivered via dump truck and end-dumped in a designated, accessible location. A flat and stable dumping area is required.