Caltrans & FHWA-Compliant Rock Slope Protection (RSP)

Engineered rip-rap and Rock Slope Protection (RSP) stone supplied to Caltrans, civil, utility, and site contractors—meeting HEC-23 gradations and California Section 72 specifications for erosion control, slope stabilization, channels, shorelines, and infrastructure projects.

When erosion control, slope protection, and hydraulic stability matter, rip rap is not just rock—it’s engineered protection.

At North Bay Materials, we supply spec-grade Rip Rap and Rock Slope Protection (RSP) used in transportation, drainage, shoreline, and infrastructure projects throughout Northern California. Our materials align with Caltrans Highway Design Manual Chapters 870 & 880 and the FHWA Hydraulic Engineering Circular No. 23 (HEC-23) standards adopted statewide for modern RSP design.

Contractors choose us because we understand:

RSP class requirements (Class I–XI)
Median stone sizing and weight tolerances
Placement methods (A & B)
Fabric class compatibility
Inspection-ready material documentation

Whether you’re building stream bank protection, bridge scour countermeasures, slope armor, guide banks, spillways, or drainage channels, we help you source the correct rip rap size the first time—so your project passes review and performs long-term under high-flow conditions.

rip rap size 18-36" stock pile at quarry

What Is Rip Rap & Rock Slope Protection (RSP)?

Rip Rap vs. Rock Slope Protection (RSP) — What Contractors Need to Know

Rip rap is a general term for large, angular rock used to control erosion.
Rock Slope Protection (RSP) is the engineered application of rip rap designed to meet hydraulic, structural, and environmental performance criteria.

For contractor-built infrastructure projects, the distinction matters.

Modern public works, DOT, and agency projects no longer accept “generic rip rap.” Instead, they require engineered RSP designed in accordance with FHWA Hydraulic Engineering Circular No. 23 (HEC-23) and adopted by Caltrans under the Highway Design Manual (HDM) Chapters 870 and 880.

What Makes RSP “Engineered” Rip Rap?

Rock Slope Protection is specified and evaluated based on:

Median particle size (D50)
Stone weight ranges (lbs to multi-ton units)
Gradation limits (D15, D50, D100)
Placement method (Method A or B)
Fabric class compatibility
Hydraulic performance under velocity, shear stress, and wave action

These parameters ensure long-term stability under:

High-flow storm events
Scour conditions
Channelized drainage
Riverbank and shoreline exposure
Bridge abutments and piers

Why Caltrans Updated RSP Standards

Following a Federal Highway Administration (FHWA) audit, Caltrans formally replaced the legacy California Bank and Shore (CaBS) methodology with HEC-23–based RSP gradations to improve consistency, performance, and constructability across projects.

Key benefits of the updated RSP standards include:

Nationwide consistency across state and federal contracts
Smaller cross-sections in some applications, reducing excavation and environmental impact
Alignment with FHWA, NCHRP, and Caltrans specifications
Improved performance in riverine, coastal, and stormwater systems

Where Engineered Rip Rap Is Commonly Used

Contractors typically specify RSP rip rap for:

Stream and river bank stabilization
Channel linings and outfalls
Bridge scour protection
Slope armor and embankments
Shoreline and coastal protection
Spillways and overflow channels
Guide banks and hydraulic control structures

If your plans reference “RSP Class,” “HEC-23,” “Section 72,” or “HDM 870/880”, you are dealing with engineered rip rap, not decorative or generic rock.

Contractor Tip

Material rejection on rip rap jobs almost always comes from incorrect sizing or gradation—not placement.
Verifying RSP class, stone weight range, and placement method before ordering prevents delays, re-handling, and inspection failures.

Caltrans Rock Slope Protection (RSP) Classes & Rip Rap Sizes

Modern Caltrans and agency projects specify Rock Slope Protection (RSP) by class, not by vague size descriptions. Each class corresponds to a median stone size, weight range, and placement method, derived from FHWA HEC-23 and adopted by Caltrans Section 72.

If your plans reference RSP Class I–XI, the table below explains what that means in practical, contractor-friendly terms.

Common RSP Classes Chart with stone weights and placement methods.

What “Placement Method” Means for Contractors

Method B
- Smaller to medium stone
- Can often be placed with conventional equipment
- Typically used for slopes, channels, and embankments

Method A
- Large to multi-ton stone
- Requires controlled placement (excavator, crane, or hoe-ram assist)
- Used where stability under high velocity, wave action, or scour is critical

Understanding placement method before ordering is critical for:

Equipment planning
Access staging
Delivery sequencing
Inspection approval

Fabric Requirements (Often Missed in Bids)

Caltrans RSP specifications also require geotextile fabric compatibility:

Fabric Class 8 → RSP Classes I–VIII
Fabric Class 10 → RSP Classes IX–XI

Using the wrong fabric class is a common inspection failure—even when the rock itself is correct.

Where Contractors Use Rip Rap & Rock Slope Protection

Engineered rip rap and Rock Slope Protection (RSP) are specified wherever soil, slopes, or structures are exposed to moving water, velocity, or scour. Today’s Caltrans and agency standards require RSP designs that account for hydraulics, geomorphology, and long-term stability, not just rock size.

Stream & River Bank Stabilization

Rip rap is used to:

Prevent bank erosion during high-flow events
Stabilize natural channels and realigned streams
Protect adjacent infrastructure and utilities

RSP sizing is typically driven by flow velocity, shear stress, and channel geometry, with Classes III–VII commonly specified depending on exposure.

Drainage Channels & Outfalls

For:

Stormwater outfalls
Culvert outlets
Open channels and swales

RSP prevents undermining, head-cutting, and downstream erosion. Many plans reference HEC-23 sizing to ensure stability under peak discharge conditions.

Bridge Scour & Abutment Protection

Rip rap plays a critical role in:

Bridge pier protection
Abutments and wing walls
Guide banks and spurs

These applications often require larger RSP classes (VII–IX) placed using Method A for precise interlocking and resistance to high-energy flows.

Slope & Embankment Armor

Used on:

Roadway embankments
Cut slopes
Retaining slope systems

Proper RSP placement reduces surface erosion while allowing drainage and minimizing slope failure over time.

Shoreline & Coastal Protection

For:

Bays, estuaries, and inland lakes
Shoreline revetments
Wave-exposed embankments

Caltrans Chapter 880 extends RSP guidance to coastal and inland lake environments, accounting for wave action, storm surge, and long-term exposure.

Concreted-Rock Slope Protection (When Specified)

Some projects call for concreted-rock slope protection, where concrete is placed to a specified penetration depth between stones.

Minimum penetration varies by RSP class and must meet Section 72 requirements to pass inspection—another detail frequently missed without material familiarity.

Why Application Matters When Ordering Rip Rap

Each use case affects:

Required RSP class
Stone weight range
Placement method
Fabric class
Equipment and access planning

That’s why contractors working with North Bay Materials don’t just order “rock”—they get application-matched material that aligns with their plans and inspection criteria.

Contractor-Grade Rip Rap Delivery — Built for Real Job Sites

Ordering rip rap isn’t just about stone size — delivery logistics can make or break your schedule.

At North Bay Materials, we specialize in jobsite-ready rip rap and RSP delivery for contractors working on infrastructure, drainage, and erosion control projects. Our delivery model is built around access constraints, staging needs, and placement planning, not retail yard pickups.

What Contractors Need From Rip Rap Delivery

We design our delivery process to support:

Active construction zones
Tight access roads and urban sites
Staged placement for excavators and loaders
Slope and channel work with limited laydown
Coordination with inspectors and superintendents

Instead of forcing contractors to adapt to yard limitations, we adapt delivery to the jobsite.

Bulk & Project-Scale Rip Rap Supply

We supply rip rap and RSP materials for:

Small to mid-sized infrastructure projects
Multi-day erosion control installs
Phased slope protection work
Emergency erosion repairs
Agency and utility-driven scopes

Whether you need single-load delivery or sequenced loads matched to placement, we help plan material flow so crews stay productive.

Why Contractors Prefer Jobsite Delivery Over Yard Pickup

No wasted labor hours on hauling
Reduced equipment congestion
Controlled delivery timing
Safer handling of large stone
Better coordination with placement equipment

For larger RSP classes and heavier stone, jobsite delivery reduces risk, re-handling, and damage.

Delivery Planning That Prevents Delays

Before scheduling delivery, we help confirm:

Access width and turning radius
Ground conditions for loaded trucks
Placement method (A or B)
Equipment on site (excavator, loader, crane)
Safe dump or staging locations

This planning prevents:

Failed delivery attempts
Unsafe dumping conditions
Schedule disruptions
Material relocation costs

A Rip Rap Supplier That Understands Specifications, Not Just Stone

Most material suppliers sell rip rap as a commodity.
We treat it as an engineered construction material.

Contractors choose North Bay Materials because we understand how Rock Slope Protection (RSP) is designed, specified, delivered, and inspected under Caltrans and FHWA standards—and we help prevent costly mistakes before they happen.

Built Around Caltrans & FHWA Standards

We work daily with projects referencing:

Caltrans Section 72 – Rock Slope Protection
Highway Design Manual (HDM) Chapters 870 & 880
FHWA Hydraulic Engineering Circular No. 23 (HEC-23) gradations
Agency and utility erosion control requirements

That means we speak the same language as:

Project engineers
Inspectors
Estimators
Superintendents

No guessing. No “close enough.”

Spec-Matching Support Before You Order

Before material is loaded, we help contractors confirm:

Correct RSP class
Stone weight range and gradation
Placement method (A or B) feasibility
Fabric class compatibility
Delivery sequencing based on equipment and access

This avoids:

Material rejection
Failed inspections
Re-handling and double hauling
Schedule delays

Contractor-First Supply Model

No retail yard confusion
No decorative rock substitutions
No vague sizing descriptions
No last-minute surprises

We focus on construction-grade aggregates, supplied and delivered with jobsite realities in mind.

Reliable Communication & Scheduling

Contractors value:

Clear availability updates
Realistic delivery timelines
Direct communication
Fast response when conditions change

Our delivery-only model allows us to stay flexible, responsive, and focused on execution, not counter sales.

Trusted by Contractors Across the Bay Area

From erosion control repairs to full-scale slope protection installs, contractors rely on us for:

Rip rap
RSP boulders
Drain rock
Base rock
Supporting aggregates

All supplied with performance, compliance, and constructability in mind.

Contractor FAQs — Rip Rap & Rock Slope Protection (RSP)

These are the most common technical and procurement questions we get from estimators, supers, and engineers sourcing rip rap for Caltrans and agency-aligned projects.

Q. What is the difference between rip rap and RSP?

Rip rap is a general term for large rock used to control erosion.
Rock Slope Protection (RSP) is rip rap that meets engineered sizing, gradation, and placement requirements defined by FHWA HEC-23 and adopted by Caltrans Section 72.

If your plans reference RSP classes, HEC-23, or HDM 870/880, generic rip rap is not acceptable.

Q. How do I know which RSP class my project requires?

RSP class is typically specified directly on:

Plan sheets
Erosion control details
Hydraulic calculations
Caltrans or agency standard notes

If only flow velocity or discharge is shown, RSP class is derived using HEC-23 design guidance. We can help interpret plan notes before you order.

Q. What is the most commonly used rip rap size?

On Northern California projects, the most commonly specified sizes are:

Class III–V for channels and embankments
Class VI–VII for slopes and drainage structures
Class VIII–IX for bridge scour and high-energy applications

Actual size depends on hydraulics, slope angle, and exposure.

Q. What does “placement method A or B” mean?

Method B: Smaller to medium stone placed conventionally
Method A: Large stone placed individually using excavators or cranes

Placement method affects equipment selection, delivery sequencing, and staging and must be considered before scheduling delivery.

Q. Does rip rap require geotextile fabric underneath?

In most Caltrans RSP applications, yes.

Fabric requirements are class-specific:

Fabric Class 8 → RSP Classes I–VIII
Fabric Class 10 → RSP Classes IX–XI

Incorrect fabric selection is a frequent inspection failure.

Q. Can rip rap be used for emergency erosion repairs?

Yes. Rip rap is commonly used for:

Storm damage response
Washouts
Slope failures
Outfall undermining

Q. Is your rip rap inspection-ready?

Yes. Our rip rap supply aligns with:

Caltrans Section 72 requirements
HEC-23 gradation concepts
HDM 870/880 guidance

We help contractors confirm compliance before delivery, reducing the risk of rejection.

Q. Do you deliver directly to construction sites?

Yes. We specialize in jobsite delivery, including:

Active construction zones
Tight access sites
Staged delivery for excavator placement

Delivery planning is coordinated with the contractor to avoid access or safety issues.

Rip Rap Supply & Jobsite Delivery Across the Bay Area

North Bay Materials provides contractor-grade rip rap and Rock Slope Protection (RSP) supply with direct-to-jobsite delivery throughout the greater Bay Area.

Our service footprint is intentionally focused on regions with active civil, utility, drainage, and erosion-control construction, allowing us to support projects efficiently without overextending logistics.

Primary Service Coverage

We regularly supply rip rap and RSP materials to projects located in:

Marin County
Sonoma County
Alameda County
Contra Costa County
San Francisco
San Mateo County

This coverage supports a wide range of project types including:

Transportation infrastructure
Municipal drainage improvements
Utility trenching and outfalls
Creek and channel stabilization
Slope and embankment protection
Shoreline and coastal work

Built for Contractor Access & Scheduling

Our delivery model is optimized for:

Urban and suburban job sites
Narrow access roads
Residential-adjacent construction
Staged delivery for active placement

Rather than requiring contractors to haul material from distant yards, we bring spec-matched rip rap directly to the project, reducing downtime and improving crew efficiency.

Regional Knowledge Matters

Working within the Bay Area means understanding:

Variable soil conditions
Seasonal storm impacts
Tight inspection windows
Agency-driven material requirements

Our familiarity with local construction conditions and inspection expectations helps contractors avoid surprises during delivery and placement.

Serving Multiple Jurisdictions, One Standard

While jurisdictions vary, most public and private projects in the region rely on FHWA-based RSP guidance and Caltrans-aligned specifications.

That consistency allows us to support:

Public works contractors
Private civil contractors
Utilities and infrastructure firms
Environmental and restoration contractors

—all with the same engineered rip rap supply approach.

Get Rip Rap Pricing From a Contractor-Focused Supplier

When your plans call for rip rap or Rock Slope Protection (RSP), accuracy and timing matter. Ordering the wrong class, size, or delivery setup can delay inspections, disrupt crews, and increase costs.

North Bay Materials helps contractors move forward with confidence by supplying spec-matched rip rap aligned with Caltrans Section 72 and FHWA HEC-23 guidance, delivered directly to the jobsite.

What We Can Help With Immediately

Confirming RSP class from plans or notes
Matching stone size, weight, and gradation
Verifying placement method compatibility
Planning jobsite delivery and staging
Providing current availability and pricing

Whether you’re bidding, mobilizing, or responding to erosion damage, we help eliminate guesswork.

Who This Is For

This service is designed for:

Civil & grading contractors
Public works contractors
Utility contractors
Environmental & restoration firms
Drainage & stormwater contractors
Infrastructure & transportation crews

If your project references RSP, HEC-23, Section 72, or HDM 870/880, you’re in the right place.

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