Here is the proper Guidelines for DTSC Vapor Mitigation system Compliance that will help you to go through the step by step process.
Pre-Design Phase
Site Assessment
- Request environmental site assessment (ESA) reports
- Review historical land use records
- Identify potential contamination sources
- Map underground utilities and structures
- Document soil composition and groundwater depth
Methane Testing
- Contract licensed environmental drilling company
- Install soil gas monitoring probes at required depths
- Collect soil gas samples per DTSC protocols
- Test for methane concentration and flow rates
- Analyze volatile organic compounds (VOCs)
- Document barometric pressure during testing
- Submit results to DTSC for zone classification
Regulatory Documentation
- Obtain DTSC vapor intrusion screening levels for site
- Verify local building department requirements
- Review EPA guidelines for vapor intrusion
- Check for site-specific regulatory conditions
Design Phase
System Design Requirements
- Engage licensed professional engineer for design
- Select vapor barrier material (minimum 15 mil)
- Design sub-slab ventilation layout
- Calculate required ventilation rates
- Specify monitoring port locations
- Design passive or active venting system based on test results
- Plan gas collection piping network
Methane Mitigation Design Elements
- Size ventilation fans for calculated flow rates
- Specify explosion-proof equipment for high methane zones
- Design redundant venting paths
- Plan for future system expansion if needed
- Include alarm systems for active systems
Plan Review Preparation
- Prepare detailed construction drawings
- Write technical specifications
- Include soil gas test results
- Submit to DTSC for review
- Submit to local building department
- Address plan check comments
- Obtain plan approval before construction
Construction Phase
Pre-Construction
- Verify contractor holds required licenses
- Conduct pre-construction meeting with all trades
- Review installation sequence
- Confirm material submittals match specifications
Vapor Barrier Installation
- Prepare sub-grade surface (remove debris, level soil)
- Install sand layer if specified (typically 4-6 inches)
- Lay vapor barrier with minimum 6-inch overlaps
- Seal all seams with approved tape or adhesive
- Protect barrier from punctures during concrete placement
- Seal around all penetrations (pipes, utilities)
- Document installation with photographs
Ventilation System Installation
- Install perforated vent pipes in sub-slab aggregate
- Connect pipes to collection manifold
- Install monitoring ports at specified locations
- Route vent pipes to exterior discharge points
- Install ventilation fans if active system required
- Wire alarm systems and monitoring equipment
- Verify all connections are airtight
Quality Control During Construction
- Inspect vapor barrier before concrete pour
- Test pipe connections for leaks
- Verify fan operation and airflow direction
- Document any field changes from design
- Photograph all installation stages
Testing and Commissioning
System Performance Testing
- Measure sub-slab pressure differential (target: -0.004 inches water column)
- Test airflow rates at monitoring ports
- Verify fan performance matches design specifications
- Check alarm system functionality
- Test methane concentrations at monitoring ports
- Document baseline system performance
Inspection Requirements
- Schedule DTSC inspector site visit
- Schedule local building department inspection
- Provide inspector access to all system components
- Address inspection comments immediately
- Obtain signed inspection approvals
Documentation Package
- Compile as-built drawings showing actual installation
- Include all testing data and results
- Photograph completed system components
- Record equipment serial numbers and specifications
- Prepare operations and maintenance manual
- Submit final documentation to DTSC
Post-Construction Phase
System Startup
- Activate ventilation system
- Verify continuous operation
- Train building owner on system operation
- Demonstrate monitoring procedures
- Explain alarm responses
Initial Monitoring Period
- Test system performance at 30 days post-activation
- Measure sub-slab pressures
- Check methane concentrations
- Verify fan operation
- Submit results to DTSC
Ongoing Compliance
Regular Monitoring Schedule
- Monthly: Check fan operation and alarm systems
- Quarterly: Measure sub-slab pressures and airflow
- Annually: Test methane concentrations at all monitoring ports
- Annually: Submit monitoring report to DTSC
- As needed: Test after significant weather events or construction nearby
Maintenance Requirements
- Replace fan filters quarterly or as recommended
- Lubricate fan motors per manufacturer schedule
- Inspect vent pipes for blockages
- Clean monitoring ports
- Test backup power systems if installed
- Keep maintenance logs
Record Keeping
- Maintain all testing records for project duration plus 5 years
- Store inspection reports and approvals
- Document all maintenance activities
- Update as-built drawings for any system modifications
- Provide records to DTSC upon request
Contingency Procedures
System Failure Response
- Contact building owner immediately
- Notify DTSC within 24 hours
- Investigate cause of failure
- Implement temporary measures if possible
- Repair system within timeframe specified by DTSC
- Re-test system after repairs
- Submit failure report and corrective actions
Elevated Methane Detection
- Re-test to confirm elevated readings
- Notify DTSC immediately
- Investigate potential causes
- Assess whether system modification needed
- Implement corrective measures
- Increase monitoring frequency until levels normalize
Required Contacts
Keep Current Contact Information For:
- DTSC regional office
- Local building department
- System design engineer
- Installation contractor
- Testing laboratory
- Equipment manufacturers
- Emergency response services
Compliance Verification
Before considering the project complete, verify:
- All DTSC plan review comments addressed
- All building department inspections passed
- System performance meets design specifications
- Operations and maintenance manual delivered
- Building owner trained on system operation
- Monitoring schedule established
- All required documentation submitted