6. Tanks - Leak Detection. NCDENR Division of Waste Management Underground Storage Tank Section

Transcription

1 6. Tanks - Leak Detection NCDENR Division of Waste Management Underground Storage Tank Section

2 Why conduct Leak Detection? Required for regulated systems: EXCEPTIONS: Temporarily closed tanks Emergency generator tanks installed before 11/1/07 Discover a release before a major contamination incident occurs

3 Leak Detection Requirements Must be conducted monthly Must detect a release from any portion of the tank Must be installed, calibrated, operated, and maintained per manufacturer s instructions

4 Leak Detection Requirements Third Party Certification: documentation that your leak detection method works for your UST system ALL METHODS HAVE LIMITATIONS - e.g. - tank size, minimum fuel levels, throughput, down time

5 Most common Leak Detection Methods for USTs A Statistical Inventory Reconciliation (SIR) B Automatic Tank Gauging (ATG) Systems C Secondary Containment with Interstitial Monitoring

6 Color-coding key for (UST-10B) checklist: SIR (Statistical Inventory Reconciliation) ATG (Automatic Tank Gauge) IM (Interstitial Monitoring) N/A (Generator tank) Unknown? Spill Bucket Overfill Equipment Vapor Recovery Tank: Corrosion Protection 1 Tank: Leak Detection 2 Piping: Corrosion Protection Tank End 1 Main Run 2 Dispenser End 3 Piping: Leak Detection Suction Pressurized

7 Tank Leak Detection on Compliance Plan: 7

8 Most Common Leak Detection Methods for USTs A Statistical Inventory Reconciliation (SIR) Automatic Tank Gauging (ATG) Systems Secondary Containment with Interstitial Monitoring

9 A. Statistical Inventory Reconciliation (SIR)

10 SIR Description: Statistical analysis of inventory, delivery, and dispensing data, using computer software, to detect leaks

11 SIR Use stick or ATG console Measure product to nearest 1/8 th inch - daily Measure water levels - monthly

12 SIR: Replace broken or unreadable tank sticks Have same person stick tanks daily Stick tanks and read meters at same time daily

13 SIR Records: Keep: Product measurements: per tank, DAILY, for 12 months 1 Water measurement: per tank, PER MONTH, for 12 months

14 SIR Use appropriate calibration charts Supply daily inventory to SIR vendor at end of month Review SIR reports when received from vendor Make sure dispensers calibrated within past 18 months

15 SIR Records: Keep SIR Reports: per tank, PER MONTH, for 12 months

16 SIR for Tank Leak Detection: SIR Product daily, Water monthly, Submit to vendor monthly Calibration charts, 12 months daily Fuel, 12 months monthly Water, 12 months SIR reports

17 Most Common Leak Detection Methods for USTs Statistical Inventory Reconciliation (SIR) B Automatic Tank Gauging Systems (ATG) Secondary Containment with Interstitial Monitoring

18 (2) ATG System How do I know if I use an ATG? Console located inside facility Probe installed at tank

19 ATG System Description: Probe permanently installed Wired to monitor Product level and temperature recorded Calculates changes in product volume Product Level Float Water Level Float

20 ATG Probe: Check if: Wires intact Capped

21 ATG Consoles:

22 ATG Console: Present and powered on No warnings No alarms

23 Fuel Mart 27 UST Raleigh Blvd Spill Bucket Overfill Prevention Flapper Valve Vapor Recovery Coaxial STP * * * Hart Road ATG Probe Dispenser Fuel Mart 27 ATG Console IM Console Rectifier

24 ATG System Testing How much is 0.2 gph leak? (gallons per hour)

25 ATG System Testing Modes: Periodic (static) test mode: Tank needs quiet time Data collected over long period of time Continuous test mode: Data gathered during many short periods, (when no product is being added to or taken from tank) e.g., CSLD, SCALD

26 ATG System Records: Keep: 1 valid 0.2 gph test result per tank, Every 30 days, for 12 months

27 ATG System Records: VARIATION If drinking water wells nearby: Keep: 1 valid 0.2 gph test result per tank, PER WEEK, for 12 months

28 ATG System - Operation and Maintenance: Know how to access and print leak test results Check testing printouts routinely Follow manufacturer s recommendations for tests and service Check console after electrical storms Do not ignore warnings or alarms

29 ATG for Tank Leak Detection: ATG Every 30 days (If drinking water wells nearby: Weekly) 12 months test results (--/--/--)

30 Most Common Leak Detection Methods for USTs Statistical Inventory Reconciliation (SIR) Automatic Tank Gauging Systems (ATG) C Secondary Containment w/interstitial Monitoring (IM)

31 (3) Secondary Containment with Interstitial Monitoring (IM) Product

32 Interstitial Monitoring: Double-walled tank Monitor space between inner and outer walls (interstice)

33 Interstitial Monitoring Electronic Sensors: Detect leaked substance: Liquid (using a Liquid-Detecting Sensor) OR Detect change in condition: Vacuum loss Change in brine level

34 Interstitial Monitoring Console: Present and powered on No warnings No alarms Symbol:

35 Fuel Mart 27 UST Raleigh Blvd Spill Bucket Overfill Prevention Flapper Valve Vapor Recovery Coaxial STP * * * Hart Road ATG Dispenser Fuel Mart 27 ATG Console IM Console Rectifier

36 Interstitial Monitoring Records 1 of 2: Keep: - 1 valid sensor status test result, - per tank, - PER MONTH, - for 12 months

37 Interstitial Monitoring Records 2 of 2: Recommended for tanks installed BEFORE 11/1/2007: - one alarm history report printed, - per tank sensor, - PER YEAR REQUIRED for tanks installed AFTER 11/1/2007: - one alarm history test result printed, - per tank sensor, - PER MONTH, - for 12 months

38 Interstitial Monitoring without sensor Double-walled tank installed BEFORE 11/1/2007 may have port or opening for checking interstice Maintain monthly log for each tank; keep previous 12 months

39 Interstitial Monitoring for Tank Leak Detection: Interstitial Monitoring Every 30 days Sensor Status (printout) Alarm history (printout Log (handwritten) (--/--/--)

40 Tanks installed after 11/1/07: REQUIREMENT: Check Tank Sensor EVERY YEAR; Complete UST-22B form

41 Interstitial Monitoring post : operability test ADD the following information ONLY if the tank was installed after Annual - sensor check UST 22-B 1 year from last check

42 Tanks installed after 11/1/07: REQUIREMENT: - If using Liquid Detecting Sensor Interstice Tightness Test Frequency: - At time of installation, - 6 to 12 months after installation - Every 3 years Complete UST-6E/23D form

43 Liquid-detecting (dry) sensor

44 Other Leak Detection Methods on UST-10B: Enhanced Leak Detection Inventory Control and Tightness Testing Manual Tank Gauging and Tightness Testing Groundwater Monitoring Vapor Monitoring Mechanical Vacuum Gauging

45 EXAM Please answer questions Take a Break We ll start again at: