Underground Storage Tanks (USTs)

Underground Storage Tanks (USTs)

NCDENRDivision of Waste Management

Underground Storage Tank Section

Rev 12-10

USTs

Release prevention

Release detection

Release Prevention

Five topics

1. Vapor Recovery2. Spill prevention3. Overfill prevention4. Corrosion Protection5. Compatibility

Release PreventionVapor Recovery

Five topics


Vapor Recovery

We DO NOT regulate this

Inspector checks:

•Present

•Operational

•Exceptions

Dual Point

Coaxial

Spill and overfill prevention

Eliminate the potential for a release during fuel deliveries

Spill and overfill prevention

UST-10B

What’s the difference?

Spill prevention:◦ Contains drips and spills of fuel that occur when delivery hose is uncoupled from fill port

Overfill prevention◦ Provides transporter with indication that tank is approaching full during delivery

Release PreventionSpill Prevention

Five topics


Spill prevention on UST-10B

Spill prevention equipment

Fuel delivered to tank here


Fill port/spill bucket


Fill ports must have spill buckets

Temporarily contains product

Typically 5 – 25 gallons

Spill bucket maintenance**

Not designed to “store” fuel

Free of water, fuel, and debris

Free of holes or defects

If there is already liquid inthe spill bucket before youget a delivery, then the spill

bucket can’t do it’s job

UST Site Diagram

UST Site Diagram for: _____________________________________________

*

USTRaleigh Blvd

Fuel Mart 27

Hart Road

Fuel Mart 27

Spill Bucket

Vapor Recovery

•

•

Release PreventionOverfill Prevention

Five topics


Overfill prevention on UST-10B

Overfill prevention equipment**

Ball float valve

Overfill alarm

Flapper valve

Overfill prevention equipment

Ball float valve at

vapor recoveryport

Fill tube with flapper valve


Five topics

1. Vapor Recovery2. Spill prevention3. Overfill prevention

• Ball float valve• Overfill Alarm• Flapper Valve

4. Corrosion Protection5. Compatibility

Ball float valves

Reduces product flow

Installed to slow delivery at 90% capacity or 30 min

before overfilling

Ball float valve restrictions**

Incompatible with UST systems that:

◦ Receive pressurized deliveries

◦ Have suction piping

◦ Have coaxial vapor recovery


Five topics




Overfill alarms

Activates an audible and/or visual warning

Alerts at 90% capacity

Must be located where alarm can be seen and/or heard from delivery site

Unable to restrict or stop flow


Five topics




Flapper valves (automatic shutoff devices)

Slows down and then stops delivery

Installed to stop fuel at 95% capacity

Not for systems that receive pressurized deliveries

Flapper valves

Your overfill responsibilities

Ensure amount of product ordered will fit

Monitor deliveries◦ Lock any extra fill ports that don’t have overfill equipment

◦ Have response supplies ready

Use signs◦ Notify delivery person of overfill device

UST Site Diagram


*

Fuel Mart 27

Raleigh Blvd

Hart Road

Fuel Mart 27

UST

Spill Bucket

Overfill PreventionFlapper Valve

*

*

*

Vapor Recovery

•

•

Release PreventionCorrosion protection

Five topics


Compliance Plan

Compliance Plan

Refer to your inspection checklist and site diagram

For each topic we cover, fill in the blanks with the correct info for YOUR facility

End result should be a basic compliance plan for your facility

Corrosion protection on UST-10B

Corrosion protection on compliance plan

Corrosion protection

Non-corrodible material

Internal lining

Cathodic protection

Release PreventionCorrosion protection

Five topics

1. Vapor Recovery2. Spill prevention3. Overfill prevention4. Corrosion Protection

• Non-corrodible material• Internal lining• Cathodic Protection

5. Compatibility

Non-corrodible material on UST-10B

Non-corrodible material**

FRP Tank

Non-corrodible material**

Jacketed Tank

Non-corrodible material records

Written verification of tank material◦ Installation invoice

◦ Repair invoice

Visual verification◦ Not typical for tanks

If you have non-corrodible materials…

Non-corrodible material (FRP,

CLAD)

N/A

Installation invoice

N/A

Release PreventionInternal lining

Five topics



5. Compatibility

Internal lining on UST-10B

Internal lining

Applying non-corrodible lining inside UST

Internal lining testing

Internal inspection within 10 years of installation,

Then every 5 years thereafter

Tightness test after every inspection

Internal lining records

National code or standard used for installation

Repair invoices

Most recent internal inspection results

Most recent tightness test results

If you have internal lining…

Internal lining

Inspection &TTT every

5 years

Inspection results,

TTT results

--/--/--(5 years

from previous Inspection)

Release PreventionCathodic Protection

Five topics



5. Compatibility

Cathodic protection on UST-10B **

Cathodic protection systems

What does “cathodic protection” mean?

Two types:

◦ Galvanic (sacrificial anode) systems

◦ Impressed current (IC or rectifier) systems

Galvanic/SA systemsImpressed current

systems

Cathodic protection systems**

BOTH types must be designed by a “corrosion expert”

◦ National Association of Corrosion Engineers (NACE)

or

◦ Professional Engineer (PE)

◦ If installed after 3/1/06, must prove system design was certified by “corrosion expert”

Release PreventionGalvanic Systems

Five topics



• Galvanic/SA Systems• Impressed Current Systems

5. Compatibility

Galvanic/SA systems

Anode corrodes instead of UST

Most common: StiP3

Galvanic/SA systems

Anodes (zinc or magnesium) connected to structure by welding or lead wires

Test every three years **

Submit Galvanic test results on UST-7A form

Must be tested by a qualified cathodicprotection tester

If you have a cathodic protection system…

Galvanic/SA system(STIP-3)

Test every 3 years

System design,UST-7A

--/--/--(3 years

from previous test)

Release PreventionGalvanic Systems

Five topics



• Galvanic/SA Systems• Impressed Current Systems

5. Compatibility

Impressed current systems

Anodes located in soil around structures to be protected

Electrical current is applied to anodes

Impressed current requirements

•Requires dedicated and protected circuit

•Power must not be interrupted (except during testing)

•Breaks in wiring result in system failure

Impressed current requirements

60 Day Readings from RECTIFIER BOX:

•Operator must inspect system every 60 days

•Record meter reading on UST-21 form

•Make sure meter NOT reading “zero”

•Make sure meter never loses power

Additional impressed current requirements

UST-21 form can be found on website

Additional impressed current requirements

Compare your 60-day readings to “as-left” readings on UST-7B

Add Rectifier Box to Site Diagram

UST Site Diagram


*

Fuel Mart 27

Raleigh Blvd

Hart Road

Fuel Mart 27

*

*

*

UST

Spill Bucket


Vapor RecoveryCoaxial

STP

ATG

Dispenser

ATG Console

Rectifier Box

probe

Test every three years**

Submit Impressed Current test results on UST-7B form

Must be tested by a qualified cathodicprotection tester

If you have a cathodic protection system…

IC system

60-day readings,

Test every 3 years

UST-21,UST-7B

--/--/--(ex. 1st of

every month)--/--/--

(3 years from previous

test)

Failed or inoperative cathodicprotection systems

IC or galvanic system test FAILS

IC system is/was without electricity

Specific requirements for each situation◦ See memo on website under “Guidance Documents”

http://www.wastenotnc.org/ust/docs/CP_Policy.pdf

Cathodic protection system problems

IC system lines to anodes broken

Cathodic protection system problems

No power to the rectifier

Release PreventionCompatibility

Five topics


Most Common Alternative Fuels**

◦ E-10 10% ethanol 90% gasoline

◦ B-20 20% biodiesel 80% petroleum diesel

◦ E-85 85% ethanol 15% gasoline

Follow the same rules that apply to traditional gas and diesel

Extra requirements!

Example of Accelerated Corrosion

Standard, non-E85 fuel STP E85 STP

Photos courtesy Iowa DNR

Same facility, same install date

UST-20 Form**

PRIOR to dispensing >10% ethanol or >20% biodiesel

UST-20 Form

Sections completed by UST owner/operator AND equipment contractor or PE

Include◦ Documents verifying compatibility OR

◦ Compatibility analysis by PE

EXAM

Tank Release PreventionPlease answer questions # 11-17

USTs

Release prevention◦ Spill prevention

◦ Overfill prevention

◦ Corrosion protection

Release detection

Release Detection

What is leak detection?

The activities and equipment used to detect releases from UST systems

Why conduct leak detection?

REQUIRED for all regulated systems

Discover a release before a major contamination incident occurs

Leak detection on UST-10B

Leak detection on compliance plan

Monthly methods

Leak detection requirements**

Must be conducted monthly (at least once every 30 days)

Must detect a release from any portion of the tank

Must be installed, calibrated, operated, and maintained per manufacturer’s instructions

Leak detection requirements**

Third Party Certified

◦ Documentation that your leak detection method works for your UST system

◦ http://www.nwglde.org

◦ Keep documents for inspection

◦ Pay attention to limitations Tank size Manifolded tanks Throughput Etc.

http://www.nwglde.org/

Monthly methods – most common**

Automatic Tank Gauging (ATG)

Systems

Secondary Containment with

Interstitial Monitoring

Statistical Inventory

Reconciliation (SIR)

ATG System

How do I know if I use an ATG?

Console located inside facility

Probe installed at tank

ATG Probe

Check:

•Capped

•Wires intact

ATG Console

•Present and powered on

•No warnings or alarms

UST Site Diagram


*

Fuel Mart 27

Raleigh Blvd

Hart Road

Fuel Mart 27

UST

Spill Bucket


*

*

*

Vapor RecoveryCoaxial

STP

ATG

Dispenser

ATG Console

probe

ATG system on UST-10B

ATG system description

Probe permanently installed

Wired to monitor

Product level and temperature info recorded

Calculates changes in product volume

ATG system testing modes

Periodic (static) test mode◦ Tank needs “quiet” time

◦ Data collected over a period of time

Continuous test mode◦ Data gathered during many short

periods when no product is being

added to or taken from tank

◦ Ex. CSLD or SCALD

ATG system operation and maintenance

Tank size

Manifolded tanks

Minimum fuel levels

Type of product (e.g. waste oil, E-85)

Maximum allowable monthly throughput

Duration of test

Waiting period after fuel delivery before test

Make sure your system is certified for your particular facility:

ATG system operation and maintenance

Know how to access and printout leak test results

Check testing printouts routinely

Follow manufacturer’s recommendations for system tests and service

Check console after electrical storms

Do not ignore warnings or alarms

ATG system testing **

How much is 0.2 gph leak?

ATG system records

Must keep one valid 0.2 gph test result per tank, per month, for 12 months

If you have an ATG system…

ATG system

12 months test results

--/--/--(ex. Every Monday)

Conduct test every

30 days

Secondary Containment with Interstitial Monitoring

How do I know if I use Secondary containment with interstitial monitoring?

Double-walled tank

May have sensors monitoring space between inner and outer walls

May have console located at facility

Interstitial monitoring on UST-10B

Interstitial monitoring description**

Periodic monitoring◦ Check interstice manually for liquids

Continuous monitoring◦ Electronic sensors in interstice connected to console

Interstitial monitoring description**

Electronic sensors:

◦ Detect leaked substance

liquid or

gaseous

OR

◦ Detect change in condition

loss of vacuum or

monitoring liquid level change

Interstitial monitoring requirements

Periodic monitoring:

◦ Manually check interstice and document at least once every 30 days

Continuous monitoring:

◦ Continuously monitor interstice with electronic sensors

◦ Check and print sensor status at least once every 30 days

Interstitial monitoring records

Must keep all records per tank, per month, for 12 months

If you have a secondary containment system with interstitial monitoring…

Interstitialmonitoring

12 months Periodic checks OR Sensor status

results

--/--/--(ex. Every Monday)

Manually check interstice

ORCheck sensor status

every 30 days

Statistical Inventory Reconciliation(SIR)

How do I know if I use SIR?

Use a tank stick to take daily measurements

Contract with a SIR vendor

Receive monthly SIR reports

SIR on UST-10B

SIR description

Statistical analysis of inventory, delivery, and dispensing data using computer software to

detect leaks

SIR operation and maintenance**

Measure to nearest 1/8th inch daily

Measure water levels monthly

Supply daily inventory to SIR vendor at end of month

Know limitations listed in third-party certification provided by SIR vendor

SIR operation and maintenance

Use appropriate calibration charts

Replace broken or unreadable tank sticks

Have same person stick tanks every day

Stick tanks and read meters at same time every day

Review SIR reports when received from vendor

SIR records

Must keep DAILY product measurements per tank, for 12 months

Must keep one water measurement per tank, per month, for 12 months

SIR records

Must keep SIR reports per tank, per month, for 12 months

If you are using SIR…

SIR

Calibration charts,12 months daily fuel and

monthly water measurements,

12 months SIR reports

TODAY(product measurement)

--/--/--(30 days from previous

water measurement)--/--/--

(day of the month to send off data to vendor)

Measure product daily,Measure water every 30 days,

Submit to vendorevery 30 days

Other Methods of Leak Detection

Other methods on UST-10B

• Enhanced leak detection page 16

• Inventory control and tightness testing page 12

• Manual tank gauging and tightness testing page 13

• Groundwater monitoring page 15

• Vapor monitoring page 14

EXAMTank Release DetectionPlease answer questions # 18-23

Enhanced leak detection

Enhanced leak detection on UST-10B

UST systems required to conduct enhanced leak detection

Installed after Jan 1, 1991 and before May 1, 2000

AND

Within 100-500 feet of a public water supply well, and/or

Within 50-100 feet of any other well for human consumption, and/or

Within 500 feet of high class surface waters

Enhanced leak detection description

Required for certain UST systems

A combination of monitoring and well sampling

Temporary method until upgrade required

Enhanced leak detection testing

Conduct 0.1 gph ATG test at least once every 30 days OR

Conduct 0.2 gph ATG test at least once every 7 days

AND

Sample wells within zones specified at least once a year

Enhanced leak detection records

Must keep one water sampling result per well for 12 months

AND

Must keep one valid 0.1 gph ATG test per tank, per month, for 12 months OR

Must keep one valid 0.2 gph ATG test per tank, per week, for 52 weeks

Enhanced leak detection upgrade

Must upgrade to .0900 secondary containment standards by Jan 1 of:

◦ 2005 – all steel or metal connected piping and ancillary equipment

◦ 2008 – all fiberglass or non-metal connected piping AND all USTs installed on or before Jan 1, 1991

◦ 2016 – all USTs installed after Jan 1, 1991