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Minutes by: Stan Shogren, Kennedy/Jenks 1 At-Large Representative, Nor Cal PUG
MEETING MINUTES August 21, 2007
Attendees: Alex Christensen Black & Veatch [email protected] Anna Chrissanthis Kennedy/Jenks [email protected] Brian Chan City of Foster City [email protected] Colin Dudley Brown & Caldwell [email protected] David Herrera City of Oakland – CEDA [email protected] Edgar Benitez Ameron Intl. [email protected] Gunawan Santoso City of Oakland – CEDA [email protected] Jimmy Dang Kennedy/Jenks [email protected] Jonathan Lee WVSD [email protected] Katie Nham CSD-1 [email protected] Russ Eberwein Harris & Associates [email protected] Sandie DeMedeiros CDM [email protected] Stan Shogren Kennedy/Jenks [email protected] Presentation: Corrosion & Cathodic Protection, by Eric Frechette, General Manager of Schiff Associates. Eric gave an excellent presentation including a background on corrosion and an explanation of soil corrosivity. He also discussed corrosion control of pipelines and corrosion monitoring. A big thank you to Eric for this presentation! General: Membership Renewals: Jonathan reported that 20 of the current 33 PUG members have renewed their membership. New Meeting Location: We are still looking for a new location with more room for PUG meetings. Until we find a new location we will continue to meet at RMC. Call for Papers: The Call for Papers for the PUG Seminar has been sent out. Jonathan reported that the most important item to include in a paper is “Lessons Learned”. Correction: Stan Shogren reported an error in the minutes of the 17 July 2007 PUG meeting. The size of the pipe in the Freeport Pipeline is 84” – 60” and not 8” – 60” as reported in the minutes. Surprise Raffle: Alex Christiansen of Black & Veatch and Anna Chrissanthis of Kennedy/Jenks Consultants were the winners of the surprise raffle. The surprise award was registration, hotel room and meals to attend the WESTT Mini No-Dig Conference in Reno in October. There will be more surprise raffles of this type at future PUG meetings. This is a benefit of PUG
Minutes by: Stan Shogren, Kennedy/Jenks 2 At-Large Representative, Nor Cal PUG
membership that has been established by the Executive Committee. Members may forward any suggestions they have for other membership benefits to the Executive Committee. Fiscal Year Membership Clarification: Jonathan reported that the PUG fiscal year is from July to June. When any new member joins their first year’s membership fee will last only until the end of the fiscal year current at the time of joining. There will be no pro-rating of membership dues for partial years. Revised Bylaws: A draft of the revised bylaws has been sent to a lawyer for legal review. After the legal review the revised bylaws will be sent out to the members (probably in September) for their review and a vote on acceptance. Financial Report: Sasha is on jury duty today so Jonathan reported that in 2006 PUG had an income of $47,510 and expenses of $38,000. The 2006 financial information has been sent to an accountant to prepare PUG’s 2006 income tax return, which is due Nov 30th each year. PUG’s 501C3 non-profit organization application has been sent to the IRS, and approval is expected soon. Once the application has been approved we do not expect that PUG will have to pay any income tax. We will just have to file a tax return each November. Project Discussions: Jennifer Glynn reported that the City of San Jose would open bids on Thursday 23 August for their Highway 87 Project. There is a microtunneling head that has been stuck under the middle of the Guadalupe River for three years. This project involves digging a 25’ deep shaft in the river to retrieve the head. Permitting has been RMC’s major problem for this project. Permits from five different agencies were required. Jennifer reports that there are lots of lawyers involved in this project. Jonathan Lee reports that West Valley Sanitation District is concluding a very successful one year long “as needed” sewer spot repair contract. WVSD wrote a generic specification for general sewer repair. They negotiate extra work for any unusual situations that come up. The success of this type of contract has been that the contractor is “on call” to respond within 48 hours. There is no long delay while WVSD negotiates individual emergency contracts for each sewer repair. All repairs are by open cut. The longest repair was a 30’ section of 10” VCP in Saratoga Avenue. WVSD reports that about 40% of the repairs have been due to root intrusion and 60 % have been caused by other utilities that have been installed under their sewers with inadequate backfill around the VCP. The average cost of a sewer repair with this contract has been $8,400. WVSD originally budgeted $150,000 for this contract, but it was working out so successfully that the board approved an additional $97,000 for the year. This contract was so successful that they are going out to bid for a new contract for two years. Jonathan suggests that all agencies use this type of contract to save money on emergency sewer repairs. David Herrera reported that the City of Oakland has this type of contract too. Jonathan also reported that WVSD has been working for two years to design a replacement for an 80-year-old VCP sewer main. It was discovered that this sewer main goes under four houses, a fountain and a bachi ball court. It also goes under a swimming pool, and the house service lateral connects to the main under the pool. Next Meeting: Our next meeting will be held TUESDAY, SEPTEMBER 18, 2007 at the offices of RMC Water & Environment located at 2001 N. Main St., Suite 400, Walnut Creek, CA 94596. The topic will be “XYZ Centerline Utility Mapping”, given by Liinda Ward of Geospatial Corporation. All member representatives are reminded to bring business cards for another raffle. Please call (925) 827-4900 ext 176 or email [email protected] to RSVP.
Corrosion Essentials, Soil Corrosivity, and Corrosion ControlEric Frechette, P.E.SCHIFF ASSOCIATES
Northern California PUG – 8/21/07
Schiff AssociatesFounded in 1959 by Melvin J. Schiff, P.E.Company Specializes in Corrosion EngineeringApproximately 35 Employees in 5 Departments
Geochemical LaboratoryEngineeringCoatingsResearch Development and Instrumentation Expert Witness/Legal
We have a General Contractor license A if you need me to dig a hole…
Corrosion Study2002 – FHWA and NACE
Direct Cost of Metallic Corrosion was $276 Billion per year (3.1% of the 1998 U.S. Gross Domestic Product)
Utilities accounted for $47.9 Billion, with 75% of that relating to Water and Wastewater
Corrosion Study (cont.)Estimated Annual Cost of Corrosion according to Water Infrastructure Network (WIN):
Drinking Water Systems $19.25 BillionSewer Systems $13.25 BillionLost Water cost $3.0 Billion
Definition of CorrosionCorrosion is the deterioration of a substance or its properties as a result of an undesirable reaction with the environment.
It is irreversible and degenerative and related It is irreversible and degenerative and related to the Second Law of Thermodynamicsto the Second Law of Thermodynamics
“…over time, differences in temperature, pressure, and density tend to even out in a physical system that is isolated from the outside world .” (Wikipedia)
- NACE International
What is Corrosion?
4 Parts of a Corrosion Cell
Anode (corroding)
Cathode (protected)
Electrolyte (Soil, Water, concrete)
Metallic Path between anode and cathode (pipe wall)
Electrochemical Corrosion Cell
Α C
e-Metallic Path
+ ions- ions
Electrolytic Path
Oxidation Half-Reaction Occurs at the Anode
M→ Mn+ + ne-o
The more electrons lost means more corrosion.
Reduction Half Reactions Occur at the Cathode
2H2O + O2 + 4e- → 4OH−
The number of electrons “consumed”
by reduction must equal the number
“liberated”
by oxidation
Pitch Seal
Air Space
Carbon and manganesedioxide mixture
Carbon rod
Protective casing
Electrolyte paste(ammonium chloride
and zinc chloride)
Zinc
Separator
Negative terminal
GraphiteGraphite--Zinc BatteryZinc Battery
Cat
hode
(car
bon
rod)
Current Flow
ConductiveElectrolyte
Switch
Current DischargingOff Anode
Anode(Zinc Casing)
Practical Use of Corrosion Cell
Steel-0.5V
Steel-0.5V
Brass-0.2V
Fe Fe +2e +2(OH)Fe(OH) +2e
++ -
-2
2H +2e H+ -2
II
An Impractical Corrosion Cell
Concrete Encased Building Metals
DI pipe/copper service Galvanic Corrosion
Above the Water Line Corrosion
Blistering
SubmergedSubmerged
UnsubmergedUnsubmerged
SpringlineSpringline
CrownCrown
AnodeAnode
ElectrolyteElectrolyte
Metallic PathMetallic Path
CathodeCathode
CorrosionCorrosion
Remove any piece of the puzzle and corrosion stops!
Common Types of Corrosion Cells
Dissimilar MetalDifferential AerationDissimilar Concentration
In short, homogeneity helps minimize anode cathode polarization
Four Basic Methods for Corrosion Control
Material Selection
Corrosion Inhibitors
Coatings
Cathodic Protection
Material Selection/Design DetailsChoose materials compatible with the environmentDo not create corrosion cell through design/construction details
Corrosion InhibitorsAlter the environment adjacent to metal to passivate and protect it
Concepts of the Four Basic Methods of Corrosion Control
Cathodic ProtectionElectrochemically alter the surface condition of the metal to move the anodic reactions elsewhere
CoatingsProvide a barrier to the electrolyte and protect the metal
Concepts of the Four Basic Methods of Corrosion Control (continued)
Material Selection/Design Details
Only works at the design stage
Must characterize the environment (#1) soil corrosivity
Choosing materials which are most compatible with the environment and cost constraints
M. J. Schiff & Associates, Inc.Consulting Corrosion Engineers - Since 1959 1308 Monte Vista Avenue, Suite 6
Upland, CA 91786-8224Phone: 909/931-1360
Table 1 - Laboratory Tests on Soil Samples
Sample DataYour Job No.MJS&A #00-0000HQ
13-Jul-01
Sample IDLot # 6@ 0-1'
Lot # 23@ 0-1'
Lot # 28@ 0-1'
Lot # 72@ 0-1'
Lot # 95@ 0-1'
Resistivity Unitsas-received ohm-cm 40,000 1,150,000 205,000 155,000 6,000saturated ohm-cm 1,150 1,400 3,400 1,300 1,200
pH 6.5 6.8 6.2 6.8 6.0
ElectricalConductivity mS/cm 0.15 0.16 0.04 0.14 0.46
Chemical AnalysesCationscalcium Ca2+ mg/kg 44 28 8 28 172magnesium Mg2+ mg/kg 7 10 7 7 49sodium Na1+ mg/kg 78 83 7 84 153Anionscarbonate CO3
2- mg/kg ND ND ND ND NDbicarbonate HCO3
1- mg/kg 238 27 24 73 NDchloride Cl1- mg/kg 82 82 32 117 181sulfate SO4
2- mg/kg ND 147 ND 56 679
Other Testsammonium NH4
1+ mg/kg 2.8 5.1 1.5 2.4 11.7nitrate NO3
1- mg/kg 7.1 10.4 5.5 6.9 60.6sulfide S2- qual na na na na naRedox mv na na na na na
Electrical conductivity in millisiemens/cm and chemical analysis were made on a 1:5 soil-to-water extract.mg/kg = milligrams per kilogram (parts per million) of dry soil.Redox = oxidation-reduction potential in millivoltsND = not detectedna = not analyzed
What Defines What Defines Corrosive Soil?Corrosive Soil?
••ResistivityResistivity
••pHpH
••SaltsSalts
Electrical ResistivityTraditional indicator of corrosivityDetermining factors:
Soluble salt contentSolubilitiesMoisture content
Resistivity Range>10,000 ohm-cm – Mildly Corrosive10,000 to 2,000 – Moderately Corrosive2,000 to 1,000 – Corrosive<1,000 – Severely Corrosive
pHHydrogen ion concentration
-log[H+] (pH of 4.0 = 10-4 moles H+ per liter)Not an indicator of bufferingIf less than 5.0 to 5.5, total acidity should be performedElevated pH generally beneficial, but must be completely uniform (caution with lime treatment)
Electrical ConductivityThe inverse of resistivityPerformed on 1:5 extractPrimarily used by us for QA/QCDetermining Factors:
Salts in solutionSoil particles in suspensionIonic speciesTemperature
Cations
Ca2+, Mg2+, Na1+, K1+, and NH4+
Provide QA/QC balance with anionsAllow for inference of salts
AnionsCO3
2-, HCO31-, PO4
3-, NO31-, F1-, Cl1-, and
SO42-
With cations comprise common soluble salts (QA/QC, resistivity)Cl1- and SO4
2- are infamous players in various corrosion/degradation reactions
Ferrous metals, concrete, etc.
ChlorideThreat to reinforced concrete when greater than 350 ppmPermeates concrete and overcomes corrosion inhibiting effects of high pH on reinforcing steel, pipe walls, pre-stressing wires, etc.
Extensive Chloride Attack
Chloride MitigationProtective concrete
Reduced water-cement ratioCorrosion inhibitorAdmixtures to reduce permeability
Coated rebarImpermeable membrane (i.e. Liquid Boot)
SulfateSulfate attacks concrete directly1,000 mg/kg to 2,000 mg/kg = Moderate 2,000 mg/kg to 20,000 mg/kg = Severe>20,000 mg/kg = Very Severe
Sulfate MitigationModerate
Water-cement ratio ≤ 0.50Compressive strength of 4000 psiType II cement
SevereWater-cement ratio ≤ 0.45Compressive strength of 4500 psiType V cement
Very Severe – same as severe, but with pozzolan (common – fly ash)
Other testsNH4
+ and NO31- (ammonium, nitrate) are
deleterious to copperSulfide/Redox
Aggressive to copper and ferrous metalsSulfate reducing bacteriaAnaerobic conditionsBlack/gray fine grained soils
Where was I?Chemistry makes me dizzy
We’re trying to characterize the environment (Material Selection/Design Details)
Soil Corrosivity study = 35% conceptual design
Corrosion Inhibitors
Mortar/cement is the most common inhibitor for steel in the worldAdmixtures can improve resistance of encased steel, particularly to chloride
Prior to FabricationLow Cost
Uniform inhibitor distribution is critical
Material Selection: AWWA C200/C205
Welded WireWelded WireFabricFabric
Steel PipeSteel Pipe
1/2” Mortar Lining1/2” Mortar Lining
3/4” Mortar Coating3/4” Mortar Coating
Coatings (characteristics to look for)PROPERTIES FBE X-TRU-COAT PRITEC TAPE COAL TAR
ENAMELMULTI-LAYER
FBE w/PE
Electr icalResistance 10 10 10 10 10 10
MoistureResistance 4 10 10 7 8 10
Adhesion 10 6 8 6 7 10
Handling,Storage,
Installation8 6 8 5 7 10
CathodicProtection
Compatibility9 7 10 7 7 10
Non-Toxic toEnvironment 7 9 10 8 4 7
TOTALSCORE 48 48 56 43 43 57
Coatings and CP Work Together
Cathodic protection can be applied without coatingsCoatings should not be used without cathodic protectionCathodic protection effectively protects defects in the coating
In many environments, it actually repairs the coating locally by depositing minerals that plug the holes in the coating system
Wax Tape at Fittings is a good coating (AWWA C217)
Polyethylene Encasement per AWWA C105
Cathodic ProtectionPrimary solution for existing structures
Pipe must be metallicBest if installed with intentional electrical continuityCoatings or encasement reduce CP
Two Basic Types of CPGalvanicConventional Impressed Current
Effect of CP Current
ANODE-0.65 volt
CATHODE-0.50 volt
Icorr= 1 mA ANODE-0.65 volt
CATHODE-0.60 volt
Icorr= .3 mA
Before Cathodic Protection After Cathodic ProtectionReduction
in corrosion current
C.P. CURRENT
Galvanic Cathodic Protection
CATHODIC PROTECTION LEGEND: ANODE LEAD WIREPIPE LEAD WIRE
DIRECTION OF POSITIVE DC CURRENTe+BURIED CATHODIC PROTECTION ANODE
SOIL e+e+e+
e+e+e+
e+e+e+
e+e+e+
e+e+e+
e+
e+e+
CP TEST BOX WITH COPPER BUSS BAR AND SHUNTS
DIRECTION OF POSITIVE DC CURRENT FLOW FROM THE BURIED ANODES INTO THE SURROUNDING SOIL AND WATER THEN EVENLY COLLECTED BACK ON THE PIPELINE
BURIED STEEL PIPELINE TO BE PROTECTED FROM EXTERNAL CORROSION
SOIL
EXISTING GRADE
INDIVIDUAL ANODE LEAD WIRES
PIPE LEAD WIRES
ANODE GROUNDBEBACKFILLED IN LOWRESISTIVITY MIXTUBENTONITE, GYPSUSODIUM SULFATE
NATIVE SOIL BACK
e+
e+e+
e+
e+
e+
e+
e+ e+
e+ e+
e+
e+
e+
Magnesium AnodesMagnesium Anodes
Impressed Current CP
CATHODIC PROTECTION LEGEND:
CP POS. CABLECP NEG CABLE
120 V AC PWR
ELECTRICAL TRANSFORMER
NON-FUSED DISCONNECT SWITCHDIRECTION OF POSITIVE DC CURRENT
DC AMMETERDC VOLTMETERV
A
DIODE
REPLACEABLE FUSE
e+
ELECTRICAL GROUND RODBURIED CATHODIC PROTECTION ANODE
SOIL
CIRCUIT BREAKER
NEG
POS
e+e+e+
e+e+e+
e+e+e+
e+e+e+
e+e+e+
e+
e+e+
A
V
COPPER GROUND ROD
CIRCUIT BREAKER RECTIFIER
ANODE JUNCTION BOX w/ COPPER BUSS BAR, SHUNTS, AND DIODE
DIRECTION OF POSITIVE DC CURRENT FLOW FROM THE BURIED ANODES INTO THE SURROUNDING SOIL AND WATER THEN EVENLY COLLECTED BACK ON THE PIPELINE
BURIED STEEL PIPELINE TO BE PROTECTED FROM EXTERNAL CORROSION
SOIL
EXISTING GRADE
INDIVIDUAL ANODE LEAD WIRES (RECTIFIER DC POS.)
ANODE HEADER CABLE(RECTIFIER DC POS.)
CATHODE CABLES (RECTIFIER DC NEG.)
ANODE GROUNDBED BACKFILLED IN HIGH CONDUCTIVITY GRANULAR COKE BACKFILL
NATIVE SOIL BACKFILL
e+
e+e+
e+
e+
e+
e+
e+ e+
e+ e+
e+
e+
e+
Air Cooled RectifierAir Cooled Rectifier
Oil Cooled RectifierOil Cooled Rectifier
Too much of a good thing (CP) is not always wonderful!
Stray Current Schematic
ANODEANODE
Protected Pipeline
Protected Pipeline
CURRENTCURRENT
CU
RR
EN
TC
UR
RE
NT
PowerSource
+-
CU
RR
EN
TC
UR
RE
NT
Affected Pipeline
Affected Pipeline
CURRENT
CURRENT
CURRENTCURRENT
Basic Philosophy “Minimum Current = Minimum $$$”
The best corrosion control measures are those which can be buried and forgotten with the structure
Materials Selection and SpecificationCoatings
Cathodic Protection (CP) is the last resortIf CP is necessary, then
Reduce current requirementMinimize Economic ImpactSimplify CP installation Standard Plans, Specs
CP Current Requirements for Water & Wastewater Industry Piping
Pipe Material Coating System Current Requirement (ma/sf)
Steel/Iron None 1 to 3
Steel AWWA C205 0.1 to 0.5
Steel/Iron AWWA C214+C205 0.002 to 0.010
Ductile Iron with PE AWWA C105 0.040
Never Spend more than $2-3/ sq ft for a coating
$$ are Directly Proportional to Current Capacity (Amps)
Life Cycle Costs = Construction + Operating CostsInitial/Construction costs ~ Amps
$3K per installed ampereOperating/Maintenance Costs ~ AmpsAnything and everything you do to reduce current requirement saves $$$
What is the Approximate Cost of Corrosion Control for Metallic Pipes?
Mortar Coating $0.50/SFJoint Bonds
DIP exothermic welds $75-90 per joint (2 bonds)Steel Bond Clips $50-75 per joint (2 clips)
Test Stations $2.50/LF (1000 foot intervals)Dielectric Coating $1.50/SFPE for DIP $0.05/inch-diam/LFCathodic Protection $3,000 per installed amp.
Whatever type of Pipe is chosen, the Four Basic Methods for Corrosion Control Apply
Material Selection/Design DetailsCorrosion InhibitorsCoatings/EncasementCathodic Protection
Electrical IsolationElectrical Continuity
Corrosion Should Not Be Used as a Scapegoat
Corrosion can be understood, mitigated and managedCorrosion is not the end of the worldWe can fix corrosion after the fact…if we know about them and things are electrically continuous and isolated from the worldCorrosion is not the most important thing in the project.
We do not care what kind of pipe goes in the ground…
Some people think that we “like” ductile iron pipeSome people think that we “go easy on” mortar coated steel pipeSome people think that we “don’t want” plastic pipe because it will put us out of businessNothing could be further from the truth
I am not Fond of PCCP
OK, we have an issue with PCCP…
…but we have worked on hundreds of miles of it. It can be made to work, but you have to pay attention…
Other Factors in Pipeline Design
Water SupplyFuture Water SupplyStructural Integrity
Short TermLong Term
Supplier and Experienced ContractorsBid Competition ($$$$)……Corrosion control
Comparison of All Steel vs All DIP
0
1
2
3
4
5
6
7
8
9
10
$1.75 $2.00 $2.25 $2.50 $2.75 $3.00 $3.25 $3.50 $4.00 $4.50 $5.00 More$/inch-diam/LF
Num
ber o
f Bid
s
All DIP BidsAll Steel Bids
37 Project Bids on 428 miles of ~ 24-inch Pipe$152 Million in Total Construction Contracts
Rural Water Projects in Dakotas1984-2005
One Example of the Effect of Bid Competition
Bid Summary Data - Bureau of Reclamation Projects
Ductile Iron Pipe Steel Pipe Comments
Avg. Bid (per inch diameter, per linear
foot)$2.17 $2.99
These are the overall average low bids submitted for each pipe on all
projects for which they submitted bids (37 project bids)
Avg Bid Ductile vs Steel $2.18 $2.23
These are the low average bids submitted by each pipe when they
both submitted a bid on a project (16 project bids)
Avg Bid Ductile, no Steel bid $2.17
This is the average low bid submitted by ductile iron pipe on those projects
where steel did not submit a bid (14 project bids)
Avg Bid Steel, no Ductile $4.74
This is the average low bid submitted by steel pipe on those projects where bonded coatings were specified for
ductile iron pipe. (7 project bids)
Summary of DIP and Steel Only Bids
0
1
2
3
4
$1.75 $2.00 $2.25 $2.50 $2.75 $3.00 $3.25 $3.50 $4.00 $4.50 $5.00 More$/inch-diameter/LF
Num
ber o
f Bid
s
DIP OnlySteel Only
Corrosion is not the most important thing in your project
Be aware of all the factorsAn engineer can do for a $1 what any darn fool can do for $5.Bidding pressure can easily pay for any corrosion control on your projectIf you screw up, don’t be afraid of cathodic protection, it is just electricity and chemistry
Questions?
Eric Frechette, P.E. –
General Manager
Schiff Associates
431 Baseline Road
Claremont, CA 91711
Ph: (909) 626-0967
Fx: (909) 626-3316
Email: [email protected]
