Cathodic_Protection_Design_Report.pdf

REPORT

CATHODIC PROTECTION SYSTEM DESIGN

LARGE VALVE VAULT REPLACEMENT

WSSC JOB NO. BT7370A22

Submitted by

Chester Dacres

DACCO SCI, INC.

10260 Old Columbia Road, Suite A1

Columbia, Maryland 21046

Submitted to

Daniel Savage

The Wilson T. Ballard Company

17 Gwynns Mill Court

Owings Mills, Maryland 21117

June 7, 2024

DSI-WTBCO-2424

DACCO SCI, INC.

CORROSION ENGINEERING - MATERIALS TECHNOLOGY - ELECTROCHEMISTRY

10260 OLD COLUMBIA ROAD, SUITE A1, COLUMBIA, MARYLAND 21046

BALT. (410) 381-9475 • DC (301) 596-7019 • FAX (410) 381-9643

dacres@daccosci.com www.daccosci.com

DSI

June 7, 2024

Daniel Savage

Design Engineer

The Wilson T. Ballard Company

17 Gwynns Mill Court

Owings Mills, Maryland 21117

RE: CATHODIC PROTECTION SYSTEM DESIGN – LARGE VALVE VAULT

REPLACEMENT - WSSC JOB NOS. BT7370A22

Dear Mr. Savage:

DACCO SCI, INC. was tasked to design a cathodic protection system for the BT7370A22 Large

Valve Vault Replacement (LVVR) Project with a design life of 30 years, to be constructed under

WSSC Job No. BT7370A22.

DACCO SCI, INC., recommends installing PRITEC (or equivalent) coating and a zinc galvanic cathodic protection system (GCPS) with five (5) insulating joints and five (5) test stations.

The proposed GCPS will be completed at an estimated cost of $42,397.32. The design calculations, cost, and time estimates are included in this report.

If there are any questions or revisions to the report, please do not hesitate to contact me.

Sincerely, Chester Dacres, Ph.D., P.E.

President

CMD/nb mailto:dacres@daccosci.com

• DACCO SCI, INC. • 10260 Old Columbia Road, Suite A1, Columbia, MD 21046 • (410) 381-9475 •

DSI-WTBCO-2424 www.daccosci.com 6/7/2024

TABLE OF CONTENTS

EXECUTIVE SUMMARY

Location of Project

RECOMMENDATIONS

CATHODIC PROTECTION SYSTEM DESIGN PROCEDURE

Current Requirement Calculations

Size and Location of Anodes

DESIGN CALCULATIONS AND COST ESTIMATES

Engineers Construction Cost and Completion Time Estimate

EXECUTIVE SUMMARY

Location of Project

DACCO SCI, INC. designed a galvanic cathodic protection system for the BT7370A22 LVVR project. The proposed LVVR contains approximately 48-feet of 72-inch diameter Steel pipe and

87-feet of 30-inch ductile iron pipe (DIP) located in Silver Spring, Montgomery County, Maryland. The proposed replacement will connect to existing prestressed concrete cylinder pipes built under Contract Nos. 1961-5411 (30-inch) and 1966-2621J (72-inch). The project location is shown below in Figure 1.

Figure 1 – Map of the BT7370A22 LVVR

Proposed

BT7370A22 Vault

SB-01

RECOMMENDATIONS

DACCO SCI, INC. recommends, a galvanic cathodic protection system with a design life of 30 years. The system should be in accordance with WSSC Specifications 02510 and 13110 that include:

1. 72-inch Steel Water Main:

a. Design using PRITEC (or equivalent) coated steel pipe.

b. Follow WSSC Standard Detail C/3.3 and C/3.4. Install an insulating joint (IJ) between the proposed steel and existing prestressed concrete cylinder pipe

(PCCP) to ensure electrical isolation of the alignment. Field coat the connection for five (5)-feet of the new side of the connection.

c. Follow WSSC Standard Detail C/3.0. Install an IJ between the proposed Steel

72x30-inch outlet and the proposed 30-inch DIP to ensure electrical isolation of the alignment. Field coat the connection for five (5)-feet of each side of the connection.

d. Install a pole mounted “insulating joint with anodes” (“IJ w/A”) type test station to each insulating joint to monitor the effectiveness of the new insulating joints and cathodic protection system for a total of three (3) “IJ w/A” test stations.

e. Install a GCPS system consisting of one (1) 30-pound GA-S-30 zinc anodes (or equivalent) attached to each test station for a total of three (3) beds of one (1) zinc anode.

2. 30-inch Ductile Iron Water Main:

a. Design using PRITEC (or equivalent) coated DIP.

b. Externally bond pipe segments to ensure electrical continuity.

c. Follow WSSC Standard Detail C/3.3 and C/3.4. Install an IJ between the proposed DIP and existing PCCP to ensure electrical isolation of the alignment.

Field coat the connection for five (5)-feet of the new side of the connection.

d. Install a flush mounted “IJ w/A” type test station to each insulating joint to monitor the effectiveness of the new insulating joints and cathodic protection system for a total of two (2) “IJ w/A” test stations.

e. Install a GCPS system consisting of one (1) 30-pound GA-S-30 zinc anodes (or equivalent) attached to each test station for a total of two (2) beds of one (1) zinc anode.

f. Bond around the vault per WSSC Standard Detail C/1.3.

Table 1 below shows the location of all new insulating joint test stations and anode beds.

Table 1 - Test Station Schedule for BTBR7370A22

ANODES

DRAWING

TEST

STATION

NUMBER

TEST

STATION

LOCATION

PIPE

SIZE

(IN)

TEST

STATION

TYPE NUMBER

SIZE

(LB) MATERIAL STATION NUMBER

CP 1 TBD

72-in STEEL X PCCP 72 IJ w/A

1 30 ZINC

0+00 72IN

CP 1 TBD

72-in STEEL X PCCP 72 IJ w/A

1 30 ZINC

0+48 72IN

CP 1 TBD

30-in DIP X PCCP 30 IJ w/A

1 30 ZINC

0+00 30IN

CP 1 TBD

30-in DIP X STEEL 30 IJ w/A

1 30 ZINC

0+35 30IN, LEFT 0+34 30IN

CP 1 TBD

30-in DIP X PCCP 30 IJ w/A

1 30 ZINC

0+48 30IN

*TBD – To be determined

**IJ w/A – Insulating Joint (IJ) with Anodes

CATHODIC PROTECTION SYSTEM DESIGN PROCEDURE

The cathodic protection design has followed specified American Society of Metals (ASM) guidelines0F

1 and examples from the American Iron and Steel Institute publication. 1F

2 Design procedures vary among organizations, but DACCO SCI, INC. is observing the following general guidelines based on the Association for Materials protection and Performance (AMPP, formerly

NACE) practices.3

1. Determination regarding whether impressed current or sacrificial anodes will be used;

2. Determination regarding the design life of the system;

3. Calculation of the maximum electric current required;

4. Determination of the number and type of anodes required and their respective spacing;

5. Calculation of the lead wire size; and

6. Determination of the location of the anodes.

1 Robert H. Heidersbach, "Cathodic Protection" reprinted in Metals Handbook: Ninth Edition, Volume 13

Corrosion, ASM International, 1987, pp. 470-477.

2 "Handbook of Corrosion Protection For Steel Pile Structures In Marine Environments", 1st edition, American Iron and Steel Institute, 1981.

3 "CP 3-Cathodic Protection Technologist COURSE MANUAL", Version 1.0, NACE International, 2014.

Current Requirement Calculations

Current requirements are calculated by determining the amount of ductile iron exposed to a corrosive environment. The pipelines for Contract No. BT7370A22 are assumed to be 98% coated.

The calculation of the current required to maintain cathodic protection is based on the following:

1. Determine the type of anode material to use as sacrificial anode anodes.

2. Calculate the current required to maintain protection of the coated ductile iron pipe for 30 years.

Size and Location of Anodes

The following three (3) factors were taken into consideration in designing the size of the anodes:

1. Total current requirement

2. Designed life of anodes

3. Soil resistivity

The total weight of anode material required to maintain protection of the pipe is dependent on the following:

1. Consumption rate of the anode material

2. Efficiency factor of the anode material

3. Utilization factor of the anode material

4. The average total current to protect the pipe

5. Design life (specified as 30 years)

After the total weight of the anode material was determined, the anode resistance was calculated.

DESIGN CALCULATIONS AND COST ESTIMATES

Table 3 and Table 2 display the results of the galvanic anode cathodic protection system design calculations.

Table 2 - Cathodic protection calculations for the 72-inch Steel

Nominal Pipe Diameter: 72 in

Pipe Outer Diameter: 72 in

Length: 48 ft

Design Life: 30 yrs

Total: 905 ft2

Coated: 887 ft2

Uncoated: 18 ft2

Current Required: 0.04 A

Anode

Type

Working

Potential

(Volts)

Efficiency

Factor

Util ization

Factor

Anode

Weight*

(lbs)

GA-S-30 -1.10 90% 0.85 35

* Based on Current Requirement Analysis.

Input

Anode Type: GA-S-30

Number of Anodes Used (N): 3

Anode Mass (Each): 30 lbs

Anode Length (L ): 5.00 ft

Anode Diameter (d ): 1.58 in

Anode Consumption Rate (CR ): 24.70 lbs / A · yr

Center-to-Center Spacing (S ): 7 ft

Anode Working Potential: -1.10 V (vs Cu/CuSO4)

Structure Potential: -0.850 V (vs Cu/CuSO4)

Soil Resistivity (r): 5,121 Ohm · cm

Output

Total Anode System Mass: 90 lbs

Single Anode Resistance (R V): 15.91 Ohm

Anode Bed Resistance: 15.91 Ohm

Anode System Resistance (R gb): 5.31 Ohm

Current Output: 0.05 A

Anode Driving Potential: 0.25 V

Anode Consumption: 41 lbs

Anode Bed Output

CATHODIC PROTECTION CURRRENT REQUIREMENT ANALYSIS

Design Parameters

Estimated Surface Area at Time of Installation

Current Requirement Analysis

SACRIFICIAL ANODE SYSTEM CALCULATIONS

Anode Bed Requirement Analysis

Consumption

Rate

(lbs / A × yr)

24.70

Anode Bed Design

Table 3 - Cathodic protection calculations for the 30-inch DIP

Nominal Pipe Diameter: 30 in

Pipe Outer Diameter: 32 in

Length: 87 ft

Design Life: 30 yrs

Total: 729 ft2

Coated: 714 ft2

Uncoated: 15 ft2

Current Required: 0.03 A

Anode

Type

Working

Potential

(Volts)

Efficiency

Factor

Util ization

Factor

Anode

Weight*

(lbs)

GA-S-30 -1.10 90% 0.85 26

* Based on Current Requirement Analysis.

Input

Anode Type: GA-S-30

Number of Anodes Used (N): 2

Anode Mass (Each): 30 lbs

Anode Length (L ): 5.00 ft

Anode Diameter (d ): 1.58 in

Anode Consumption Rate (CR ): 24.70 lbs / A · yr

Center-to-Center Spacing (S ): 7 ft

Anode Working Potential: -1.10 V (vs Cu/CuSO4)

Structure Potential: -0.850 V (vs Cu/CuSO4)

Soil Resistivity (r): 4,700 Ohm · cm

Output

Total Anode System Mass: 60 lbs

Single Anode Resistance (R V): 14.61 Ohm

Anode Bed Resistance: 14.61 Ohm

Anode System Resistance (R gb): 7.32 Ohm

Current Output: 0.03 A

Anode Driving Potential: 0.25 V

Anode Consumption: 30 lbs

Anode Bed Output

CATHODIC PROTECTION CURRRENT REQUIREMENT ANALYSIS

Design Parameters

Estimated Surface Area at Time of Installation

Current Requirement Analysis

SACRIFICIAL ANODE SYSTEM CALCULATIONS

Anode Bed Requirement Analysis

Consumption

Rate

(lbs / A × yr)

24.70

Anode Bed Design

Engineers Construction Cost and Completion Time Estimate

Table 4 and Table 5 below display the detailed cost and time estimates for construction of the

GCPS including labor. The cathodic protection construction time estimate is expected to be accomplished concurrently (not sequentially) with construction efforts.

Table 4 – GCPS Cost Estimate

Table 5 – GCPS Time Estimate

MATERIALS INSTALLATION

UNIT COST TOTAL COST UNIT COST TOTAL COST

5 each Zinc Anodes (GA-S-30) $123.15 $615.75 $75.00 $375.00

5 each Test Stations $65.00 $325.00 $150.00 $750.00

5 each Splice Kits (#8 AWG) $11.29 $56.45 $33.00 $165.00

5 each Cu-CuSO4 Reference Electrode $133.00 $665.00 $33.00 $165.00

28 ft 24-inch #2 AWG HMWPE Jumper Bond $7.71 $215.88 $0.00 $0.00

59 ft #8 AWG HMWPE Cable $0.76 $44.84 $0.00 $0.00

100 ft #6 AWG THWN Cable $0.98 $98.00 $0.00 $0.00

100 ft #12 AWG THWN Cable $0.22 $22.00 $0.00 $0.00

3 each 20Pk Thermite Weld Metal (#2, #4 AWG) $107.46 $322.38 $440.00 $1,320.00

2 each 20Pk Thermite Weld Metal (#6, #8, #10, #12 AWG) $59.70 $119.40 $440.00 $880.00

2 each 50 Use Thermite Weld Mold (#2 AWG) $79.25 $158.50 $0.00 $0.00

1 each 50 Use Thermite Weld Mold (#6 AWG) $79.25 $79.25 $0.00 $0.00

1 each 50 Use Thermite Weld Mold (#8, #10, #12 AWG) $79.25 $79.25 $0.00 $0.00

7 each 10Pk Handicaps (#2, #4, #6 AWG) $22.20 $155.40 $0.00 $0.00

1 each 20Pk Handicaps (#8, #10, #12 AWG) $8.90 $8.90 $0.00 $0.00

10 cubic ft Concrete $5.07 $50.70 $75.00 $750.00

3 each Insulating Joint (30'') $521.78 $1,565.34 $300.00 $900.00

2 each Insulating Joint (72'') $6,787.62 $13,575.24 $300.00 $600.00

1 lot Misc. Supplies $1,000.00 $1,000.00 $0.00 $0.00

2.5 days Testing $0.00 $0.00 $500.00 $1,250.00

1 each Test Report $0.00 $0.00 $2,000.00 $2,000.00

Subtotal $19,157.28 $9,155.00

20% contingency $3,831.46 $1,831.00

Subtotal $22,988.74 $10,986.00

Cathodic Protection Cost $33,974.74

25% Contractor Markup $8,493.68

Total Cathodic Protection Cost $42,468.42

USE

QUANTITY UNIT MATERIALS ITEM

Item Quantity Days Total Days

Test station Installation 5 1.0 per TS 5

Anode Beds 5 1.0 per anode 5

IJ Installation 5 1.0 per IJ 5

Wire Bond Connections 28 0.083 per bond 3

SUBTOTAL 18

Contingencies (10%) 2

TOTAL DAYS 20