B08-140P2024R0083-Amd2_0002.pdf

(x)

140P2024R0083 x x

1 copies of the amendment; (b) By acknowledging receipt of this amendment on each copy of the offer submitted ; or (c) By separate letter or electronic communication which includes a reference to the solicitation and amendment numbers. FAILURE OF YOUR ACKNOWLEDGEMENT TO BE

RECEIVED AT THE PLACE DESIGNATED FOR THE RECEIPT OF OFFERS PRIOR TO THE HOUR AND DATE SPECIFIED MAY RESULT IN REJECTION OF YOUR

OFFER. If by virtue of this amendment you desire to change an offer already submitted , such change may be made by letter or electronic communication, provided each letter or electronic communication makes reference to the solicitation and this amendment, and is received prior to the opening hour and date specified.

x

PDS

Denver CO 80225-0287 P.O. Box 25287 12795 W. Alameda Pkwy DOI, NPS, DSC Contracting Services

PDS

Denver CO 80225-0287 P.O. Box 25287 12795 W. Alameda Pkwy NPS, DSC Contracting Services Div

07/08/20240002

13. THIS ITEM ONLY APPLIES TO MODIFICATION OF CONTRACTS/ORDERS. IT MODIFIES THE CONTRACT/ORDER NO. AS DESCRIBED IN ITEM 14.

12. ACCOUNTING AND APPROPRIATION DATA (If required) is not extended.is extended, Items 8 and 15, and returning

Offers must acknowledge receipt of this amendment prior to the hour and date specified in the solicitation or as amended , by one of the following methods: (a) By completing

The above numbered solicitation is amended as set forth in Item 14. The hour and date specified for receipt of Offers

11. THIS ITEM ONLY APPLIES TO AMENDMENTS OF SOLICITATIONS

FACILITY CODE CODE

10B. DATED (SEE ITEM 13)

10A. MODIFICATION OF CONTRACT/ORDER NO.

9B. DATED (SEE ITEM 11)

9A. AMENDMENT OF SOLICITATION NO.

CODE

8. NAME AND ADDRESS OF CONTRACTOR (No., street, county, State and ZIP Code)

7. ADMINISTERED BY (If other than Item 6)CODE 6. ISSUED BY

PAGE OF PAGES

4. REQUISITION/PURCHASE REQ. NO.3. EFFECTIVE DATE2. AMENDMENT/MODIFICATION NO. 5. PROJECT NO. (If applicable)

1. CONTRACT ID CODE

AMENDMENT OF SOLICITATION/MODIFICATION OF CONTRACT

07/08/2024

CHECK ONE A. THIS CHANGE ORDER IS ISSUED PURSUANT TO: (Specify authority) THE CHANGES SET FORTH IN ITEM 14 ARE MADE IN THE CONTRACT

B. THE ABOVE NUMBERED CONTRACT/ORDER IS MODIFIED TO REFLECT THE ADMINISTRATIVE CHANGES (such as changes in paying office, C. THIS SUPPLEMENTAL AGREEMENT IS ENTERED INTO PURSUANT TO AUTHORITY OF:

D. OTHER (Specify type of modification and authority) appropriation data, etc.) SET FORTH IN ITEM 14, PURSUANT TO THE AUTHORITY OF FAR 43.103(b).

E. IMPORTANT: Contractor is not is required to sign this document and return __________________ copies to the issuing office.

ORDER NO. IN ITEM 10A.

14. DESCRIPTION OF AMENDMENT/MODIFICATION (Organized by UCF section headings, including solicitation/contract subject matter where feasible.)

GLAC 307606 - Replace Swift Current Water Distribution System

The purpose of this amendment is to provide for the following:

1. Site Visit Sign In Sheet

2. Responses to Questions received to date.

3. Temporary Power Hookup location and photos.

4. Tank Inspection Report

All other terms and conditions of the solicitation remain unchanged.

16A. NAME AND TITLE OF CONTRACTING OFFICER (Type or print)15A. NAME AND TITLE OF SIGNER (Type or print)

15C. DATE SIGNED 16B. UNITED STATES OF AMERICA 15B. CONTRACTOR/OFFEROR 16C. DATE SIGNED

(Signature of person authorized to sign) (Signature of Contracting Officer)

Vicki Freese-supler

STANDARD FORM 30 (REV. 11/2016)

Prescribed by GSA FAR (48 CFR) 53.243

Previous edition unusable

Except as provided herein, all terms and conditions of the document referenced in Item 9 A or 10A, as heretofore changed, remains unchanged and in full force and effect .

GLAC 307606- Replace Swiftcurrent Utilities 140P2024R0083

Questions and Answers

Quest Site Showing Questions Government Response Amendment # Date Notes

Will the tank need to be empty to be worked on?

The existing storage tank will be emptied by the park before construciton begins. It will not be filled up again until the new system is commissioned. 1 7/12/2024

Does the tank supply the Park housing during construction?

No, the contractor is responsible for constructing and operating temporary drinking water and fire water systems separate from the existing tank. See plan set sheets C6.1 and C6.2. 1 7/12/2024

What is the existing pipe material?

The as-built information provided to the A/E team does not specifically call out existing pipe material. The existing water pipes could be a combination of HDPE, PVC, galvanized and AC pipe. 1 7/12/2024

Is there any transite pipe?

Yes - there could some areas where asbestos abatement may be necessary. 1 7/12/2024

What is the quantity of existing pipe?

The majority of existing pipe is getting abandoned in place, besides where it crosses the alignment of the new pipe. There is estimated over 21,000 LF of existing water pipe in the project area (including services and mains). 1 7/12/2024

Questions and Answers

Are there culverts to be installed in the road to the tank?

Yes, culverts and open-top cross drains. See plan sheets C5.1- C5.6. 1 7/12/2024

Is electric/telemetry hardwired on the road to the tank or wireless? Hardwired. 1 7/12/2024

Is the water from the wells chlorinated before or after it goes to the tank? Before, see plan sheet C3.4. 1 7/12/2024

Does the water main that cuts diagonally through the wooded area north of Route 3 following an existing Yes, see plan sheet C2.9. 1 7/12/2024

Are there any residents expected during the shutdown season?

Yes - a listing of residents who will be maintaining residency will be provided after contract award. 1 7/12/2024

Where is access required in the ranger/residential area?

There is only one way in and one way out of the residential area.

Access is required in and out at that location. 1 7/12/2024

How is pipe abatement quantified?

There is an estimated 120 LF of AC pipe removal potentially required for this project. All of this is from crossing the existing assumed AC pipe in the campground area, assuming 10’ of pipe removal per crossing (12 crossings). This is an estimate for bids, contractor to verify during construction. 1 7/12/2024

Will the SCADA CLINS include telemetry from the tank to the well?

There is no direct telemetery from tank to well. All SCADA work will fall under CLIN 3. 1 7/12/2024

Questions and Answers

Is there 1 well pump or 2 well pumps included in the scope of work?

Two well pumps are included in the work. 1 7/12/2024

What is the generator’s fuel source?

Diesel, gas or propane?

Propane, see specification section 263215. 1 7/12/2024

What does the generator power?

The well pump, telemetry controls, and the chlorine pump.

Basically what is needed to keep the water system functioning during a power outage. 1 7/12/2024

Is there no CLINS for mobilization?

No there is no separate CLIN for mobilization costs. It is up to the Offeror to determine the best placement for these costs within the existing CLIN structure. 1 7/12/2024

Are workers allowed to stay in the park during construction?

No - all contractor personnel must obtain housing outside of the park. 1 7/12/2024

Existing well demo plans indicate the entire well is being demolished?

No, see plan sheet C1.4, well note. 1 7/12/2024

Where does the electric run from the well?

To the chlorination building, see sheet C3.1. 1 7/12/2024

What is the size of the water tank and what is it made of?

The tank is concrete 40'x40' and holds 140,000 gallons. 1 7/12/2024

How do you want us to quantify the price for patching the tank in preparation for coating?

The tank inspection report from 2021 is attached to Addendum 1.

There is one spot where there may be a crack that may require patching. 1 7/12/2024

Refer to tank inspection report in Addendum 1.

Questions and Answers

Road base is called out near the culverts at the tank road is it intended to run road base on the entire road?

Detail B/C5.4 shows the roadway typical cross section for the entire road. 1 7/12/2024

Does the Park want to keep the trench spoils?

No these need to be hauled off and disposed at an appropriate licensed facility. 1 7/12/2024

Is the fire alarm notification system identified on the drawings? No 1 7/12/2024

Can temporary power be pulled from the utility box inside the cabin loops?

Yes. 1 7/12/2024 Refer to hookup location and photos in Addendum 1.

Are all meters going to be demoed or abandon?

They will be removed as well as their vault. See plansheet C1.4. 1 7/12/2024

Where are we responsible for asphalt removal?

There are existing asphalt pavement sidewalks in the campground above the service lines to the camground bathrooms. Other than that, all asphalt will be removed by

FHWA. 1 7/12/2024

Is there a booster pump as part of the temporary fire system? See plan sheet C6.2. 1 7/12/2024

Does the fire alarm system need to be connected to the temporary fire water No 1 7/12/2024

31 Is there a detail for the buried electrical Yes, see plan sheet E1.7. 1 7/12/2024

Can the main safety, superintendent and other management personnel have dual roles on this project?

No - each management personnel personnel must be separate and apart i.e. separate Quality Control, Site Superintendent and Safety Officer. 1 7/12/2024

Questions and Answers

How far away from the building do we need to tie the service lines in?

Five (5') feet - please see Detail C/C4.4 on Drawing Sheet 62. 1 7/12/2024

Will FHWA be only other contractor working in the area for coordination purposes? Yes 1 7/12/2024

Was pipe bursting done and if so, can Offerors obtain the locations where this was performed?

Pipe bursting was not done in this project and is not relevant to the project. 1 7/12/2024

Are there two well pumps or one pump for two wells?

There are two pumps, one for each well. 1 7/12/2024

Is the generator for the pumps and chlorination system or will the generator need to be sized to also provide for power for the buildings

Only the pumps and chlorination system. The generator has already been sized, see plan sheet E1.2. 1 7/12/2024

Will pre-construction staking being performed by the NPS?

No, the contractor is responsible for this effort. 1 7/12/2024

Will the contractor be required to sign the trail closures?

No, the NPS will provide any necessary signage as it relates to trail closures. 1 7/12/2024

Does the water line go directly to the chlorination building?

The water line goes directly from the two wells to the chlorination building. 1 7/12/2024

If there are cracks found in the tank - will repairs be needed? If so is there a percentage estimate of the number of cracks to be repaired?

The tank inspection report from 2021 is attached to Addendum 1.

There is one spot where there may be a crack that may require patching. 1 7/12/2024

Include tank inspection report in Addendum 1.

What is the approximate distance from the tank to the chlorination building and electrical?

Approximately 2,500'. Use the scale on the plan sheets to determine the exact distance. 1 7/12/2024

Questions and Answers

Will the tank be drained every year? Yes, at the end of the season, usually in September. 1 7/12/2024

Is there a temporary power source to be identified in the cabin area and is it required to provide temporary power to the cabins?

Yes, see Addendum 1. Temporary power for cabins is not necessary if no one is living in the cabins. 1 7/12/2024

Include hookup location and photos in Addendum 1.

Do the fire alarms need to stay active during construction? Yes. 1 7/12/2024

46 What is the cutoff date for questions? 29-Jul-24 1 7/12/2024

Additional electrical hookup location:

Swiftcurrent Water Storage Tank Condition Assessment Report National Park Service

Glacier National Park, Swiftcurrent, MT

December 30, 2021

This Page Intentionally Left Blank

Table of Contents Introduction

Inspection Methods

Visual Inspection

Testing for Surface Soundness

Detection of Contamination by pH

Field Observations

Site Security

Overview of Interior

Interior Walls of the Concrete Tank

Concrete Support Columns

Influent, Overflow, and Drain Piping

Intersect of the Walls to the Floor

Interior Roof

Tank Level Sensor Metal Components

Recommendations

Rehabilitation and Repair Measures

Montana DEQ Circular 1 and Circular 3 Requirements

Maintenance and Prevention

Introduction On December 6, 2021, HDR’s Corrosion professionals performed a dry flat footed condition assessment and corrosion investigations in the Swiftcurrent concrete underground water tank.

The 40’ x 40’ concrete reservoir is thought to have been built in the 1980’s. The purpose of

HDR’s investigations was to assess the condition of the existing concrete structure to determine the extent of rehabilitation.

The field visit team on December 6, 2021 consisted of Lizzy English Muir (HDR engineer and

NACE corrosion inspector) and Anders Nord (HDR project engineer). The inspector performed destructive testing and visual observations on the interior concrete and the metal components within the tank. The exterior of the concrete structure was buried underground and inaccessible for inspection.

The following safety equipment was used and provided by each entity at listed:

National Parks Service (NPS)

• An aluminum tripod for vertical extraction,

• Climbing rope with 3:1 system anchored to truck for mechanical advantage for horizontal rescue supervised by onsite Search and Rescue personnel,

• Air blower, air ducting, and generator oriented downwind from entrance,

• One (1) gas monitoring device, and

• Two (2) radios,

• Key for entrance into access hatch,

• Permitted Confined Space Entrance paperwork.

HDR, Inc.

• Two (2) rental gas monitoring devices,

• Lighting,

• Harness,

• Eye Protection,

• Tools for inspection,

• Cameras,

• Rainbow Indicator Spray.

Upon arrival, the HDR team noted 2-3 inches of snow coverage at the site covering the aluminum manway entrance as well as the base of the 6-inch gooseneck vent with screen.

The areas and components that were accessible for investigation for condition assessment and presence or absence of were as follows:

1. Site Security

2. Site signage, locked gate, secure fence

3. Vent and screen

4. Manway rim and lid

5. Intrusion alarm

6. Concrete around manway rim, interior and exterior

7. Concrete support columns

8. Interior ladder rungs

9. Drain

10. Fill

11. Overflow

12. Roof interior

13. Shell Walls

14. Floor/ Wall Intersect

15. Floor

Permit Required Confined Space inspections can be limited for various reasons. In this case the safety equipment limited the access to all areas of the tank due to the safety cable length being shorter than the width of the interior dimensions. As a buried structure the exterior shell and roof were not accessible and therefore not investigated. Additionally, because this water system is a noncommunity groundwater system water, quality sampling is not required and therefore not available to include in the assessment. The areas and components that were not accessible for investigations at the time of the field visits include:

1. The northwestern shell wall.

2. Interior roof penetration of tank vent.

3. Interior roof on northwestern half of the tank.

4. Entire exterior of the buried structure.

5. Constituents in the water: conductivity, chlorides, hardness (calcium and magnesium), traces of iron, Total Dissolved Solids.

Inspection Methods

Visual Inspection Inspection and testing were performed on foot from inside of the tank. HDR visually inspected the exposed concrete for signs of defects, physical damage, chemical damage, discoloration, spalling, staining, efflorescence, contamination, or signs of deterioration. The steel and other metal components were examined for signs of corrosion and metal loss.

Visual inspection also included checking for compliance to Montana Department of

Environmental Quality (MDEQ) Circular 1 and Circular 3. References made to MDEQ will be followed up in the Recommendations section.

Testing for Surface Soundness A number of hard, sharp objects can be used to test the soundness of concrete including a screwdriver, file, or pocket knife. These objects can be used to lightly scratch across the concrete surface and if the objects loosen particles or produce a gouge, the surface is not sound. Another technique which was the primary technique used by HDR during the investigation is the use of a hammer. If when the hammer is lightly struck against the concrete and the hammer re-bounds sharply with no more than a small fracture at the impact area, the surface is sound. If it lands with a dull thud and leaves powdered dusts in the indentation, the surface is not sound. The thud is an obvious difference from the sound and feel of the sharper rebounding when struck on concrete of acceptable condition.

Detection of Contamination by pH HDR used the Germann Instruments Rainbow Indicator that can be easily sprayed by hand to approximate the pH of the concrete, which can also be compared to the color coordination rainbow located on the bottle. Depending on the color that the concrete turns, the pH is indicated. The color orange indicates a pH of 5, yellow indicates a pH of 7, green indicates a 9, purple indicates an 11, and blue would mean the concrete is highly alkaline at a pH of 13.

Alkaline concrete is crucial for the binding agent to work effectively, and a pH of 11 to 13 is ideal. Chemical effects on the concrete can produce an acidic byproduct where disintegration and softening of the concrete continues.

Field Observations

Site Security Upon entering the site it was observed that the manway hatch door was properly locked and there was no property fence, signage, or intrusion alarm on the access hatch. The minimum requirements per MDEQ is to provide, as a minimum, means to lock entrances. Other measures for security are encouraged but not required.

Figure 1 Swiftcurrent Tank Site

Vent and Screen

The 6-inch gooseneck tank vent appeared to be in good condition, with no significant corrosion.

The base of the vent was covered in ice and snow and could not be properly investigated. The vent screen was damaged and corroding and not performing in the intended manner as required by MDEQ. MDEQ requires the screen be a much finer mesh (24-mesh or 0.03 inch openings) than what was onsite, and the screen must adequately protect from birds, bats, other animals, insects, rain and windborne contaminants. The inverted U shape of the gooseneck is acceptable as long as the opening of the vent is 24” above the ground of top of the roof.

Figure 2 Tank Vent Screen

Manway Hatch

The single aluminum 24” x 24” access hatch was in good condition. The seal on the lid was intact and well secured to the lid. It was observed there was no intrusion alarm but was locked upon arrival.

Figure 3 Aluminum Cover and Curb Around Tank Access

The steel frame around the perimeter of the entrance inside the throat of the opening showed surface rust that has led to spalling on the concrete and will likely continue to spall and deteriorate if rust is not removed. The rusted steel is the dark material between the white frost and the concrete in Figure 4. The concrete closest to the rusted steel is crumbling away and exposing aggregate

Figure 4 Throat Frame Corroded and Frosty (white)

Access Ladder Rungs

The ladder rungs were not used for entrance, instead the Safety Tripod lowered the inspector down past the rungs and the supply air ducting. The condition of the rungs were progressively worse towards the top of the access throat in the air space. The rungs lower down in what would be the immersion space appeared to be in satisfactory condition, but still with minor rust that appears to have delaminated old protective coatings from the substrate. In Figure 5 the photo on the left shows the condition of the rungs in the air space, and the photo on the right shows the rung still coated in off-white colored protective coating.

Figure 5 Corroding Ladder Rungs

Overview of Interior As requested by NPS personnel, measurements of tank dimensions and pipe diameters were taken and recorded. The following drawings are renderings of the tank construction, based on field measurements. Thickness of concrete and depth of concrete over reinforcement is unknown. The dimensions in Figure 6 are of the concrete components. The floor was a 40 foot by 40 foot square and the four (4) support columns were 14 ½” square prisms that supported the roof from the floor for a height of 11’1”.

The metal components were also measured for diameter and height and the orientation of those are depicted and labeled in Figure 7.

The condition of the tank concrete, overall, is in good condition with very little evidence of spalling from corroded rebar or exposed aggregate from physical or chemical damage. The condition of the concrete in the tank is well represented in Figure 8, as well as the suspected common water level that can be seen with the band of light/dark staining along the wall.

Figure 6 Concrete Structure Dimensions

Figure 7 Metal Components Dimensions

Figure 8 Typical Condition of Interior Concrete

Interior Walls of the Concrete Tank Visual inspections and some destructive testing with a hammer and chisel were performed to assess the condition of the concrete on the interior walls of the tank. Discoloration (or orange staining) due to settling of iron oxide deposit was prevalent on the tank floor and walls on the southeast half of the tank. This staining is likely from the corroding metal components in the vicinity. Throughout the tank there was a lighter off-white film of mineral deposits that terminated at the high-water level the entire perimeter of the tank. Using a hammer and a chisel at various locations in the tank, a softened acidic layer of concrete was easily removed to a depth range of ¼” to ½” at which point pH measurements were taken, with a result range of 11 to 13. See example of pH testing on the wall with Rainbow Indicator in Figure 9. This acidic layer is likely due to the presence of chlorine residual in the tank. This acidic layer is not of immediate concern as there is minimal exposed aggregate in the tank and only a few areas of spalling due to exposed tie rods. While the depth of concrete cover over the reinforcement is unknown, there was little evidence of spalling due to steel rebar reinforcement.

Figure 9 Concrete pH Testing on Small Chiseled Area

Figure 10 demonstrates the honeycombing associated with voids in the concrete due to poor workmanship and improper vibrating while concrete was being poured in the forms.

Figure 10 Honeycombing on Wall; Iron Oxide Staining on Floor

Located in the upper portion of the wall approximately 6-feet up from the floor there was a small area of spalling associated with corroding reinforcing steel rebar. Moisture intrusion into the concrete can contribute to the steel rusting and rust occupies a greater volume than the steel.

The combination of the rust with further expansion from moisture will create tensile stresses in the concrete, which can eventually cause cracking, delamination, and spalling. There were only a few instances of this condition observed in the tank, but should be addressed and not left to continue. In Figure 11, a hammer is used for scale underneath an exposed and corroded piece of steel within the concrete joint.

Figure 11 Hammer and Corroding Steel in Joint

Concrete Support Columns The support columns were in good condition with minimal concrete deterioration. There were locations where concrete repair will be required due to deterioration, minor spalling, and honeycombing at the base. Figure 12 provides an accurate portrayal as to the general condition of support columns in the tank. Aside from minor flaws, they are in sound structural condition.

The film of mineral deposits can also be clearly seen in contrast to the concrete above the high-water line.

Figure 12 Overall View of Support Columns, Four Total

The support column base shown in Figure 13 is another occurrence of spalling due to exposed steel, likely a tie rod from formwork. Additionally, at the base of the column in more evidence of honeycombing from improper or lack of vibration during concrete pour. On the floor is more evidence of iron oxide deposit staining and more highly concentrated directly under the tie rod.

Figure 13 Support Column Base with Spalling and Honeycombing

Influent, Overflow, and Drain Piping All three of the tank pipes are located very near the entrance ladder rungs. They are aligned parallel to the southeast wall and penetrate vertically through the floor, as shown in Figure 14.

The 4-inch fill pipe stands at a height of 9’ 11.5” and the 6-inch overflow vertical piping stands at a height of 9’10”. The fill and overflow piping appear to be in good condition with very little surface rust on the exterior and with protective coatings still intact. The interior of these pipes was not accessible for inspection. The base of these pipes at the floor penetrations were not causing any spalling in the concrete. Less obvious in the photo on the right, is the floor drain, which has been circled for more clarity and is shown in Figure 15.

Figure 14 Alignment of Fill, Overflow, and Drain Piping

The 10-inch drain piping is flush with the floor and has a protective silt stop collar to prevent rocks and debris from entering drain line back into distribution system. The top edge and interior of the drain piping have surface corrosion but did not appear to have contaminated the surrounding concrete to cause spalling. If abrasive blasted, any degraded concrete will easily be removed. The silt stop collar is heavily corroded in some spots, especially at the welds between the collar and the vertical members.

Figure 15 Tank Drain and Removable Silt Stop Collar

Intersect of the Walls to the Floor It was observed that the concrete lip at the intersection of the wall to the floor was in varying degrees of deterioration. In some areas the deterioration was minor with some exposed aggregate on the edges but still maintaining original form and seal of the cold joint. In other areas of the tank, including in corners, the concrete lip was completely disintegrated. The two images in Figure 16 demonstrate the two degrees of degradation of the corner lip as well as the iron oxide deposit staining on the floor. Chlorine is heavier than water and tends to sink over time, which could contribute to higher degradation of lower elevation concrete due to chemical attack.

Figure 16 Deteriorated Wall/ Floor Lip; Iron Oxide Deposit Staining

Interior Roof The concrete of the roof appeared to be in good condition. The hammer soundness test and the chisel etching for pH were not performed on the roof due to inaccessibility. Staining from iron oxide, honeycombing, and spalling were not found through visual inspections on the roof.

Of concern were the efflorescence throughout the roof uniformly distributed as tiny formations, but also as lager stalactite formations aligned together suggesting a crack in the roof.

Sometimes this mineral formation can be left behind from evaporated water high in calcium and magnesium, or can be an indication of a crack where water is seeping through and pulling the minerals from groundwater or from the concrete itself. Cracks in the concrete roof are a concern and should be investigated further upon abrasive blasting of superficial layers.

Figure 17 Efflorescence Stalactites

Tank Level Sensor Metal Components The existing metal components that make up the tank level sensing system are corroded and may be affecting the functionality of the components. Furthermore, the persistent rusting process will continue to shed iron oxide onto the floor and into the water system potentially affecting water quality including color, odor, and taste.

Figure 18 Level Sensor Junction Box and Transducer

Recommendations It is the opinion of HDR Corrosion Specialists that the following recommendations are not an immediate need. These recommendations will, however, prevent further corrosion, deterioration of concrete, decline of stored water quality (taste, odor, and color), and will increase the expected life of the tank greatly.

Rehabilitation and Repair Measures

• Interior concrete:

o Pressure Wash, or if needed use Ultra High Pressure Water Jetting, to remove approximately ¼ - ½ inch of contaminated concrete throughout the entire interior of the tank including walls, floor, ceiling and four (4) columns. Contractor must achieve ICRI CSP 5 or greater.

o Measure pH of freshly exposed concrete surface and verify with engineer that a pH of 11 or greater is achieved.

o In areas with form ties exposed or if abrasive blasting reveals exposed rebar use:

Rebar/Reinforcement corrosion coating and bonding agent: Abrasive blast to remove all loose material, apply NSF 61 approved product.

Use ICRI Guide No. 03730 Guide for Surface Preparation for the Repair of Deteriorated Concrete Resulting from Reinforcing Steel Corrosion

Repair areas of missing/deteriorated reinforcing steel rebar in accordance with ICRI Guide No. 03730.

o Non-Structural Concrete Repair Mortar and Protection

Xypex Megamix II, or NSF 61 certified equal, to fix any spalling, honeycomb, worm holes and bugholes for areas where concrete is deteriorated beyond a depth of ½ inch. (Includes spalling at frame of access hatch on exterior.)

Xypex Concentrate, or NSF 61 certified equal- slurry applied on entire floor, shell walls, ceiling/ interior roof, and support columns to enhance future chemical protection and crack healing.

o High Strength, Moisture-Tolerant, Epoxy Grouting and Sealing Adhesive (Epoxy

Grout): Apply to properly prepared concrete cracks upon discovery, especially on the interior roof where efflorescence are visible before abrasive blasting occurs.

• Intersect of the interior shell walls to the floor.

o NSF 61 Certified Elastomeric Sealant and Adhesive: to provide a seal at construction joints on the interior surfaces of the tank including along Wall/floor, Wall/roof, Column/floor intersections. Example Xypex FCM 80- flexible cementitious product OR Sika=Flex 1A.

• Tank Piping:

o Plug drain line at fitting, remove surface rust by abrasive blast to SSPC-SP 10, coat newly abraded steel with NSF 61 rated 100% solids epoxy.

o Replace corroded drain line collar/Silt Stop with new coated carbon steel collar or

FRP collar of equal diameter. Should be removable.

• Miscellaneous Metals o Level Transducer and Transmitter Box- Replace components or use hand tool to remove surface rust, recoat.

o Vent Screen – Replace dielectrically isolated stainless steel 24-mesh screen.

(Also DEQ requirement).

o FRP Ladder– remove steel rungs including embedded portions, replace with FRP ladder and epoxied anchored bolts.

o Manway Hatch Frame – Abrade to remove surface rush, coat with NSF 61 100% solids epoxy.

Montana DEQ Circular 1 and Circular 3 Requirements The following requirements are for new and modified water systems.

• DEQ 1; 7.08 Access – Install a new 24-inch (or consider 36-inch) access hatch on the opposite end of the tank elevated 24 inches above the ground and with overlapping 2-inch cover onto a 4-inch curb, similar to existing hatch.

• DEQ 1; 7.09 Vents - Replace vent screen with 24-mesh non-corrodible screen.

(Example: 304 stainless steel screen dielectrically isolated between dissimilar metal of carbon steel vent.)

• DEQ 1; 7.011 Safety – Confined Space Entry placard at entrance.

• DEQ 1; 7.0.17 Disinfection – before putting into service, tank to be disinfected per

AWWA Standard C652. Recommendation is to dispose of all chlorinated water after procedure and not send into distribution system.

Maintenance and Prevention

• Collect water quality samples annually until repairs have been made.

• Schedule inspections every 5 years to keep record of deterioration.

• Provide a parking and turnaround area that does not include driving over the tank unless documentation of design and reinforcement are located.

• Maintain only minimal chlorine residual in tank.

• If tank use ever changes to anything containing chlorides or sulfates, increase inspection frequency.