Dixon Engineering, Inc. · 2020. 5. 28. · Report Prepared: December 4, 2017 . Reviewed by Ira M. Gabin, P.E.: December 11, 2017 . Dixon Engineering Inc. 815 W. Liberty St. , Suite

Dixon

Engineering, Inc.

Preliminary Maintenance Inspection

2,000,000 Gallon Concrete Reservoir

(Dulles Airport-West)

Metropolitan Washington

Airport Authority

Washington D.C.

Inspection Performed: November 1, 2017 Report Prepared: December 4, 2017

Reviewed by Ira M. Gabin, P.E.: December 11, 2017

Dixon Engineering Inc.

815 W. Liberty St. , Suite 1, Medina, OH 44256

Phone (330) 983-0062

Fax (330) 725-0512

http://www.dixonengineering.net

[email protected]

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CONCLUSIONS:

1. The exterior roof is in good condition. There are a few concentric and radial hairlinecracks at the roof joints. No spalling was found on the roof.

2. The shotcrete overlay on the exterior sidewalls is in good condition. There are severalhorizontal and vertical spider cracks near the equator and at the construction joints.Cracks appear to be in the outer lay of the shotcrete. There is no efflorescence on thewalls associated with the cracks. There is a spalled area at the connection to the roof.

3. The interior roof is in good condition. There are minor concentric cracks at the roofjoints. Minor spalling is present on the roof. The roof to sidewall junction is in goodcondition.

4. The interior sidewalls are in good condition. There are a few horizontal cracks on thebottom third. No spalling was found on the sidewall.

5. The interior floor slab is in good condition. There are a few diagonal cracks. No spallingwas found on the floor. Sediment distribution indicates the cracks are not leaking.

6. The exterior coating is an acrylic system on the sidewalls and roof that is in poorcondition with extensive delamination and erosion.

7. The interior sidewall coating appears to be an epoxy system on 25 feet of the east wallthat is in poor condition. The coating is has poor adhesion with delamination anderosion. The tank has an elastomeric coating system on the floor joints that is in faircondition with areas of delamination.

RECOMMENDATIONS:

1. Complete the recommended work in 1-2 years. The coating work is the greatest cost andlargest part of the recommendations. The repairs and upgrades should be completedduring the next major tank rehabilitation project when coating work is completed.

2. Remove the exterior spalling concrete and repair with an epoxy concrete repair system.

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3. Remove the deteriorated caulk in the gap for the sidewall to roof connection. Apply new caulk in the sidewall to roof connection gap at the top of the sidewall.

4. Water dampen abrasive blast clean the exterior and apply a two coat acrylic latex system.

5. Clean out the interior floor cracks and fill with an epoxy repair system. Coat the surface of the crack with an elastomeric coating system. Remove the non-adhering coating from the floor joints and re-apply an elastomeric system.

6. Abrasive blast clean and paint interior piping.

7. Replace the wet interior cleats with a new ladder that contains a fall prevention device.

8. Coat the exterior ladder and handrails with an acrylic overcoat system over a SSPC-SP6water damped blast standard when the exterior is coated. The cost would be incidental toexterior recoating.

9. Add a contingency to replace the fill and overflow pipes if it found that there is extensive steel loss once pipes are abrasive blast cleaned.

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THIS PAGE IS BLANK

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INSPECTION:

On November 1, 2017, Dixon Engineering, Inc. (DIXON) performed a preliminary maintenance inspection on the 2,000,000 gallon (Dulles Airport-West) concrete reservoir owned by the Metropolitan Washington Airport Authority. Purposes of the inspection were to evaluate the interior and exterior coatings’ performance and life expectancy; assess the condition of concrete surfaces and the tank’s appurtenances; review safety and health aspects; and make budgetary recommendations for continued maintenance of the tank. All recommendations, with budgeting estimates for repairs, are incorporated in this report. The inspection was performed by Shannon Vidika, Project Manager. The inspector was assisted by Kyle Lay and Larry Houck, Staff Technicians. Scheduling and arrangements for the inspection were completed through Priyam Shah with Metropolitan Washington Airport Authority. The tank bottom was covered with approximately ½ inch of sediment that was flushed from the interior. A source of water for cleaning and vacuum truck were provided by the Owner. Following the inspection, chlorine was added to disinfect the tank per AWWA Standard C652-11 method No. 3.

TANK INFORMATION:

The tank was built in 1960 by Crom with a height to high water line of 29 feet and a diameter of 120 feet. The tank is pre-stressed concrete. The tank is partially underground with 26 feet above grade. The walls are precast panels. The roof is domed and constructed from precast panels. The floor is poured in place. The exterior is coated with an acrylic system and the wet interior is not coated except for floor joints and a section of the east sidewall.

CONDITIONS AND RECOMMENDATIONS:

EXTERIOR STRUCTURE CONDITIONS:

The roof is constructed of precast concrete slabs with construction joints. The roof is in good condition overall. There are a few cracks that are tight and run along the radial and concentric construction joints. The edges of the cracks are intact and the cracks likely formed during the original construction and now appear dormant. No efflorescence is present on the roof cracks and there are no spalls on the roof.

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The sidewalls were are constructed of preformed concrete slabs with construction joints, the walls were wrapped in wire for pre-stressing and then a layer of gunnite was sprayed over the wiring. The sidewalls are in good condition overall. There are several horizontal cracks that are tight and are located on the lower sidewall near the equator and at the construction joints. The edges of the cracks are intact and likely formed during the original construction and now appear dormant. No efflorescence is present on the walls at the cracks.

There are a few spalled areas at the sidewall to roof connection. Most of the spalls are shallow and likely caused by aggregate close to the surface creating a thin layer of cement that popped off.

There is a sealed expansion joint between the roof and the sidewall that is in good condition. Some of the sealant has deteriorated or is missing leaving openings to the backer rod.

EXTERIOR STRUCTURE RECOMMENDATIONS:

Repair the spalls by removing all of the loose concrete and apply a cementitious mortar, larger repairs are to be made using a concrete mix.

At the sidewall to roof connection repair the caulk by removing all dried and cracked caulk and fill missing areas with new caulking.

INTERIOR STRUCTURE CONDITIONS:

The roof is in good condition overall. There are a few cracks that are tight and run along the concentric construction joints. The edges of the cracks are intact and likely formed during the original construction and now appear dormant. Minor efflorescence is present on the roof at the cracks. There are minor spalls at the roof cracks.

The sidewalls are in good condition overall. There are a few horizontal cracks that are tight and run along the bottom ⅓ of the sidewall. The edges of the cracks are intact. The cracks likely formed during the original construction and now appear dormant. No efflorescence is present on the walls at the cracks. There are no spalls on the sidewall.

There is a tight joint between the sidewall and floor is that is in good condition. The water stop was not visible and could not be inspected.

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The floor was poured in-place. There are a few cracks that are tight and run perpendicular to the sidewall and at construction joints. The edges of the cracks are intact and likely formed during the original construction and now appear dormant. No efflorescence is present on the floor at the cracks. There are a no spalls on the floor.

The tank bottom was covered with approximately ½ inch of sediment that was flushed from the interior. Sediment was uniform across the floor indicating no leaks through the floor slab.

The tank has one concrete column that is in good condition overall and used to support the fill line and overflow pipe. The ladder cleats are attached to the side of the column for access. The column is imbedded into the floor but is not attached to the roof or sidewall.

INTERIOR STRUCTURE RECOMMENDATIONS:

Clean out the interior floor cracks and fill with an epoxy repair system. Coat the surface of the crack with an elastomeric coating system. Remove the non-adhering coating from the floor joints and apply an elastomeric system.

EXTERIOR COATING CONDITIONS:

The walls and roof are coated with a multiple coat acrylic system that is poor condition overall.

The coating on the sidewalls is in poor condition. Adhesion of the sidewall coating is in poor condition with large areas of delamination to the substrate.

The coating on the roof is in poor condition overall. Adhesion of the roof coating is poor with large areas of delamination to the substrate and topcoat erosion.

The exterior steel appurtenances including the roof handrails and sidewall ladder are coated with an unknown system. There are several spot failures on the roof handrails and leg ladder.

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EXTERIOR COATING RECOMMENDATIONS:

Plan and budget for total exterior coating removal and recoating in approximately one to two years. Fading will continue and more rust spots will occur decreasing the tank’s aesthetic appearance. Total removal is recommended because the coating failures are extensive with poor adhesion and will not support additional coating.

Water dampen abrasive blast clean to remove all existing coating.

The bare concrete would be coated with two full coats of acrylic. The coating will supply a protective barrier. Coating will minimize further weathering and will protect any crack and spall repairs performed. The tank would be removed from service during the painting project. This is necessary to reduce moisture condensation on the surface.

Coat the exterior steel appurtenances with an acrylic overcoat system over a SSPC-SP6 blast standard when the exterior is coated. Cost would be incidental to the concrete coating.

WET INTERIOR COATING CONDITIONS:

There is no coating on the wet interior roof.

The wet interior sidewall coating is an epoxy system located on 25 feet of the east sidewall and is in poor condition. The coating has poor adhesion with delamination and erosion.

The wet interior floor is coated at construction joints and at previous cracking. The coating is an elastomeric system that is in fair condition with areas of delamination.

The wet interior steel appurtenances including the fill line, draw line, and ladder cleats are coated in an unknown system that is in poor condition overall. There is no coating remaining on the steel appurtenances and there is significant scale corrosion.

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WET INTERIOR COATING RECOMMENDATIONS:

Low pressure wash the floor construction joints to remove the non-adhering coating. Apply an elastomeric coating system to the floor construction joints and cracks that have been repaired. Cost is incidental to the crack repairs to the floor.

Remove the coating system on the interior steel appurtenances by abrasive blast cleaning the metal to a near white metal (SSPC-SP10) condition and apply an epoxy coating system with a zinc primer. Wet interior coating systems must be approved for potable storage tanks contingent upon meeting requirements of NSF/ANSI 61.

Note: After wet interior steel appurtenances are abrasive blast cleaned an inspection will need to be performed to check the steel condition and determine if the fill and overflow pipes will need to be replaced.

SITE CONDITIONS:

The tank site is average size and is fenced. There is an average staging area for the contractor’s equipment. There is another tank to the east and two radio towers to the west. The tank is located on the ground of the Dulles International Airport. The tank is partially underground with 26 feet of sidewall above grade.

OVERFLOW PIPE CONDITIONS:

The tank has an 8 inch diameter overflow pipe that is attached to concrete column and extends up to the high water line. The overflow pipe is routed into the floor of the interior and runs underground to a storm drain. The section of pipe in the wet interior is covered with extensive scale corrosion.

HATCH AND MANWAY CONDITIONS:

The roof has 30 x 30 inch square flip-top square roof hatch that is in good condition.

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VENT CONDITIONS:

The vent is a flow through design with two hinged screens. If frozen or plugged, the screens will hinge allowing air to flow in and out. The screen that hinges in can be moved inward by birds roosting on the lip next to the screen. There was no evidence of bird activity near the vent.

LADDER CONDITIONS:

The exterior sidewall ladder is in good condition and is equipped with a cable type fall prevention device that is in good condition. The ladder is bolted to the concrete sidewall. Ladder sections are welded together with a small steel plates.

The wet interior contains 23 ladder cleats attached to the concrete column, from the roof to the floor that are in fair condition with surface rusting and possible steel loss.

LADDER RECOMMENDATIONS:

Remove the ladder cleats from the wet interior and install a new fiberglass ladder attached to the concrete column. A new fall prevention system would also be installed.

ROOF HANDRAIL AND PAINTER’S RAIL CONDITIONS:

Handrails are located on the roof to either side of the sidewall ladder. The handrails are in good condition but are somewhat flimsy.

FILL/DRAW PIPE CONDITIONS:

The fill pipe penetrates through the wet interior floor. The pipe is attached to the concrete column and extends 8 feet up from the floor. The pipe is covered with scale corrosion.

The tank is drained from a separate 16 inch draw pipe. The draw pipe is located in the sump. The pipe is flush with the sump wall and there is scale corrosion around the pipe opening.

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FILL/DRAW PIPE RECOMMENDATIONS:

Add a piping contingency to replace the fill and overflow pipes if it found that there is extensive steel loss once pipes are abrasive blast cleaned.

DIXON ENGINEERING, INC. CONCRETE TANK FIELD INSPECTION REPORT

DATE: November 1, 2017 OWNER: Metropolitan Washington Airport Authority CLIENT CODE: 51-08-68-01 TANK NAME: Dulles Airport (West) LOCATION: Street: 1 Saarinen Circle

City: Dulles State: Virginia

TANK SIZE: Capacity: 1,000,000 gallons Diameter: 120 feet (estimated) Height to overflow (HWL): 26 feet (estimated) Sidewall Height: 29 feet (estimated)

CONSTRUCTION: Pre-stressed Type of Roof: Dome Tank Layout: Above grade

DATE CONSTRUCTED: 1960 MANUFACTURER: Crom CONTRACT NUMBER: Unknown

COATING HISTORY: EXTERIOR

DATE LAST COATED Unknown

CONTRACTOR Unknown PAINT SYSTEM Acrylic

SURFACE PREPARATION N/A

PAINT MANUFACTURER Unknown

PAINT SAMPLES No HEAVY METAL

COATING ON STEEL

Yes

PERSONNEL: Inspector Kyle Lay, Top person Shannon Vidika, Ground person Larry Houck

TYPE OF INSPECTION: Preliminary Maintenance METHOD OF INSPECTION: Dry DATE LAST INSPECTED: Unknown

SITE CONDITIONS: Fenced: Yes Site large enough for contractor’s equipment: Yes Control building: Yes-to southeast Neighborhood: Airport property Power lines within 50 feet: No Site drainage: Away from tank Indications of underground leakage: No Shrub, tree, etc. encroachment: No

Site Comments: Two standing towers to west; another reservoir to east

CRACK GRADES Crack Grade Width

1 Tight, no separation - dormant 2 Tight to up to fingernail width 3 Fingernail width up to 1/8 inch 4 1/8 up to 1/4 inch 5 Greater than 1/4 inch

EXTERIOR: SIDEWALL:

Concrete condition: Good Rusting at surface: No Coating Present: Yes

Location: Entire sidewall Type of coating: Acrylic Coating condition: Poor Describe coating: Delaminating and erosion throughout

Lettering: No Logo: No

Cracking ( exterior sidewall): Number of cracks: 30± Total length of cracking: 300± feet

Crack Descriptions: Location: East side near equator

Grade: 1 Length: 2-20 feet Number of cracks: 10-20

EXTERIOR: Orientation: Horizontal Active: No Efflorescence present: No

Location: South side near equator Grade: 1 and 2 Length: 3-40 feet Number of cracks: >5 Orientation: Horizontal Active: No Efflorescence present: No

Location: West side Grade: 1 Length: 10-40 feet Orientation: Horizontal Active: No Efflorescence present: No

Cracks appear to be leaking: No

Spalling (exterior sidewall): Number of areas spalled: 1 Spall Descriptions: Location: Southeast roof/sidewall connection

Length and width: 3 feet x 10 inches Maximum depth (inches): 1 ½ inch (estimated) Reinforcing steel visible: No

Exterior Sidewall comments: Coating failures throughout; 300+ spots total; cracks appear to have been previously repaired

Roof: Concrete condition: Good Rusting at surface: No Coating Present: Yes

Location: Entire roof Type of coating: Acrylic Coating condition: Poor Describe coating: Delaminating

EXTERIOR: Cracking (exterior roof):

Number of cracks: 4-10 Total length of cracking: 400± feet

Crack Descriptions: Location: Hairline cracks; circular at joints; minor and not active

Grade: 1 Orientation: Radial Active: No Efflorescence present: No

Spalling (exterior roof): Number of areas spalled: None

Exterior Roof comments: Coating failures throughout entire roof

Tank Sidewall To Roof Connection: Type of bearing pads: Foam backed Condition of sidewall to roof connection: Good Describe condition: Spalling

Describe any cracking or spalling at joint and cause if determinable: Foam visible in one spot just to right of ladder; caulking also present at roof/sidewall connection; caulk is in good condition

EXTERIOR APPURTENANCES:

Overflow pipe: Overflow comments: Exits wet interior floor; not visible outside

Exterior ladder: Height to start of ladder: 1 foot Ladder material: Steel Toe clearance: Less than 7 inches Width of rungs: 15 ¾ inch Thickness of rungs: ¾ inch Shape of rungs: Rebar Coating condition: Fair Material condition: Good Fall prevention device: Yes

EXTERIOR APPURTENANCES: Type: Cable Condition: Good

Vandal Guard: Yes Condition: Good

Exterior ladder comments: Crevice rusting at ladder connections; swinging gate at top of ladder

Roof handrail: Location: Both sides of ladder Length: 10 feet each (estimated) Height: 42 inches Mid-rail height: 24 inches Coating condition: Fair Metal condition: Good Handrail comments: Handrail is a little wobbly

Roof hatch: Number: 1 Neck size: 30 x 30 inch Hatch security: None Coating condition: Good Metal condition: Fair Hatch comments: Northwest side of roof; minor coating failures on wet interior side of lid

Secondary hatches: N/A

Ventilation: Number: 1 Type: Flow-through Location: Roof Size: Two hinged 12 x12 inch screen sections

Vent material: Aluminum Coating condition: Not coated Material condition: Good Screen condition: Good

Percent of screen open: 100

CRACK GRADES Crack Grade Width

1 Tight, no separation - dormant 2 Tight to up to fingernail width 3 Fingernail width up to 1/8 inch 4 1/8 up to 1/4 inch 5 Greater than 1/4 inch

WET INTERIOR: Tank roof:

Concrete condition: Good Rusting at surface: No Coating Present: No

Cracking (interior roof): Number of cracks: 4-10

Crack Descriptions: Location: Four circular joints with minor cracking and efflorescence in small spots

Grade: 1 Length: Varies Orientation: Radial Active: No Efflorescence present: Yes

Cracks appear to be leaking: No

Spalling (interior roof): Number of areas spalled: 10-20 Spall Descriptions: Location: Small spalls along four circular joint seams

Diameter (inches): 2-4 (estimated) Maximum depth (inches): ½-1 (estimated) Reinforcing steel visible: No

Interior roof comments: Hard to photograph spalls due to mist in tank before and after

WET INTERIOR: Tank Sidewall:

Concrete condition: Good Rusting at surface: No Coating Present: Yes

Location: Sidewall (approximately 25 foot section, east side only) Type of coating: Presumed epoxy Coating condition: Poor Describe coating: Delaminating and erosion

Cracking (interior sidewall): Number of cracks: 10-20 Total length of cracking: 150-200 feet

Crack Descriptions: Location: Horizontal bottom ⅓ of tank

Grade: 1 Length: 150-200 feet Orientation: Horizontal Active: No Efflorescence present: No

Spalling (interior sidewall): Number of areas spalled: None

Tank floor: Concrete condition: Good Rusting at surface: No Coating Present: Yes

Location: At joints Type of coating: Elastomeric Coating condition: Fair Describe coating: Showing minor delamination

Cracking (interior floor): Number of cracks: 6-10 Total length of cracking: 75-100 feet

WET INTERIOR: Crack Descriptions: Location: Between joint seams in 4-5 (pre shaped sections)

Grade: 1 Length: 3-20 feet Orientation: Perpendicular to wall Active: No Efflorescence present: No

Cracks appear to be leaking: No

Spalling (interior floor): Number of areas spalled: None

Wall to Floor Junction: Floor to wall separation: No

Curb present: No Water stop accessible: No

Sediment and Sump: Sediment depth: ½ inch Sediment distribution: Uniform Could sediment distribution indicate a leak: No Sump present: Yes

Size: 24 x 24 x 24 inches This sump is used for: Draw pipe

WET INTERIOR ACCESSORIES: Tank cleats: (x23)

Cleat material: Steel Coating condition: Poor Material condition: Fair Fall prevention device: No Interior ladder comments: Cleats attached to a free standing concrete pillar that measures 12 ½ x 30 inches; pillar not attached to sidewall or roof

Roof Beams: N/A

WET INTERIOR ACCESSORIES: Columns:

N/A

Overflow: Type of inlet: Funnel Condition: Fair Coating condition: Poor Overflow comments: Corrosion cells throughout; attached to concrete pillar

Fill pipe: Diameter: 8 inches Height above floor: 8 feet Configuration: Stubs at floor One way valves present: No Deflector on end: No Removable silt ring: No Mixing system: No Coating condition: Poor Metal condition: Fair Fill pipe comments: Corrosion build up throughout pipe; attached to free standing pillar

Separate draw pipe: Diameter: 16 inches Height above floor: In the sump; 6 inches below the floor Deflector over end: No Removable silt ring: No Draw pipe comments: Located inside sump; horizontal orientation

Baffle walls: N/A

Other roof penetrations (not previously noted): N/A

Other sidewall pipe penetrations (not previously noted): N/A

Field Inspection Report is prepared from the contractor’s viewpoint. It contains most of the information the contractor needs to prepare his bid for any repairs or repainting. The Engineer uses it to prepare the engineering report. Cost estimates are more accurate if contractor problems can be anticipated. While prepared from the contractor’s viewpoint, the only intended beneficiary is the owner. These reports are completed with diligence, but the accuracy is not guaranteed. The contractor is still advised to visit the site.

2,000,000 gallon concrete reservoir (West) owned by the Metropolitan

Washington Airport Authority.

1) Exterior sidewalls are in good

condition with cracking at

construction joints.

2) Spider cracking in sidewall

shotcrete and areas of

delaminated coating.

3) Same.

4) The sidewall coating is in

poor condition with large areas

of delamination.

5) Same.

6) Same.

7) Sidewall spalling at the roof

connection.

8) Same.

9) Caulk missing with foam

backer rod exposed at sidewall to

roof connection.

10) Sidewall ladder with cable

fall prevention device.

11) Sidewall ladder is bolted into

the concrete. The bolts are

rusting.

12) Ladder sections are welded

together with small plates.

13) The roof is in good condition

with cracking at the construction

joints.

14) Same.

15) Same.

16) The roof coating is in poor

condition with erosion and

delamination.

17) Same.

18) Same.

19) Flow through vent at center

of the roof.

20) Vent screens are intact.

21) Roof hatch to the wet

interior.

22) Swing gate at the top of the

sidewall ladder.

23) 10 foot roof handrails to

either side of the sidewall ladder.

24) Small bolts securing handrail

to the roof.

25) Wet interior roof is in good

condition with minor cracking at

the construction joints. Roof is

not coated.

26) Same.

27) Same.

28) The sidewalls are is in good

condition with minor cracking.

29) Same.

30) Same.

31) 25 foot section of east

sidewall was coated. Coating is

in poor condition with erosion

and delamination.

32) Same.

33) Same.

34) The floor slab is in good

condition.

35) There are a few cracks in the

floor.

36) Same.

37) The floor construction joints

have been coated.

38) The floor joint coating is

delaminating in a few areas.

39) Same.

40) Platform at the top of the

concrete column for access to the

interior.

41) Ladder cleats attached to the

concrete column. Cleats have

areas of corrosion.

42) Closer view of ladder cleat

with corrosion.

43) Fill pipe with heavy scale

corrosion.

44) Overflow pipe with heavy

corrosion.

45) Single concrete column used

to support ladder cleats, fill, and

overflow lines. Column is not

attached to the roof or sidewall.

46) Top of overflow pipe.

47) Sump in the floor for

removing sediment.

48) Draw line in sump pit with

scale corrosion.