Abandoned in Place

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CITY OF HALBROOK — PUBLIC UTILITIES, WATER DIVISION

Acoustic Leak Detection: Weekly Exception Report

Period: Week 36 (Sept 1 – Sept 7)
Prepared by: D. Okafor, Leak Detection Analyst
Loggers deployed: 214
Exceptions: 3

  • AL-1180, Mercer Ave & 9th. Continuous hiss, 600–900 Hz, 24 h. Probable service leak. Crew assigned.
  • AL-1904, Depot Rd hydrant H-311. Intermittent, 06:00–07:10. Irrigation. Close.
  • AL-2207, Fenner St valve V-88. Non-hydraulic, rhythmic impulse, 02:00–04:00 nightly. See note.

Note, AL-2207: Short, sharp impulses in irregular groups, separated by long silences. Not consistent with leak noise, pump cycling or traffic. Correlated with AL-2208 (Fenner St, V-91). Correlation places the source approx. 140 ft east of V-88. Recommend field verification.


WORK ORDER WO-24-11873

Type: Field verification, acoustic exception
Location: Fenner St, 140 ft E of V-88
Opened: 09/09, 08:12 · Assigned: Crew 4 (T. Ruiz, K. Pell)

Field notes (T. Ruiz, 09/10, 02:40): Ground mic on pavement at marked location. Faint knocking audible, approx. 4 to 6 ft down. Checked as-builts on tablet. Active 8” ductile main runs along the north side of the street. Signal is on the south side, over the 1926 6” cast iron main, abandoned in place 1971. Per as-builts: drained, capped at Larch Ct and at Orr St, all services transferred to the new main and old taps cut and plugged at the curb.

Old main should be dry and empty. Knocking stopped while we stood on it. Restarted after we walked back to the truck.

Closed: 09/11. Resolution: Source located on abandoned asset. No action required.


CUSTOMER SERVICE CALL LOG (extract), Fenner St addresses

09/14, 07:55. 1207 Fenner St. Caller reports knocking in the pipes overnight, around 3 a.m. Advised water hammer, normal in older homes. Offered pressure check.

09/19, 08:30. 1215 Fenner St. Caller reports tapping sound “under the house.” Advised water hammer.

09/22, 09:02. 1207 Fenner St (repeat). Caller states she tapped on her kitchen pipe with a spoon to make it stop and it tapped back. “Same number.” Caller asked whether anyone works in the street at night. Advised no night crews scheduled. Ticket forwarded to Leak Detection per caller request.


Acoustic Leak Detection: Weekly Exception Report

Period: Week 39 (Sept 22 – Sept 28)
Prepared by: D. Okafor

Note, AL-2207 (continuing): Signal persists 02:00–04:00 nightly. Correlated position has changed. Week 36: 140 ft east of V-88. Week 37: 122 ft. Week 38: 104 ft. Week 39: 85 ft.

The source is moving west, toward V-88, at roughly 18 ft per week.

Pattern analysis attached. Impulses arrive in groups. Group sizes recorded on the night of 09/25, in order: 1, 1, 2, 1, 3, 1, 4, 1, 5, 1, 6. Recording ends there at 04:00. The groups resume the next night at 1.

Requesting CCTV inspection of the abandoned main.


From: Okafor, Dana
To: Brandt, Michael (Water Distribution Supervisor)
Date: Wed 10/02, 06:14
Subject: Fenner / AL-2207

Mike,

I know you said leave it. I went out at 2:30 this morning and opened hydrant H-402, which is the last hydrant still bolted to the old main (dead, no water, painted out). I hit the barrel with a wrench three times and then once. Three, pause, one. I’ve used that as a test pattern on new loggers for years.

AL-2207 recorded my four taps at 02:41:07. At 02:41:19 it recorded three taps, a pause, and one tap, from the old main, 70 ft east.

Then it moved. Correlation puts it at 52 ft by 03:00.

Please approve the CCTV crawler. I want to see what’s in there.

Dana


From: Brandt, Michael
To: Okafor, Dana
Date: Wed 10/02, 07:48
Subject: RE: Fenner / AL-2207

Dana,

Do not open H-402 again. It’s an abandoned asset and if somebody gets hurt on it, it’s on us. Nobody goes on Fenner at night alone, that’s policy, you know that.

Approved for CCTV, day shift only, two people. Use the small crawler, it’ll fit a 6”.

And it’s probably a rodent or a loose valve stem banging in the draft. I live at the end of Fenner on Larch Court, and believe me, every pipe on that side of town knocks.

Mike


CCTV PIPE INSPECTION LOG

Asset: Abandoned 6” CI main, Fenner St (H-402 access, inspection eastbound)
Date: 10/06 · Start: 10:22 · Operator: K. Pell · Observer: D. Okafor
Equipment: Crawler unit C-2 on 400 ft tether

  • 0 ft, 10:22. Start. Pipe dry. Light tuberculation.
  • 38 ft, 10:29. Plugged service tap (12 o’clock). Plug intact.
  • 61 ft, 10:33. Plugged service tap. Plug intact.
  • 84 ft, 10:38. Scrape marks in deposits, both walls, approx. 3 to 9 o’clock. Not consistent with flow. See photo 6.
  • 96 ft, 10:41. Plugged service tap. Plug threaded partly out. Photo 8.
  • 133 ft, 10:47. Scrape marks continue.
  • 140 ft, 10:49. Clear area in deposits approx. 4 ft long. Pipe wall clean to bare iron. Photo 11.
  • 152 ft, 10:51. Camera faces east. Object at edge of lighting range. Photo 14. Unable to identify.
  • 152 ft, 10:51. Object no longer in frame.
  • 152 ft, 10:52. Tether tension spike. Crawler pulled forward approx. 6 ft.
  • 158 ft, 10:52. Video lost.
  • 10:58. Tether retrieved by hand from H-402.

Operator remarks (K. Pell): Tether came back intact, full length to 158 ft. Crawler not recovered. The connector is a threaded collar. It was not broken. It was unscrewed.

Photo 14: [Withheld from file per supervisor. See M. Brandt.]


Acoustic Leak Detection: Weekly Exception Report

Period: Week 41 (Oct 6 – Oct 12)
Prepared by: D. Okafor

Note, AL-2207: Knocking continues 02:00–04:00. Position: 31 ft east of V-88.

Second signal on the same main from the night of 10/06 on: a steady electric motor whine with a gear tick, matching crawler C-2’s drive motor. Active approx. 02:15–02:30 nightly. It travels the length of the abandoned main from the Orr St cap to the Larch Ct cap and back. C-2’s battery is rated for 90 minutes and should have been dead by 10/06, 12:30.

Each night the knocking group sizes now start at 1 and continue past 6. Last night’s final group was 11. That’s the number of plugged service taps between the Orr St cap and V-88.

I have the AL-2207 audio from every night since Week 36. I can play it for anybody who wants to tell me it’s a valve stem.


HALBROOK POLICE DEPARTMENT — INCIDENT REPORT (excerpt)

Case: 24-008817 · Type: Missing person / welfare check
Reported: 10/16, 07:20, by M. Brandt, City of Halbrook Public Utilities

Narrative: City vehicle W-27, assigned to Dana OKAFOR, was found unoccupied on Fenner St at approx. 05:30 by a resident of 1207 Fenner, with the engine off and the driver’s door open. Valve vault cover at V-88 removed and lying beside the vault. Hydrant H-402 open, operating nut removed.

The vault is approx. 5 ft deep and 4 ft square and contains the gate valve for the active main and the capped end of the abandoned main. There is no opening large enough for an adult. Recovered from the vault floor: a city-issued tablet (screen cracked, operating), one pipe wrench, one hard hat. Recovered from the vault wall: a hand-drawn chalk diagram of Fenner St with eleven marks along the south side. The tablet was open to a logger audio file.

Resident at 1207 Fenner states she heard knocking in her kitchen pipes from approx. 02:30 to 03:00, “louder than before, and fast, like somebody in a hurry.” She did not hear a vehicle or voices.

OKAFOR’s phone was not recovered. Last activity: an outgoing call at 02:51.


VOICEMAIL TRANSCRIPT

Mailbox: M. Brandt, mobile · Received: 10/16, 02:51 · Length: 0:47
Transcribed from the voicemail attached to the incident file.

Mike, it’s Dana. I’m at V-88. I know. I know.

It’s right under me. It’s at the cap. I’ve been tapping the pattern and it’s been tapping it back, and then it stopped doing it back and started doing it first, and Mike, it’s not my pattern any more, it’s —

[knocking, 4 seconds]

It’s counting the old taps. All eleven are open now. It went up every one of them and it came back down. I can hear it in the plugs. It’s not coming out at the hydrant. It doesn’t want the hydrant.

It wants the ones that are still connected.

[knocking, close to the microphone, 2 seconds]

Mike, where does the old main cap off at the other —

[recording ends]


Acoustic Leak Detection: Weekly Exception Report

Period: Week 43 (Oct 20 – Oct 26)
Prepared by: (automatic: analyst position vacant)
Exceptions: 1

  • AL-2207, Fenner St valve V-88. No signal. No exception. Removed from watch list.
  • AL-3310, Larch Ct & Fenner St, active 8” main. Non-hydraulic, rhythmic impulse, 02:00–04:00 nightly. Correlation places source on customer side of service at 18 Larch Ct. Impulse pattern: groups of three, pause, one. Recommend field verification.

Assigned to: M. Brandt

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