HELIOSOpen AI Infrastructure Observatory
Static snapshot. This site serves two different things: 1,853 data centres reported by OpenStreetMap contributors nationwide, and 13 sites Helios infers from Arizona parcel records, exported on July 29, 2026. The first is a map of what has been recorded; the second is an argued hypothesis with an evidence chain. This is a point-in-time export, not a live view. See meta.json or the methodology.

AZ-MESA-001

Mesa, Maricopa County, Arizona · hyperscale campus Reported

Download evidence & provenance
0 No known developmentStage 7: Operational8 Expansion
Confidence (Id. / Stage)
64% / 73%
high
Site area
83.2
acres across 1 parcel
Evidence records
11
first signal 2013-11-04
Estimated load
100–399 MW
inferred from acreage — see the estimates panel
Summary. 1 parcel(s) totalling 83.2 acres near 3740 S SIGNAL BUTTE RD, Mesa. Title of record is held by PLATYPUS DEVELOPMENT LLC. Helios has not established which organization, if any, operates or will operate a facility here.

Evidence timeline

12 chronological entries
  1. 4 Nov 2013
    Shell entity ownershipInferred

    Title is held by PLATYPUS DEVELOPMENT LLC, whose name shows single-purpose-entity characteristics (pass-through legal form (LLC); minimal descriptive name). This is a weak signal only: project-specific entities are routine in ordinary commercial real estate and imply no particular parent.

    OwnerName = PLATYPUS DEVELOPMENT LLC
    Source: Maricopa County Assessor Parcel LayerView original evidenceRetrieved 2026-07-25sha256:77af6d6d43fe$.features[6].attributes.OwnerNameExtraction confidence 45%
  2. 4 Nov 2013
    Large industrial parcel acquisitionReported

    Organization-held industrial parcel of 83.2 acres transferred for $113,576,875 on 2013-11-04, at or above the 20-acre campus-scale threshold.

    DeedNumber = 20130962087; DeedDate = 2013-11-04; LotSize_Acre = 83.17146
    Source: Maricopa County Assessor Parcel LayerView original evidenceRetrieved 2026-07-25sha256:77af6d6d43fe$.features[6].attributes.DeedDateExtraction confidence 90%
  3. 4 Nov 2013
    Stage advanced to Operational

    Stage advanced from 0 (No known development) to 7 (Operational) at 73% confidence. Principal evidence: Assessor classifies property use as data centre; Grading or construction permit; Backup-generator air permit.

    Unclassified → OperationalDetected 4649 days after the factConfidence at transition 73%
  4. 14 Jun 2022
    Substation applicationExtracted

    ACC docket E-01345A-22-0148: Initial CEC application — Signal Butte Substation. Filed by Arizona Public Service Company on 2022-06-14. Helios ingested a recorded fixture, not a live scrape.

    Requests approval to construct a 230/69 kV substation and short loop-in of an existing 230 kV circuit near S Signal Butte Road, Mesa.
    Source: Arizona Corporation Commission eDocketView original evidenceRetrieved 2026-07-28sha256:c3c1150bf8f6$.docket.filings[0]Extraction confidence 85%
  5. 9 Jan 2023
    Substation applicationExtracted

    ACC docket E-01345A-22-0148: Amended single-line and site plan. Filed by Arizona Public Service Company on 2023-01-09. Helios ingested a recorded fixture, not a live scrape.

    Updates the proposed substation footprint and confirms 230 kV loop-in alignment.
    Source: Arizona Corporation Commission eDocketView original evidenceRetrieved 2026-07-28sha256:c3c1150bf8f6$.docket.filings[1]Extraction confidence 85%
  6. 15 Jul 2026
    Grading or construction permitReported

    City of Mesa commercial building permit PMT26-07994 at 3740 S SIGNAL BUTTE RD, opened 2026-04-27, status: Issued - Permit approved and issued and in inspection phase. Matched to parcels by normalized address; no coordinates in source.

    PMT26-07994; COM; 3740 S SIGNAL BUTTE RD; Issued - Permit approved and issued and in inspection phase
    Source: City of Mesa Building PermitsView original evidenceRetrieved 2026-07-25sha256:55cca827c961$[28]Extraction confidence 75%
  7. 22 Jul 2026
    Grading or construction permitReported

    City of Mesa commercial building permit PMT26-12780 at 3740 S SIGNAL BUTTE RD, opened 2026-07-13, status: In Review - Plans are being reviewed or awaiting revisions. Matched to parcels by normalized address; no coordinates in source.

    PMT26-12780; COM; 3740 S SIGNAL BUTTE RD; In Review - Plans are being reviewed or awaiting revisions
    Source: City of Mesa Building PermitsView original evidenceRetrieved 2026-07-25sha256:55cca827c961$[9]Extraction confidence 75%
  8. 23 Jul 2026
    Grading or construction permitReported

    City of Mesa commercial building permit PMT26-13495 at 3740 S SIGNAL BUTTE RD, opened 2026-07-23, status: In Review - Plans are being reviewed or awaiting revisions. Matched to parcels by normalized address; no coordinates in source.

    PMT26-13495; COM; 3740 S SIGNAL BUTTE RD; In Review - Plans are being reviewed or awaiting revisions
    Source: City of Mesa Building PermitsView original evidenceRetrieved 2026-07-25sha256:55cca827c961$[2]Extraction confidence 75%
  9. 25 Jul 2026
    Dedicated substation proximityCalculatedStanding condition

    Luna Substation tagged 69 kV lies 0 m from the site boundary, close enough for a dedicated connection to be practical. Proximity is a locational precondition, not evidence that this substation serves the site.

    name = Luna Substation; operator = Salt River Project; max_voltage_kv = 69.0
    Source: OpenStreetMap Power Infrastructure (Overpass API)View original evidenceRetrieved 2026-07-25sha256:b780b9bfc5c6OSM elementExtraction confidence 95%
  10. 28 Jul 2026
    Assessor data center classificationReportedStanding condition

    Maricopa County Assessor currently classifies this parcel's property use as DATA CENTERS (use code 1507).

    PropertyUseDescription = DATA CENTERS
    Source: Maricopa County Assessor Parcel LayerView original evidenceRetrieved 2026-07-25sha256:77af6d6d43fe$.features[6].attributes.PropertyUseDescriptionExtraction confidence 95%
  11. 28 Jul 2026
    Backup generator air permitExtractedStanding condition

    EPA ECHO lists PLATYPUS DEVELOPMENT as a Clean Air Act facility (NAICS 518210). Program text and/or hosting NAICS are consistent with backup generation at a data-processing site. Coordinates may be geocoded. Programs: NSPS, NSPSM, OTH.

    PLATYPUS DEVELOPMENT; NSPS, NSPSM, OTH
    Source: EPA ECHO Air Facility RecordsView original evidenceRetrieved 2026-07-25sha256:71c269ae37b2$.Results.Facilities[348]Extraction confidence 80%
  12. 28 Jul 2026
    Backup generator air permitExtractedStanding condition

    EPA ECHO lists PLATYPUS CAMPUS EMERGENCY GENERATORS as a Clean Air Act facility (NAICS 518210). Program text and/or hosting NAICS are consistent with backup generation at a data-processing site. Coordinates may be geocoded. Programs: Title V; NESHAP Reciprocating Internal Combustion Engines.

    PLATYPUS CAMPUS EMERGENCY GENERATORS; Title V; NESHAP Reciprocating Internal Combustion Engines
    Source: EPA ECHO Air Facility RecordsView original evidenceRetrieved 2026-07-25sha256:ed532dd13219$.Results.Facilities[0]Extraction confidence 80%

Why Helios believes this

64% High
Confidence
73%
high
Supporting weight
+79.1
10 contributions
Countervailing weight
0.0
0 contributions
Evidence diversity
6
distinct kinds across 11 records
+19.00
Assessor classifies property use as data centre
Maricopa County Assessor currently classifies this parcel's property use as DATA CENTERS (use code 1507).
base 20 × extraction confidence 0.95 × recency 1.00
+14.93
Grading or construction permit
City of Mesa commercial building permit PMT26-13495 at 3740 S SIGNAL BUTTE RD, opened 2026-07-23, status: In Review - Plans are being reviewed or awaiting revisions. Matched to parcels by normalized address; no coordinates in source.
base 20 × extraction confidence 0.75 × recency 1.00
+13.60
Backup-generator air permit
EPA ECHO lists PLATYPUS DEVELOPMENT as a Clean Air Act facility (NAICS 518210). Program text and/or hosting NAICS are consistent with backup generation at a data-processing site. Coordinates may be geocoded. Programs: NSPS, NSPSM, OTH.
base 17 × extraction confidence 0.80 × recency 1.00
+7.46
Grading or construction permit
City of Mesa commercial building permit PMT26-12780 at 3740 S SIGNAL BUTTE RD, opened 2026-07-13, status: In Review - Plans are being reviewed or awaiting revisions. Matched to parcels by normalized address; no coordinates in source. (occurrence 2, weight reduced)
base 20 × extraction confidence 0.75 × recency 0.99
+6.80
Backup-generator air permit
EPA ECHO lists PLATYPUS CAMPUS EMERGENCY GENERATORS as a Clean Air Act facility (NAICS 518210). Program text and/or hosting NAICS are consistent with backup generation at a data-processing site. Coordinates may be geocoded. Programs: Title V; NESHAP Reciprocating Internal Combustion Engines. (occurrence 2, weight reduced)
base 17 × extraction confidence 0.80 × recency 1.00
+6.21
Dedicated substation application
ACC docket E-01345A-22-0148: Amended single-line and site plan. Filed by Arizona Public Service Company on 2023-01-09. Helios ingested a recorded fixture, not a live scrape.
base 25 × extraction confidence 0.85 × recency 0.29
+4.05
Large industrial parcel acquisition
Organization-held industrial parcel of 83.2 acres transferred for $113,576,875 on 2013-11-04, at or above the 20-acre campus-scale threshold.
base 18 × extraction confidence 0.90 × recency 0.25
+3.70
Grading or construction permit
City of Mesa commercial building permit PMT26-07994 at 3740 S SIGNAL BUTTE RD, opened 2026-04-27, status: Issued - Permit approved and issued and in inspection phase. Matched to parcels by normalized address; no coordinates in source. (occurrence 3, weight reduced)
base 20 × extraction confidence 0.75 × recency 0.99
+2.66
Dedicated substation application
ACC docket E-01345A-22-0148: Initial CEC application — Signal Butte Substation. Filed by Arizona Public Service Company on 2022-06-14. Helios ingested a recorded fixture, not a live scrape. (occurrence 2, weight reduced)
base 25 × extraction confidence 0.85 × recency 0.25
+0.68
Single-purpose entity holds title
Title is held by PLATYPUS DEVELOPMENT LLC, whose name shows single-purpose-entity characteristics (pass-through legal form (LLC); minimal descriptive name). This is a weak signal only: project-specific entities are routine in ordinary commercial real estate and imply no particular parent.
base 6 × extraction confidence 0.45 × recency 0.25
+0.00
High-voltage substation in close proximity
Luna Substation tagged 69 kV lies 0 m from the site boundary, close enough for a dedicated connection to be practical. Proximity is a locational precondition, not evidence that this substation serves the site.
base 0 × extraction confidence 0.95 × recency 1.00

Scored by helios-rule-based version 0.1.0 on 2026-07-28, using evidence available as of 2026-07-28. Weights are domain-reasoned starting points, not values fitted to outcomes; calibration is deferred until a historical backtest exists to calibrate against.

Location

Estimated demand

none of this is a filed figure
Power capacityInferred

199.6 MW

99.8plausible range399.2

Assembled acreage x assumed power density, adjusted for stage.

What this assumes

Power density is an industry assumption, not a property of this site. Helios does not know the building footprint, rack density or how much of the assembled land will be built on.

stage
7
total acres
83.1715
MW per acre low
1
MW per acre high
4
MW per acre likely
2
stage density multiplier
1.2
Cooling waterInferred

2,395,200 GPD

239,520plausible range9,580,800

Estimated power x assumed cooling water intensity.

What this assumes

Cooling type is not recorded in any source Helios ingests. A closed-loop or air-cooled design approaches zero water use; evaporative cooling can exceed a gallon per kWh. The band is wide because the practice is.

gal per kwh low
0.1
gal per kwh high
1
gal per kwh likely
0.5

Operator and ownership

Operator not established
PLATYPUS DEVELOPMENT LLCLLCPossible single-purpose entity
  • pass-through legal form (LLC)
  • minimal descriptive name

Helios records the entity of record only. Shell-company indicators are flags for human review and do not constitute an attribution to any parent.

Parcels

APNAddressAcresDeed
304-33-005S3740 S SIGNAL BUTTE RD83.172013-11-04

Infrastructure dependencies

Luna SubstationInferredLikely dedicated
0 m away · 69 kV · Salt River Project · match confidence 95%
Unnamed substationInferredLikely dedicated
0 m away · 69 kV · match confidence 95%
500.0 kV circuitInferred
637 m away · 500 kV · match confidence 33%
500.0 kV circuitInferred
656 m away · 500 kV · match confidence 33%
500.0 kV circuitInferred
667 m away · 500 kV · match confidence 33%
500.0 kV circuitInferred
685 m away · 500 kV · match confidence 32%

10 further dependencies not shown.

Dependencies are inferred from spatial proximity. A nearby substation makes a connection practical; it is not evidence that one exists.

Attribution

  • Parcel data courtesy of Maricopa County Assessor / Maricopa County GIS.
  • Power infrastructure data (c) OpenStreetMap contributors, ODbL.

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