Most site plans treat dry utilities as something that gets sorted out later. Water and sewer get designed early because gravity forces the issue. Power, telecom, and gas get a note on the sheet and a hope that the serving utility will work around whatever is already drawn.
That hope is where schedules go to die.
What are dry utilities?
Dry utilities are the services that carry energy or signal rather than fluid: electric power, natural gas, telecommunications, fiber, and cable. Wet utilities carry water, sewer, and storm drainage.
The distinction matters for one practical reason. Your civil engineer designs the wet utilities. The serving utility designs the dry ones, on its own standards, on its own schedule, and usually after the site plan is already set. That handoff is where developments lose months.
Why dry utilities delay projects more often than wet ones
Wet utilities have physics on their side. Storm drain and sanitary sewer run on gravity, so their elevations get locked early and everything else moves around them. Nobody forgets them.
Dry utilities have no such forcing function. They can theoretically go anywhere, which means they get deferred, and by the time anyone asks the serving utility what it actually needs, the plat is recorded and the pads are set.
Four things then happen in sequence:
The easement isn’t there. Electric and gas both need dedicated easements at widths the utility specifies, not widths the site plan found convenient. Discovering this after recording means a replat, and a replat is a municipal review cycle you did not budget.
The transformer has nowhere to sit. Pad-mounted equipment needs clear working space, vehicle access for a line truck, and separation from anything that would block it. It also cannot sit inside a sight visibility triangle, a fire lane, or the landscape feature the architect put at the entry. Something moves, and it is rarely the transformer.
The trench conflicts. Joint trench carrying electric, gas, and telecom has to cross the wet utilities somewhere. Wet wins, because gravity does not negotiate. Every crossing that was not planned becomes a field change.
The equipment is not there. Transformers, switchgear, and metering equipment carry lead times that have stayed long since 2021. If nobody ordered against the energization date, the trench is open, the pad is poured, and the project waits for a truck.
Any one of these adds weeks. Together, on a project with a financing deadline or a tenant commitment, they compound into a real number.
The Arizona-specific part
Arizona adds constraints that generic dry utility advice misses.
Service territory is not intuitive. APS and SRP boundaries interleave across the Valley in ways that do not follow municipal lines. Tucson Electric Power, Southwest Gas, and the rural electric cooperatives each cover their own footprint with their own standards. Two parcels across a street from each other can have different serving utilities and different design requirements. Confirm territory before you assume a standard applies.
Caliche is a cost item, not a footnote. Trench depth that pencils cleanly on paper meets a caliche layer or rock at eighteen inches and the excavation cost changes character. Geotechnical data at trench depth, not just at foundation depth, is worth having before the joint trench is priced.
Monsoon compresses the construction window. Open trench during a summer storm season is a schedule risk and a safety one. Projects that miss a spring window often wait out the season.
Heat affects sizing. Ambient temperature derating is real for conductor and transformer sizing in this climate. A design copied from a cooler market will be undersized.
The permits stack. The serving utility’s approval is not the municipality’s permit, and neither is ADOT’s encroachment permit if any part of the work touches state right of way. These run in parallel with different reviewers and different clocks.
How to coordinate dry utilities before the site plan locks
The work is not complicated. It is just sequenced differently than most teams assume.
- Confirm the serving utilities. Electric, gas, and telecom, by parcel, verified against territory maps rather than assumed from the nearest neighbor.
- Calculate load and apply early. The service application starts the utility’s clock. A will serve letter confirms the utility will provide service and under what conditions. Applying late does not make the utility move faster, it just moves your start date.
- Get the standards before you draw. Each utility publishes its own requirements for easement width, separation, bedding, cover depth, and equipment clearance. These are not interchangeable. Design to the wrong standard and you redesign.
- Composite the dry utilities against the civil plan. One drawing showing electric, gas, telecom, and the wet utilities together, at the same scale, before anything is final. Most conflicts are visible in ten minutes on a composite that nobody made.
- Align easements with the plat. Dedicate what the utilities require while the plat is still a draft. This is the single highest-leverage step, because it is the cheapest thing to fix now and the most expensive thing to fix later.
- Design the joint trench. Electric, gas, and telecom sharing a trench have to meet each utility’s separation and bedding requirements, and each crossing of a wet utility needs a resolved elevation. Joint trench also needs an agreement between the parties, which takes time to execute.
- Schedule backward from energization. Identify long-lead equipment, place orders against the date the project needs power, and treat that date as fixed rather than as the output of everything else.
- Verify in the field and document as-built. What got installed is what the next contractor will dig around. Accurate records now prevent a strike later.
What usually gets missed
A short list of items that show up late on Arizona site work:
- Streetlight circuits, and who owns, feeds, and maintains them
- Backbone capacity, when the serving feeder cannot carry the new load without an offsite upgrade
- Telecom carrier commitment, which often does not firm up until a developer signs, leaving telecom designing last into whatever space remains
- Temporary construction power, planned separately from permanent service
- Franchise agreements for facilities in municipal right of way
- Secondary service routing to individual pads or buildings, distinct from the primary that gets all the attention
Who this affects
Developers and land planners setting a site plan. Civil engineers who own the wet utilities and inherit the dry utility conflicts. General contractors pricing trench and coordinating a joint trench crew. Municipal and public agency project managers running infrastructure with a fixed funding calendar. Utility project managers absorbing developer work into their own program.
Different roles, same failure mode. Dry utilities get treated as a downstream task rather than a design input.
How ARUSI approaches dry utility coordination
ARUSI is a Service-Disabled Veteran-Owned Small Business (SDVOSB) engineering firm in Phoenix that has designed utility infrastructure across Arizona since 1987.
Our role on dry utility work is engineering and coordination, not construction. We identify the serving utilities, prepare the design to each utility’s published standards, composite the dry utilities against the civil plan, resolve the conflicts on paper, and carry the submittals through utility and municipal review. When the design needs subsurface information, we coordinate the geotechnical work that informs trench depth and cost.
The reason we push this work earlier is straightforward. A conflict caught on a composite drawing costs an afternoon. The same conflict caught in an open trench costs a change order and a schedule slip, and it is the developer who pays for both.
Talk to us before your next site plan locks. A short conversation about serving utilities, easements, and lead times at the concept stage is worth more than a redesign later.
