Percolation tests and stamped septic designs for Eloy, Toltec, and the surrounding Santa Cruz Flats. 48-hour permit-ready reports from a firm that only designs and never bids installs.
Start Your ProjectEloy sits at the junction of Interstate 10 and Interstate 8, roughly 55 miles from both Phoenix and Tucson, and that crossroads position built its job base. Republic Plastics, Schuff Steel, Otto Industries, Owens Corning, and National Gypsum operate out of more than 700 acres of industrial park, and Skydive Arizona runs a world-class drop zone at Eloy Municipal Airport. The rooftops are catching up. The Census Bureau counted 15,624 residents in 2020 and estimated 19,199 by mid-2024, and Arizona Office of Economic Opportunity estimates for the year ending July 2025 put growth at 2.8 percent, more than double the statewide 1.2 percent. September 2025 brought the city its first hospital, Exceptional Community Hospital at 340 E. Milligan Road, at I-10 and Sunshine Boulevard.
The City of Eloy publishes a bright-line rule that settles most building plans here. If an existing sewer main runs within 400 feet of your parcel and you are building a house, you must connect to it. If no main is that close, the city sends you to Pinal County for a septic permit. Sewer mains reach only a limited area around Eloy's historic core, and extending one is entirely the owner's expense, engineered plans and all, so in practice outlying land defaults to septic. That is why the Toltec and Toltec Arizona Valley subdivisions in ZIP 85131 run on septic even where city water reaches the lot line, and why rural acreage along Battaglia Road, Hanna Road, and the Sunland Gin corridor typically plans on septic from the start. Robson Ranch is the exception; it drains to the private, state-regulated Picacho Sewer Company rather than a city main or a tank.
Every septic parcel in that picture needs the same two documents before Pinal County will act: a soil and percolation report and a stamped septic design. That is the whole of what Perc Test AZ does. We test the dirt, we produce the design, and we step aside. We never bid installations, so your report sizes the system your soil requires rather than the one a contractor hopes to sell, and the permit-ready paperwork reaches you within 48 hours of fieldwork.
Eloy is built on the flat basin fill of the old Santa Cruz Flats. There is no bedrock problem here and no granite; the obstacles live in the top four feet of dirt. The city's own General Plan soils map, exhibit EP-3, lists roughly 40 USDA soil series across the planning area, names like Mohall, Coolidge, Laveen, and La Palma. Two of them tell most of the perc story. The Casa Grande series, Arizona's official state soil, blankets much of the basin floor, and the Toltec series was named for Eloy's own Toltec community, with its type location right here in Pinal County.
The two behave nothing alike under a perc test. Casa Grande soils carry a sodium-affected clay loam subsoil running 18 to 35 percent clay, and the USDA rates their permeability slow or very slow; sodium disperses the clay, the pores seal when wetted, and water in a test hole just sits there. Toltec soils start friendlier, a well-drained fine sandy loam with moderate permeability, but at 20 to 40 inches down, commonly near 36, the profile hits a calcic zone packed with 80 to 95 percent silica-lime cemented hardpan fragments, caliche running up to 55 percent calcium carbonate. That is precisely the depth where a disposal trench bottom and a perc hole want to be.
Testing settles which soil you actually have. Our borings run past trench depth and record each layer as it comes up, so the report shows exactly where the pan starts and how fast every horizon accepts water. A sandy Toltec profile above the caliche often percs well and supports a routine conventional system. A Casa Grande clay loam may need a larger disposal field or an alternative system to satisfy county criteria, and it is far cheaper to learn that from a test hole than from a rejected application or a stalled escrow.
Percolation tests and full R18-9-A310 site investigations on Eloy and Toltec parcels, with permit-ready reports usually in your hands 48 hours after fieldwork.
Stamped conventional and alternative septic designs matched to your perc data and lot, formatted for Pinal County Aquifer Protection review.
Builders and installers: we test and design only. Your client stays your client, and the installation bid stays yours.
The City of Eloy does not issue septic permits, and neither does ADEQ directly. Every onsite system around Eloy is permitted by the Pinal County Aquifer Protection Division, which runs the septic program under authority delegated by the Arizona Department of Environmental Quality from its office at 85 N. Florence Street in Florence. The division approves conventional systems up to 24,000 gallons per day and alternative systems up to 3,000 gallons per day, inspects construction, and keeps the county's septic location records. Our Pinal County service page covers how that same office handles the rest of the county.
Before the division will issue a construct permit, Arizona Administrative Code R18-9-A310 requires a documented site investigation, a surface and subsurface characterization performed by a qualified investigator. Our field reports are built to that rule section, so a county reviewer sees the data in the format the code demands. If you want the whole sequence laid out, from application through final inspection, read our step-by-step Pinal County septic permit guide before you schedule fieldwork.
Eloy's water and sewer rules are separate. The city requires a water hookup for parcels in platted subdivisions or within 100 feet of a water line, but sewer mains serve only a limited area near the city's core. Land listings in Toltec Arizona Valley say it plainly: the entire area is on septic.
A perc test and a stamped design are the first two items Pinal County will ask for on that lot.
The city's published threshold is 400 feet. If an existing sewer main runs within 400 feet of your parcel and you are building a house, you must connect; if not, the city refers you to Pinal County for a septic permit.
Extending a main to reach your land is entirely at your expense, which is why outlying Eloy parcels almost always end up on septic.
It can slow one down, but it rarely kills a project. Toltec series soils hit a cemented calcic zone around 20 to 40 inches down, and Casa Grande series clay loams perc slowly because of their sodium-affected subsoil.
If your soil misses conventional criteria, we design the alternative or oversized system that meets Pinal County's rules instead.
Fieldwork gets scheduled quickly, and the permit-ready report typically follows within 48 hours of the site visit.
We are a design-only firm with no installation bid waiting at the end, so nothing in the process is slowed down to sell you something.
Call (602) 584-7430 or tell us about your parcel online. We schedule fieldwork fast and deliver permit-ready reports in 48 hours.
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