Closed Landfill Assessments, City of Stone Ford, Arizona

Ten site reports in one template, one per closed landfill, each with its site record, QC review, final review and a shared change log. Eight reports are issued as Rev 0. Two are waiting on five items, and two sites moved to a higher risk tier during QC review.

Sources: 7 documents and field sampling, Sep 202610 closed landfills, City of Stone FordTemplate: Closed Landfill Assessment Report v3Prepared Nov 5, 2026

Summary

Placeholders

5 placeholders left in 2 reports

Salt Cedar Flat Dump (3) and Dry Lake Road Landfill (2) cannot be issued yet. The City still has to provide an APN, the closure year and a current owner, a 1975 aerial photo is missing, and the lab has not reported the RO-2 resample. The other eight reports were issued as Rev 0 on Nov 2–3.

The data request is compiled in CL-41.

Risk tiers

Two sites moved from Tier 3 to Tier 2

The site records first used the wellhead protection area from the 2009 inventory, which reflects the 1998 boundary. Under the City’s 2021 Wellhead Protection Plan (p. 7), Ocotillo Wash Dump and Tinaja Road Landfill are inside the 10-year time-of-travel zone of the Ocotillo wellfield. QC review caught it in QC-S02-01.

The change ran through the site record, Figure 1 and Sections 2, 4, 7 and 8.

Final review

One comment corrected six reports

The runoff sample from Stone Ford Wash had been screened against the Aquifer Water Quality Standards. Section 6.3 of the template now screens surface water against Arizona’s surface water quality standards, and the six reports with runoff or surface water samples were rewritten the same day.

No risk tier changed.

Reports by site

Where each report stands, from site record to issued report. Drag the timeline or play it back. Click a site to open its report, site record, review comments and changes.

Show
8Reports issued
5Placeholders left
41Review comments
41Change log entries

Shared change log

Every change to the ten reports, the template and the site records, with its reason. A change that touches several reports has one entry.

    Sources and method

    Sources

    • Scope_of_Work_Closed_Landfill_Assessments.pdfCity scope: ten sites, sampling scope, four-tier risk ranking, report requirements12 pages
    • Report_Template_Closed_Landfill_Assessment_v3.docxShared report template with eight sections, two figures and one results table18 pages
    • Closed_Landfill_Inventory_2009.pdfPrior City inventory: location, footprint, volume, nearby water, wells64 pages
    • Sanitation_Dept_Records_1948-1989.pdfScanned Sanitation Department records: years of operation, waste types, cover212 pages
    • Field_Sampling_Logs_Sep2026.xlsxSampling locations, boring logs and depth to water, one tab per site10 tabs
    • Lab_Reports_Oct2026.pdfLaboratory reports for soil, groundwater, runoff and landfill gas88 pages
    • Wellhead_Protection_Plan_2021.pdfCity wellhead protection plan with time-of-travel zones, replaces the 1998 plan24 pages

    Method

    1. One site record per landfill. Location, history, waste, geology, nearby water, sampling and results were pulled from the sources and stored with file and page. Conflicting values were flagged and resolved with the source stated.
    2. One report per landfill. All ten reports use Closed Landfill Assessment Report template v3. Text, figures and the results table are built from the site record. Where a source was missing, a placeholder was set.
    3. QC review. Each report was checked against its site record and the sources. A comment on a fact was fixed in the site record and carried into every report that uses it.
    4. Final review. Draft B was reviewed site by site. A comment on the template was fixed in the template and in every affected report.
    5. Change log. Each change was logged with date, author, affected reports, sections and reason.

    Assumptions and limitations

    • Risk tiers follow the City’s four-tier ranking in the scope of work. A tier is a screening-level ranking and does not replace a site-specific risk assessment.
    • Soil is screened against the Arizona Soil Remediation Levels (SRLs), groundwater against the Aquifer Water Quality Standards (AWQS) and the upgradient well, and runoff and surface water against Arizona’s surface water quality standards. Landfill gas is reported as percent of the lower explosive limit (LEL, 5% methane by volume).
    • All ten sites stopped taking waste before Oct 9, 1991, so 40 CFR Part 258 (RCRA Subtitle D) does not apply directly. Its explosive-gas limits are used as screening levels.
    • Sampling is screening level, with 3 to 7 locations per site. Results reflect the September 2026 sampling event.
    • Coordinates are NAD83(2011) State Plane, Arizona Central zone (FIPS 0202), in international feet. Elevations are NAVD 88.
    • The reports for Salt Cedar Flat Dump and Dry Lake Road Landfill remain at Draft B until the placeholders are filled and the final reviewer signs off.
    • ADEQ has announced a review of the Aquifer Water Quality Standards, but no adopted change was found when the sources were checked. Confirm the standards in force with ADEQ before the reports are finalized.