Submittal package
The technical evaluation handed to the Approval Authority, structured the way it will be evaluated — every assumption, data gap, and consequence written into the document rather than left in a spreadsheet cell.
Package contents
Technical evaluation · 40 CFR 122.44(j)(2)(ii) ·
NPDES NP0041882 · prepared 2026-07-15
1
Introduction and basis
Why the reissued permit triggers this evaluation, and how the most
restrictive of six protection pathways sets each limit.
2
Pollutants of concern
17 pollutants selected from permit limits,
2025 detections, and industrial user categories; PFOA/PFOS screened out and disclosed.
3
Monitoring data
184 results across four quarters of 2025;
non-detects substituted at half the detection limit, none excluded.
4
Removal efficiencies
Observed removals from paired influent and effluent data for
15 of 17 pollutants; mercury mass balance carried as an open item.
5
Maximum allowable headworks loading
Controlling pathway and derived MAHL for each pollutant ·
Table 5-1. Biosolids standards control seven limits.
6
Allocation to industrial users
Uniform concentration across all 12 permitted
users, defended against the mass-proportional alternative.
7
Summary
Six limits tighten, four relax, seven unchanged against the 2021 study
of record; adoption recommended.
A
Appendix A — Full limits table
All 17 pollutants with MAHL, MAIL, and every derivation input.
B
Appendix B — Monitoring results
The 184 analytical results with detection limits and qualifiers.
C
Appendix C — Compliance schedule
For the three industrial users above one or more proposed limits on adoption.
D
Appendix D — 2026 sampling plan
Closes the thallium and silver data gaps; corrects mercury biosolids timing.
Proposed limits
Table 5-1 · the controlling pathway sets each value ·
measured against the limits codified in 2021
| Pollutant | 2021 mg/L | Proposed mg/L | Binding pathway | Change |
|---|---|---|---|---|
| CadmiumCd | 0.110 | 0.058 | Biosolids — Class A | Tightens 47% |
| MercuryHg | 0.050 | 0.034 | Biosolids — Class A | Tightens 32% |
| Arsenic (total)As | 0.100 | 0.099 | Biosolids — Class A | No change |
| CopperCu | 2.700 | 1.916 | Acute aquatic life | Tightens 29% |
| ZincZn | 0.590 | 0.650 | Activated sludge inhibition | Relaxes 10% |
| LeadPb | 0.254 | 0.254 | Activated sludge inhibition | No change |
| + 11 further pollutants — full table in Appendix A | ||||
Limits resting on reference removal rates rather than observed site data
— thallium and silver — are identified as provisional in the document text.
Disclosed assumptions & data gaps
Reviewers ask about these first — the document answers before they ask
PFOA and PFOS were screened out.
No criterion applies to the receiving water at this time and no industrial user is a
known source; revisited at the next permit cycle. §2
Thallium is provisional — no 2025 influent data.
Its limit derives from the human health criterion with a 40%
reference removal rate; added to the 2026 sampling plan. §3
Silver removal uses a reference rate.
9 non-detects in 12 samples is below
the 8-pair minimum for an observed removal efficiency. §3
Mercury mass balance closes at 61%.
Attributed to biosolids sampling timing; the limit derives conservatively from the
biosolids standard and is not sensitive to the gap. §4
Cadmium and mercury are over-allocated.
Committed industrial loading exceeds the allowable industrial loading at current
permitted flows; a compliance schedule accompanies the package as Appendix C. §6
Sign-off
RV
R. VasquezPretreatment coordinator · preparer
Prepared
TA
T. AblemanPlant superintendent · reviewer
Pending
AA
Approval AuthorityState pretreatment program
Not sent
Sign-off freezes the study record — criteria version, sample data, and
every derivation input. Later changes create a revision, not an edit.
Approval Authority checklist
What the evaluator looks for, in order
Evaluation within 180 days of permit reissuance
40 CFR 122.44(j)(2)(ii)
Every permit-limited and detected pollutant carried through the evaluation
Non-detect substitution stated; no results excluded without cause
Removal rates observed from at least 8 paired samples,
or a reference rate disclosed
Most restrictive of six protection pathways controls each limit
Allocation method stated and defended against challenge
Compliance path for users above proposed limits · Appendix C
Reviewer sign-off on the study record
Adoption into the sewer use ordinance, after approval
History
R. Vasquez sent the package to internal review
2026-07-15
R. Vasquez assembled the submittal package
2026-07-15
R. Vasquez selected uniform concentration allocation
2026-07-13
System pinned criteria library v6 to this study
2026-07-11
R. Vasquez created study 2026 permit cycle update
2026-07-02