Phase-by-Phase Subdivision and the Common Plan Question

Required. The 1-acre threshold is applied to the entire area of disturbance associated with a larger common plan of development or sale, not to the piece in front of you.

Indicators here all point one way: one owner, one master plan, one set of covenants, five phases marketed as one project, and common infrastructure and access. The regulated area is the 46 acres. Subdividing the work into sub-1-acre increments, and taking separate NOIs for other phases, does not reset the threshold - coverage has to address the whole plan, even if implementation is phased.

Two aggravating facts:

• The TMDL. Where a TMDL with a construction-phase wasteload allocation exists, coverage commonly attaches regardless of area, and the SWPPP must be consistent with the TMDL.
• The local permit. The county grading permit does not substitute for NPDES coverage, and a grading permit issued without a SWPPP in the file signals the local reviewer was not given the full picture.

Practical consequences of proceeding without coverage: unauthorized discharge, enforcement and penalty exposure for the operator, potential third-party suit, and stop-work risk that costs far more than the SWPPP. Advise a single NOI covering the 46-acre plan with a SWPPP that is phased but cumulative, filed before any soil is disturbed.

The TMDL converts generic BMP selection into a load-reduction obligation. The plan should contain:

1. A statement of the applicable TMDL and the assigned reduction (here, 20% construction sediment load), with the receiving water and impairment named.
2. A demonstration of how the 20% is met, not just a list of BMPs. That means: a load estimate for the site under the plan, the selection of measures that produce the reduction, and a reasoned narrative tying the two together. Typical measures: shorter exposure windows, rapid stabilization of the 0.9-ac pad and driveway, perimeter controls installed before clearing and maintained, velocity dissipation at outlets, and - where the creek is close and the soil is fine-grained - a chemical treatment or filtration step.
3. Monitoring and response. The permit's inspection frequency and any benchmark sampling, plus the operator's corrective-action trigger and reporting pathway when a benchmark is exceeded.
4. Escalation logic. What the operator does if treatment measures do not achieve the intended reduction: additional measures, agency notification, expanded sampling.

A stamped drawing cannot carry any of this. What the contractor asked for - an 'erosion control plan' drawing - is roughly 20% of the deliverable and none of the compliance.

You are not the regulator and you have no stop-work authority, but you do control what you sign and you have a duty to be clear in writing.

• Decline to sign a partial deliverable. You cannot certify an erosion control plan you did not prepare or that omits SWPPP elements the permit requires. An engineer or CPESC signature on a plan implies the plan is complete and adequate; signing this one would be misleading.
• Put the advice in writing, dated, addressed to the owner and the contractor. State plainly that the project is a larger common plan, that NPDES coverage is required before disturbance, that the TMDL applies, and that proceeding Monday without coverage exposes the operator to enforcement. Send it before Monday, so it cannot be characterized as after-the-fact.
• Do not conceal the county's gap. Recommend that the owner, as the appropriate party, notify the county that a SWPPP is required and was not part of the submittal. Client confidentiality does not extend to assisting a misrepresentation to a public agency; if the owner refuses, escalate internally and reconsider the engagement.
• Keep your record. File notes, correspondence, and the basis for your advice. If the project proceeds uncovered, your record is what distinguishes advice given and ignored from advice never given.