SWPPP Site Maps & Erosion Control Schematics
The map is the part of the plan an inspector actually opens — where the controls are, where the water goes, and where the site stops. A narrative can be skimmed; the map gets studied. Terradyne draws the erosion-control exhibits that make a stormwater plan legible — for the reviewer approving it, the crew building from it, and the inspector walking it.
What is a SWPPP site map?
Terradyne prepares erosion-control schematic site maps for the SWP3 — the BMP layout exhibit. It is the drawing that turns the plan's paragraphs into geometry: every control, every flow path, every disturbed area, placed where a boot can find it.
What the permit requires on the map
The map's contents are not a style choice — they are enumerated. TXR150000 requires the SWP3 to include a detailed site map indicating property boundaries, drainage patterns and approximate slopes anticipated before and after major grading activities, areas where soil disturbance will occur, and locations of all controls and buffers, either planned or in place. The site map must also indicate locations where temporary or permanent stabilization practices are expected to be used. The zoomed-out view is required too. The SWP3 must also include a map showing the general location of the site, such as a portion of a city or county map. Together they answer the two questions every reviewer asks first: where is this site, and what is happening on it.
The details people forget
Some required map elements live in odd corners of the permit. When a SWP3 is required, TXR150000 requires concrete washout areas to be shown on the associated site map. A washout pit that exists on the ground but not on the exhibit is a finding — the map has to carry the whole compliance picture, not just the perimeter.
A map is only right until the site changes
TXR150000 requires the permittee to revise or update the SWP3, including the site map, within seven days of a change in design, construction, operation, or maintenance that has a significant effect on the discharge of pollutants and has not been previously addressed in the SWP3. A map that no longer matches the site is a finding waiting to be written. Keep the exhibit moving with the phases. Phase lines move, controls come out, new areas open — the exhibit either moves with them or stops being true.
How the schematic gets drawn
The exhibit starts from your civil sheets — grading, drainage, and utilities — and reduces them to the single question the stormwater reviewer is asking: where does water leave this site, and what does it pass through on the way out. Controls are drawn at install scale and labeled in the same field language the crews and the inspection reports use, so the map, the ground, and the paperwork all say the same words. Phasing gets its own treatment: an exhibit that shows every phase at once is technically complete and practically unreadable, so the drawing is organized the way the work will actually happen.
Turnaround matters because a submittal can sit waiting on nothing but the map. The desk works from the files you already have — no survey mobilization, no waiting on a design cycle — and delivers an exhibit consistent with the narrative it belongs to.
Reading the exhibit like an inspector
An inspector reads a site map backwards: find the discharge points first, walk upstream, and check that every control the drawing promises is standing on the ground. A good exhibit makes that walk easy — and makes the differences obvious when something has moved. That is the real function of the drawing: not decoration for the binder, but the reference the whole compliance conversation happens against. The same read is worth doing yourself before every major phase change — five minutes with the exhibit can catch what a formal walk would otherwise find.
The Terradyne schematic
Terradyne's schematics are not PE-stamped documents; when a professional engineer's seal is required, that is a separate arrangement. Terradyne draws standalone schematics for projects that arrive with no civil erosion-control sheet, and for cities that ask for a separate exhibit. Either way the drawing arrives build-ready: scaled, labeled in field language, and consistent with the narrative it belongs to.
Frequently Asked Questions
What must the site map show?
The boundaries, the drainage — slopes and flow patterns before and after grading — the areas being disturbed, every control and buffer planned or placed, and where stabilization will happen. If it matters to runoff, it belongs on the exhibit.
Is a general location map also required?
Yes — alongside the detailed exhibit, the plan carries a wider view placing the site in its city or county context, so a reviewer who has never driven past the project can orient in one glance.
How quickly must the map be updated when the site changes?
Within days, not phases — significant changes to design, construction, operation, or maintenance start a short clock on revising the plan and its map together. A current exhibit is a compliance requirement, not housekeeping.
Is the schematic a sealed engineering document?
No — it is the plan's BMP layout exhibit, not a stamped civil sheet. When a jurisdiction requires a professional engineer's seal, that is arranged separately, and the schematic still does its job as the working map.
Can the schematic be drawn against an existing plan?
Yes — the exhibit can be produced for a narrative that already exists, working from your current civil files. The drawing has to agree with the plan it joins, so any mismatch found along the way gets flagged rather than inherited.
Request a bid
Send your grading plan or civil set to bids@terradynegroup.com or call (214) 878-7392 for an erosion-control schematic. If the plan exists but the exhibit is missing or stale, say so — a map can be drawn to an existing narrative from the SWPPP Narrative & Manual Preparation desk, and changes ride through Addendum & Re-Permit.