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Commission a site survey and build a base map

Create an accurate base map of the land showing boundaries, contours, water, vegetation and existing features. Every later layout decision is drawn on this map.

How

1. Hire a licensed land surveyor to mark the boundaries and produce a topographic survey. For septic and drainage design, contour intervals of 1 to 2 feet (about 0.3 to 0.6 m) are preferred over the coarser intervals on national topographic maps.
2. Ask for existing features on the survey: trees above a set trunk size, rock outcrops, streams, springs, wet areas, existing tracks, fences, buildings, wells and any buried services.
3. Add north arrow, scale, elevations and any easements found in site-3.
4. Get the survey as a digital file (CAD or GIS) and as a printed sheet, so you can trace layers on top.
5. Make overlays for the studies in site-5 to site-7: sun and shade, water flow, wind, and vegetation.

Do these first

• site-3

Sources

1. Onsite Wastewater Treatment Systems Manual, Chapter 5: Treatment System Selection. US Environmental Protection Agency (copy hosted by Iowa State University), accessed 2026-11

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