A site plan is only as strong as the ground data underneath it. Reviewers compare your design against existing conditions, and if the survey behind those conditions has gaps, the comments come back fast. A missed water line, an unclear right-of-way, or a benchmark tied to the wrong datum can push a project back by weeks.

Most of these problems are easy to catch early. Before a site plan goes to review, developers should confirm the survey control, existing improvements, utilities, access points, and the specific details the reviewing agency expects to see. Good land surveying gives your engineer a clean base to design from and gives the review team fewer reasons to send plans back.

Confirm Survey Control Before Site Design Moves Forward

Survey control is the set of fixed reference points that ties every measurement on your site to a known position and elevation. It includes the horizontal coordinate system and the vertical datum, which is the baseline used to measure heights. If the control is wrong or inconsistent, every grade, pipe slope, and building elevation built on it will carry the same error.

Ask your surveyor which datums were used and make sure your civil engineer is working from the same ones. Many current projects use NAVD 88 for elevations, but older plans, flood maps, and utility records may reference a different datum. Mixing them can shift elevations enough to cause real drainage and floodplain problems.

Also ask where the site benchmarks are and how they’ll be protected during clearing. Benchmarks get knocked out by equipment all the time. Losing one mid-project means extra field work and possible delays during construction staking.

Document Existing Improvements That Affect the Proposed Layout

An existing conditions survey shows what’s on the ground right now. That usually means buildings, slabs, pavement, curbs, fences, retaining walls, signs, and light poles. Your engineer needs this to plan demolition, match existing grades, and avoid designing around features that aren’t really there.

Pay close attention to anything near the property lines. A neighbor’s fence, driveway, or shed may cross onto your parcel, or your old improvements may cross onto theirs. These encroachments can affect setbacks, parking counts, and buildable area, so they’re better found now than during review.

Some jurisdictions also require tree surveys, landscape buffers, or protected features to be shown on the plan. Requirements vary by municipality and project type. Check the local ordinance early so your surveyor can pick up those items in the same field visit.

Locate Utilities and Site Features That Create Design Constraints

Utilities are one of the most common reasons site plans stall. A good survey shows surface evidence like manholes, valves, meters, poles, and inlets, along with pipe sizes and invert elevations where they can be measured. Underground lines marked through the one-call utility locate system can also be picked up and mapped.

Be aware that public locate services usually mark only the lines owned by member utilities. Private water, sewer, and electric lines on commercial sites often go unmarked. If your site has older buildings or past uses, ask whether a private locator or a subsurface utility investigation makes sense.

Easements and Recorded Constraints

Physical features tell only part of the story. Recorded easements for drainage, utilities, or access can limit where you build even when nothing is visible on the ground. Your surveyor should plot easements from the title commitment so your engineer can design around them.

Flood zone lines, drainage paths, and steep slopes belong in this step too. A topographic survey shows how water moves across the site and where grading will be hardest. These details shape stormwater design, and stormwater is often where reviewers look hardest.

Verify Access Points Before Finalizing Circulation Plans

Access is where a site plan meets the public road, and reviewers check it carefully. Your survey should show existing driveways, curb cuts, road edges, and the right-of-way line along every frontage. The right-of-way is the strip of land owned or controlled by the road authority, and it’s often wider than the pavement suggests.

Confirm who controls each road before your engineer finalizes the driveway layout. State highways, county roads, and city streets can each have their own permit process and spacing rules. What works on one road may not be allowed on another.

If the site relies on a shared driveway or cross-access with a neighbor, make sure that easement is recorded and shown correctly. Access that exists only by habit won’t hold up well in review. It can also create problems later with lenders and buyers.

Coordinate Survey Details With the Site Plan Review Team

Every reviewing agency has its own checklist. Some want a sealed boundary survey attached to the plan set. Others ask for specific notes, a recent survey date, or certain features shown within a set distance of the property.

Request the checklist early, or ask for a pre-application meeting if your municipality offers one. Share it with your surveyor and engineer so everyone is working toward the same target. This one step heads off many of the comments that cause resubmittals.

Keep your survey current as the project moves forward. If demolition happens, a neighbor builds, or new utilities go in, the existing conditions may no longer match. A quick field update is cheaper than a round of review comments.

Frequently Asked Questions

What type of survey do I need before submitting a site plan?

Most site plans rely on a boundary survey combined with a topographic and existing conditions survey. Commercial projects involving a sale or loan may also need an ALTA/NSPS survey. The exact requirement can vary by municipality, lender, and project scope. Ask your reviewing agency and your surveyor early so the right scope is ordered the first time.

How old can a survey be for site plan review?

There’s no single rule that applies everywhere. Some agencies accept any sealed survey that still reflects current conditions, while others set a time limit. Lenders and title companies often have their own date requirements. If your survey is more than a few months old, ask whether an update is needed before you submit.

Will the one-call locate service find all the utilities on my site?

Usually it won’t find everything. Public locate services mark lines owned by member utilities, but private lines are often left unmarked. Commercial and redeveloped sites tend to have more private utilities than people expect. A private locator or subsurface investigation can fill those gaps before design is finished.

Why does the vertical datum matter so much?

The vertical datum is the reference point for every elevation on your plans. If your survey, flood map, and utility records use different datums, the numbers won’t line up. That can affect finished floor elevations, pipe slopes, and floodplain compliance. Confirming the datum early keeps your design and your review consistent.

How long does a site plan survey take?

Timing depends on the size of the site, the scope of work, and how busy the surveyor is. A small lot may take a week or two, while a larger commercial tract can take longer. Research on deeds, easements, and plats adds time as well. Order the survey as soon as you have site control so it doesn’t hold up design.