Of all the factors that affect the building potential of a marina site, what one factor is the most critical? In my opinion, it’s the soil characteristics. The soil classifications for a marina are frequently a mystery to marina owners and they are frequently overlooked by assessors. Fortunately, thanks to our friends at the USDA (http://soils.usda.gov/ and http://websoilsurvey.nrcs.usda.gov/app/), we can now use free online maps to determine soil types with a high degree of certainty. Everything you need to map and understand what the soil classifications mean is at these two URLs.
Using the web soil survey system, you get a map with the soil boundaries outlined, a legend and Selected Soil Interpretations, which really helps determine the building potential of the soils. By reading about the soil types, you can get a handle on the following:
- How wet the soil type generally is
- Whether ponding occurs frequently
- How well the soil would support a building or a boat via dry storage
- How sandy or solid the soil is
But don’t stop there! Most counties have a Soil Survey prepared. Although the maps tend to be more dated than the web soil survey, there is a wealth of descriptive data for each soil in the county. Not only will it corroborate the web soil survey descriptions, you’ll also typically get the following:
- Slopes where this soil typically occurs
- How well or poorly it is drained
- Typical soil composition (sand, clay, etc.)
Once again, don’t stop there! You’ll typically find tables in the Addenda that will give you all kinds of useful tabular data. For instance:
- Percolation rating
- How wet soils would be for basements
- How wet the soils would be for septic systems
- How good the soils are for road fill
- A water management rating
- Flooding frequency and high water table depth
Another place you can go to get confirmation and further information is the county or local planning and zoning office. On staff are friendly environmental planners who can confirm or deny your conclusions from the above. They can also tell you whether something is possible or probable. Of course, a wetlands survey is necessary to take any construction to the conceptual stage, as any planning and zoning official will state.
OK, so maybe I’m the only one who gets thrilled by this stuff. What’s important is that the development potential of a site can be severely restricted or even non-existent based on the soils alone. Also, soils are an important characteristic for determining the magic word that kills development: wetlands. I can’t count how many times I’ve visited marinas that have plenty of land for dry storage (storing boats on the site, especially during winter) but don’t because the soil is comprised of soft materials and/or is frequently wet.
I’ve also been involved in consulting and appraisal assignments where the investor/purchaser wanted to expand the buildings or construct new facilities (like adding a boat repair business), but didn’t know that the soil wouldn’t support it. With online soil mapping, this should never be discovered too late.
Of course hiring a professional is a good idea, but you can do a lot yourself before going to a wetlands/soil expert. You may find that the soils are too difficult to develop and save yourself a lot of time and money.
In Part 3 I’ll be talking about the one land valuation area that appraisers just don’t want to address – wetlands.
