Alternatively, you could talk to the county health department about doing another perc test – just because it failed once doesn’t necessarily mean it’s impossible (though it is a fair indication that you won’t have much luck). You could also try investigating some alternative septic options, like building a mound septic system. I don’t have any experience with these, but it could be worth your while to investigate it further.
Since land is often a unique commodity, it can often be a pain for you or an agent to try and sell it.  Land is often hard to value, and most buyers lack vision for what it could become.  And that’s not to mention the fact that you have to be available to show it and explain the same land package over and over again to lots of potentially interested buyers.

Comparables for land can be trickier than for home sales in your area. Although the assessor's valuation on your taxes can provide a starting point, consider factors like whether your property has utilities to the property line, views, zoning and any preapproved building plans to determine its worth. Location is always one of the most critical factors. In San Francisco's Pacific Heights area, for example, a buildable cul-de-sac lot of less than 4,000 square feet can sell for more than $9 million.

First impressions are lasting in real estate. When selling a home you would never leave out your dirty laundry for potential buyers to see, and you should also clean up your lot before it is shown and marketed.  Cut the grass (or weeds), remove trash and take marketing photos of your property when it is looking its best. Some sellers even plant wildflowers to make their vacant land look beautiful. It’s like staging a home, but you’re just working with raw land instead.