posted 10 years ago
On first glance, it sounds as if you have a good deep soil of relatively suitable conditions. if you've no hole filled with rock then chances are it's a more spread out infiltration pipe, with perforations - does that sound familiar at all? If you have a perforated pipe, then you need to take care not to plant something too thirsty and invasive over it or it may clog the perforations.
If I lived in a hot, dry climate, I'd certainly make use of any irrigated lush areas in my garden. If I wasn't sure about the history of the chemicals going down the drain, I'd probably go for firewood crops rather than food crops. If health store cosmetics, cleaners and soaps were all that was ever used I'd plant fruit and nut trees.
Does that help at all?