Unless you can get another plot directly,one presumes you have paid rent already?, then why not see if you can succeed. I am sure further analysis of your location/site appraisal will provide some options. Your committee chairman may give a little supportive help; I am sure Charles &/or forum members would be pleased to see photos/Streetview/googlemap, even Ordinance survey details to assertain the options.
There would be no harm in DIGGING(!) a trench across a section to examine the soil strata and observe water table movements. If its a historic allotment, one feels the local conditions are probably caused by bad practice/neglect and could be resolved with effort.
I know how difficult it is to get an allotment, in most areas there are waiting lists, and in this Local authority, they are in deficit of provision against new builds, of some 400 plots.
I resolved by gaining an ‘odd corner’ on agricultural land from a ‘contact’.
