The burden of proof in a civil case in Pennsylvania is, for most claims, by a perponderence of the evidence - or more simply put, that what you claimed occurred was more likely than any other explaination.
The Defendant's identity - as the property owner, or a leseee, can be identified and contacted through a bit of reasearch at the county courthouse, where you will find property records. They may even be available online.
Given the minor damage, it would seem to me you could bring a claim against the owner of the property - or the lessee if it is a tenant that operates the wash - in the local magistrate's court. You would not requre an attorney - nor would it make economic sense to hire an attorney - to prosecute this claim.
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