A few ideas.
Call your local waste disposal authority.
Your local Fire Department may know where such substances can be disposed of.
Check your city/county's website for their environmental protection/management department. If there isn't information on their website, find a phone number and call them. If there is no info online, call City Hall or the county main office and ask.
Somebody in the city/county government has to know where that kind of stuff can be taken - if they dont have a specific place, they are being very irresponsible, and I would be asking WHY they dont have a list of places for hazardous waste disposal...
We interrupt this thread for a Public Service Announcement:
Dumping things like old motor oil and antifreeze down the storm drains DOES put that stuff into the water supply.
Most (not all, but most) storm drain systems are not hooked into the city sewer systems (it would overwhelm the sewer system during a big storm). Instead, they take storm runoff and direct it to a watershed area - untreated. This watershed area DOES feed the water supply systems, as well as streams, rivers and lakes.
(disclaimer: I did work for a civil engineering office as a drafter for a time. I do have first hand knowledge of how this stuff is designed)
Another FYI - pouring down the drain, even diluted, especially if you are on a septic system, is really not a good idea either. It does kill off the essential bacteria in the system, which can cause all sorts of problems, including but not limited to back-ups.
And a city sewer system is not really much more than a giant septic system. (disclaimer: the other half is a septic pumper - he could tell some stories...)
So Please - Think before you dump!
now back to your regularly scheduled programming...