Checkboxes in form, change URL encoding method?

I have a form that uses GET method and submits to a different page. The form consists of checkboxes that the user can select multiple values. For example, the checkboxes have a name of school_facilities[]

When the user submits, the form is correctly adding ?school_facilities[]=foo&school_facilities[]=bar however, for the results to display correctly on the results page, the URL needs to be ?school_facilities=foo-,-bar instead. How can I achieve this?

Thank you!