They might soon hide the ash trays at Lansdale Borough Hall.   A proposal to ban smoking at the 21 Park and Recreation Department properties has been expanded to include Borough Hall, the Waste Water Treatment Plant and all other borough facilities.   Council Vice President Paul Clemente cited health and safety issues as well as eliminating the need to revisit the issue at a later date as he made his case for a wider ban.   The proposal to prohibit lighting up in borough parks would still allow it in designated smoking areas.   Indications are that provision would remain intact when the Borough Council Administration and Finance Committee takes up discussion of a wider ban on September 5th.