The Newtown Planning and Zoning Commission has given a stamp of approval to the site development plan of a proposed substation of the Sandy hook Volunteer Fire and Rescue Company.  During a public hearing last week, a presentation of the plans was made.  The fire company's main location is on Riverside Road, but they've outgrown the substation, located on Route 34.  The building constructed in the 1960s will be more than doubled to about 3,500 square feet.  The two new garage bays would be added to the rear of the building, with a fire engine moving into one bay and the other left open for any future equipment.  The old space in the building would be renovated for offices, bathroom facilities and a storage area.