By JOAN JOSEPHSON OBSERVER Staff Writer The municipalities in Northern Chautauqua County that do not provide municipal sewer service are mostly rural in nature. They include the towns of Arkwright, Charlotte, Stockton and Portland and the villages of Cassadaga and Sinclairville. These communities depend on septic systems for disposal of sewage. These systems must meet state and county health codes that are outlined in a fist-full of documents that can be obtained through the Internet. They include an application for sewage disposal installation and an operating permit, site plan description, percolation tests and a soil characteristic chart. In addition, the county health department requires the building lot being considered for a septic system be at least 20,000 square feet to keep water wells at least 50 feet from the septic tanks and 100 feet from other system components. Once the application and required tests are completed, they have to be returned to the health department