#611 ON-SITE TESTING AND EVALUATION

Transcription

1 OBJECTIVES: After completing this chapter, you will be able to... Identify which natural and man-made surface features have minimum horizontal isolation distances. Understand which onlot system components are associated with the minimum required isolation distances. Recognize the site conditions and surface features that are always unsuitable for an onlot system. Revised MEETING THE CERTIFICATION, TRAINING, AND RESOURCE NEEDS OF PENNSYLVANIA S SEWAGE ENFORCEMENT OFFICERS

2 Identifying Site Features A site can have several natural and man-made features that must be identifi ed before an onlot system permit may be issued. System components have minimum horizontal isolation distances to several select features. These isolation distances directly infl uence the location of any site testing for an onlot system absorption area. Title 25, Section The local agency SEO must understand which features have required isolation distances, and be able to correctly identify them in the fi eld. These features may affect where components of the onlot sewage system can be installed. The SEO must correctly identify the features and maintain their corresponding isolation distances at all times. An SEO measures 100 feet from a well. MEETING THE CERTIFICATION, TRAINING, AND RESOURCE NEEDS OF PENNSYLVANIA S SEWAGE ENFORCEMENT OFFICERS

3 NATURAL FEATURES The following is a summary of horizontal isolation distances for natural features. Distance to Treatment Tank Streams Lakes/ponds Other surface waters Distance to Absorption Area 50 Feet: Streams Water courses Lakes/ponds Other surface waters Distance to Spray Field 50 Feet: Streams Water courses Lakes/ponds Other surface waters Surface drainageways Rock outcrop Identify shallow pinnacle Slope greater than 25% Rock outcrop Sinkholes Sinkholes MEETING THE CERTIFICATION, TRAINING, AND RESOURCE NEEDS OF PENNSYLVANIA S SEWAGE ENFORCEMENT OFFICERS

4 NATURAL FEATURES Some natural features may be diffi cult to recognize in the fi eld. The SEO must be careful to identify each of these features and obtain accurate measurements. Surface Drainageways and Streams Surface drainageways have a signifi cantly smaller isolation distance requirement (10 feet) than streams (50 feet) from an absorption area. Consequently, it is important to be able to establish the difference between the two. All water courses are surface drainageways, but not all surface drainageways are water courses. When dealing with a water course, the isolation distance should be measured from the top or break point of the observable bank. If no break point exists, begin the measurement from your best estimate of where the edge of the water flow occurs during a peak flow event. A water course is a stream with a defi ned bed and banks. A stream channel often, but not always, contains fl owing water. Examples of surface drainageways that are not water courses include swales, hollows, and saddles. None of these have defi ned beds and banks. Water courses include streams that may be described as perennial, intermittent, and ephemeral. MEETING THE CERTIFICATION, TRAINING, AND RESOURCE NEEDS OF PENNSYLVANIA S SEWAGE ENFORCEMENT OFFICERS

5 Identifying Site Features MAN-MADE FEATURES The following chart summarizes the horizontal isolation distances from man-made features. Distance to Treatment Tank 50 Feet: Individual water supply (geothermal, occupied, and unoccupied wells) Water supply system suction line Water supply line under pressure Distance to Absorption Area Individual water supply (geothermal, occupied, and unoccupied wells) Water supply system suction line Mine subsidence areas Boreholes Water supply line under pressure Detention basin Retention basin Stormwater seepage beds Distance to Spray Field Individual water supply (geothermal, occupied, and unoccupied wells) Water supply system suction line Mine subsidence areas Boreholes Water supply line under pressure MEETING THE CERTIFICATION, TRAINING, AND RESOURCE NEEDS OF PENNSYLVANIA S SEWAGE ENFORCEMENT OFFICERS

6 TO TREATMENT TANK Cistern used as a water supply Property line Easement Right of way Driveways Swimming pools Occupied buildings TO ABSORPTION AREA Cistern used as a water supply Property line Easement Right of way Driveways Swimming pools Occupied buildings 5 Feet: Other active onlot systems TO SPRAY FIELD Cistern used as a water supply Property line Easement Right of way Driveways Roads Unoccupied buildings Swimming pools Occupied buildings MEETING THE CERTIFICATION, TRAINING, AND RESOURCE NEEDS OF PENNSYLVANIA S SEWAGE ENFORCEMENT OFFICERS

7 Unsuitable Sites A potential absorption area site may be unsuitable if the minimum isolation distance requirements cannot be maintained. There are other specifi c site conditions that may cause a site to be unsuitable. Title 25, Section The following site characteristics are unsuitable for any absorption area or spray fi eld proposal, regardless of the soil profi le conditions. When these situations are encountered, onlot systems may not be permitted, and no further testing may be necessary. An onlot system permit must be denied if any of the following conditions or surface features are present: The slope is greater than 25 percent. The area is identifi ed as a fl oodway or is within 50 feet from the top of a stream bank. Rock outcrops are within the proposed absorption area. Limestone sinkholes or closed depressions are within the proposed absorption area or spray fi eld. Soil fi ll has been in place for less than four years. The soil has been disturbed. MEETING THE CERTIFICATION, TRAINING, AND RESOURCE NEEDS OF PENNSYLVANIA S SEWAGE ENFORCEMENT OFFICERS

8 Unsuitable Sites DISTURBED SOIL The regulations do not specifi cally address what determines when soil has been disturbed. However, the defi nitions listed in Chapter 73 do characterize undisturbed soil. Go to Chapter 3 Workbook and complete the following exercise: EXERCISE 3-1: Minimum Distances Undisturbed soil is soil or a soil profile unaltered by removal or other man-induced changes, except for agricultural activities, that would adversely affect the siting or operation of onlot systems. Site Suitability Many factors infl uence site suitability for onlot systems that are permitted by the SEO. Isolation distance requirements are only part of the site evaluation review. Another important factor that directly infl uences site suitability is slope, which will be reviewed in Chapter 4. MEETING THE CERTIFICATION, TRAINING, AND RESOURCE NEEDS OF PENNSYLVANIA S SEWAGE ENFORCEMENT OFFICERS

9 KEY POINTS: The SEO should know which surface features have minimum horizontal isolation distance requirements. Treatment tanks, absorption areas, and spray fi elds each have separate isolation distance criteria. The presence of certain site conditions will result in the denial of a permit for an onlot system installation. Before conducting any on-site testing, the SEO should identify all potential surface limitations. Go to the #611 Chapter 3 materials to print and complete the Chapter 3 Quiz. This quiz was designed to check your understanding of the chapter materials. MEETING THE CERTIFICATION, TRAINING, AND RESOURCE NEEDS OF PENNSYLVANIA S SEWAGE ENFORCEMENT OFFICERS