2019.02.04 CC Packet - Laserfiche WebLink

Home

Effective April 28, 2015 Chapter Four Subsurface Sewage Treatment System Regulations SECTION 11 GROUNDWATER INVESTIGATION 11.1 Necessity of Investigation. A preliminary groundwater evaluation must be conducted for all proposed MSTS according to this Section. 11.2 Preliminary Investigation. The following information must be ascertained from the best available information: (1) The size of the soil dispersal system, proposed loading rate, and system geometry; (2) The geocode(s) or parcel identification number(s) of the parcel(s) where the proposed soil dispersal area is to be located; (3) Any anticipated discharges from nondomestic sources to the proposed MSTS; (4) The location of the MSTS on a United States Geological Survey quadrangle topographic map, including the area within a one -mile radius of the proposed soil treatment system; (5) A determination of the general geology, periodic soil saturation, regional groundwater setting, and aquifers used for water supply and a description of the general site hydrology characteristics, including, but not limited to, identification and estimated depth measurements to geologic units and aquifers, and identification of groundwater confining strata; (6) A determination whether the proposed system is in a drinking water supply management area, inner wellhead management zone, source water protection area, or groundwater sensitive area; (7) An assessment of all water supply wells within a 300-foot radius of the proposed soil treatment area with a minimum assessment of well locations and casing depths from well construction log records. If no records exist, the well locations and casing depths must be estimated; (8) A determination or estimation of groundwater flow direction; and (9) An assessment of nitrogen impacts from the system. 11.3 Field or Further Investigation. The designer must consult with the Department to determine whether the Department will require a field or further groundwater investigation and, if so, the extent of the investigation. The field or further investigation must be conducted if information gained in Section 11.2 indicates that a proposed system is a potential contaminant threat to a regional water table, an aquifer, water supply well(s), or surface waters. The threats of concern include, but are not limited to, fecal organism contamination, nitrate contamination, or phosphorus impacts to surface waters. 11.4 Monitoring. The designer must consult with the Department to determine if effluent or groundwater monitoring is required and, if so, the extent of the monitoring. Monitoring must be conducted if information gained in Section 11.2 and 11.3 indicates that a proposed system is a potential contaminant threat to a regional water table, an aquifer, or a water supply well or impacts surface waters. The potential groundwater mound height must be monitored under all MSTS during operation. 11.5 Hydrological Interpretations. The information gathered in this part must be used to estimate or measure if the system adequately protects the groundwater and surface water as prescribed in Section 4.8. The interpretation must include an evaluation of whether contaminant plumes will intersect water supply well capture zones. 11.6 Groundwater Report. All information required in Section 11 must be submitted for review and approval of the Department prior to final design, including all applicable information delineated on a map. 42 Washington County Development Code