A. Soil Classifier. Soil mapping based upon onsite determination of soil characteristics shall be conducted to determine soil suitability for septic systems. Soil survey and mapping shall be by a Soil Classifier.
B. Number of Borings. There shall be a sufficient number of soil borings throughout the proposed acreage for platting so as to allow intensive mapping of soil characteristics and limiting factors related to suitability for private sewage disposal systems. The mapping and overlay of such characteristics shall be of sufficient detail to minimize the potential for inclusions and to determine the existence of at least ½ acre of suitable soils on each proposed lot. There shall be at least one boring on each acre of the proposed subdivision. The location of all borings shall be shown on the soil map overlay.
C. 200 Foot Grid System. A 200 foot grid system shall be established and one boring at each grid point shall be performed. In addition, sufficient additional borings shall be completed to adequately identify each soil mapping unit as well as variations within mapping units as far as depth to limiting layer.
D. Department Notification. The Department shall be notified at least 24 hours before commencement of onsite borings so that the Department may observe the borings and sampling procedures, if it so desires. Any boring conducted without the Department being notified may not be acceptable.
E. Soil Classifiers Report. A map and log of each soil series mapped on the site shall be prepared and included in the Soil Classifier's report. Specific boring logs shall be submitted in a format as required by the Department. These reports shall include, at a minimum, soil texture and permeability classifications by depth, along with the depth to any limiting layer.
F. Soil Update. The date(s) of all fieldwork shall be indicated. Soil borings shall be valid for one year after the test date, after which time an update is required by the soil classifier.
G. Soil Mapping. The entire subdivision area shall be mapped showing soil types present with boundaries of each defined, considering areas of transition. This mapping shall be coordinated with site topography, and shall be of the same scale as the tentative and final plats.
H. Soil Boundaries. The map shall also depict areas of seasonal high groundwater or other limiting layers as determined by the Soil Classifier’s observation of the drainage characteristics of the soil. Long-term monitoring of observation wells approved by the Department may be used to supplement this information (See § 8.04.420 N). Boundaries of the following areas shall be defined:
1. Actual or seasonal high groundwater or other limiting layer at less than 18 inches from the natural soil surface.
2. Actual or seasonal high groundwater or other limiting layer at 18 inches to 30 inches from the natural soil surface.
3. Actual or seasonal high groundwater or other limiting layer at 30 inches to 42 inches from the natural soil surface.
4. Actual or seasonal high groundwater or other limiting layer at 42 inches to 60 inches from the natural soil surface.
5. Actual or seasonal high groundwater or other limiting layer greater than 60 inches from the natural soil surface.
I. Map Of Boring Locations. A detailed map showing the soils present and locations of borings shall be provided. The signature(s) of the Soil Classifier(s) by whom the soil mapping was done and the report prepared, must be affixed to both the report and the soil map.
J. Topography. The topography of the subdivision shall be shown in one (1) foot contours.
K. Suitable Soils. Only soil types depicted on the site soil map, where the limiting layer is a minimum of thirty (30) inches from the natural soil surface may be considered as non-critical or suitable soils.
L. Restricted Soils. Soils not considered suitable for septic systems shall not be included in the ½ acre of required soils, and in addition, shall be indicated as being restricted for septic systems on the tentative and final plats.
M. Tanks in Septic Restricted Areas. Septic tanks, lift stations and aeration devices will be allowed in areas which are septic restricted due to critical soils provided that provisions are made to ensure that the inlet and outlet inverts, tops of tanks, lift stations and aeration devices are water tight.
N. Usable Size And Configuration. The developer must prove to the satisfaction of the Department that each lot on the tentative and final plats has at least ½ acre of suitable soil in a continuous area and of usable size and configuration.
O. Building Sewer/Forcemain Easements. When access to the septic suitable area will require the crossing of easements, lot lines or roadways, building sewer or forcemain easements shall be designated and provisions for protecting the force- main or building sewer (i.e. sleeving) shall be specified.
(Ord. O-201711-51-031, passed 11-14-2017)