N.J. Admin. Code § 7:9A-5.8

Current through Register Vol. 56, No. 21, November 4, 2024

Section 7:9A-5.8 - Criteria for recognition of zones of saturation

(a) Criteria for recognition of zones of saturation shall include but not be limited to the following:

1. Any layer within or below the soil profile which exhibits mottling shall be considered a zone of saturation.

2. Any layer within or below the soil profile from which ground water seepage is observed shall be considered a zone of saturation.

3. Any layer within or below the soil profile which is below the static water level observed within a soil profile pit or boring shall be considered to be a zone of saturation.

(b) The upper limit of the zone of saturation, which is the seasonally high water table, shall be determined by one of the following means:

1. Where mottling is observed, at any season of the year, the seasonally high water table shall be taken as the highest level at which mottling is observed, except when the water table is observed at a level higher than the level of the mottling.

2. Where mottling is not observed, the seasonally high water table shall be determined based upon either of the following methods:

i. During the months of January through April, inclusive, water levels may be measured directly within soil profile pits or borings. Whenever the Department determines that there has been a significant departure from normal climatic conditions the Department may, with due notice to the administrative authority, lengthen or shorten the period allowed for direct measurement during any given year. In low lying coastal areas where groundwater levels fluctuate with the tides, measurements shall be taken at the time of highest groundwater elevation in response to tidal fluctuation; or

ii. During other times of the year, the depth to the seasonally high water table may be obtained from the Soil Conservation Service County Soil Survey Report provided that the soil series present at the site is identified based upon comparison of soil profile morphology observed within a soil profile pit, and the soil profile description provided for the soil series in question within the County Soil Survey Report. In cases where the seasonal high water table is shown as a range of elevations in the County Soil Survey Report, the highest elevation of the range shall be used as the seasonal high water table.

3. When the determination of seasonally high water table must be made in disturbed ground recognized as prescribed in 7:9A-5.10, direct observation during the months of January through April inclusive is the only method which shall be permitted.

(c) When a hydraulically restrictive horizon, a hydraulically restrictive substratum, or a massive rock substratum is not present throughout or immediately below the zone of saturation, the zone of saturation shall be considered a regional zone of saturation.

(d) Any zone of saturation which occurs above a hydraulically restrictive horizon, a hydraulically restrictive substratum, or a massive rock substratum shall be considered a regional zone of saturation unless a perched zone of saturation is identified based upon the criteria given in (e) below. When doubt exists as to whether the zone of saturation is regional or perched, and an interceptor drain is proposed to remove the zone of saturation below the disposal field, the administrative authority may require a hydraulic head test to be performed as prescribed in 7:9A-5.9.

(e) A zone of saturation shall be considered to be perched whenever any of the following conditions are met:

1. The zone of saturation is present immediately above a hydraulically restrictive horizon underlain by a layer of permeable unsaturated soil which is free of mottling and has a chroma of four or higher;

2. Water is observed ponded above a hydraulically restrictive horizon at the bottom of the soil profile pit but this water drains away naturally when the depth of the pit is extended below the bottom of the hydraulically restrictive horizon; or

3. Water is observed seeping into a profile pit immediately above a hydraulically restrictive horizon, a hydraulically restrictive substratum or a massive rock substratum and this seep is eliminated by means of a trench excavated upslope of the profile pit which intercepts and diverts laterally moving ground water away from the profile pit.

(f) Any zone of saturation which is present below a hydraulically restrictive horizon shall be considered an artesian zone of saturation whenever any of the following conditions are met:

1. Artesian conditions have been observed in contiguous geologic formations or are known to exist in adjacent areas underlain by similar soils and/or geologic substrata;

2. Water-bearing strata which are present below the hydraulically restrictive horizon are known to be inclined and to have outcrop areas upslope or at elevations higher than the elevation of the site; or

3. An unsaturated zone of substantial thickness and continuity is not observed below the hydraulically restrictive horizon. To prove the absence of an artesian condition, the unsaturated zone must be free of mottling and have a chroma of four or higher. When this determination is made during the months of January through April inclusive, the unsaturated zone must be a minimum of one foot in thickness. At times of the year other than January through April inclusive, the unsaturated zone must be a minimum of four feet in thickness. Whenever the Department determines that there has been a specific departure from normal climatic conditions, the Department may, with prior written notice to the administrative authority, adjust or modify the length of seasons for application of the criteria set forth in this paragraph.

(g) When any of the conditions in (f) above are met, the administrative authority shall not approve the removal of the hydraulically restrictive horizon for the purpose of installing a soil replacement disposal field unless it is determined by means of a hydraulic head test, as prescribed in 7:9A-5.9, that an artesian zone of saturation is absent below the hydraulically restrictive horizon.

N.J. Admin. Code § 7:9A-5.8