N.J. Admin. Code § 7:26F-4.2

Current through Register Vol. 57, No. 1, January 6, 2025

Section 7:26F-4.2 - Ground water investigation requirements

(a) The owner shall investigate ground water pursuant to (b) below to determine whether the discharge from a heating oil tank system contaminated the ground water when:

1. Any portion of the heating oil tank system is located within the seasonal high ground water table or within two feet of either ground water or bedrock; or

2. As required pursuant to N.J.A.C. 7:26F-3.4

(a)2i(4) and (a)3iv and 3.5(a)5.

(b) To investigate ground water contamination, the owner shall:

1. Locate ground water sampling points as follows:

i. When the ground water is sampled prior to soil remediation, bias the ground water sampling point location to within 10 feet of the point of discharge in the expected downgradient ground water flow direction;

ii. When the ground water is sampled after soil remediation and the excavation extends less than 20 feet in any direction from the center line of the tank:

(1) Bias the ground water sampling point location to within 10 feet outside of the excavation in the expected downgradient ground water flow direction; or

(2) Where site conditions prohibit sampling of the ground water within 10 feet outside of the excavation in the expected downgradient ground water flow direction, locate the ground water sampling point within the excavation, after backfilling the excavation pursuant to N.J.A.C. 7:26F-3.3(f); or

iii. When the ground water is sampled after soil remediation and the excavation extends 20 feet or more in any direction from the center line of the tank:

(1) Locate a ground water sampling point within the excavation, biased in the expected downgradient ground water flow direction, after backfilling the excavation pursuant to N.J.A.C. 7:26F-3.3(f); and

(2) Locate a ground water sampling point in a location outside the backfilled excavation from which the heating oil tank was removed, but within 10 feet of the backfilled excavation, biased in the expected downgradient ground water flow direction;

2. Install each ground water sampling point as follows:

i. For an unconsolidated formation:

(1) For monitoring wells, extend the well screen to five feet above the ground water table and 10 feet below the ground water table, and otherwise install the well pursuant to the Well Construction and Maintenance; Sealing of Abandoned Wells rules at N.J.A.C. 7:9D;

(2) For all other sampling technologies, the sampling interval shall extend across the ground water table; or

ii. For a consolidated formation:

(1) If ground water is encountered, extend the borehole to 10 feet below the first ground water encountered and complete construction of the well as a permanent well pursuant to the Well Construction and Maintenance; Sealing of Abandoned Wells rules at N.J.A.C. 7:9D-2.4(b);

(2) If ground water is not encountered by a depth of 35 feet into bedrock, then secure the borehole and inspect the location after a 24-hour equilibration period:

(A) If no measurable ground water or free product is detected after 24 hours, then no further ground water remediation is required; or

(B) If ground water or free product is detected in the borehole, then complete construction of the well as a permanent well pursuant to the Well Construction and Maintenance; Sealing of Abandoned Wells rules at N.J.A.C. 7:9D-2.4(b);

3. Sample ground water in accordance with the most recent version of the Department's Field Sampling Procedures Manual available at www.nj.gov/dep/srp/srra/guidance and, if, the excavation was not backfilled pursuant to N.J.A.C. 7:26F-3.3(f)prior to August 6, 2018, then include the volume of water that fills the excavation when determining the volume of water to be purged prior to sampling, in accordance with the Department's Field Sampling Procedures Manual in effect on the date that the ground water sampling is performed;

4. Analyze all ground water samples for the applicable parameters listed in N.J.A.C. 7:26F-2.2, Table 2-1; and

5. Evaluate the data to determine compliance with the applicable ground water remediation standards, N.J.A.C. 7:26D-2.1(a):

i. If all of the analytical results are at or below the applicable ground water remediation standards, then no further remediation of ground water is necessary other than to complete the heating oil tank system remediation pursuant to N.J.A.C. 7:26F-6 and 7; and

ii. If any analytical result is above an applicable ground water remediation standard, then either:

(1) Collect two confirmation samples, evenly spaced and using similar purging and sampling techniques, within 60 days after the initial sample and average the results of the two confirmation samples and the original sample to determine compliance with the applicable standard:

(A) If the average does not exceed the applicable ground water remediation standard, then no further remediation of ground water is necessary other than to complete the heating oil tank system remediation pursuant to N.J.A.C. 7:26F-6 and 7; or

(B) If the average exceeds the applicable ground water remediation standard, then delineate the ground water contamination pursuant to (c) below; or

(2) Delineate the ground water contamination pursuant to (c) below;

(c) When the owner has confirmed the presence of ground water contamination, the owner shall:

1. Conduct a receptor evaluation pursuant to N.J.A.C. 7:26F-6;

2. Delineate the horizontal and vertical extent of ground water contamination by locating ground water sampling points in a downgradient direction based on topographic relief, the location of surface water bodies, structural controls in the bedrock or soils, location of pumping wells and subsurface conduits at or below the water table or based on data from adjacent sites; and

3. Implement a ground water remedial action pursuant to N.J.A.C. 7:26F-4.3.

N.J. Admin. Code § 7:26F-4.2

Adopted by 50 N.J.R. 1715(b), effective 8/6/2018