Ala. Admin. Code r. 335-6-15-.26

Current through Register Vol. 43, No. 1, October 31, 2024

Section 335-6-15-.26 - Preliminary Investigation Requirements

(1) Unless directed to do otherwise by the Department, or under the conditions identified in paragraph (2) of this rule, owners and operators required to perform a preliminary investigation must obtain and provide information about the site and the nature of the release, including information gained while confirming the release or completing the initial abatement measures in Rule 335-6-15-.25. This information must include, but is not necessarily limited to the following:

(a) Type of current and most likely future land use for the tank property and any likely affected properties, e.g., residential, commercial, agricultural;

(b) Results of a well inventory within 1000 feet of the site which includes the location, and where available, information on the depth and elevation and ownership of each well;

(c) Location of any public water supply wells, springs or reservoirs which are within one mile of the site;

(d) A description of the hydrogeologic environment, including type and nature of geologic materials, location of surface waters, surrounding land and water users, and the location of all underground utilities, water lines, sewers or other conduits;

(e) A determination of the uppermost aquifer and an initial evaluation of the potential for hydraulic interconnection with lower aquifers. This evaluation at this stage may be made based upon the results of site soil sampling and borings and available literature data;

(f) Results of soil sampling collected from the area which is most likely to have been affected by a release of a regulated substance;

1. A sufficient number of soil samples shall be collected to accurately represent the area and depths affected by a release;

2. Soil sampling shall be performed to a depth which adequately represents the zone most likely to have been contaminated by a release; and

3. Soil sampling shall be sufficient to determine if free product is present on the water table.

(g) Where soils are encountered which have a total petroleum hydrocarbon concentration of greater than 100 ppm and such soils extend to within 5 feet of the seasonal high water table, groundwater samples shall be collected and analyzed at a minimum of one up-gradient and three down-gradient locations unless directed to do otherwise by the Department.

(2) Upon approval by the Department, the following procedures may be used in satisfying the requirement for a preliminary investigation or closure assessment when the underground storage tank excavation pit is completely open and available for representative sample collection. If the conditions identified in subparagraph (2)(d)1. and 2. of this rule cannot be met; however, the preliminary investigation requirements of paragraph (1) must be complied with, unless directed to do otherwise by the Department.

(a) Soil samples shall be collected from the sides and base of the underground storage tank pit. At least one sample shall be collected from each side of the pit and at least one sample from the pit bottom for every underground storage tank that was present in the excavation. Side samples shall be collected from the lowest one-third of the underground storage tank wall. One sample per 10 lineal foot shall be collected from the base of piping trenches. Samples from the underground storage tank pit sides, base, and piping trenches shall be representative of the area being sampled.

(b) Analyze soil samples for the presence of total petroleum hydrocarbons.

(c) Determine the elevation of the groundwater table. Information on the elevation of the water table may be obtained from a boring located adjacent to the underground storage tank pit or from a nearby location. Water table elevation data may also be obtained when topographical features provide surface indications of the water table, and this data is substantiated by literature values.

(d) If the conditions identified in 1. and 2. in the table below are met, the Department may consider the investigation to be complete and no further action will be required. If the conditions identified in 1. and 2. in the table below cannot be met, the Department may require additional investigative actions or a preliminary investigation, in accordance with paragraph (1) of this rule, to be conducted.

Total Petroleum Hydrocarbon Concentration		Depth to Groundwater
1.	100 ppm or less for each sample	5 feet or more below base of underground storage tank excavation
2.	10 ppm or less for every sample	No restrictions

(3) Monitoring wells must be constructed in a manner acceptable to the Department or the Department may require them to be properly closed. Except where cross-contamination of aquifers is of concern, general construction details for monitoring wells should conform to the requirements of rules 335-6-15-.17(f)6. through 8., 10. through 14. and 20., and where cross-contamination is of concern, monitoring well construction details must be reviewed in advance by the Department. The Department may require modification of proposed construction details.

(4) All samples shall be analyzed for parameters which are appropriate to the nature of the stored substance and according to the methods specified in rule 335-6-15-.32.

(5) Within 60 days of release confirmation, or notification by the Department that a Preliminary Investigation is required, under the conditions of paragraph (1) of this rule, the owners and operators must submit the information collected in compliance with this rule to the Department in a manner that demonstrates its applicability and technical adequacy, and in a format and according to a schedule required by the Department. If the procedures under paragraph (2) of this rule apply, the results of the investigation must be submitted within 45 days of release confirmation or notification by the Department that an investigation is required.

(6) Preliminary investigation and closure site assessments must be performed in accordance with accepted geologic practices by a licensed professional geologist or registered professional engineer experienced in hydrogeologic investigations.

(7) Upon review of the results of the Preliminary Investigation, the Department may require a Secondary Investigation to be completed in accordance with rule 335-6-15-.28.

(8) The Department may require additional sampling and analyses to be performed if it is determined that the number or location of samples, or methods used in the analysis of such samples are not sufficient to characterize the area and soil depths most likely to have been contaminated by a release.

(9) Management, treatment and disposal of soils, purge water and free product must comply with applicable local, state and federal requirements.

Ala. Admin. Code r. 335-6-15-.26

Effective April 5, 1989. Amended: Filed August 28, 2003; effective October 2, 2003. Amended: filed July 2, 2007; effective August 6, 2007.

Amended by Alabama Administrative Monthly Volume XXXVI, Issue No. 02, November 30, 2017, eff. 12/8/2017.

Amended by Alabama Administrative Monthly Volume XL, Issue No. 05, February 28, 2022, eff. 4/14/2022.

Author: Sonja Massey, Curt Johnson, Lee Davis, Dorothy Malaier

Statutory Authority:Code of Ala. 1975, § 22-36-3.