§ 78a.59a. Impoundment embankments.
(a) Embankments constructed for well development impoundments for oil and gas operations must meet the following requirements:
(1) The foundation for each embankment shall be stripped and grubbed to a minimum depth of 2 feet below existing contour prior to any placement and compaction of fill.
(2) Any springs encountered in the embankment foundation area shall be drained to the downstream toe of the embankment with a drain section 2 feet by 2 feet in dimension consisting of PennDOT Type A sand, compacted by hand tamper. Geotextiles may not be used around sand. The last 3 feet of this drain at the downstream slope must be constructed of AASHTO # 8 material.
(3) The minimum top width of the embankment must be 12 feet.
(4) The inside and outside slope must have a slope no steeper than 3 horizontal to 1 vertical.
(5) Soils to be used for embankment construction must be classified in accordance with ASTM D-2487 (Unified Soils Classification). Soil samples must be classified at a minimum rate of one sample per 10,000 cubic yards of placed fill with at least one test per source with an additional test conducted each time the material changes. At least one sample must be classified in accordance with ASTM D-2487. Soils utilized during embankment construction shall be described and identified in accordance with ASTM D-2488—09A (Standard Practice for Description and Identification of Soils (Visual-Manual Procedure)). Soil identification and description in accordance with this procedure shall be performed at a minimum rate of one sample per 1,000 cubic yards of placed fill. Results of testing of materials shall be provided to the Department upon request.
(6) The embankment must be constructed out of soils designated as GC, GM, SC, SM, CL or ML, only. Soils with split designations when one of the designations is not GC, GM, SC, SM, CL or ML may not be used. Soils must contain a minimum of 20% of No. 200 sieve materials or larger. Results of testing of materials shall be provided to the Department upon request.
(7) Particles greater than 6 inches in any dimension may not be used for embankment construction.
(8) Soil used in embankment construction must be compacted. Soil compaction shall be conducted in accordance with the following:
(i) Compaction shall be conducted with a sheepsfoot or pad roller.
(ii) The maximum loose lift thickness must be 9 inches.
(iii) Soil shall be compacted until visible nonmovement of the embankment material.
(iv) Soil shall be compacted to a minimum of 95% of the standard proctor in accordance with ASTM D698 (Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort). Satisfactory compaction shall be verified by field density testing in accordance with ASTM D1556 (Standard Test Method for Density and Unit Weight of Soil in Place by the Sand Cone Method) or ASTM D6938 (Standard Test Method for In-Place Density and Water Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth)) with a minimum of one test per 2,000 square yards of lift surface and at least one test per lift.
(9) Exposed embankment slopes shall be permanently stabilized using one or a combination of the following methods:
(i) Exposed embankments shall be limed, fertilized, seeded and mulched, and permanent vegetative ground covering in compliance with § 102.22 (relating to site stabilization) shall be established upon completion of construction of the impoundment.
(ii) Compacted rock fill or riprap placed on the downstream face of the embankment as a cover having a minimum depth of 2 feet. The rock fill must be durable, evenly distributed and underlain by a Class 2, Type A geotextile.
(b) The owner or operator may request approval from the Department to deviate from the requirements in this section. The request must demonstrate that the alternate practice provides equivalent or superior protection to the requirements of this section.
Cross References This section cited in 25 Pa. Code § 78a.59b (relating to well development impoundments); and 25 Pa. Code § 78a.63a (relating to alternative waste management).
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