25 Pa. Code § 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.
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