9 Va. Admin. Code § 20-81-130

Current through Register Vol. 41, No. 9, December 16, 2024

Section 9VAC20-81-130 - Design and construction requirements

The design and construction of all sanitary, CDD and industrial landfills shall be governed by the standards set forth in this section.

A. Both the landfill capacity (in cubic yards) and the daily disposal limit shall be specified.

B. All facilities shall be surrounded on all sides by natural barriers, fencing, or an equivalent means of controlling vehicular and public access and preventing illegal disposal. All access will be limited by gates, and such gates shall be securable and equipped with locks, except, in the case of industrial disposal sites where the solid waste disposal landfill is on site of the industrial facility where access is limited.

C. All landfill access roads shall be provided with a base capable of withstanding anticipated heavy vehicle loads and shall be all-weather roads extending from the entrance of the landfill to the working face.

D. All facilities, except captive industrial, shall have an adequately lighted and heated shelter where operating personnel can exercise site control and have access to essential sanitation facilities. Lighting, heat, and sanitation facilities may be provided by portable equipment as necessary.

E. Aesthetics shall be considered in the design of a landfill or site. Use of artificial or natural screens shall be incorporated into the design for site screening and noise attenuation. The design shall reflect those requirements, if any, that are determined from the long-range plan for the future use of the site. Noise attenuation shall be less than 80 dBA at the facility boundary.

F. All landfills shall be equipped with permanent or mobile telephone or radio communications except at industrial landfills where other onsite resources are available.

G. Two survey benchmarks shall be established and maintained on the landfill site, and their location identified or recorded on drawings and maps of the landfill.

H. Surface water runoff. Facilities shall be designed to provide and maintain:

1. A run-on control system to prevent flow onto the active portion of the landfill during the peak discharge from a 24-hour, 25-year storm;

2. A run-off control system from the active portion of the landfill to collect and control at least the water volume resulting from a 24-hour, 25-year storm. Run-off from the active portion of the landfill unit shall be handled in a manner that will not cause the discharge of:

a. Pollutants into waters of the United States, including wetlands, that violates any requirements of the Clean Water Act, including, but not limited to, the Virginia Pollutant Discharge Elimination System (VPDES) requirements; and

b. A nonpoint source of pollution to waters of the United States, including wetlands, that violates any requirement of an areawide or statewide water quality management plan that has been approved under § 208 or 319 of the Clean Water Act, as amended; and

3. Drainage structures shall be installed and continuously maintained to prevent ponding and erosion, and to minimize infiltration of water into solid waste cells.

I. A fire break of 50 feet shall be designed between the limits of waste and all tree lines.

J. Bottom liner.

1. Sanitary landfills.

All sanitary landfills shall be underlain by a composite liner system as follows:

a. Subtitle D Liner System.

(1) Base preparation to protect the liner by preventing liner failure through subsidence or structural failure of the liner system.

(2) A lower liner consisting of at least a two-foot layer of compacted soil or augmented soil with a hydraulic conductivity of no more than 1x10^-7 cm/sec.

(3) An upper component consisting of a minimum 30 mil flexible membrane liner (FML). If high density polyethylene (HDPE) is used as an FML, it shall be at least 60 mil thick. The FML component shall be:

(a) Installed in direct and uniform contact with the compacted soil liner;

(b) Placed in accordance with an approved construction quality control/quality assurance program submitted with the design plans; and

(c) Placed with a minimum of 2.0% slope for leachate drainage.

b. Alternate Liner System. FML/Geosynthetic Clay Liner (GCL).

(1) The alternate liner system presented below is the minimum that is required under these regulations requiring no demonstration. If additional components to this alternate system are incorporated into the liner design, no demonstration will be required.

(2) A controlled subgrade with a minimum thickness of 12 inches shall be provided immediately beneath the alternate liner. The controlled subgrade shall consist of soils having a Unified Soil Classification of SC, ML, CL, MH, or CH and shall be compacted to a minimum of 95% of the maximum dry density, as determined by ASTM D698 (Standard Proctor). The surface shall be rolled smooth and be free of rocks or stones in excess of 0.75 inches prior to placement of the overlying GCL.

The surface shall be prepared to meet the liner manufacturer's and the installer's specifications. The liner manufacturer's/installer's specifications shall consider compaction, soft areas, proof rolling, maximum grain size, rocks, and other subgrade imperfections that may affect the liner. The liner installer shall provide written acceptance of the subgrade before installing liner on it.

(3) A lower liner consisting of geosynthetic clay liner (GCL) with a hydraulic conductivity of no more than 1x10^-9 cm/sec. The GCL shall have appropriate overlap between adjacent panels so as to minimize the risk of panel shrinkage and/or transverse shortening creating panel separation, and be installed with a minimum 12-inch overlap on the panel ends and 6-inch overlap between adjacent panels. If the liner system will be exposed prior to the placement of a protective cover layer for periods in excess of two months, a discussion of the adequacy of the GCL overlap shall be included in the certification report. Granular bentonite shall be spread on all seams prior to placement of overlapping panels, or other means per manufacturer's specifications.

(4) An upper component consisting of a minimum 30 mil flexible membrane liner (FML). If high density polyethylene (HDPE) is used as an FML, it shall be at least 60 mil thick. The FML component shall be:

(a) Installed in direct and uniform contact with the GCL;

(b) Placed in accordance with an approved construction quality control/quality assurance program submitted with the design plans;

(c) Placed with a minimum of 2.0% slope for leachate drainage; and

(d) Leachate collection aggregate/protective cover materials shall be placed as soon as practical following the completion of the FML installation. At a minimum, this material should be placed within three months of final acceptance of the FML surface by the CQA engineer.

c. Additional alternate liner systems.

(1) Additional alternate liner systems may be approved if the owner or operator of the landfill demonstrates to the satisfaction of the director that the proposed alternate liner system design will ensure that the maximum contaminant levels (MCL) promulgated under § 1412 of the Safe Drinking Water Act ( 40 CFR Part 141) will not be exceeded in the uppermost aquifer at the disposal unit boundary.

(a) The demonstration shall be based on the consideration of the following factors:

(1) The hydrogeologic characteristics of the landfill and surrounding land;

(2) The climatic factors of the area;

(3) The volume and physical and chemical characteristics of the leachate;

(4) The quantity, quality, and direction of flow of groundwater;

(5) The proximity and withdrawal rate of the groundwater users;

(6) The availability of alternative drinking water supplies;

(7) The existing quality of the groundwater, including other sources of contamination and their cumulative impacts on the groundwater, and whether the groundwater is currently used or reasonably expected to be used for drinking water;

(8) Public health, safety, and welfare effects; and

(9) Practicable capability of the owner or operator.

(b) The demonstration shall be supported by the results of a mathematical modeling study based on the EPA MULTIMED model.¹ Other models may be used if accompanied by justification describing the reasons for inapplicability of the MULTIMED model.²

¹Sharp-Hansen, S., C. Travers, P. Hummel, T. Allison, R. Johns, and W. B. Mills. A Subtitle D Landfill Application Manual for the Multimedia Exposure Assessment Model (MULTIMED 2.0), United States Environmental Protection Agency, Athens, Georgia, 1995.

²For a listing and review of models see Travers, C.L., and S. Sharp-Hansen, Leachate Generation and Migration at Subtitle D Facilities: A Summary and Review of Processes and Mathematical Models, United States Environmental Protection Agency, Environmental Research Laboratory, Athens, Georgia (1991).

2. CDD and industrial landfills.

All landfills shall be underlain by a liner system as follows:

a. Compacted clay:

(1) A liner consisting of at least one-foot layer of compacted soil with a hydraulic conductivity of no more than 1x10^-7 cm/sec.

(2) The liner shall be placed with a minimum of 2.0% slope for leachate drainage.

(3) The liner shall be covered with a minimum one-foot thick drainage layer.

b. Synthetic liners:

(1) Synthetic liner consisting of a minimum 30 mil thick flexible membrane. If high density polyethylene is used, it shall be at least 60 mil thick. Synthetic liners shall be proven to be compatible with the solid waste and its leachate.

(2) The liner shall be placed in accordance with an approved construction quality control/quality assurance program submitted with the design plans.

(3) The surface under the liner shall be a smooth rock-free base or otherwise prepared to prevent liner failure.

(4) The liner shall be placed with a minimum of 2.0% slope for leachate drainage.

(5) The liner shall be covered with a 12-inch thick drainage layer for leachate removal and a six-inch thick protective layer placed above the drainage layer, both composed of materials with a hydraulic conductivity of 1x10^-3 cm/sec or greater (lab tested).

c. Other liners:

(1) Other augmented compacted clays or soils may be used as a liner provided the thickness is equivalent and the hydraulic conductivity will be equal to or less than that for compacted clay alone.

(2) The effectiveness of the proposed augmented soil liner shall be documented by using laboratory tests.

(3) The liner shall be placed with a minimum of 2.0% slope for leachate drainage.

d. In-place soil:

(1) Where the landfill will be separated from the groundwater by low hydraulic conductivity soil as indicated by laboratory tests, which is natural and undisturbed, and provides equal or better performance in protecting groundwater from leachate contamination, a liner can be developed by manipulation of the soil to form a liner with equivalent thickness and hydraulic conductivity equal to or less than that of the clay liner.

(2) The liner shall be prepared with a minimum of 2.0% slope for leachate drainage. Interior liner slopes of 33% will be allowed provided that adequate runoff and erosion controls are established. All interior slopes shall be supported by necessary calculations and included in the design manual.

e. Double liners required or used in lieu of groundwater monitoring shall include:

(1) Base preparation to protect the liner.

(2) A bottom or secondary liner that is soil, synthetic, or augmented soil as indicated in subdivision 2 a, b, c, or d of this subsection.

(3) A witness or monitoring zone placed above the bottom or secondary liner consisting of a 12-inch thick drainage layer composed of material with a hydraulic conductivity of 1x10^-3 cm/sec or greater (lab tested) with a network of perforated pipe, or an equivalent design.

(4) The primary liner as indicated in subdivision 2 a, b, or c of this subsection.

(5) The primary liner will be covered with a minimum 12-inch thick drainage layer and a six-inch thick protective layer, placed above the drainage layer, both composed of materials having a hydraulic conductivity of 1x10^-3 cm/sec or greater (lab tested).

(6) A program for monitoring the witness zone shall be established. The program will monitor the quantity and quality of liquids collected from this zone and shall be designed to detect waste constituents most likely associated with the waste accepted at the landfill. The program will also establish a leakage action rate beyond which groundwater contamination will be assessed through a groundwater monitoring program in accordance with 9VAC20-81-250.

f. If five-foot separation from seasonal high ground water can be demonstrated, a separate area may be established to receive only stumps, brush, leaves, and land-clearing debris. Such an area may be constructed without a liner or a leachate collection system, but may not receive any other solid waste.

K. Each site design shall include a decomposition gas venting system or gas management system (see 9VAC20-81-200) , except at CDD and industrial landfills if the owner or operator can demonstrate to the department that gas formation is not a concern.

L. Leachate control and monitoring systems are subject to the requirements in 9VAC20-81-210.

M. A groundwater monitoring system shall be installed at all landfills in accordance with 9VAC20-81-250, except for the exemption of double-lined CDD or industrial landfills referenced in this section.

N. Final contours of the finished landfill shall be specified. Design of final contours shall consider subsequent site uses, existing natural contours, surface water management requirements, and the nature of the surrounding area. The final elevation of the landfill shall be limited by the structural capacity of the liner and leachate collection and removal system and by stability of foundation and slopes. The final contour shall not cause structural damage or collapse of the leachate collection system.

O. Finished side slopes shall be designed as set forth in 9VAC20-81-160 D 3 of this part.

P. All landfills shall be constructed in accordance with approved plans, which shall not be subsequently modified without approval by the department.

Q. Construction quality assurance program.

1. General.

a. A construction quality assurance (CQA) program is required for all landfill units. The program shall ensure that the constructed unit meets or exceeds all design criteria and specifications in the permit. The program shall be developed and implemented under the direction of a CQA officer who is a professional engineer.

b. The CQA program shall address the following physical components, where applicable:

(1) Foundations;

(2) Low-hydraulic conductivity soil liners;

(3) Synthetic membrane liners;

(4) Leachate collection and removal systems including an 18-inch protective layer;

(5) Gas management components; and

(6) Final cover systems.

2. Written CQA plan. The owner or operator shall develop and implement a written CQA plan that shall include observations, inspections, tests, and measurements. The plan shall identify steps that will be used to monitor and document the quality of materials and the condition and manner of their installation. The CQA plan shall include:

a. Identification of applicable units, and a description of how they will be constructed;

b. Identification of key personnel in the development and implementation of the CQA plan, and CQA officer qualifications;

c. A description of inspection and sampling activities for all unit components identified in subdivision 1 b of this section including observations and tests that will be used before, during, and after construction to ensure that the construction materials and the installed unit components meet the design specifications. The description shall cover sampling size and locations; frequency of testing; data evaluation procedures; acceptance and rejection criteria for construction materials and constructed components; plans for implementing corrective measures; and data or other information to be recorded;

d. Structural stability and integrity of all components of the unit identified in subdivision 1 b of this subsection;

e. Proper construction of all components of the liners, leachate collection and removal system, gas management system if required under subsection K of this section, and final cover system, according to permit specifications and good engineering practices, and proper installation of all components (e.g., pipes) according to design specifications;

f. Conformity of all materials used with design and other material specifications;

g. The permeability of the soil liner.

(1) The ability of the soil to be used as a liner material must be demonstrated using a test pad. At least one test pad shall be required for every source of low permeability liner soil. If soil sources are consistent (i.e. similar USCS soil type, liquid and plastic limits, grain size distribution, moisture density relationship, and permeability characteristics) one test pad will be adequate provided that the third-party quality control firm agrees. In the event that soils are not uniform within a borrow source an additional test pad shall be constructed for each soil type.

The test pad shall establish the range of criteria (compaction, moisture content, USCS classification, and grain size) that can be expected to achieve a low permeability soil liner meeting the requirements of the permit. To achieve these results the test pad's permeability shall be correlated with grain size analysis, liquid and plastic limits, moisture content, relative compaction, remolded permeability, undisturbed Shelby tube sample permeability, and the in-situ permeability determined by field tests performed on the test pad.

(2) Following the completion of the test pad the remaining low permeability liner system shall be certified by testing the constructed liner to determine its conformance to the acceptable criteria established during the test pad construction. Such tests shall include compaction, moisture content, grain size, and the liquid and plastic limits of the soil. Any area that does not conform to the established criteria shall be further tested by obtaining an undisturbed Shelby tube sample of the constructed liner and performing a laboratory permeability on it. In addition to testing any liner areas that do not conform to the established test pad acceptance criteria, a minimum of one additional laboratory permeability test shall be performed on each acre of constructed liner.

3. Certification. Once construction is complete, the owner or operator shall submit to the department by certified mail or other equivalent method with a return receipt or hand delivery a certification signed by the CQA officer that the approved CQA plan has been successfully carried out and that the unit meets the requirements of this section. Documentation supporting the CQA officer's certification shall be submitted to the department upon request. An additional professional engineer's certification is required under the provisions of 9VAC20-81-490 A. Wastes shall not be accepted until the facility receives a Certificate to Operate (CTO) per 9VAC20-81-490 A.

9 Va. Admin. Code § 20-81-130

Derived from Virginia Register Volume 27, Issue 12, eff. March 16, 2011.

Statutory Authority

§ 10.1-1402 of the Code of Virginia; 42 USC § 6941 et seq.; 40 CFR Part 258.