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Subpart 383.7: Design and Construction Of Land Disposal Facilities

(Statutory authority: Environmental Conservation Law, arts. 3, 17, 19, 27, 29)

[Effective Date March 14, 1993]

Contents:

Sec.

§383-7.1 Applicability.

(a) The design and construction of the land disposal facility must be approved by the department in the permit and must comply with the requirements of this subpart.

(b) Sections 383-7.2 through 383-7.7 specify the minimum design and construction requirements for a land disposal facility in New York State. The applicant must demonstrate that land disposal facilities using aboveground disposal comply with the requirements of sections 383-7.2, 383-7.3, 383-7.4 and 383-7.5 of this Part; land disposal facilities using below- ground disposal comply with the requirements of sections 383-7.2, 383-7.3, 383-7.4 and 383-7.6 of this Part; and underground mined repositories comply with the requirements of sections 383-7.2, 383-7.3 and 383-7.7 of this Part.

(c) Land disposal facilities using any combination of these disposal methods must comply with all the requirements for each disposal method.

§383-7.2 Design and construction requirements applicable to all disposal methods.

(a) The land disposal facility and associated facilities and systems must be designed and constructed in accordance with standard engineering and/or construction practices.

(b) The design and construction of the land disposal facility must be carried out under the direction of a licensed engineer. The licensed engineer will be responsible for observing, documenting, and certifying that the design and construction of the land disposal facility comply with the requirements of this Part and the of the permit. All engineering certifications must bear the engineer's seal and signature, and the date of certification.

(c) To provide for quality assurance during design and construction, the applicant must

(1) implement a quality assurance and quality control (QA/QC) program during all engineering design activities and submit documentation of the QA/QC program in the application for a permit;

(2) develop a QA/QC program for construction to control the procurement of materials and equipment and all construction activities;

(3) submit the construction QA/QC program as part of the application for a permit; and

(4) implement the construction QA/QC program, as approved by the department in the permit.

(d) The construction QA/QC program required by section 383-7.2(c) of this Part must incorporate testing protocols for construction including:

(1) the frequency of inspection;

(2) field testing;

(3) sampling and field testing procedures and equipment to be utilized;

(4) the calibration of field testing equipment;

(5) the frequency of performance audits;

(6) the laboratory procedures to be followed including equipment calibration;

(7) QA/QC of laboratory procedures;

(8) the limits for test failure; and

(9) a description of the corrective procedures to be used upon test failure

(e) Both QA/QC programs required by Section 383-7.2(c) of this Part must:

(1) include all of the QA criteria listed in the United States Nuclear Regulatory Commission's publication, "Quality Assurance Guidance for a Low-Level Radioactive Waste Disposal Facility" (NUREG-1293), Revision 1, April 1991 (see Section 383-1.8 of this Part), and

(2) contain provisions for auditing the effectiveness of the programs and implementing any necessary corrections to the programs.

(f) The permittee must submit a construction certification report to the department within 45 days after completion of each major phase of the land disposal facility construction as defined in the permit. This report must reference the project information submitted and approved in accordance with the application requirements of subpart 383-3 of this Part and must include the following:

(1) documentation and certification that the land disposal facility has been constructed in accordance with the engineering plans and specifications approved in the permit and in accordance with the construction requirements of this subpart;

(2) documentation and certification that all materials meet the materials requirements of the design specifications approved in the permit;

(3) results of all quality assurance and quality control testing performed, including

(i) documentation of any failed test results;

(ii) descriptions of procedures used to remove, replace, or correct any improperly installed material or equipment; and

(iii) documentation of all retesting performed.

(4) construction record drawings (i.e., as-built drawings) and a comprehensive narrative including daily reports from the engineer responsible for overseeing construction and a series of colored photographs showing the progress of construction of major project features. The report and each record drawing must be certified and stamped by a licensed engineer.

(g) Survey control. Survey control for design and construction must be established in accordance with subpart 383-11 of this Part.

(h) Seismic design. Disposal units and other structures that may be used to house waste at any time must be designed to remain functional during and following subjection to inertia forces resulting from the design basis ground motion, as defined in Section 383-7.2(h)(3) of this Part. The seismic analysis and design must be performed by individuals with relevant qualifications and experience. The seismic design must be based on the following analyses:

(1) Ground motions. Ground motions must be defined in terms of both peak ground motions and response spectra. The acceleration time histories necessary to perform the analyses required by Sections 383-7.2(h) (4) and (5) of this Part must be consistent with the response spectral estimates in the period range of interest.

(2) Methodology. Both deterministic/statistical and probabilistic methods must be used to determine the design basis ground motion. Probabilistic estimates of ground motion must include the effects of all potential sources surrounding the site. Earthquake recurrence models must be established for each source. Source geometry and ground motion attenuation variability must be taken into account. Where possible, uncertainty in any of the above inputs must be included in the analysis. The basis of deterministic/statistical estimates must inlcude site-specific information. A target magnitude and a distance or distance range must be selected based on either the MCE of each potential source surrounding the site or on the magnitude range which most influences the hazard, as determined from the probabilistic analysis. In cases where the distance from site to source is well defined , estimates of median ground motion may be made by means of an acceptable ground motion attenuation relationship. In cases where the site lies within a source region, ground motions may be defined by estimating the median ground motions of a suite of accelerograms recorded at sites having similar properties, in the near field of earthquakes which occurred in similar tectonic environments and whose magnitude is within 0.5 magnitude units of the target magnitude.

(3) Design basis ground motion. The design basis ground motion shall be:

(i) the probabilistic estimate having a mean annual exceedance probability of 10-3(i.e., an average return period of 1000 years), or

(ii) the largest deterministic/statistical estimate, or

(iii) the ground motions which most severely affect or control the design of individual site features.

In cases where the implied annual exceedance probability of the largest deterministic/statistical estimate differs significantly (greater than a half order of magnitude) from 10-3, a review of assumptions is required to determine the reason for the discrepancy.

(4) Site response analysis. A site response analysis must be performed to numerically evaluate the soil response due to the design basis ground motion. The site response analysis must be based on modelling appropriate to the soil behavior and the site topography. The results of the analysis must describe the motion at the ground surface by means of time histories and/or response spectra. Three-dimensional and nonlinear effects must be incorporated into the analysis as necessary where such effects are significant. Site response analysis is not required for structures founded on rock or soil deposits which can be shown will not alter the magnitude and frequency characteristics of the ground motion.

(5) Seismic analysis of structures . A seismic analysis must be performed to evaluate the performance of the disposal units and other structures that may be used to house waste at any time when subjected to the motion at the ground surface estimated in the analyses required by section 383-7.2(h)(4) of this Part. The seismic analysis of the disposal units may be performed either by direct integration methods or by modal analyses. Soil-structure interaction effects and nonlinear and three-dimensional effects must also be incorporated as necessary where such effects are significant.

(i) The land disposal facility must be designed and constructed to ensure that the combined releases of radioactivity to the environment due to all site activities comply with section 382.11 of this Title.

(j) The land disposal facility must be designed and constructed to comply with sections 382.20 through 382.35 of this Title.

(k) A land disposal facility authorized pursuant to section 1854-c of the Public Authorities Law must be designed and constructed to comply with the terms and conditions of the certification issued by the department in accordance with Part 382 of this Title.

(l) The disposal units must be designed and constructed to accommodate gas generation, in a manner that provides reasonable assurance that the performance objectives will be met.

(m) The design and construction of the disposal units must be compatible with the operating requirements of waste emplacement and with unit closure and post-closure requirements.

(n) Unless otherwise authorized by the department, the land disposal facility must be designed and constructed to provide for disposal of Class B and C waste in disposal units separate from those containing Class A waste. The department may authorize the disposal of Class A waste with Class B and C waste if the Class A waste meets the stability requirements of Section 382.81(b) of this Title.

(o) All waste handling and treatment facilities, including any incinerators, must be designed and constructed to facilitate access for operation, inspection, testing, and maintenance. Releases of radioactivity from these facilities to the environment must be maintained as low as reasonably achievable.

(p) The land disposal facility must be designed and constructed to include the monitoring systems required by subpart 383-10 of this Part.

(q) The land disposal facility developed pursuant to section 1854-c of the Public Authorities Law must be designed and constructed to provide disposal units of capacity sufficient for the disposal of all low-level radioactive wastes, as estimated by the Commission and approved or amended by the decision of the department pursuant to section 382.6(f)(6) of this Title, to be generated in New York State and requiring disposal in a land disposal facility for a period of at least 30 years beginning on January 1, 1993.

(r) The land disposal facility must be designed and constructed to minimize safety hazards to all persons on the site.

(s) The land disposal facility must be designed and constructed to provide sufficient space for repairs of disposal units, as well as recovery or retrieval of waste, if applicable, without interfering with other disposal units or operations on the disposal site.

(t) The land disposal facility must be designed and constructed to minimize the visual impact of the facility on the surrounding area.

(u) The land disposal facility must include landscaping designed by a licensed landscape architect.

(v) The land disposal facility design and construction must incorporate the provisions for site security required by sections 383-14.2 and 14.3 of this Part.

(w) Except for the spoils resulting from construction of an underground mined repository, construction and demolition debris from on-site construction must remain on the site and be disposed of pursuant to Part 360 of this Title. Mine spoils may be sold or used off site.

§383-7.3 Design and construction requirements for associated facilities and support systems.

(a) General requirements.

(1) The design life of each associated facility and support system must be consistent with the performance objectives and the required period for which the facility or system must reliably function.

(2) Design details of the associated facilities and support systems, including all utility services, must be provided as part of the application. The design details must describe each associated facility and support system including components; design criteria codes; standards used for design; and the impact of the shutdown of the associated facility or support system on overall land disposal facility operations.

(b) Utility systems. The land disposal facility design must provide for utility systems and services necessary for facility construction and operation, including communication, electrical service, water supply, lighting, sanitary waste disposal, fuel delivery, and storage. Details on the design of each system must be provided as part of the application and include a designation of system components, design criteria, codes, and standards used in the design, the impact of system failure on facility operation, and necessary emergency standby or backup systems to be incorporated.

(c) Security. The land disposal facility design must include site security facilities in accordance with subpart 383-14 of this Part.

(d) Receiving area. The land disposal facility design must include a receiving area that will provide adequate space, based on the expected rate and frequency of waste shipments to the facility, for the temporary storage of waste prior to inspection.

(e) Inspection and testing facilities. The land disposal facility design must include facilities for the waste package inspection and testing program required by section 383-8.4 of this Part.

(f) Facilities for unacceptable wastes. The land disposal facility design must include a separate area of adequate size for storage of unacceptable wastes awaiting reprocessing, repackaging, or return to the generator or shipper, and facilities properly equipped to isolate and return or reprocess all unacceptable waste received.

(g) Temporary storage facilities. The land disposal facility design must include facilities for temporary storage of waste at the disposal facility. The temporary storage facilities must be designed to:

(1) safely store, at a minimum, a six-month volume of waste;

(2) provide shielding which meets the requirements of section 382.13 of this Title;

(3) keep the waste dry, protected from the elements and major natural phenomena, and segregated from other activities on the site that could adversely affect the integrity of the waste package or the waste form;

(4) provide the separate storage areas required by sections 383-8.5 (c) (3) and (4) of this Part;

(5) store and prevent the decomposition of the radioactive wastes identified in section 383-8.3(a)(1) through (3) of this Part prior to incineration on the site, if applicable (for example, by storage in a freezer);

(6) provide for prompt response to fires;

(7) provide for ease of decontamination and minimization of the spread of contamination; and

(8) provide for waste minimization for waste generated at the disposal site.

(h) Waste treatment facilities. Unless provisions are made for off-site waste treatment, the land disposal facility design must include on-site waste treatment facilities that are capable of treating and packaging for disposal all waste generated from on-site activities including equipment and vehicle washdown; runoff collection; waste packaging, volume reduction, inspection, testing, sampling, analysis, treatment, incineration, and handling; and environmental monitoring.

(i) Site grading and surface water control. The disposal site design must include grading and surface water control features to direct surface water drainage and upgradient surface water away from the disposal units at velocities and gradients that would not result in erosion or deposition that could adversely affect the ability of the land disposal facility to meet the performance objectives.

(j) Surface drainage collection and treatment. The land disposal facility design must include one or more surface drainage systems serving those portions of the site on which waste is present at any time for any reason, including transportation, receipt, inspection, storage, treatment, or disposal. These surface drainage systems must meet the following requirements:

(1) Each surface drainage system must be designed to handle the peak runoff from a 1-in-500 year design storm.

(2) The design of the surface drainage systems must provide for the collection , sampling, treatment (if necessary), and release of the collected runoff in accordance with the applicable requirements of this Title.

(k) Fire prevention and protection provisions. The land disposal facility design must incorporate provisions for adequate fire prevention and protection including necessary equipment, systems, and facilities for preventing fires and protecting the land disposal facility and personnel from fire and radiation exposure hazards in case of a fire.

The fire prevention and protection provisions must meet the following minimum requirements:

(1) All fire prevention and protection provisions must be designed and constructed in accordance with the National Fire Protection Association Codes NFPA 801-1991, "Recommended Fire Protection Practice for Facilities Handling Radioactive Materials" and NFPA 901-1990, "Uniform Coding for Fire Protection" (see section 383-1.8 of this Part);

(2) Fire protection systems must include on-site and off-site warning systems and an on-site alarm system for reporting and responding to a fire.

(3) The fire prevention and protection provisions must include fire-retardant building materials, fire detection equipment, fire fighting equipment, fire extinguishing systems; and

(4) The fire prevention and protection provisions must be designed to respond to all credible fires that may occur at the land disposal facility including the following:

(i) fires in closed disposal units;

(ii) fires in disposal units that have not yet been closed;

(iii) fires in the waste storage area; and

(iv) fires resulting from transportation accidents.

(l) Emergency facilities. The land disposal facility design must include emergency facilities for responding to radioactive waste spills, personnel injuries, and other operation emergencies. The following emergency systems and facilities must be included in the land disposal facility design:

(1) emergency personnel showers and decontamination facilities which must be clearly posted and located in potential hazard areas for quick and easy access for personnel decontamination purposes;

(2) on-site warning and alarm systems to alert on-site personnel of an accident occurrence and the need for response;

(3) on-site facilities to administer first aid and treatment to injured personnel; and

(4) on-site laboratories to promptly analyze environmental radiation samples;

(5) an on-site emergency control center; and

(6) on-site emergency training facilities.

(m) Emergency standby power and systems. The land disposal facility must be designed and constructed to include emergency standby power and/or adequate backup systems to maintain, during a power outage or other related emergency occurrence, the operation of all systems that are essential to facility operation and/or health and safety including the following:

(1) security and alarm systems;

(2) monitoring and operations warning systems;

(3) ventilation systems in waste storage and handling areas and buildings;

(4) lighting in all critical operations areas; and

(5) other essential systems and services that, were they to become inoperable, would pose a potential health risk to the facility personnel, the surrounding public, and/or the environment.

(n) Incinerators. Incinerators on the site must comply with the applicable provisions of Parts 200, 201, 211, 212, 219, 257, and 373 of this Title.

(o) The land disposal facility must include adequate office space for the department's on-site environmental monitors as required by section 383-15.1 of this Part.

§383-7.4 Additional design and construction requirements for aboveground and belowground disposal units.

(a) Loads and load combinations.

(1) The disposal units must be designed and constructed to withstand the loads and load combinations, including dead load, live load, soil and surcharge loading, and loads resulting from major natural phenomena, without undergoing deformation, settlement, or cracking that could adversely affect the ability of the land disposal facility to meet the performance objectives.

(2) All design loads and load combinations must include appropriate load factors and safety factors in accordance with standard engineering practices unless otherwise specified in these regulations. In the absence of, or deviation from, relevant codes and standard engineering practice, the applicant must provide in the application the rationale for selection of particular loads, safety factors, and/or related structural analysis methods.

(b) Structural analysis and design.

(1) Structural analysis and design must be performed under the direction of a licensed engineer and reviewed and certified by a licensed engineer. The licensed engineer must have a minimum of 10 years experience in structural analysis and design involving structures and materials similar to those proposed for the disposal units, but not necessarily disposal units for radioactive waste.

(2) Documents containing detailed design and construction plans and specifications must be submitted in the permit application. These documents must include descriptions of the foundations, structures, structural systems and major components; design drawings; material properties and reasons for selecting particular materials; design calculations, including pertinent assumptions, criteria and data references; seismic analysis; descriptions and copies of all computer programs used in design, including method of validation; listings of all relevant codes and standards followed; construction sequence; and a description of all special procedures to provide reasonable assurance that the performance objectives will be met.

(3) The bearing capacity of the foundation soils must be verified by testing. The foundation design must be based on the determined bearing capacity and include a safety factor consistent with standard engineering practice to prevent subsidence or shifting of the structure that could adversely affect the ability of the land disposal facility to meet the performance objectives.

(c) Design of Concrete Structures

(1) Standard. The analysis and design procedures to be used for concrete structures must, at a minimum, be in compliance with the 1989 edition of the American Concrete Institute Manual of Concrete Practice (see section 383-1.8 of this Part). For structural steel members and components, the analysis and design must, at a minimum, be in compliance with the ninth edition (1990) of the American Institute of Steel Construction Manual of Steel Construction (see section 383-1.8 of this Part).

(2) Use of Reinforcement.

(i) The use of steel reinforcement must be minimized in concrete structures that form the essential components of the disposal units. Steel reinforcement may be utilized to control shrinkage and thermal stresses to minimize cracking of concrete during the construction and operation periods, but must not be relied upon for long-term stability following facility closure.

(ii) The load-bearing capacity for any structural component must be at least 1.5 times the maximum design load assuming the concrete cover to the reinforcement and the reinforcement itself are not effective.

(iii) In minimizing the reinforcing steel required, the concrete members of the components essential to the stability of the disposal units must be designed to place as much of the structure as possible in compression throughout the design life of the disposal units while meeting the other design requirements and providing reasonable assurance that the performance objectives will be met. The design must be accomplished without the use of pre-stressing mechanisms such as rods or wires.

(iv) The use of alternative, corrosion-resistant reinforcing materials that can meet the design requirements may be proposed in the permit application.

(d) Quality and durability of construction materials.

(1) General material requirements.

(i) Construction materials used in all structures and components of the disposal units must be of adequate composition, quality and quantity to provide reasonable assurance that the structures and components will function as designed and that the performance objectives will be met. The materials must be tested and shown to meet the standards of quality and durability as specified in the plans and specifications approved in the permit, to be compatible with all other components of the disposal unit, and to provide reasonable assurance of long-term performance. All materials must be monitored for radioactive contamination prior to use. An operating portal monitoring system approved by the department will be sufficient to satisfy this requirement.

(ii) Where no codes or standards exist, or the recognized codes and standards do not adequately address the properties required, the applicant must submit documentation in the application describing the rationale of choice, test methods and data, and/or the in-service history that substantiates the selection and the use of the material for the intended application.

(iii) All synthetic and manufactured materials must be installed in accordance with the engineering plans and specifications approved in the permit and, unless otherwise authorized by the department, in accordance with the manufacturer's recommendations.

(2) Concrete materials.

(i) Concrete material types and proportioning, concrete placement, and curing must be specified to achieve the required design strength, minimize shrinkage and heat of hydration, and maximize density, impermeability, durability, and resistance to chemical attack. Admixtures and constituent materials the sole purpose of which is construction convenience and which may have a possible long-term detrimental effect on the concrete must not be used.

(ii) The materials used in the concrete, including admixtures and the concrete constituents, must be tested and approved as compatible, nonreactive, and acceptable for the application. The testing methods must be identified in the application .

(iii) Concrete constituents must be selected to avoid possible reactivity between the cement alkalis and the aggregate and any potential reactivity of the materials with the disposed waste.

(3) Structural steel, concrete reinforcing, and miscellaneous metals.

(i) Structural steel and miscellaneous metals utilized in the construction of the disposal units must be protected against corrosion. The use of corrosion-resistant metals must be evaluated and may be used if approved by the department.

(ii) Reinforcing steel and other metals embedded in concrete must be protected against corrosion. The design of concrete disposal units must compensate for protective methods that affect concrete bonding.

(4) The quality assurance and control program for the construction of concrete disposal unit structures must include field radiography, transmission, or back-scatter beam technology or other non-destructive techniques and related testing as specified in the QA/QC program required by section 383-7.2(c) of this Part to detect any voids or cracks that could lead to subsequent shielding or stability problems.

(e) Water infiltration resistance.

(1) Concrete structures and concrete components must be designed and constructed to minimize the occurrence of cracking.

(2) The use of construction joints must be limited to the maximum extent practicable. Construction and expansion joints that are installed must contain waterstops and joint sealants. The waterstops and joint sealants selected must have proven durability and compatibility with the concrete and other materials with which they will be in contact.

(3) Construction and expansion joints in the concrete must be designed to resist leakage.

(f) External drainage.

An exterior passive filter and drainage system must be located under and around the base of each disposal unit to divert any water that has infiltrated the soil or rock around the disposal unit to a foundation drain and a sump so that any infiltrated water can be monitored, collected, and treated as necessary throughout the operation, closure, and post-closure periods.

(g) Internal drainage.

(1) The disposal units must be designed and constructed with an internal drainage system to minimize the contact of infiltrating water with the waste. The drainage system must be designed and constructed to ensure the passive release of infiltrating water to the permeable bottom layer of buffer material required by section 383-7.4(h) throughout the operation, closure, and post-closure periods.

(2) The drainage system must include collection sump(s) (separate from the exterior drainage system and sump) so that any water that infiltrates the disposal unit can be collected and monitored as required by section 383-10.5 of this Part.

(h) Retention of radionuclides.

The disposal unit must be designed and constructed with a permeable bottom layer (or layers) of buffer material that has the capacity to retard the release of radionuclides from the disposal unit caused by water that may infiltrate the disposal unit and the waste. The properties of the buffer material, the rationale for selecting a particular buffer material, and the required buffer layer thickness must be documented as part of the application.

(i) Security and intrusion resistance.

(1) The design of the disposal units must incorporate provisions to meet the requirements of sections 382.33(a) or 382.34 of this Title.

(2) The design of the disposal units must include provisions to prevent unauthorized entrance during operations.

(j) Sealing requirements.

The inner surfaces of the disposal unit must be sealed to protect against water infiltration and damage by other elements. The coating or sealer material selected must have been demonstrated to have durability, impermeability, bonding strength (with respect to concrete and similar structural materials), and tensile strength.

§383-7.5 Additional design and construction requirements for aboveground disposal units.

Aboveground disposal units must be designed to be free-standing, engineered structures that can be visually inspected during the operation period. The disposal unit must be designed to accommodate a multilayered earthen cover, or an alternative approved in the permit, that provides protection to the disposal unit and long-term containment of the waste.

(a) Loads and load combinations.

The disposal unit must be designed to accommodate the loads and load combinations resulting from the placement of a multi-layer earthen cover over and around the disposal unit and the construction equipment required to place the cover, if such a cover is required by the permit.

(b) Protective enclosure.

(1) The disposal unit must be provided with a separate and independently supported protective enclosure that will function during the operation period.

(2) The protective enclosure must be designed to meet the following requirements:

(i) the protective enclosure must be freestanding and provide weather and frost protection to the disposal units until the end of the operation period;

(ii) the protective enclosure must be capable of being removed during facility closure without adversely affecting the performance of the disposal units; and

(iii) the protective enclosure must be watertight and capable of being easily inspected and repaired throughout the operation period.

(3) The roof of the protective enclosure and of the disposal unit must be sloped at a gradient of no less than two percent and sufficient to facilitate drainage and prevent ponding of water.

(c) A multilayer earthen cover which may be required during facility closure under section 383-9.5 of this Part must meet the design and construction requirements in section 383-7.6(c) of this Part.

(d) To facilitate inspection during the operation period, the major structural components of the disposal units must not be covered with materials that would mask structural defects such as cracking or settlement or that would unreasonably impede any required repairs.

§383-7.6 Additional design and construction requirements for belowground disposal units.

(a) Protective enclosure.

(1) Each disposal unit must be provided with a separate, independently supported protective enclosure that will function from the beginning of operations until disposal unit closure.

(2) Protective enclosure design. The protective enclosure must be designed to meet the following requirements:

(i) the protective enclosure must be freestanding and provide weather and frost protection to the disposal unit;

(ii) the protective enclosure must be capable of being removed at disposal unit closure without adversely affecting the performance of the disposal units; and

(iii) the protective enclosure must be watertight and capable of being easily inspected and repaired.

(3) The roof of the protective enclosure and of the disposal unit must be sloped at a gradient of no less than two percent and sufficient to facilitate drainage and prevent ponding of water.

(b) Water Infiltration Resistance.

The exterior of the disposal units must be protected against water infiltration by at least two barriers to water infiltration. Each barrier must function independently (i.e., the effective performance of each barrier must not require the presence or proper performance of any other barrier). The barriers may be sealant materials, bentonite impregnated panels, polymeric sheet membranes, or other materials or structures.

(c) Cover.

(1) A cover must be installed over the disposal unit during disposal unit closure. The cover must be designed and constructed to

(i) protect the disposal unit against frost, weathering, erosion, and burrowing animals;

(ii) provide resistance to water infiltration;

(iii) direct percolating or surface water away from the waste; and

(iv) protect against inadvertent intrusion, if required by sections 382.33(a) or 382.34 of this Title.

(2) The cover must be sufficiently thick to place the roof of the disposal unit below the maximum depth of frost penetration.

(3) The design of a multilayer cover must include stability analyses to demonstrate that no sliding or sloughing will occur at any interface between the various components under the most severe conditions anticipated. Such analyses must be based on the results of tests of interfaces between the same materials as proposed in the cover design.

(4) The requirement for a cover may be satisfied by either a multi-layer cover meeting the requirements of section 383-7.6 (d) or an alternative design meeting the requirements of sections 383-7.6(c)(1) through (3).

(d) Multi-layer Earthen Cover Requirements.

(1) Unless an alternative design is approved by the department, a multilayer earthen cover must meet the following requirements. The cover must be composed of, at a minimum, the following layers from the disposal unit upward:

(i) Compacted low permeability barrier layer. A low permeability barrier layer consisting of a low permeability soil material must be constructed to resist the infiltration of water into the underlying waste disposal unit(s).

(ii) Polymeric sheet membrane layer. A polymeric sheet membrane layer must be installed over the compacted low permeability barrier layer to resist water infiltration into the underlying disposal unit area.

(iii) A subsurface drainage layer. Immediately above the polymeric sheet membrane, a subsurface drainage layer, consisting of a free-draining gravel material, must be installed. Above the subsurface drainage layer, a geosynthetic filter fabric must be installed and covered by a protective sand layer.

(iv) An anti-erosion and burrow barrier layer. An anti-erosion and burrow barrier layer must be installed above the subsurface drainage layer to protect the multilayer earthen cover against frost action, erosion, root penetration, and damage caused by burrowing animals.

(v) Common fill layer. A common fill layer must be constructed over the anti-erosion and burrow barrier layer providing a separation between the anti-erosion and burrow barrier layer and the surface topsoil layer. The common fill layer will help maintain adequate moisture content within the topsoil layer for promoting growth of the vegetation cover.

(vi) Topsoil layer. A topsoil layer must be designed and constructed to maintain vegetative growth over the multilayer earthen cover.

(2) The installation and grading of adjacent material layers within the earthen cover must incorporate geosynthetic filter fabric and/or other design provisions to minimize the risk of soil particles migrating into and clogging the underlying layers.

(3) The surface and intermediate material layers composing the earthen cover must be graded to provide for positive drainage away from the disposal unit. The surface of the earthen cover must be at a slope that will not promote erosion. The minimum slope must not be less than 4 percent and the maximum slope must not be more than 25 percent.

§383-7.7 Additional design and construction requirements for underground mined repositories.

(a) General requirements.

(1) The applicant must use site-specific geologic information in designing and assessing requirements for the underground mined repository.

(2) Documents containing detailed design and construction information must be submitted in the permit application. In addition to the documents required pursuant to subpart 383-3 of this Part, these documents must include all relevant site-specific data and descriptions regarding the characteristics of the geologic unit or units around the excavation; proposed support and rock stabilization methods; design calculations of critical support elements; seismic analyses, and a map or maps of the underground mined repository at a scale of not less than one inch to 100 feet.

(3) The underground mined repository must be designed and constructed so that any surficial subsidence resulting from the mine will not create a significant depression that could result in surface waters' ponding and draining into the groundwater system in which the underground mined repository is constructed.

(4) The underground mined repository must be designed so that areas under construction are isolated from radioactive waste already in place.

(b) Structural stability requirements.

(1) Structural stability analyses must be performed by a licensed engineer utilizing site-specific engineering properties.

(2) The underground mined repository and associated facilities must be designed to remain structurally stable after the occurrence of any single design-basis major phenomena.

(3) The excavation techniques used in construction must be designed and implemented to minimize:

(i) the potential for increasing the flow of groundwater through the surrounding rock; and

(ii) the potential for creating a pathway for groundwater or radionuclide movement.

(4) The proposed excavation and underground support systems must be based on site-specific engineering properties of the geologic unit. A minimum factor of safety of two must be used in the design for calculated load conditions under normal operating conditions.

(5) The design and construction of the facility must be sufficiently flexible to allow for necessary modifications in design and/or construction if conditions are encountered in the geologic unit that are significantly different from those used in the design of underground supports and in the stability analyses. If such conditions are encountered, the design and/or construction must be modified by a licensed engineer as necessary to comply with the requirements of this Part and must be approved by the department as a modification of the permit. Design calculations and analyses for any changed conditions must be submitted to the department in the application for permit modification. Construction inspection and documentation must be performed to verify that these changes have been incorporated into the construction.

(c) Water infiltration.

(1) The underground mined repository must be designed and constructed to minimize and control water infiltration into the underground mined repository during the operation period and, as necessary to safely perform facility closure, during the closure period. During facility closure, the underground mined repository will be sealed. After it has been sealed, the underground mined repository will be allowed to revert to the natural hydrologic conditions.

(2) The underground mined repository geometry and disposal units must be designed and constructed to direct water that enters the repository during the operation period away from the radioactive waste already in place.

(3) The disposal units must be designed and constructed with an internal drainage system to minimize the contact of infiltrating water with the waste during the operation period. The drainage system must include collection points so that any water infiltrating the disposal units during the operation period and, as necessary, during facility closure can be monitored, tested, and treated as necessary, before release.

(4) The disposal units must be designed and constructed to minimize the flow of groundwater through the disposal unit once the underground mined repository has been sealed and allowed to revert to the natural hydrogeologic conditions.

(5) Hydrogeologic data used to assess water infiltration characteristics and establish related design and construction requirements for the underground mined repository must be gathered at the elevation at which the underground mined repository is to be constructed.

(d) Bulkheads, seals, and other engineered barriers.

Bulkheads are engineered structural barriers or partitions dividing the underground mined repository into waste disposal compartments and work areas. Seals are engineered features that employ techniques such as water stops, rock keyways, grouts, coatings, adhesive agents, or fluids to achieve airtight and/or watertight closure of the underground mined repository and waste disposal units. Other engineered barriers are designed features of the underground mined repository that serve to isolate or prevent water seepage and/or radionuclide migration from one area or disposal unit to another area of disposal unit; or from the underground mined repository to the surface environment.

(1) The underground mined repository design must incorporate bulkheads, seals, and other engineered barriers to prevent the premature infiltration of water into open areas, the escape of radioactive or hazardous gases, and the intrusion of personnel into filled disposal units from the open areas.

(2) Those bulkheads, seals, and other engineered barriers whose performance is critical to ensure that the underground mined repository facility will meet the performance objectives must be designed based on site-specific analyses.

(3) Bulkheads must be designed to isolate filled and closed units from active work areas and prevent the release of radionuclides from the closed units.

(4) Seals must be designed to deter radionuclide migration from the mined repository and disposal units.

(i) Seals for shafts and boreholes connecting the underground mined repository area with the ground surface must be designed to maintain their integrity and not serve as pathways for radionuclide migration away from the repository for a period sufficient to meet the performance objectives.

(ii) Seals for shafts and boreholes must be designed and located so they do not become infiltration pathways that could adversely affect the ability of the underground mined repository to meet the performance objectives.

(5) Materials and placement methods for bulkheads, seals, and other engineered barriers must be selected to minimize:

(i) the potential for creating a pathway for groundwater to contact the waste; and

(ii) for radionuclide migration through existing pathways.

(e) Ventilation.

Air exiting the ventilation system of the underground mined repository must be monitored and treated, as necessary, to meet the requirements of section 382.11 of this Title.