N.Y. Comp. Codes R. & Regs. Tit. 6 §§ 363-4.4

Current through Register Vol. 46, No. 45, November 2, 2024

Section 363-4.4 - Hydrogeologic investigation report

(a) A hydrogeologic investigation report is required and must contain the following:

(1) A description of the geology and hydrology of the existing or the facility in sufficient detail to determine the suitability of the site for the disposal of waste. The report must be submitted under the stamp and signature of a professional geologist or professional engineer licensed and currently registered to practice in the State of New York. The scope and extent of the hydrogeologic investigation must be based on the hydrogeologic complexity of the site and the ability of the site to restrict contaminant migration, and include:

(i) an understanding of groundwater and surface water flow and how it relates to local and regional patterns, including a groundwater table elevation map with groundwater flow direction calculated from hydraulic head measurements;

(ii) a definition of the critical stratigraphic section;

(iii) the establishment of an environmental monitoring system capable of readily detecting a contaminant release from the facility; and

(iv) a description of the engineering properties of the site, which provide the basis for the design and construction of the facility including the; and contingency plans relating to groundwater or surface water contamination or gas migration.

(2) Raw field data, analytical calculations, maps, flow nets, cross-sections, interpretations (with alternative interpretations where applicable), and conclusions. All maps, drawings and diagrams must have a minimum scale of 1:24,000, unless otherwise approved by the department. The description must include:

(i) Regional geology. A discussion of the regional geology demonstrating how the regional geology relates to the facility's geology and the location of nearby sensitive environments must include:

(a) bedrock stratigraphy and structural geology, including formation and member names, geologic ages, rock types, thicknesses, the units' mineralogical and geochemical compositions and variabilities, rock fabrics, porosities, bulk permeabilities, and other distinctive features;

(b) glacial geology, including a discussion of the formation, timing, stages, and distribution of glacial deposits, advances and retreats, and hydrologic characteristics of the surficial deposits, such as kames, eskers, outwash moraines, etc.;

(c) major topographic features, their origin and their influence upon drainage basin characteristics; and

(d) surface water and groundwater hydrologic features, including surface drainage patterns, recharge and discharge areas, wetlands and other sensitive environments, inferred regional groundwater flow directions, aquifers, aquitards and aquicludes, primary water supply and principal aquifers, public water supply wells, and private water supply wells identified in the water supply well survey; any known peculiarities in surface water and groundwater geochemistry; and any other relevant features.

(ii) Facility geology. Hydrogeologic conditions at the facility in three dimensions and their relationship to the proposed facility. The report must:

(a) define site geology, surface water and groundwater flow, and must relate site-specific conditions to the regional geology;

(b) describe the potential impact the facility may have on surface and groundwater resources and other receptors, including changes in hydrogeologic conditions that may occur with site development, and the potential for and effects of off-site contaminant migration;

(c) describe hydrogeologic conditions in sufficient detail to establish a comprehensive understanding of groundwater flow that can be quantified and verified through hydrologic, geochemical, and geophysical measurements;

(d) provide sufficient data to specify the location and sampling frequency for environmental monitoring points, form the basis for contingency plans regarding groundwater and surface water contamination and explosive gas migration, and support the design of the facility;

(e) specifically discuss all units in the critical stratigraphic section. This evaluation must include maps, cross-sections, other graphical representations, and a detailed written analysis of the following:

(1) all hydrogeologic units (e.g., aquifers, aquitards and aquicludes), and how they relate to surface water and groundwater flow. This must include all hydrogeologic data collected during the site investigation and explain and evaluate the hydrologic and engineering properties of the site and each specific unit; and

(2) local groundwater recharge and discharge areas, high and low groundwater tables and potentiometric surfaces for each hydrogeologic unit, vertical and horizontal hydraulic gradients, groundwater flow directions and velocities, groundwater boundary conditions, surface water and groundwater interactions, and an evaluation of existing water quality.

(b) Any aspect of the site investigation that deviates from these requirements of this section must be identified and justified in the site investigation report and must be approved by the department.

(c) The applicant must employ current, standard, and generally accepted methods and procedures in obtaining the required hydrogeologic information.

(1) The department may approve of alternative or innovative methods; however, the department may initially require redundant technologies to prove the reliability of a new method.

(2) A professional geologist licensed and currently registered to practice in the State of New York State, having experience in similar hydrogeologic investigations, must supervise all procedures in a manner that ensures the accuracy of the data and precludes environmental degradation.

(3) The location of all installations, geophysical and geochemical surveys, and seismic lines for the proposed investigation must be shown on a map with the same scale and coordinate grid system used in the application.

(d) Literature search. A comprehensive search for pertinent and reliable information concerning regional and site-specific hydrogeologic conditions is required. The literature search must include, as available, records and reports of the Department of Health, the Department of Transportation, the U.S. Soil Conservation Service, and the New York State Geological Survey; basin planning reports, groundwater bulletins, water supply papers, professional papers and other open file reports of the U.S. Geological Survey; bulletins, circulars, map and chart series, memoirs and other publications of the New York State Geologic Survey; publications and bulletins of the Geological Society of America and other professional organizations; publications of the EPA and the department; college and university reports; and aerial photography and remotely sensed imagery.

(e) Surficial geologic mapping. The facility must be mapped to determine the distribution of surficial deposits on and surrounding the site based on information from the hydrogeologic investigation, field evaluations, and field confirmation of all interpretations made on the site itself. The surficial geological map must be submitted under the stamp and signature of a professional geologist or professional engineer licensed and currently registered to practice in the State of New York.

(f) Test pits. Test pits may be used to determine shallow stratigraphy. The test pits must be logged by a professional geologist or engineer licensed to practice in the State of New York, and with experience in similar hydrogeologic investigations. Logs must be kept and include: elevations; surface features before excavation; depth of the test pit and of all relevant horizons or features; moisture content of units; standard soil classifications, stratigraphy, soil structure, bedrock lithology, and brittle or secondary structures in soil and bedrock; active seepage; and a sketch showing these features for each test pit. Test pits must be promptly backfilled and compacted with the excavated materials. The department may require that undisturbed soil samples be taken and tested in accordance with paragraph 363-4.4(l)(2) of this section.

(g) Water well surveys. A survey of public and private water wells within one mile downgradient and one-quarter mile upgradient of the facility must be conducted. Surveys must obtain, where available, the location of wells, which must be shown on a map with their approximate elevation and depth, name of owner, age and usage of the well; stratigraphic unit screened; well construction; static water levels; well yield; perceived water quality; and any other relevant data that can be obtained.

(h) Geophysical and geochemical surveys. The department may require the use of geophysical and geochemical methods, such as electromagnetic, resistivity, seismic surveys, remote sensing surveys, downhole geophysics, isotope geochemistry, and soil gas analysis to justify the interpretations and conclusions of the site investigation report, to provide information between boreholes, and to aid in the siting of wells. The geophysical and geochemical surveys must be submitted under the stamp and signature of a professional geologist or professional engineer licensed and currently registered to practice in the State of New York.

(i) Tracer studies. The department may require the use of tracer studies to aid in understanding groundwater flow, including:

(1) Where a site overlies limestone or dolostone bedrock or karst environments. Tracer studies must identify areas of groundwater flow from the facility attributed to secondary permeability, any recharge or discharge areas on and surrounding the site, groundwater storage, and seasonal variations of water levels; and

(2) To monitor sites with existing contamination, in accordance with subdivision 363-5.1(g)(2) of this Part.

(j) Site investigation work plan. The site investigation work plan must clearly define the scope of the intended investigation, all methods used in investigating the hydrogeologic conditions of the site and any specific hydrogeologic questions to be addressed.

(k) Monitoring wells and piezometers.

(1) General requirements.

(i) Monitoring wells and piezometers must define the three-dimensional flow system within the critical stratigraphic section.

(ii) Construction techniques must ensure that groundwater samples and water level measurements characterize discrete stratigraphic intervals, and prevent leakage of groundwater or contaminants along the well annulus. If leakage is detected, it must be corrected or the well properly sealed.

(iii) Monitoring wells and piezometers may be placed individually or as well clusters. Well clusters consist of individual wells at varying depths in close proximity, each installed in its own boring. Multiple wells placed into one large borehole are prohibited unless prior department approval in writing is obtained.

(iv) Soil borings, soil samples, and rock cores must characterize each stratigraphic unit within the critical stratigraphic section.

(v) Precautions must be taken during drilling and construction of monitoring wells to avoid introducing contaminants into a borehole. Only potable water of known chemistry may be used in drilling monitoring wells or piezometers unless otherwise approved by the department in writing.

(vi) All equipment placed into the boring must be properly decontaminated before use and between boreholes. The initial cleaning at the site must ensure that no contaminants from the last site drilled will be introduced into the borings. All equipment must be properly decontaminated between holes.

(vii) Where possible, upgradient wells should be drilled first.

(viii) The use of drilling mud must be avoided unless prior department approval is granted in writing. If drilling mud is used, the material used must avoid the introduction of contaminants. Drilling mud must not be used within ten feet of the screened interval.

(ix) Air systems and drilling lubricants must not introduce contaminants into the borehole.

(x) Well borings must have a minimum diameter that is two inches larger than the outside diameter of the well screen and riser to ensure that a tremie pipe may be properly used.

(xi) Wells and well borings must not be placed through or into waste unless prior department approval has been granted in writing and sufficient safety precautions are employed. If waste is unexpectedly encountered during drilling, then drilling of that boring must cease, the hole must be properly sealed, cuttings properly disposed of and the department notified.

(2) Construction of monitoring wells and piezometers.

(i) Well screens and risers must be constructed of materials selected to last for the required monitoring period of the facility without contributing contaminants to, or removing contaminants from, the groundwater. All materials used are subject to department approval. Joints, caps, and end plugs are to be secured by either welds, threads with thread seal tape, or force fittings. Solvents and glues or other adhesives are prohibited. Caps must be vented to allow for proper pressure equalization. The inside diameter of each well screen or riser pipe must be nominally two inches in diameter and must allow for proper development and for surveying and sampling equipment to be used within the screen and casing. A permanent mark should be made at the top of the riser pipe to provide a datum for subsequent water level measurements.

(ii) Well screens are required for all wells and piezometers, unless otherwise approved by the department. All screens used must be factory-constructed, non-solvent welded/bonded, continuous-slot, wire-wrap screens of a material appropriate for long-term monitoring. The slot size of the screen must be compatible with the sand pack. Water table variations, site stratigraphy, expected contaminant behavior, and groundwater flow must be considered in determining the screen length, materials, and position. Where existing contamination is suspected or known, downhole geophysical techniques may be required by the department to aid in selecting well screen elevations.

(iii) The sand pack surrounding the well screen must consist of clean inert siliceous material. Grain size must be based on a representative sieve analysis of the zone to be screened. The sand pack must minimize the amount of fine materials entering the well and must not inhibit water inflow to the well. The sand pack must be placed in the annular space around the well screen and extend above the top of the screen by two feet or 20 percent of the screen length (whichever is greater). In addition, the sand pack must extend six inches below the bottom of the screen. The sand pack material must be placed using an appropriate method and must avoid bridging. Alternative methods of placing the sand pack must be approved by the department in writing. The sand pack must be checked for proper placement. A finer-grained sand pack material (100 percent passing the No. 30 sieve and less than two percent passing the No. 200 sieve) six inches thick must be placed at the top of the sand pack between the sand and the bentonite seal.

(iv) Bentonite must be placed above the sand pack using a tremie or other method approved by the department to form a seal at least three feet thick. A six to 12-inch fine-grained sand pack must be placed above the bentonite seal to minimize grout infiltration. If bentonite pellets or chips are used, full hydration of the bentonite is required prior to emplacement of overlying materials.

(v) Grout of cement/bentonite, bentonite, or other suitable, low-permeability material must completely fill the remaining annular space to the surface seal. The grout mixture must set-up without being diluted by formation water, and must displace water in the annular space to ensure a continuous seal. The grout mixture must be placed under pressure using a tremie or other method approved by the department. Auger flights or casing must be left in the hole before grouting to prevent caving. The cement used must be appropriate for the groundwater chemistry of the site.

(vi) A protective steel casing, nominally at least two inches larger in diameter than the well casing, must be placed over the well casing or riser pipe and secured in a surface well seal to adequately protect the well casing. A distinctive, readily visible marker must be permanently attached to or near the protective casing to identify the well and ensure visibility. A drain hole must be drilled at the base of the protective casing. A vent hole must be located near the top of the protective casing to prevent explosive gas build up and to allow water levels to respond naturally to barometric pressure changes. The annulus of the protective casing should be filled with gravel. A locking cap must be installed with a minimum of a one-inch clearance between the top of the well cap and the bottom of the locking cap when in the locked position. A weather-resistant padlock must be placed on the protective casing. Padlock keys must be maintained at the facility and provided to department staff upon request.

(vii) A concrete surface seal designed to last throughout the planned life of the monitoring well must be constructed. The surface seal must extend below the frost depth to prevent potential well damage. The seal must be designed to prevent surface run-off from entering the well casing. In areas where traffic may cause damage to the well, bollards or other suitable protection for the well are required. Any damaged or deteriorated surface seals must be reported to the department and repaired or replaced in an appropriate manner. The department may allow alternate designs when documentation is presented that demonstrates the intent of the regulations are met or exceeded.

(viii) Alternative construction methods for piezometers and wells that are not to be part of the environmental monitoring plan may be approved in writing by the department if those methods meet the requirements set forth in subparagraph 363-4.4(k)(1)(ii) of this subdivision.

(3) Well and piezometer development. All wells and piezometers must be developed as soon as possible after installation, but not before the well seal and grout have set. Water must not be introduced into the well for development, except with written approval of the department. Any contaminated water withdrawn during development must be properly managed. Development must not disturb the sand pack or the strata above the water-bearing zone or damage the well. The entire saturated screened interval must be developed. The department may require multiple attempts at well development to increase the likelihood of obtaining sediment free water. Development methods must be appropriate for formation conditions. The selected method must minimize to the greatest extent possible the amount of turbidity in the well.

(4) Survey. The locations and elevations of all existing and abandoned test pits, soil borings, monitoring wells, and piezometers must be surveyed to obtain their precise location and plotted on a map in the site investigation report. The vertical location of the ground surface and the mark made on the top of the monitoring well and piezometer risers must be accurately measured to the nearest 100th foot.

(5) Well replacement. All wells must be properly protected to ensure their integrity throughout the active life, post-closure period, and custodial care period of the facility. If, in the opinion of the department, water quality or other data show that the integrity of a well is lost, the well must be replaced and sampled within a time period acceptable to the department (but not to exceed 120 days) after written notification by the department. The initial sample for the replacement well must be analyzed for baseline parameters in the Water Quality Analysis Tables in this Subpart.

(6) Well abandonment. All soil borings, rock cores or other abandoned wells that are not completed as monitoring wells or piezometers must be fully sealed in a manner appropriate for the geologic conditions to prevent contaminant migration through the borehole. Generally, sealing must include:

(i) overboring or removal of the casing to the greatest extent possible, followed by perforation of any casing left in place. All casing and well installations in the upper five feet of the boring, or within five feet of the proposed level of excavation, must be removed;

(ii) sealing by pressure injection with cement bentonite grout, using a tremie or other method acceptable to the department. The cement must extend the entire length of the boring to no less than five feet below the ground surface or the proposed excavation level. The screened interval of the borehole must be sealed separately and tested to ensure its adequacy before sealing the remainder of the borehole. Where the surrounding geologic deposits are highly permeable, alternate methods of sealing may be required to prevent the migration of the grout into the surrounding geologic formation. The well must be backfilled to at least five feet below ground surface with appropriate native materials compacted to avoid settlement; and

(iii) the sealed site must be restored to a safe condition. The site must be inspected periodically after sealing for settlement or other conditions that may require remediation.

(7) Well extension. All well extensions must be constructed to ensure the future use of the well. Well extensions shall be designed to maintain the future integrity of the well casing and to prevent surface water intrusion into the well casing. Failure of a well extension will require well replacement.

(l) Geologic sampling.

(1) All borings and rock cores must be sampled continuously to the base of the critical stratigraphic section. For well clusters, continuous samples must be collected from the surface to the base of the deepest well. Other wells in the cluster must be sampled at all stratigraphic changes, and at the screened interval. At sites where the geology is not of a complex nature the department may allow a reduction in the number of wells requiring continuous sampling. Soil borings must be sampled using the split spoon method, or other approved methods such as continuous sonic core sampling, and bedrock or boulders must be sampled by coring with standard size NX or larger diameter core bits. Samples must be retained in labeled glass jars or wooden core boxes. All samples must be securely stored and accessible throughout the life of the facility. The location of the storage area must be designated in the facility manual.

(2) A representative number of undisturbed samples must be collected from test pits and borings using appropriate methods to identify the characteristics of all cohesive soil units. These samples must be analyzed in the laboratory for: Atterberg limits; gradation curves by sieve or hydrometer analysis or both; undisturbed permeabilities; and visual descriptions of undisturbed soil structures and lithologies. Laboratory analysis of non-cohesive soil units may also be required.

(m) Logs.

(1) Complete drilling logs must be provided to the department for all soil borings. These logs must provide detailed soil classification according to the Unified Soil Classification System (USCS). The USCS visual method must be used on all samples supplemented by the USCS laboratory tests on a representative number of samples from each stratigraphic unit and each screened interval. Logs also must contain a description of the matrix, clasts, mineralogy, roundness, color, appearance, odor, and behavior of materials using an appropriate descriptive system. A clear description of the system used must be included with the logs. All well logs must contain drilling information observed in the field including: moisture content, location of the water table during drilling, water loss during drilling, depth to significant changes in lithology, depth to bedrock, sample recovery (measured in tenths of a foot), hammer blow counts, the method of drilling, any anomalous features (e.g., gas in the well), and the use and description of drilling fluids or additives, including the source, and calculated and actual amounts of materials used.

(2) Rock core logs must describe the lithology, mineralogy, degree of cementation, color, grain size, and any other physical characteristics of the rock; percent recovery and the rock quality designation (RQD); other primary and secondary features, and contain all drilling observations and appropriate details required for soil boring logs. A clear photograph of all labeled cores must also be taken and submitted with the logs.

(3) Well completion logs must contain a diagram of the installed well, all pertinent details on well construction, a description of the materials used, and elevations of all well features.

(4) Copies of original field logs must be submitted to the department upon request.

(n) In situ hydraulic conductivity testing. In situ hydraulic conductivity testing must be done in all monitoring wells and piezometers, unless otherwise approved by the department. The testing method used must not introduce contaminants into the well. If contamination is known or suspected to exist, all water removed must be properly managed. Hydraulic conductivities may be determined using pump tests, slug tests, packer tests, tracer studies, isotopic geochemistry, thermal detection, or other suitable methods.

N.Y. Comp. Codes R. & Regs. Tit. 6 §§ 363-4.4

Adopted New York State Register September 20, 2017/Volume XXXIX, Issue 38, eff. 11/4/2017

Amended New York State Register June 7, 2023/Volume XLV, Issue 23, eff. 7/22/2023

Amended New York State Register June 21, 2023/Volume XLV, Issue 25, eff. 7/23/2023