A.
There are areas within Mine Hill Township that are underlain by carbonate
bedrock such as limestone and dolomite and/or have been extensively
mined. Known areas that have been previously mined are identified
on the Mine Hill Township Mined Areas Overlay Map, Appendix II of
this chapter.[1]
[1]
Editor's Note: Appendix II is included as an attachment to this chapter.
B.
The solution of limestone bedrock and/or the subsidence of soils
over openings leading to mines caused surface depressions, open drainage
passages, and the development of irregular, subsurface rock topography
known as "karst." These conditions make such areas unstable and susceptible
to further subsidence and surface collapse. As a result, the alteration
of drainage patterns in these areas by the placement of impervious
coverage, grade changes, or increased loads from site improvements
can lead to land subsidence and sinkholes. The presence of both known
and unknown areas where mining activities were performed in the past
poses a substantial risk to proposed development, as well as to existing
properties immediately adjacent to the development.
C.
Fractures or solution openings and fissures in the limestone rock
or mine collapses may lead to public or private water supplies, making
those sources especially susceptible to groundwater contamination.
Contamination of water sources can occur from solid and liquid wastes,
contaminated surface water, septic tank effluent, or other hazardous
substances moving through fractures or solution openings and fissures
within the rock. Of particular concern is the potential for previously
mined areas to collapse, which could result in substantial damage
to public and private development.
D.
Carbonate aquifers are an important source of groundwater in Mine
Hill Township and surrounding areas. The Township relies on a clean
supply of subsurface water to foster and promote human health, welfare
and economic and social development. Therefore, the purposes of enacting
this chapter are to protect, preserve and enhance a sensitive and
valuable potable groundwater resource area and to reduce the frequency
of structural damage to public and private improvements by sinkhole
collapse or subsidence in areas of limestone geology or past mining
activities, thus protecting the public health, safety and welfare
and ensuring orderly development within the Township.
E.
The provisions of this section shall be applicable to development
activities in the entire Township requiring preliminary major subdivision
approval or preliminary major site plan approvals from the Township.
Minor subdivisions, proposed nonresidential development, or multistory
residential construction are also governed by this section.
A.
General procedures for geotechnical investigation.
(1)
The applicants filing for preliminary major subdivision or preliminary
major site plan approvals and minor subdivision, nonresidential or
multistory residential construction from Mine Hill Township shall
undertake a geotechnical investigation program. All projects shall
first complete the Phase I requirements. The submission of the Phase
II requirements shall be based on the recommendation of the municipal
geotechnical consultant (hereafter the "MGC") appointed by the Planning
Board, as authorized by the Municipal Land Use Law, pursuant to this
section following a review of the Phase I documents.
(2)
The geotechnical investigation program shall be prepared by
a professional engineer or geologist with experience in karst terrain
or mining areas. The municipality's geotechnical consultant (MGC)
shall be similarly qualified to review all projects submitted.
(3)
The geotechnical investigation program shall identify the geologic
nature of the materials underlying the site.
(4)
The geologic investigation report shall evaluate site information
gathered during the geotechnical investigation and provide recommendations
for the planning, engineering design, and construction techniques
to be utilized. All design recommendations shall minimize, to the
greatest extent practical, impacts upon water quality and structural
hazards associated with limestone formations and potential voids due
to past mining activities.
(5)
In that the results of the geologic investigation are essential
for the planning, engineering, design and construction techniques
to be utilized on the project, the geologic investigation program
shall be completed and the geologic investigation report filed with
the formal application for preliminary major subdivision or preliminary
site plan approvals. Prior to the submission of an application for
minor subdivision, preliminary major subdivision or preliminary major
site plan approvals, the applicant may, and is encouraged, to consult
or meet informally with the municipal geotechnical consultant or the
Planning Board Engineer as deemed necessary to receive guidance on
their investigation.
B.
Geotechnical investigation program process. For all properties located
in the Township, a comprehensive geologic investigation program shall
be conducted by the applicant. The purpose of this program is to provide
the Planning Board and Township with sufficient data to define the
nature of all existing geologic conditions that may affect construction
and land use activities on the site. Specifically, the investigation
shall yield information that will identify any existing geologic conditions
for which appropriate site design and/or engineering solutions may
be necessary to minimize any adverse environmental impacts caused
by the project as well as possible structural designs. The geotechnical
investigation program consists of the following:
(1)
The applicant shall complete the Phase I requirements outlined in Subsection C. Upon completion, the applicant shall have the option to submit the information to the Township to obtain an informal review and guidance prior to proceeding with Phase II.
(2)
The applicant shall complete the Phase II requirements outlined in Subsection D if required by the Planning Board. Upon completion, the applicant shall have the option to submit the information to the Township to obtain an informal review and guidance prior to proceeding with the on-site geotechnical investigation.
(4)
The submission of a geotechnical investigation report by the
applicant.
(5)
MGC review of the geotechnical investigation report and submission
of final recommendations to the Township.
C.
Phase I requirements:
(1)
Unites States Geologic Survey 7.5 minute topographic quadrangle
maps with the parcel identified.
(2)
USDA Soil Conservation Service soil survey map indicating soils
present on the parcel.
(3)
Information from any special reports completed by the New Jersey
State Geological Survey, United States Geologic Survey, or the New
Jersey Department of Environmental Protection.
(4)
Plat locating all past mine and mine opening locations within
500 feet of the property. This plat shall be based upon published
mapping and historical searches of past mining activities and shall
also address mine depth, angle of descent, and length of all mines,
mine openings, and shafts.
(5)
Aerial photograph print of the proposed site and surrounding
area at a minimum scale of one inch equals 1,000 feet obtained during
periods of minimum foliage.
(6)
Location of all known water production wells and well log information
within 1/2 mile of the project.
(7)
A project sketch plat at a minimum scale of one inch equals
200 feet with existing surface water bodies, location of any existing
water production wells, faults, outcrops, springs, sinkholes, disappearing
streams, surface water flows and evidence of mine subsidence.
(8)
Narrative describing efforts to date if any to seal, cap, or
otherwise render existing mines safe for building, development or
use of land affected by the mines in question. If mines have been
capped, sealed, or made safe, information should be provided that
indicates the location and type of work, the dates the work was done,
and the contractor that performed the work.
(9)
Written narrative describing proposed activity.
(10)
If the project includes the storage or manufacturing of toxic
or hazardous materials, provide the explanation of the activity and
safeguards to be employed.
(11)
Other published geologic information which the applicant deems
pertinent, such as information from other geologic investigation programs
which are on file with the Municipal Clerk, other agencies or from
past experience.
D.
Phase II requirements:
(1)
General requirements:
(a)
Test borings and test pits are to be used as the primary means
of identifying potential geologic hazards. Percussion probes and other
geophysical techniques (e.g., seismic refraction and reflection, ground
penetrating radar, magnetic gravity and conductivity) can be used
to provide data between test borings and pits.
(b)
Proposed exploration techniques which are not outlined in this
section may be submitted to the MGC for review and possible inclusion
in the approved investigation program. Alterations to the planned
program can be made during the progress of the field investigation
upon request to the MGC if so required by the nature of the encountered
subsurface conditions.
(c)
The intention of the site investigation program is to define
the nature and limits of possible design, construction and operating
concerns that could result from the existence of carbonate soil and/or
rock formations mining voids underlining the proposed development
site.
(d)
The name and address of the New Jersey licensed engineer practicing
in the field of geotechnical engineering, New Jersey licensed well
driller, and geologic consultant familiar with the region geology
to be used shall be supplied.
(2)
Direct testing procedures:
(a)
Provide the number of proposed test borings and/or test pits.
The minimum number of borings required is shown in the following table.
However, the MGC may require additional tests as site conditions warrant.
Test pits may not be used in lieu of test borings for the requirements
in the table for foundations.
|
Type of Development
|
Foundations
|
Infrastructure
|
Stormwater Management
|
|---|---|---|---|
|
Residential
| |||
|
1 to 10 dwellings
|
1 per dwelling
|
1 per 1,000 feet roadway
|
2 per basin
|
|
11 to 50 dwellings
|
0.15 per dwelling
|
0.75 per 1,000 feet roadway
|
2 per basin
|
|
>50 dwellings
|
0.1 per dwelling
|
0.5 per 1,000 foot roadway
|
2 per basin
|
|
Nonresidential
| |||
|
0 to 500 square feet building area
|
0.4 per 1,000 square feet building area
|
0.33 per 1,000 square yards impervious
|
2 per basin
|
|
5,001 to 10,000 square feet building area
|
0.2 per 1,000 square feet
|
0.3 per 1,000 square yards impervious
|
2 per basin
|
|
>10,000 square feet building area
|
0.2 per 1,000 square feet building area
|
0.2 per 1,000 square yards impervious
|
2 per basin
|
(b)
Provide the anticipated depth of borings. All borings shall
have a minimum depth of 65 feet. If rock is encountered within 50
feet of ground surface, a minimum of 15 feet of rock is to be cored.
Rock cores shall be a minimum of two feet in diameter, to be obtained
by double tube, split barrel coring device or equivalent. Rock coring
is to continue until RQD values are greater than 80%. "RQD" is defined
as rock quality designation. It is computed by taking the total length
of rock within the core run with core lengths greater than four inches
and dividing it by the total length of rock core obtained.
(c)
Describe the boring techniques to be used. Unless written approval
is obtained, all test borings will be drilled using rotary wash without
use of drilling muds. Water losses in borings are to be monitored
as to depth and quantities. Air loss, drilling speed and rod drops
must also be monitored.
(e)
Provide a description of proposed monitoring wells, including
location and material specifications; all wells are to have protective
locked casings. A key to the well casings shall be provided to the
Township Engineer.
(f)
Describe anticipated soil and rock sampling procedures. Sampling
shall be in accordance with ASTM D410, D1586, D1587 and D2113.
(g)
Indicate how borings and test pits shall be logged in accordance
with the Unified Soil Classification System and in relation to the
geologic original of the constituents of the encountered materials.
(h)
Provide the number and depth of proposed test pits. The minimum
bottom area of pits shall be 10 square feet and shall encounter rock
surface over 50% of the pit area.
(i)
Describe the proposed method of test pit backfill. Test pit
backfill shall be composed of excavated material placed in layers
and compacted to pre-excavation density, unless authorized otherwise
by MGC.
(j)
Provide the proposed number and types of Piezo meters to be
used. Piezo meters shall be installed and monitored in sufficient
locations to identify depth to seasonal high-water table and the rate
and direction of groundwater flow.
(k)
Provide descriptions of any other proposed method of measuring
groundwater levels and rate and direction of flow.
(l)
If the subject development is within 500 feet of past mining
activities, additional test borings shall be required at locations
to be determined by the MGC. Additional test boring depth over and
above the sixty-five-foot minimum may be required, depending upon
the historical data provided on the past mine activities. A plan detailing
the additional test borings shall be submitted for review by MGC.
The purpose of the additional test borings is to ensure that mining
voids are isolated.
(m)
Provide a description of methods for the geotechnical testing
of the properties of soils, rock and water.
(3)
Indirect testing procedures:
(a)
Any indirect test procedure shall be approved by the MGC prior
to start of work. Indirect testing procedures shall not reduce the
number of test borings required for foundations under Table No. 1.
(b)
Provide the proposed number, anticipated depths, and measuring
techniques of proposed percussion probes.
(c)
Describe the proposed number of seismic refraction and reflection
tests and equipment to be used.
(d)
Describe the proposed number of ground penetrating radar tests
and equipment to be used.
(e)
Describe the proposed number of magnetic, gravity or conductivity
tests and equipment to be used.
(f)
Described the geologic reconnaissance factors to be examined,
i.e., vegetative changes, observable seeps or groundwater discharge,
circular depressions, swales.
(g)
Described any other geologic reconnaissance field investigation
techniques proposed.
(4)
Maps, drawings and other documentation:
(a)
Provide the location of the site on 1:24,000 scale USGS topographic
quadrangle map and general site plan showing proposed locations of
all field testing procedures in relation to the planned development
at a minimum scale of one inch equals 100 inches.
(b)
Provide timetable of proposed field investigation, laboratory
testing, test data receipt and final report to the Township.
(c)
Described proposed technical inspection procedures during investigation.
Continuous technical supervision of the field investigation is required.
(d)
Describe any special factors or conditions the applicant wishes
to bring to the attention of the MGC.
E.
On site investigation protocol.
(1)
On-site investigations and tests undertaken pursuant to this chapter shall not begin until the applicant has submitted the appropriate fees as required in § 310-254 and has provided proper notice to the municipality. The applicant shall be responsible for providing, at least 15 days prior to the commencement of any testing procedures, written notice of same to the Municipal Clerk and MGC, which notice shall be transmitted by certified mail, returned receipt requested, or served personally. All site investigations shall be properly closed.[2]
(2)
The proposed development site shall be subject to inspect by
MGC or designated municipal inspectors at any time. All testing data
and results shall be made available to municipal officials and inspectors
on demand.
(3)
All samples taken shall be properly preserved and shall be available
for examination by the municipality upon request until final action
is taken by the Planning Board on the application. All samples are
to be stored for possible review by the Township for a period of not
less than 10 years by the developer.
F.
Geotechnical investigation report requirements.
(1)
At the completion of the field investigation, a formal site
investigation report shall be submitted and include any of the following
required information gathered during the testing protocol:
(a)
Logs of all borings, test pits, and probes, including evidence
of cavities, loss of drilling fluid circulation during drilling, voids
encountered and similar cavities.
(b)
Type of drilling or excavation technique employed.
(c)
Drawings of monitoring or observation wells as installed with
results of monitoring.
(d)
Time and dates of explorations and tests.
(e)
Reports of chemical analyses of on-site surface water and groundwater
and the potential for reaction with the underlying rock with an assessment
of the likelihood of formation of solution cavities.
(f)
Names of individuals conducting the tests, including the licensed
geotechnical engineer, the New Jersey licensed well driller, and the
geologic consultant.
(g)
Analytical methods used on soils, water samples, and rock samples.
(h)
A one-inch-equals-one-hundred-feet-scale topographic map of
the site (at a contour interval of two feet) locating all test pits,
borings, wells, seismic or electromagnetic conductivity or other geophysical
surveys in relation to the proposed development, as well as any mines,
mine shafts, sinkholes, etc., discovered during the investigation.
(i)
Analysis of the groundwater, including any potentiometric maps
constructed from site data or aquifer tests with rate and direction
of flow.
(j)
A geologic interpretation of the observed subsurface conditions,
including soil and rock type, jointing (size and spacing), faulting,
voids, fracturing, grain size, and the likelihood of sinkhole formation,
especially in projects where water form storm sewers, roof drains,
septic systems, etc., is being discharged into the ground.
(2)
The report shall also define the extent of geotechnical findings
at the site in relation to the planned development or land use. The
engineering solutions proposed to minimize environmental and structural
impacts for the useful life of the project as well as during construction
must be clearly detailed together with the justifications for the
conclusions reached. The report shall, as a minimum, address the following:
(a)
The probable effects of the proposed development upon Township
water resources and the likelihood of future sinkhole formations.
(b)
The appropriateness of the site for the proposed development
and the appropriateness of the location and design of proposed roadways,
buildings, facilities for stormwater management, utilities, water
supply and sewage disposal.
(c)
The adequacy of support for buildings, roadways, utility lines,
detention basins, and other infrastructure. Foundations shall be reinforced
to span a minimum of 10 feet over soft soils or voids.
(d)
The need for O-ring gaskets or other watertight joints for stormwater
and sanitary sewer construction. Stormwater and sanitary sewer lines
shall be designed and constructed with watertight joints, which have
been tested to ensure their integrity.
(e)
The need for infiltration and exfiltration testing on storm
sewer lines that shall be built.
(f)
The need for automatic shutoff devices for pressurized utility
lines.
(g)
The need for site grading and blasting limitations.
(h)
The need to seal, cap, or make safe any mines, mine shafts or
sinkholes found during the investigation. Where remediation is required,
the location of the work and the methods to be utilized to perform
the work shall be shown.
(i)
General methodology for management of sinkholes, minor voids
or solution cavities, depressions, or other questionable areas that
have been discovered during construction.
(j)
Provisions for inspection and monitoring during construction
and any long-term inspection or monitoring that may be recommended,
including the consultants that are proposed to be retained for such
purposes.
G.
Municipal review of geotechnical investigation report. The MGC review
of the geotechnical investigation report for proposed development
shall consider the data, formal reports, maps, drawings and related
submission materials. The MGC shall advise the Township whether or
not the applicant has provided the municipality with:
(1)
Sufficient design, construction and operational information
to ensure that the proposed development of the tract will not adversely
impact on the health, safety and welfare of the community.
(2)
Proof that the proposed method of development on the tract will
minimize any adverse effects on the quality of surface or subsurface
water and will not alter the character of surface and/or subsurface
water flow in a manner detrimental to known on-site or off-site conditions.
(3)
Specific details ensuring that design concepts and construction
and operational procedures intended to protect surface and subsurface
waters will be properly implemented to protect against possible sinkhole
creation and mine or mine shaft collapse.
(4)
Specific details on inspection and monitoring procedures to
be following during construction and after project completion.
(5)
The following note on the final subdivision plat or final plan
for any project: "This site is underlain by limestone formations and/or
past mining activity which are susceptible to sinkholes and subsidence.
The occurrence of sinkholes and/or subsidence is not predictable,
and therefore the municipality, its employees, the Municipal Engineer,
and the municipal geotechnical consultant assume no liability for
any damages which may occur on private property as a result of the
formation of sinkholes or subsidence."
A.
Acceptable methods for the remedying of the hazards caused by mining or carbonate soils [ARM(s)] are recognized below in Subsection B(1)(a); alternate methods, acceptable under certain field conditions as specified by the Township Engineer, MGC, or qualified mining expert, are also recognized and described in Subsection B(1)(b) and (c).
B.
Performance shall be in accordance with the approved geotechnical
investigation report where applicable and these chapter provisions,
dependent upon field conditions as determined by the Township Engineer,
MCG, or designated expert. The Township's experts shall review and
approve the forms of repair which may be applicable under the given
set of field conditions.
(1)
Acceptable methods.
(a)
Filling.
[1]
Fine material of 1/2 inch in diameter or less shall be introduced
into the mine voids or solution cavity as a slurry with water, obtained,
when available, from the voids themselves. The slurry shall be mixed
in a tank and permitted to fill the voids by gravity or by pressure
pumping via a pipe, either metal or plastic, let down into the void
area to the maximum depth penetrable consistent with the historical
data. The filling process shall be continued from opening to opening
in the bedrock until each opening will accept no more fill material
and the bedrock level is reached. The amount of solid fill hydraulically
introduced by gravity shall be carefully measured; unless 95% of the
calculated voids are filled, pressure filling to 50 # PSI pressure
head through a drill hole which has penetrated the void must be resorted
to and shall be continued until, in the opinion of the Township Engineer,
MGC, or such other expert(s) as the Township may decide to consult,
the voids are safely eliminated. Boulders, large rock and ungraded
overburden may be used on top of the finds to top off the upper several
feet over the course of time.
[2]
If the developer can demonstrate that suitable fill material
cannot be obtained in the area at reasonable cost, then one or more
of the alternate methods described in the ensuing subsections may
be employed, by written authority of the Township Engineer, MGC, or
designated expert.
(b)
Capping. Following removal of overburden to bedrock level along
the entire strike length of the vein subsidence and to 25 feet in
either direction beyond the farthest edge of the last opening determined
to exist on all veins to be capped, capping shall consist of bridging
the void space either by a reinforced concrete slab or by concrete
beams and a reinforced slab poured on top. Such beam slab or slab
construction must be capable of withstanding a total superimposed
load of 1,800 pounds per square foot measured directly over the center
of the opening. The slab or beam and slab construction must cover
the opening completely and extend from five feet into the footwall
to 15 feet into the hanging wall of the rocks enclosing the void.
Field conditions may dictate reinforcement of bedrock or a longer
beam over the opening if, in the judgment of the Township Engineer,
MGC, or such other expert(s) as the Township may decide to consult,
such reinforcement or longer beam is necessary. The beam and/or slab
construction shall be level, and, if precast, each slab shall butt
tightly against each adjoining slab.
(c)
Plugging. Wherever cross-trenching to bedrock has disclosed
a mine opening dipping at 45+/- degrees or less and not larger than
three feet measured at right angles to the dip nor six feet in length
along strike, such opening may be remedied by placing boulders of
sufficient diameter fully to close the measurement across the dip,
i.e., boulders of at least four feet in diameter, set side-by-side
in sufficient number fully to close the opening along strike (Shea,
1977, "Abandoned Magnetite Iron Mines of New Jersey," Figure 21, available
in Township Clerk's office). Smaller boulders must be so placed as
effectively to plug all spaces between the layer boulders, followed
by a further thickness of small boulders or broken rock effectively
to create an interlocking mat. Such plugging shall be done under the
supervision of the Township Engineer, MGC or designated expert.
(2)
Lines of surface subsidence. As indicated in Subsection B(3) of this subsection, where existing mine information indicates the land to be developed is traversed by mine workings, in order to eliminate the hazardous impact or voids by ARMs, it shall be required of the applicant (developer) that the line(s) of surface subsidence known or suspected to exist upon the property to be developed shall be excavated to bedrock. Such excavation shall expose in its entirety the vein and all sections thereof from which past mining has removed the ore to the bedrock surface for the full strike length of the vein within the property to at least 25 feet past the last known opening in either direction.
(3)
Excavation to bedrock. Excavation to bedrock may, if the applicant
(developer) so elects, be preceded by cross-trenching through to bedrock
at each subsidence to determine whether such subsidence is caused
by collapse into the mined-out void beneath or whether the pit or
depression represents initial prospecting to bedrock without subsequent
removal of the ore. If no void is located, and the particular pit
is 25 feet or more beyond the nearest collapsed void on the line of
strike, and there are not further pits on line of strike, then excavation
to bedrock along the entire line of strike, as described above, may
be terminated at this pit upon written approval of the Township Engineer,
MGC, or such other expert(s) as the Township has authorized to supervise
such excavation and trenching procedures.
(4)
Mining on more than one vein. Wherever the historical record
or surface evidence indicates that mining has been carried out on
more than one vein within a width of 50 feet, center to center of
subsidences, the entire width of the vein system shall be stripped
to bedrock, in accordance with the procedure set.
(5)
Topsoil and landscaping.
(a)
Topsoil from the excavated areas shall be stockpiled for reuse
in restoring the surface of all excavated areas, or areas disturbed
by the excavating and/or trenching procedures conducted in accordance
with these requirements. Not less than four inches of topsoil shall
be placed upon all excavated and disturbed areas.
(b)
Upon completion of the placing of monuments [Subsection B(9)] and compliance with all other provisions of this chapter applicable to surface restoration, the developer shall cause to be landscaped by appropriate shrubbery and trees all mining areas that he has remedied in accordance with the applicable paragraphs of this § 310-203.
(6)
Less than 5,000 cubic yards of void space. Whenever historical data shows or indicates that the abandoned mine or mines occurring within and/or extending into adjoining lands contain less than 5,000 cubic yards of void space, such mines shall be filled in accordance with Subsection B(1) of this subsection, after excavation to bedrock along the line of strike in accordance with the procedures outlined in Subsection B(2) and (3).
(7)
More than 5,000 cubic yards of void space. Whenever historical data shows or indicates that such abandoned mine or mines contains void space in excess of 5,000 cubic yards, capping in accordance with the specifications set forth above in Subsection B(1)(b) shall be permitted by the Township in lieu of filling, unless the Township Engineer, MGC, or such other expert(s) which the Township may decide to appoint for the supervision of these procedures for elimination of the hazards resulting from the existence of mining voids, recommends against capping. In determining whether capping or plugging shall be permitted in lieu of filling, the extent of the void areas to be filled, the effectiveness of capping or plugging as compared to filling, taking into consideration the existence or possible existence of pinched areas, timbers, rocks or ore pillars, voids inaccessible to any means of observation or addition, although not intended to be the decisive factor, relative costs of these two acceptable remedial methods shall be considered in all situations where void space is indicated to be in excess of 5,000 cubic yards. Consideration shall also be given to the danger of potential pollution of groundwaters and adjacent and nearby properties by discharge and runoff from any proposed use of individual sewerage disposal systems as a result of their proximity to areas which were formerly mined and which have not yet been filled, it being recognized that filling but not capping or plugging is more effective with respect to the elimination of such pollution problems related to the use of individual sewerage disposal systems.
(8)
Supervision of corrective measures. Any and all filling, capping or plugging, as well as excavating to bedrock and cross-trenching or any other tests made to determine the extent of the voids in accordance with the requirements of this § 310-203, shall be performed under the supervision of the Township Engineer, MGC, or such other expert as the Township shall have authorized and designated to supervise and inspect all work relating to these corrective measures to eliminate the hazards presented by these mining voids. The developer shall notify the Township not less than 15 days prior to commencement of any work or procedures relating to filling, capping, excavating to bedrock, cross-trenching or other testing to determine the extent of voids, to permit the Township to provide expert on-site supervision and inspection of the entire process. Failure to so notify the Township and to perform the required corrective work under the supervision and inspection of the designated Township expert shall be reason for withholding final approval of such work and/or final approval of the development plan in question and building permit(s) for the building(s) forming a part of the development in question. In determining the amount of inspection fees required pursuant to § 310-254 of Article XXXI, Fees and Deposits, the cost of this capping, filling or plugging work, excavation work, cross-trenching and other methods of testing used to determine the extent and location of the voids shall be included as a part of the calculation of such fees to assure the cost of such expert supervision and inspection by the Township's designated expert is reimbursed to the Township by the developer.
(9)
Survey and monuments. The margins of the line of voids and vein exposures uncovered by the stripping of overburden to bedrock as prescribed in Subsection B(2) and (3) above, as the mandatory preliminary step prior to filling or capping, shall be surveyed at the applicant's expense by a licensed New Jersey land surveyor and tied in to existing permanent survey markers or other acceptable existing points of reference. It shall be the purpose of the survey to establish on the final land surface over such filled or capped or plugged voids their exact location by means of monument or other appropriate lasting material at least three feet in length, four inches to six inches above final ground level. Monuments shall be set on the center line of the original void, one monument at each end of the void and a third halfway between or at twenty-five-foot intervals if the original void was determined to be in excess of 50 feet measured along strike. The surveyor shall keep and maintain careful field notes of all measurements and shall record same on a plan at scale of one inch equals 10 feet, which shall be submitted to the Township as part of the required as-built plans for the development in question. Such survey work shall be under the supervision of such other expert(s) as the Township may designate for such purpose. Further, elevations shall be set to the nearest one-hundredth of a foot on each monument by closed leveling from a permanent point, the elevation of which is known and established from the nearest United States Geological Survey benchmark.
(10)
Annual examination. An annual check of the elevation of the monuments shall be conducted at the expense of the owner of the property which is the subject of the development application by a licensed New Jersey land surveyor to determine whether subsidence has occurred. Such checks shall take place each year under the supervision of the Township Engineer, MGC, or such other expert designated by the Township for such purpose, for five years following the original placement of the monuments and each five years thereafter for 25 years within 30 days of the anniversary of the original establishment of the elevations thereof. A written report of the results of such annual check shall be filed with the Planning Board and Township Council. Evidence of subsidence in excess of normal settling four inches or less in the first year, two inches or less thereafter, shall cause the area of known filled or capped or plugged voids and any structure or improvements located thereon to be withdrawn from further use, occupancy or development of any kind completed, inspected and approved by the Township. Such corrective measures shall be initiated only upon submission to the Planning Board of an amended development plan setting forth in detail what measures are proposed, and the approval of such plan by the Planning Board. Such corrective measures shall then proceed to be implemented under the supervision of the Township for such purpose, in the same manner as any improvement required as a part of an approved development plan is installed and/or in withdrawal of the certificate of occupancy for any building located upon the property in question, and shall also constitute a violation of this chapter for which the owner of the property shall be subject to a fine and/or imprisonment in accordance with § 310-271 of this chapter of the Code of the Township of Mine Hill.
The Planning Board shall not grant final approval to a development plan involving a development in any of these mining zones or carbonate soil areas until the hazards of the voids on the property which is the subject of the application, and on the adjoining properties, have been eliminated by either filling or capping or plugging in accordance with the procedures described above in § 310-203B(1)(c) or performance guarantees equal to 120% of the cost of eliminating such hazards (by the method approved by the Planning Board as a part of a minor subdivision plan or a preliminary major site plan or subdivision plan approvals of the development plan in question), as estimated by the Township Engineer, MGC, or by such other expert as the Township may designate for such purpose, has been posted with the Township in accordance with the procedures and requirements of § 310-203 of this chapter of the Code of the Township of Mine Hill.
A.
Completion of filling or capping. In any event, notwithstanding the
grant of final approval to a development plan for development in any
of these mining zones and the posting of performance guarantees to
ensure completion of the filling, capping or plugging of the voids,
no building permits for the construction of any building to be constructed
upon the property which is the subject of the application shall be
issued until the filling and/or capping work required as part of the
Planning Board approval has been completed and inspected and approved
by the Township Engineer, MGC, or by such other expert(s) as the Township
may designate for such purpose.
B.
As-built plans. In accordance with the requirements of this chapter
of the Code of the Township of Mine Hill, as-built plans of all work
required and performed in connection with filling and/or capping or
plugging the voids caused by prior mining activities shall be furnished
to the Township upon completion, inspection and approval of such work
by the designated Township representative. Such as-built plans shall
be furnished immediately upon completion of rendering the mine safe
and prior to release of any of the performance guarantees furnished
to assure elimination of the hazards created by these mining voids.
Maintenance guarantees with respect to all work relating to the elimination of the voids caused by mining or carbonate soils by capping and/or filling in accordance with the requirements and procedures set forth in § 310-203B(1)(a), (b) and (c) above, consistent with the maintenance guarantee provisions of Subsection A of this section, shall be furnished to the Township at the time of final approval of the development plan for the use in question. In any event, no building permit for the construction of any building upon the property which is the subject of a development plan in any of these mining zones shall be issued until satisfactory maintenance guarantees regarding such work have been posted with the Township, and in particular, to insure the required annual survey and report on subsidence as is required by § 310-202F.
A.
Amount of maintenance guarantee. Maintenance guarantees covering
the work related to elimination of the hazardous mining voids shall
be 15% of the actual cost of such work, or of the estimate of such
cost as determined by the Township Engineer or such other expert designated
by the Township for such purpose, unless the Planning Board determines
that a sum less than 15% is adequate, taking into consideration the
total cost of the work in question, as well as the extent of such
work and the degree of danger presented by such voids.
In accordance with Article XXXI, Fees and Deposits, of this chapter, the Planning Board, at both the time of minor subdivision plan review and review of applications for preliminary and final major site plan and subdivision plan approvals for a use in any of these mining zones, shall review the adequacy of fees paid to date by the applicant in terms of expenses incurred and to be incurred by the Township in processing and reviewing such development plan and in supervising the work related to the elimination of the hazards of the mining voids by filling and/or capping. In accordance with § 310-255 of this chapter, prior to granting preliminary and final approval (as the case may be) and in view of the extensive fees and expenses which the Township anticipates it will incur to secure the advice and supervision of professional experts (geologists, mining engineers, etc.), which will be required to adequately protect the interests of the Township in its objective to ensure the area in question is rendered safe for human entry prior to commencement of construction, the Township shall require the applicant to pay whatever additional amounts are reasonably required pursuant to § 310-205A to assure the Township that all expenses incurred and to be incurred by it in connection with the remedial work associated with the development plan in question are reimbursed to the Township by the applicant. In any event, no building permit shall be issued for any building to be erected upon the property which is the subject of any such development plan until all fees assessed to the applicant in accordance with said sections of this chapter and provisions of this section are paid in full by applicant.
No subdivision or site plan approval shall be granted for any portion or section of any tract of land in the Township, whether or not such portion or section is intended to be developed currently and notwithstanding the fact that available and known information regarding prior mining operations indicates no mining took place upon such portion or section, unless and until a development plan encompassing the entire tract is presented to the Planning Board for approval, which plan must include provisions for elimination (by capping or filling) of the hazards resulting from the existing voids caused by prior mining or carbonate soils upon the tract in question, and/or upon adjoining properties. It is the purpose of this provision to prohibit any development upon any portion of a tract of land unless and until the entire tract is rendered safe for human entry and elimination of the hazards of the mining voids by either capping or filling in accordance with the procedures and requirements of § 310-203B(1) through (10). The plan need only be conceptual regarding development of those portions of the entire tract which applicant does not intend to develop at the present time.
No principal building or building intended for human occupancy shall be built over the voids filled, capped, plugged or covered in accordance with the above requirements of § 310-203 above, nor shall such buildings be located within the immediate area of such filled or capped voids determined as follows:
A.
If filling has taken place. No end (outside) wall of any principal
building or building intended for human occupancy shall be located
closer to the filled mine void than 10 feet from the edge of the filled
void on the footwall side or closer to the filled mine void than 20
feet from the edge of the filled void on the hanging wall side.
B.
If capping or plugging has taken place. No end (outside) wall of
any principal building or building intended for human occupancy shall
be located closer to the mine void than the point of intersection
with the final surface grade by a line drawn at an angle of 350°
from each end of the concrete beam or slab forming the cap to such
final surface grade, said angle of 350° being the angle between
such intersecting line(s) and the bedrock upon which the cap has been
placed.
A.
Buildings and structures of lightweight construction, which are detached
from the principal building, and which are not primarily intended
for human occupancy, such as garages, storage and utility sheds and
structures, and parking areas and driveways, may be constructed and
located over capped or filled voids and in the restricted areas immediately
adjacent thereto (as identified above). However, the weight of any
such building, structure or improvement erected over the plugged,
capped or filled void or in the said restricted area immediately adjacent
thereto shall not exceed 1,500 pounds per square foot, including the
weight of the soil, overburden or fill.
B.
No building permit for any such lightweight construction shall be
issued, however, until the expert(s) designated by the Township for
such purpose has reviewed detailed plans and specifications for such
construction and, based upon such review and consideration of the
plugging, capping and filling work which has taken place upon the
site in question, reports to the Planning Board that such construction
may safely be permitted both from a point of view of human safety
and safety of construction.
A.
Tax Lots 1 and 4, Block 1201. Tax Lots 1 and 4, Block 1201, shall
be considered as a single tract or parcel of land for all purposes
involving a development plan for a conditional use on any portion
or section of said Tax Lots 1 and 4. Furthermore, all known information
and data regarding the mining operations and works in this district
(see, in particular, the sources specified above in the Mined Areas
Overlay Map, Appendix II[1]) indicate that the mining activities and works which took
place on said Tax Lots 1 and 4 and on adjoining Tax Lot 5, Block 1201,
were part of a single mining operation known as the "Randall Hill
Mine." All available data indicates the main line of depressions which
marks the principal vein mined at this location constitutes one continuous
line extending in a general northeasterly direction from Randall Avenue
across said Lot 5 into Lot 1 and across Lot 1 for over 2,000 feet.
Thus, all available data indicates the void left by the mining of
this series of principal veins may constitute one continuous void
which crosses the property line dividing said Lots 1 and 5. Furthermore,
all available mining information indicates a major shaft is located
upon Lot 5, and several additional shafts, including the main central
shaft in close proximity to said boundary line between said Lots 1
and 5, are located upon the southwesterly most portion of said Lot
4. In view of this integral relationship between said Tax Lots 1 and
4 and Tax Lot 5 (Block 1201), the following limitations are placed
upon the development of these properties for any of the uses authorized
in the zone district in which the tax lots are located:
(1)
No development plan for a use upon Tax Lots 1 and 4 shall be approved by the Planning Board, unless the plans and proposals for filling and/or capping the mine voids on said Lot 4 include also filling and/or capping of the voids located upon said Lot 5. No final approval of any such development plan shall be granted unless all the mine voids located on both Lot 4 (including Lot 1) and Lot 5 (Block 1201) have been filled, capped or plugged or performance guarantees to assure such capping or filling have been posted by the applicant in accordance with § 310-205A.
(2)
The applicant for the development of Lot 4 shall furnish satisfactory
proof to the Planning Board that permission has been secured from
the owner of said Lot 5 to perform the required filling, capping or
plugging of the mine voids located on said Lot 5.
(3)
In the event the applicant for development of Lots 1 and 4 establishes
to the satisfaction of the Planning Board that, despite diligent effort
on the part of applicant, permission upon reasonable terms cannot
be secured from the owner of Tax Lot 5 to fill, cap or plug the mine
voids located on said Lot 5, the following additional restrictions
shall control the development of Lots 1 and 4 for conditional use:
(a)
No principal building shall be erected upon Lot 1 closer than
500 feet to the common property line dividing Lots 1 and 5.
(b)
No auxiliary building or lightweight construction as described in § 310-209 above which is not intended for human occupancy shall be erected closer than 100 feet to said common property line.
(c)
A chain-link fence at least eight feet high, with an arm atop
each post carrying three strands of barbed wire directed toward Lot
1, shall be erected along the entire length of said common property
line between said Lots 1 and 4.
(d)
There shall also be erected along the entire length of the remaining
three property lines of said Lot 5 the same type of chain-link fence
(with the strands of barbed wire directed outward from Lot 5) as specified
immediately above, unless the applicant establishes to the satisfaction
of the Planning Board that, despite diligent effort on the part of
applicant, permission upon reasonable terms cannot be secured from
the owner of Tax Lot 5 to erect such fence around Tax Lot 5.
[1]
Editor's Note: Appendix II is included as an attachment to this chapter.
B.
Additional restrictions. Whenever available mining data indicates
that mining occurred upon property immediately adjacent to the property
which is the subject of a conditional use application before the Planning
Board, and that the mining activities upon such adjacent property
were conducted within 250 feet of the common property line between
such property and the property which is the subject of the use development
application, then the following restrictions, requirements and conditions
shall apply:
(1)
If the subject property and the adjacent property are owned by the same person or persons, then the applicant shall be required (in accordance with the procedures established herein for and as a part of securing preliminary and final approval of a conditional use in a mining district) to eliminate the hazardous impact of the subsurface voids left by such prior mining activities upon such adjacent property by capping, filling or plugging such voids upon such adjacent property in accordance with procedures and requirements of § 310-203 above to the limit of such voids or for a distance (along each line of depressions) of 500 feet into such adjacent property measured from its common boundary line with the property which is the subject of the use application. The Planning Board shall not grant final approval to a development plan involving a use in any of these mining zones until the hazards of the voids on any such adjacent property within 500 feet of the subject property have been eliminated or performance guarantees to insure the required capping, filling or plugging on such adjacent property is properly completed have been posted in accordance with the requirement of said subsection.
(2)
All the requirements of § 310-203 shall be equally applicable to the elimination of mining hazards located upon such subject property.
(3)
If the adjacent property upon which mining activity was conducted
within 250 feet of the common boundary line with the subject property
is not owned by the same person or persons who own(s) the subject
property, the adjacent property shall nevertheless be rendered safe
from the hazards of the prior mining activities to the extent and
in the same manner as required for the subject property immediately
above where both properties are owned by the same person(s) as a condition
of final approval of the pending development plan, unless the applicant
for development establishes to the satisfaction of the Planning Board
that, despite diligent effort on the part of applicant, permission
upon reasonable terms cannot be secured from the owner(s) of the adjacent
property to fill, cap or plug the mine voids located thereon (or to
perform the tests and activities described above to determine whether
or not capping and/or filling is required).
(4)
In the event the applicant cannot secure permission from the
owner of the adjacent property to fill, cap or plug the mine voids
located thereon for a distance of 500 feet into the adjacent property
(or to take the necessary steps to determine whether capping and/or
filling are necessary in accordance with the standards and requirements
of this chapter), then the following additional restrictions shall
control the development of the conditional use upon the property which
is the subject of the development application:
(a)
No principal residential building shall be erected upon the
subject property closer than 250 feet and no principal commercial
or industrial building closer than 150 feet to the common property
line dividing such property and the adjacent property upon which prior
mining activity took place within 200 feet of such common line.
(b)
No auxiliary building or lightweight construction as described in § 310-209 above which is not intended for human occupancy shall be erected closer than 100 feet to said common property line.
(c)
A chain-link fence at least eight feet high, with an arm atop
each post carrying three strands of barbed wire directed toward the
subject property, shall be erected along the entire length of said
common property line between the subject property and the adjacent
property; limited, however, to that portion of the common property
line located within the Overlay Mining District in question or running
along an Overlay Mining District line.
(d)
In any event, no principal residential building shall be erected
upon the property which is the subject of the use development application
closer than 300 feet from any area which was previously mined (or
any area where there is reason to believe same was previously mined,
based upon all available mining data and information) located upon
such adjacent property which has not been rendered safe by capping,
filling or plugging (or investigated to determine if capping, filling
or plugging is required) in accordance with the standards hereinabove
set forth.
(e)
Similarly, no principal commercial or industrial building (i.e., any nonresidential principal building) shall be erected upon the property which is the subject of the use application closer than 250 feet from any such area which was previously mined located upon any such adjacent property which has not been rendered safe by capping, filling or plugging (or investigated to determine if capping, filling or plugging is required) in accordance with the requirements of § 310-203.
(f)
The requirements established herein to render the adjacent property
safe from hazards resulting from prior mining activities by plugging,
capping or filling the voids located upon such adjacent property shall
not apply if such adjacent property is separate tracts of land and
not part of Lot 1, Block 411, or Lot 1, Block 1101, whether or not
such property is owned by the same person(s) who own(s) the property
which is the subject of the use application pending before the Planning
Board.
(g)
Except as stated in Subsection B(4)(e) above in this subsection, all other requirements controlling development of property adjacent to property upon which uncorrected mining hazards (voids) exist shall be applicable where the adjacent property is located in the Overlay Mining District, including, in particular, the requirement to fence along the common property line.
(h)
Under no circumstances shall any principal residential building be erected upon any property which is the subject of a use development application closer than 300 feet, or any nonresidential principal building closer than 200 feet to the nearest known abandoned mine workings, at which location there exists or there is good reason to believe (based on all available mine data and information) there exists a subsurface mine void which has not been rendered safe by capping, filling or plugging in accordance with the procedures established by Article XXVII.
The investigations, reports and maps described above in the
Mined Areas Overlay Map, Appendix II, reveal that iron mining operations
took place in various sections of Mine Hill Township which are not
in any of the mining districts established by this chapter of the
Code of the Township of Mine Hill, as amended. Notwithstanding the
fact that a particular tract, parcel or lot may not be located in
any of the various mining districts shown upon the current Zoning
Map of the Township of Mine Hill, no building permit shall be issued
or a development plan shall be approved (involving a site plan, subdivision
or variance application) unless or until the property in question
is rendered safe from the hazards resulting from such prior mining
operations in accordance with the standards and procedures hereby
established with respect to and governing conditional uses in these
said mining districts.
A.
Application of standards. In addition to complying with the general requirements of Article XXVII, Requirements and Standards for Development on Critical Geologic and Previously Mined Lands, any property owner or developer seeking either a building permit for any residential, commercial or industrial use (including even a permit for one single-family dwelling) or approval of a development plan for any type of use shall apply to the Planning Board for review and approval of the plans for the proposed construction and development. The Planning Board in reviewing such application shall apply all the standards, requirements, terms and conditions applicable to establishment of a use in the Overlay Mining District, hereinabove set forth, and shall not approve the proposed construction or proposed development (and consequently no building permit shall issue) unless the plans and other data submitted by the property owner or developer indicate that the subject property and property immediately adjacent thereto will be rendered safe for both construction and human entry by the elimination of all mining hazards in accordance with such standards, requirements, terms and conditions.
In certain situations, a specific mining or geologic hazard
may not be identified while the geologic investigation program is
underway and may be discovered during or after construction. In such
cases, the applicant shall:
A.
Report the occurrence of the hazard to the Municipal Clerk and MGC
within 24 hours of discovery.
B.
Halt construction activities which would impact the mining or geologic
hazard.
C.
Prepare a report on the mining or geologic hazard which analyzes
the impact of the hazard and details a remediation plan for review
and approval by the MGC.
D.
After obtaining approval from the municipality, perform necessary
remediation of the hazard to prevent or minimize damages to buildings,
structures, utilities, driveways, parking areas, roadways, or other
site improvements, and to minimize pollution of the groundwater.
E.
Repair any damage to improvements and restore ground cover and landscaping.
F.
In those cases where the hazard cannot be repaired without adversely
affecting the previously approved site plan or subdivision plan, the
applicant shall file an amended application for site plan or subdivision
approval in compliance with the provisions of this chapter.
A.
Compliance with this chapter is required prior to the granting of preliminary major subdivision, preliminary major site plan, minor subdivision approvals and approvals for projects involving nonresidential or multistory residential uses, unless waivers have been granted by the Planning Board pursuant to § 310-215. The enforcement officials for any application requiring approval under this chapter are the Township Engineer and/or the MGC.
B.
Failure to comply with any of the conditions in this chapter may
result in the issuance of a stop-work order, revocation of building
permits, or denial of certificate of occupancy requests. Remedial
and corrective measures may be mandated if the appropriate construction
and site planning techniques, as outlined in the applicant's approved
geotechnical investigation report, are not followed and result in
actions that adversely impact karst features or past mining voids.
A.
It is recognized that the Municipal Land Use Law, particularly N.J.S.A.
40:55D-53(h), provides a limitation on engineering inspection fees
which shall, in all cases, be reasonable and shall, except for extraordinary
circumstances, be limited to the greater of $500 or 5% of the cost
of improvements, which cost of improvements shall be determined pursuant
to N.J.S.A. 40:55D-53.4.[1]
B.
It is also recognized that when the testing methodology provided
for herein has been employed and determines the existence of critical
geological formations and mining voids underlying the site of the
proposed development, extraordinary and exceptional construction methods
may be required to be employed by the developer during the construction
of site improvements, which work is required to be witnessed by the
Township Engineer or his representative or the MGC.
C.
The construction of improvements in developments underlain by critical
geological formations and mining voids is herewith deemed to constitute
an extraordinary circumstance, thereby rendering inapplicable the
engineering inspection fee limitations otherwise complying with the
requirements of N.J.S.A. 40:55D-53.
A.
In limestone and past mining areas, the alteration and development
of land may be hazardous with respect to the safety of structure foundations,
create unstable land as a result of changes in drainage and grading,
and contaminate groundwater and surface water.
B.
The exact occurrence of sinkholes and/or subsidence is not always
predictable; therefore, the administration of these regulations shall
create no liability on behalf of the municipality, the Municipal Engineer,
the MGC, municipal employees, or municipal agencies as to damages
that may be associated with the formation of sinkholes or subsidence.
Compliance with these regulations represents no warranty, finding,
guarantee, or assurance that a sinkhole and/or subsidence will not
occur on an approved property. The municipality, its agencies, consultants,
and employees assume no liability for any financial or other damages
that my result from sinkhole activity.
C.
It is also noted that sinkholes and ground subsidence may occur in
areas outside the subject property and/or in areas of carbonate geology
or past mining activities presently not identified as such. The applicant
and/or property owner shall always make independent investigations
of these matters prior to using this land for construction of a building
or structure or any activity that alters the soil and bedrock materials.
