[HISTORY: Adopted by the Township Council
of the Township of Pohatcong 9-8-1998. Amendments noted where applicable.]
A.
There are areas within Pohatcong Township which are
underlain by carbonate bedrock such as limestone and dolomite. The
solution of this bedrock causes 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 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.
B.
Fractures or solution openings and fissures in the
limestone rock 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.
C.
Carbonate aquifers are an important source of groundwater
in Pohatcong Township. 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, thus protecting the public
health, safety and welfare and insuring orderly development within
the Township.
The provisions of this chapter shall be applicable
to development activities in the Carbonate Area District requiring
preliminary major subdivision approval or preliminary site plan approval
from the Pohatcong Township Planning Board.
A.
The Carbonate Area District is hereby created and
shall be any area identified as such upon the Pohatcong Township Carbonate
Area District Map. The district shall be constituted as secondary,
or as an overlay, to the zoning districts heretofore established by
the Zoning Map and may encompass all or portions of more than one
existing zoning district. Regulation of the CAD shall be in addition
to those requirements governing the existing zoning district.
B.
The Carbonate Area District shall contain two areas
which shall be known as the "Carbonate Rock District" and the "Carbonate
Drainage Area."
(1)
Carbonate Rock District (CRD). The Carbonate Rock
District is composed of those areas of the municipality underlain
by limestone or carbonate rocks. The geologic mapping utilized to
prepare the CRD overlay boundary is derived from New Jersey Geologic
Survey and United States Geological Survey maps. These maps are interpretations
developed from available field observations and subsurface date. Additional
unmapped areas of limestone rocks my exist in Pohatcong Township.
The provisions of this chapter may therefore be applied to any development
which, in the opinion of Pohatcong Township, is located in an area
underlain by limestone. The CRD map shall be updated as information
is developed through the application of this chapter.
(2)
Carbonate Drainage Area (CDA). The Carbonate Drainage
Area shall consist of all lands which drain surface water into the
Carbonate Rock District. Changes in the quantity, quality and rate
of discharge of surface water runoff from lands upslope of the Carbonate
Rock District can adversely affect the CRD. Therefore, development
activities in the CDA which may alter the surface drainage patterns
or affect the water quality or increase runoff into the CRD shall
be subject to the requirements of this chapter.
A.
All applicants filing for preliminary major subdivision approval or preliminary site plan approval from the Pohatcong Township Planning Board whose site is located in whole or in part within the Carbonate Area District (CAD) shall undertake a geotechnical investigation program as defined in § 115-5.
[Amended 4-15-2003 by Ord. No. 03-3]
B.
The geotechnical investigation program shall be prepared
by a professional engineer or geologist with experience in karst terrain.
The municipality's geotechnical consultant (GTC) shall be similarly
qualified to review all projects submitted.
C.
The geotechnical investigation program shall identify
the geologic nature of the materials underlying the site.
D.
The geologic investigation report shall evaluate site
information gathered during the geotechnical investigation, and provide
recommendations for the planing, 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.
E.
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 approval. Prior to the submission of an application for
preliminary major subdivision or a preliminary site plan the applicant
may, and is encouraged, to consult or meet informally with the municipal
geotechnical consultant or the Planning Board as deemed necessary
to receive guidance on their investigation.
[Amended 4-15-2003 by Ord. No. 03-3]
For properties located in the Carbonate Rock
District (CRD) a comprehensive geologic investigation program shall
be conducted by the applicant. The purpose of this program is to provide
the Planning Board 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 investigations shall
yield information which shall demonstrate that the proposed development
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. The geotechnical
investigation program for CRD properties shall be conducted in accordance
with the five phases defined herein. For properties which can document
that they are located in the Carbonate Drainage Area (CDA), only the
Phase I portion of the geotechnical investigation program is required.
A.
Phase I: Compilation and evaluation of existing data. The applicant shall prepare a Phase I submission in accordance with the requirements in § 115-6. The Phase I submission is a compilation and evaluation of existing data from various sources for the purpose of making general determinations of the types and depth of rock on the site, the extent of fracturing and faulting and an assessment of the potential development hazard which the conditions may pose. The Phase I submission will be evaluated by the GTC for the purposes of ensuring that the applicant has sufficient and current information available for preparation of a plan for detailed investigation of the proposed development site. Upon receipt of the Phase I submission, the GTC will review the submission and within 30 days from its receipt recommend to the Planning Board whether the submission is satisfactory and whether he recommends all or any portions of the Phase II requirements be waived. The Planning Board shall act on the recommendations of the GTC and notify the applicant within 30 days from the receipt of his report.
B.
Phase II: Proposed investigation methodology. The applicant shall prepare a Phase II submission in accordance with the requirements in § 115-7. The Phase II submission is a detailed outline of how the proposed on-site investigation will be conducted and shall include references to site specific investigation techniques, number of tests, equipment to be used, and investigation objectives. Upon receipt of the Phase II submission, the GTC will review the submission and within 30 days from its receipt recommend to the Planning Board whether the submission is satisfactory. The Planning Board shall act on the recommendations of the GTC and notify the applicant within 30 days from the receipt of his report.
C.
Phase III: On-site geotechnical investigation. The applicant shall perform an on-site geotechnical investigation in accordance with the approved Phase II submission and in accordance with the requirements in § 115-8 with observation by the municipal GTC. No on-site testing shall be conducted by the applicant until the Phase II submission has been approved by the Planning Board.
D.
Phase IV: Geotechnical investigation report. The applicant shall submit a geotechnical investigation report in accordance with the requirements in § 115-9. The report shall summarize the on-site testing and geotechnical findings, shall include recommendations to minimize the potential for environmental and structural impacts resulting from development and shall address remediation techniques for the handling of sinkholes or solution cavities discovered during construction.
E.
Phase V: Planning Board review and approval. The Municipal
GTC shall review the geotechnical investigation report and make final
recommendations to the Planning Board within 30 days from the receipt
of the geotechnical investigation report. The Planning Board shall
act on the recommendations of the GTC and notify the applicant of
whether the report is satisfactory within 30 days from the receipt
of his report.
Phase I requirements shall be as follows:
A.
United States Geologic Survey seven-and-one-half-minute
topographic quadrangle maps with parcel identified.
B.
United States Department of Agriculture Soil Conservation
Service soil survey map indicating soils present on parcel.
C.
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.
D.
Site plan map at a scale of one inch equals 1,000
feet identifying proposed development site and boundaries of site
that are within the CRA and/or CDA as designated on the municipal
CAD map.
E.
Aerial photograph print of the proposed site and surrounding
area at a minimum scale of one inch equals 1,000 feet obtained during
period of minimum foliage.
F.
Location of all known water production wells and well
log information within 1/2 mile of the project.
G.
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, and surface water flows.
H.
Written narrative describing the proposed activity.
I.
If the project includes the storage or manufacturing
of toxic or hazardous materials, provide an explanation of the activity.
J.
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 or other agencies.
K.
Properties that are located within the Carbonate Drainage
Area (CDA) shall be required to document that the proposed development
of the property will not increase the volume or rate of stormwater
runoff or concentrate flows into solution prone areas thereby increasing
the risk of sinkhole collapse on adjoining properties. The applicant
shall also address measures, both structural and nonstructural, which
will be employed to prevent the discharge of contaminated surface
waters into limestone aquifers.
[Added 4-15-2003 by Ord. No. 03-3]
A.
General requirements:
(1)
Test borings and test pits are to be used as the primary
means of identifying potential geologic hazards. Percussion probes
may also be used. Geophysical techniques (e.g., seismic refraction
and reflection, ground-penetrating radar, magnetic, gravity, conductivity,
and resistivity) can be used to provide data between test borings
and pits.
[Amended 4-15-2003 by Ord. No. 03-3]
(2)
Proposed exploration techniques which are not outlined
in this chapter may be submitted to the GTC 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 GTC if so required by the nature of the encountered
subsurface conditions.
(3)
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 underlying the proposed development site.
(4)
Name and address of New Jersey licensed engineer,
New Jersey licensed well driller, and geologic consultant to be used
shall be provided.
B.
Direct testing procedures.
[Amended 4-15-2003 by Ord. No. 03-3]
(1)
Provide number of proposed test borings. The minimum
number of borings required is shown in the following table; however,
the municipal geotechnical consultant may require additional tests
as site conditions warrant.
|
Type of Development
|
Foundations
|
Infrastructure
|
Stormwater Management
| |
|---|---|---|---|---|
|
Required Number of Soil Borings
| ||||
|
Residential
|
1 per dwelling
|
1 per 500 feet roadway
|
2 per basin
| |
|
Nonresidential
|
1 per 2,000 square feet of building area
|
1 per 12,000 square feet of impervious
|
2 per basin
| |
(2)
Provide anticipated depth of borings. If rock is encountered
within 40 feet of ground surface, a minimum of 10 feet of rock is
to be cored. Rock cores shall be a minimum of two inches in diameter
to be obtained by double tube, split barrel coring device or equivalent.
(3)
Describe 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. Drilling speed and rod drops
must also be monitored. Air loss should be monitored if percussion
probes are used.
(4)
Describe proposed borehole grouting techniques. Grouting
shall be in accordance with N.J.A.C. 7:9D-1.1 et seq.
(5)
Provide the PH of the groundwater based upon a minimum
of two samples taken from the borings.
(6)
Describe anticipated soil and rock sampling procedures.
Sampling shall be in accordance with ASTM D420, D1586, D1587 and D2113.
(7)
Borings and test pits shall be logged in accordance
with the Unified Soil Classification System and in relation to the
geologic origin of the constituents of the encountered materials,
i.e., light yellow brown silty clay (CH), with occasional angular
dolomite fragments, moderately stiff, residual soils, some stained
paleo jointing.
(8)
Provide 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.
(9)
Describe 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 the GTC.
(10)
Provide description of methods for the geochemical
testing of the properties of soils, rock and water.
C.
Indirect testing procedures.
(1)
Provide the proposed number, anticipated depths, and
measuring techniques of proposed percussion probes.
(2)
Describe the proposed number of seismic refraction
and reflection tests and equipment to be used.
(3)
Describe the proposed number of ground penetrating
radar tests and equipment to be used.
(4)
Describe the proposed number of magnetic, gravity,
conductivity or resistivity tests and equipment to be used.
[Amended 4-15-2003 by Ord. No. 03-3]
(5)
Describe geologic reconnaissance factors to be examined,
i.e. vegetative changes, observable seeps or groundwater discharge,
circular depressions, swales.
(6)
Describe any other geologic reconnaissance field investigation
techniques proposed.
D.
Maps, drawings and other documentation.
(1)
Provide the location of the site on 1:24,000 scale
United States Geologic Survey topo 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
feet.
(2)
Provide timetable of proposed field investigation,
laboratory testing, test date receipt and final report to the Planning
Board.
(3)
Describe proposed technical inspection procedures
during investigation. Continuous technical supervision of field investigation
is strongly recommended.
(4)
Describe any special factors or conditions the applicant
wishes to bring to the attention of the GTC.
A.
On-site investigations and tests undertaken pursuant to this chapter shall not begin until the applicant has submitted the appropriate fees as required in § 115-13 and has provided proper notice to the municipality. The applicant shall be responsible for providing, at least 15 days prior to commencement of any testing procedures, written notice of same to the Municipal Clerk, which notice shall be transmitted by certified mail, returned receipt requested or served personally. All site investigations shall be properly closed in accordance with N.J.A.C. 7:9-9.1 et seq.
B.
The proposed development site shall be subject to
inspection by the GTC or designated municipal inspectors at any time.
All testing date and results shall be made available to municipal
officials and inspectors on demand.
C.
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.
[Amended 4-15-2003 by Ord. No. 03-3]
A.
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:
(1)
Logs of all borings, test pits, and probes, including
evidence of cavities, loss of drilling fluid circulation during drilling,
voids encountered and similar cavities.
(2)
Type of drilling or excavation technique employed.
(3)
Time and dates of explorations and tests.
(4)
Names of the individuals conducting the tests if other
than the New Jersey licensed engineer, New Jersey licensed well driller,
or geologic consultant provided in the Phase II requirements.
(5)
Analytical methods used on soils, water samples, and
rock samples.
(6)
A topographic map of the site at a scale of one inch
equals 100 feet (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.
(7)
Depth to groundwater encountered in borings.
(8)
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 from storm sewers, roof
drains, septic systems, etc. is being discharged into the ground.
B.
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
bases for the conclusions reached. The report shall, as a minimum,
address the following:
(1)
Methods taken to avoid the probable effects of the
proposed development, including increased loadings on the soils, changes
in drainage patterns, new in-ground discharges from septic systems,
detention basins, swales, etc. on future sinkhole formation along
with recommendations for remediation to minimize the potential for
structural failures.
(2)
Methods taken to avoid the probable effects of the
proposed development on the potential for groundwater contamination
considering the depth of the rock and extent of voids and fracturing,
along with recommendations for remediation to minimize the potential
for contamination.
(3)
Based upon the nature of the proposed development
and considering the types of materials to be stored on the site, types
of chemicals, pesticides, fertilizers etc. to be used on-site, the
report should address the anticipated acidity of future surface water
runoff and its probable effects on the potential for increased solutioning
of the underlying rock.
(4)
The appropriateness of the site for the proposed development
and the appropriateness of the location and design of proposed roadways,
buildings, and facilities for stormwater management, water supply
and sewage disposal.
(5)
The adequacy of support for buildings, roadways, utility
lines.
(6)
General methodology for remediation of sinkholes or
solution cavities, depressions, or other questionable areas which
have been discovered during the investigation or which could be discovered
during construction.
(7)
Provisions for inspection and monitoring during construction
and any long-term inspection or monitoring which may be recommended.
It is strongly recommended that the developer employ the services
of an expert in construction in karst terrain to be on site during
all construction activities requiring excavation.
(8)
Based upon the geotechnical investigation, the report
shall recommend construction methods and specifications to be utilized
in the construction of the project to minimize the potential for structural
failure and groundwater contamination. As a minimum, the following
standards shall be adhered to during the construction of the project
and shall be incorporated into the preliminary subdivision plans or
preliminary site plans for the project:
(a)
Building foundations should be reinforced to
span a minimum of 10 feet of soft soils or voids.
(b)
Detention basins, swales and ditches shall be
lined or constructed utilizing impervious materials to minimize infiltration.
(c)
Roof drains shall be connected to storm drainage
systems to minimize infiltration.
(d)
Stormwater pipes, sanitary sewer lines and water
lines shall be designed and constructed with watertight joints which
have been tested to ensure their integrity.
(e)
Pipe materials, joints, construction methods
and materials and infiltration or exfiltration testing shall be subject
to the approval of the municipal engineer.
(f)
Backfill and bedding in utility trenches shall
minimize water infiltration to the subsurface.
(g)
Pressurized utility lines shall provide for
automatic shutoff when sudden pressure loss is detected.
(h)
Site grading, blasting and excessive depths
of cuts for utility lines shall be minimized.
The GTC's review of the geotechnical investigation
report for proposed development in the CRD shall consider the data,
formal reports, maps, drawings and related submission materials and
shall advise the Planning Board whether or not the applicant has provided
the municipality with:
A.
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.
B.
Proof that the proposed method of development of the
tract will minimize any adverse effects on groundwater quality, and
will not alter the character of surface water flow in a manner detrimental
to known on-site or off-site conditions.
[Amended 4-15-2003 by Ord. No. 03-3]
C.
Specific details insuring that design concepts and
construction and operational procedures intended to protect against
structural failures and contamination of groundwater will be properly
implemented.
[Amended 4-15-2003 by Ord. No. 03-3]
D.
Specific details on inspection procedures to be followed
during construction and after project completion.
E.
The following note shall be provided on the final
subdivision plat or final site plan for any project located within
the CRD: "This site is underlain by limestone formations 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 geotechnnical
consultant assume no liability for any damages which may occur on
private property as a result of the formation of sinkholes or subsidence."
In certain situations, a specific 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 within 24 hours of discovery.
B.
Halt construction activities which would impact the
geologic hazard.
C.
Prepare a report on the geologic hazard which analyzes
the impact of the hazard and details a remediation plan for review
and approval by the municipal geotechnical consultant.
D.
After obtaining approval from the municipality, perform
necessary remediation of the hazard to prevent or minimize damage
to buildings, structures, utilities, driveways, parking areas, roadways,
and 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 site plan or subdivision, 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 or preliminary site plan approval unless waivers have been granted by the Planning Board pursuant to § 115-14. The enforcement officials for any application requiring approval under this chapter are the Municipal Engineer and/or the municipal GTC.
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 certificates of occupancy. Remedial
and connective measures may be mandated if the appropriate construction
and site planning techniques, as outlined in the applicant's approved
geotechnical report, are not followed and result in actions which
adversely impact karst features.
A.
Application fee. For any project in the CAD requiring
a submission, the applicant shall pay an application fee of $500.
B.
Review fee. Funds shall be placed in escrow for review
of the application as follows:
C.
Inspection fee. It is recognized that
the Municipal Land Use Law, particularly N.J.S.A. 40:55D-53h, 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.
D.
It is also recognized that when the testing methodology
provided for herein has been employed and determines the existence
of critical geological formations underlying the site of the proposed
development, extraordinary and exceptional construction methods may
be required to be employed by the developer during site improvements,
which work is required to be witnessed by the Municipal Engineer or
his representative.
E.
The construction of improvements in developments underlain
by critical geological formations is herewith deemed to constitute
and extraordinary circumstance, thereby rendering inapplicable, the
engineering inspection fee limitations other provided by N.J.S.A.
40:55D-53h and enabling the charging of inspection fees in excess
thereof which, in all cases, shall be reasonable and shall otherwise
comply with the requirements of N.J.S.A. 40:55D-53.
A.
In limestone areas the alteration and development
of land may be hazardous with respect to the foundation safety of
structures, the creation of unstable land as a result of changes in
drainage and grading, and the contamination of ground and surface
waters.
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 municipal geotechnical consultant, municipal
employees, or municipal agencies as to damages which may be associated
with the formation of sinkholes or subsidence. Compliance with these
regulations represents no warranty finding, guarantee, or assurance
that 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 which may result from
sinkhole activity.
C.
It is also noted that sinkholes and ground subsidence
may occur in areas outside the CRD and/or in areas of carbonate geology
presently not identified as such. The applicant and/or property owner
should always make independent investigations of these matters prior
to using this land for construction of a building or structure or
any activity which alters the soil and bedrock materials.
