[HISTORY: Adopted by the Township Committee
of the Township of Washington 3-18-1997 by Ord. No. 97-4. Amendments
noted where applicable.]
A.
The Musconetcong and Pohatcong Valley areas of Washington
Township are underlain by carbonate bedrock formations of limestone
and dolomite. Solutioning of the bedrock by acidic groundwater in
the past has resulted in surface depressions, filled or partially
filled channels in the bedrock and the development of irregular, subsurface
rock topography known as karst. Such areas are unstable and may be
susceptible to subsidence and surface collapse. The alteration of
drainage patterns in these areas by the placement of impervious coverage,
grade changes or increased loads from site improvements can enhance
instability and lead to land subsidence and sinkholes.
B.
Carbonate aquifers are the source of potable water
for Washington Township and Washington Borough. Solutioning and fractures
in the limestone bedrock may lead to public or private water supply
sources in the carbonate aquifer, making those sources 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 openings within
the rock.
C.
The purposes of this chapter are to protect the valuable
potable groundwater resource of the carbonate aquifer 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 of the citizens
of Washington Township.
For the purposes of this chapter, the following
definitions shall apply:
The Board constituted pursuant to the Municipal Land Use
Law, N.J.S.A. 40:55D-1 et seq., which, for applications involving
site plan or subdivision approval, is the Planning Board or Zoning
Board of Adjustment of this township.
Development (as defined in the Municipal Land Use Law) in the Carbonate Rock District which requires major subdivision or major site plan approval under Chapter 64, Development Regulations, of this Code.
The arrangement of a sedimentary rock in layers of varying
thickness and character.
A general term for the rock that underlies soil or other
unconsolidated material.
Rock consisting chiefly of calcium and magnesium carbonates.
Those land areas underlain by carbonate rock formation, as
shown on the Washington Township Carbonate Rock District Map, annexed
to this chapter as an appendix.[1] (Additional information regarding land areas underlain
by carbonate rock, as an aid to interpreting the map, can be gained
from the New Jersey Geological Survey's Warren County Geology Map,
found in a publication entitled "Environmental Geology of Warren County,
New Jersey," by G.C. Herman et al [Open File Map 15B, NJGS, 1994]).
A shallow, dish-shaped hollow on the land surface which,
in area of limestone geology, may be indicative of old sinkholes or
incipient collapse.
A stream that enters the subsurface through a sinkhole or
other surface entrance.
A carbonate rock that contains more than 15% magnesium carbonate.
A surface or zone of rock fracture along which there has
been noticeable differential movement.
A program which identifies the geologic nature of the bedrock
materials underlying a site and provides solutions directed at preserving
the water quality and assuring the safety of any planned facility
or improvement built over carbonate rocks.
A fracture in rock, generally more or less vertical or transverse
to bedding, along which no appreciable movement has occurred.
A type of topography that is formed over limestone or dolomite
by dissolving or solutioning of the carbonate rocks, characterized
by sinkholes, closed depressions, caves, solution channels, internal
drainage and irregular bedrock surfaces.
A carbonate sedimentary rock consisting chiefly of calcium
carbonate. Limestone is commonly used as a general term for that class
of rocks which consists of at least 80% calcium or magnesium carbonate.
In this chapter, the term "limestone" shall be used generically to
refer to carbonate rocks, limestone formations and Precambrian marbles.
A localized land subsidence, generally a funnel-shaped or
steep-sided depression, caused by the dissolution of underlying carbonate
rocks or the subsidence of the land surface into a subterranean passage,
cavity or cave. Sinkholes are formed by the underground removal of
soil and rock material.
Tubular or planar channels formed by solution in carbonate
rock terrains, usually along joints and bedding planes. These openings
are the main water carrier in carbonate rocks.
Opening in the soil or rock materials.
[1]
Editor's Note: The Carbonate Rock District Map is included at the end of this chapter.
The provisions of this chapter shall pertain
to applicable development activities in the Carbonate Rock District.
The Carbonate Rock District (CRD) is hereby created and shall be the area identified as such upon the Washington Township Carbonate Rock District map, which is annexed to this chapter as an appendix. In this district, special submissions to the approving authority and special design features and remediation measures are required in an application involving, and as a condition of approval of, applicable development activities, as the same are important to protect the public safety and welfare, due to difficulties imposed to development arising from limestone geology. These requirements for the CRD shall be in addition to the requirements of Chapter 64, Development Regulations, regarding applications for development and in addition to zoning requirements for the applicable zoning district.
The following requirements shall apply to applicable
development activities proposed in the Carbonate Rock District (CRD).
A.
General requirements.
(1)
For all applicable development activities in the CRD,
a comprehensive site geotechnical investigation program shall be conducted
by the applicant to provide the approving authority with sufficient
data to define the nature of existing geologic conditions that may
limit construction and development activities on the site. The investigation
program shall be designed to produce information and provide recommendations
for site planning, engineering design and construction techniques
to minimize any adverse environmental and safety related impacts caused
by the development proposal. The location of all sinkholes, disappearing
streams or other karst features identified during the geotechnical
investigation program shall be shown on all preliminary and final
subdivision and site plans. The plans shall also detail any site remediation
techniques or preventative measures proposed to stabilize or reduce
the incidence of occurrence of any karst features.
(2)
The geotechnical investigation program shall be prepared
by an individual retained by the applicant who is a New Jersey-licensed
professional engineer or qualified geologist with experience in karst
terrains. The township may retain, with respect to the application
involved, a geotechnical consultant (GTC) who shall have one or more
of the same qualifications to review all projects submitted.
B.
Specific requirements.
(1)
Checklist submissions.
(a)
An investigation program shall be commenced
by completing the Carbonate Rock District Phase I and Phase II Checklists
(or requesting a waiver, at the time of filing the application, from
the Phase II Checklist requirements). Said checklists[1] (copies of which are attached to and made part of this
chapter) shall be submitted to the approving authority secretary by
the applicant as part of the application for an applicable development
activity. If any waiver of the Phase II checklist requirements is
requested, the checklist then shall be reviewed by the GTC within
14 days of receipt by the approving authority secretary. The GTC shall
recommend that a waiver of the Phase II Checklist be granted or that
it not be granted. If a Phase II Checklist waiver is not granted,
the approving authority, or its authorized review committee, shall
act to require the applicant to provide the Phase II Checklist and
its information or otherwise rule the application incomplete. The
Phase I and Phase II Checklists shall be reviewed by the GTC and a
report shall promptly be made to the approving authority advising
whether the checklists are complete. The approving authority shall
rule on the completeness of the checklist(s) within 45 days of the
date of their submission.
[1]
Editor's Note: The checklists are included
at the end of this chapter.
(b)
After Phase I and Phase II Checklists have been
deemed complete by the approving authority, and, if the application
for development has been determined by the approving authority to
be otherwise complete, a permit shall be issued to the applicant authorizing
the commencement of the testing procedure, the results of which shall
be part of the material required and to be considered by the approving
authority as part of the application for preliminary subdivision or
site plan approval (as the case may be).
(2)
Field investigations and findings.
(a)
Any on-site investigations and tests shall not
begin until the applicant has received approval of his investigative
plan and a permit has been issued. Additionally, notification shall
be given at least 15 days in advance of the commencement of testing,
in writing, by certified mail, return receipt requested, or personal
service of said notice on the Township Clerk.
(b)
The applicant shall arrange to have the proposed
development site available for on-site inspection by the GTC or designated
township inspectors at all times while the filed investigation program
is in progress, and testing data and results shall be made available
to township officials and township inspectors on demand, but at no
less frequent intervals than bimonthly.
(c)
At the completion of the field investigation,
a formal written report including the following shall be submitted
to the approving authority: a description of the project; a general
plan, to scale, of the entire project, showing the location of the
project with respect to surface water, existing wells (within 1/2
mile) and adjacent property owners; logs of all borings, test pits
and probes, including evidence of incipient cavity formations, loss
of circulation during drilling, voids encountered, type of drilling
or excavation techniques employed; drawings of monitoring or observation
wells as installed; time and dates of explorations and tests; reports
of chemical analyses of on-site surface and ground water; names of
individuals conducting tests if other than the professional engineer
referred to in the checklist; analytical methods used on soils, water
samples and rock samples; a one inch to 100 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, as well as the location of all sinkholes, disappearing
streams or other karst features identified during the field investigation;
an analysis of the groundwater regime with rate and direction of flow;
a geologic interpretation of the observed subsurface conditions, including
soil and rock type, jointing (size and spacing), faulting, voids,
fracturing, grain size and sinkhole formation.
(d)
The site investigation report should define
the extent of geotechnical concerns at the site in relation to the
planned development or land use. The proposed engineering solutions
to minimize environmental impact as a result of the project, both
during construction and in the foreseeable future, must be clearly
detailed, together with the basis for the conclusions reached. Special
consideration should be given in the report to innovative control
of surface water flows, as well as protection and replenishment of
groundwater.
(e)
All samples taken shall be preserved and shall
be available for examination by the township upon request until final
action is taken by the approving authority on the application.
(3)
Review and approval.
(a)
Geotechnical investigation program. The GTC
shall review the findings of the field investigation program and shall
consider the data, formal reports, maps, drawings and related submission
materials and shall advise the approving authority of his/her findings.
If the geotechnical investigation program undertaken as required by
this chapter is inadequate to make an informed decision as to whether
the requirements of this chapter for approval of the application for
development have been met, the approving authority, upon the recommendation
of the GTC, may require additional investigation or evaluation. The
precise nature and extent of such additional investigation and the
reasons therefor shall be identified in the approving authority determination.
At the request of the applicant, the approving authority shall rule
on the adequacy of the geotechnical investigation program within 45
days of receipt of the report from the GTC.
(b)
Major subdivision and site plan approval. The
approving authority shall review and consider the findings of the
geotechnical investigation program in its deliberations with respect
to the granting of major subdivision and site plan approval and apply
the following standards in its determination as to whether the requirements
of this chapter have been met and whether the application for development
approval should be granted:
[1]
Within the CRD, no residential or nonresidential
development shall be permitted which involves the discharge of any
liquid (including septic wastewater) into or on the soils unless there
is a positive demonstration by the applicant that such discharge will
not chemically react with the underlying geology so as to increase
significantly the likelihood that solution cavities or sinkholes will
result.
[2]
The major subdivision or site plan for any development
to which this chapter applies shall address and respond in a satisfactory
manner to those problems which have been identified in the geotechnical
investigation program, and, as a minimum, shall address and so respond
to Subsection B(3)(b)[2][a] through B(3)(b)[2][m] below. Approvals
of major subdivisions or site plans shall be contingent upon the positive
demonstration by the applicant that the following issues, Subsection
B(3)(b)[2][a] through B(3)(b)[2][m], have been appropriately addressed
and satisfactorily responded to:
[a]
Site selection, facility layout and structural
design shall be performed in a manner that will minimize any adverse
effects on the quality of surface or subsurface water and will not
alter the flow of surface and subsurface water in any detrimental
manner.
[b]
Adequate support is provided for structures,
roads and subsurface utility lines to span soft soils or sinkholes.
[c]
Stormwater and sanitary sewer lines are designed
and constructed with watertight joints.
[d]
All pipe for storm drainage installations shall
be reinforced concrete culvert pipe with rubber gaskets in sizes 12
inches and above. For smaller pipe, to be used for roof drains, underground
stormwater management or other uses, pipe shall be PVC pipe with glued
joints to form a watertight seal.
[e]
A trench backfill detail for storm drain, sanitary
sewer and all utilities shall be provided on the plan indicating a
relatively impermeable soil for pipe bedding and backfill of the trench.
Imported backfill material (from the quarry) and excavated material
from the site may be used for trench backfill with the approval of
the Township Engineer if it meets the following minimum requirements:
[f]
The backfill material to be used one foot above,
below and around the pipe or utility shall be free of stone two inches
in size or larger.
[g]
The backfill material to be used one foot above
the pipe or utility shall be free of stones six inches or larger.
[h]
backfill material shall be installed and compacted
in six-inch to eight-inch lifts. Moisture content shall be controlled
and maintained with the optimum limits to obtain 95% compaction based
upon testing of the material.
[i]
Reports of testing of material to be used for
backfill shall be provided for review and approval of the Township
Engineer, indicating that the material is suitably impermeable for
the intended use.
[j]
Typical details for repair of sinkholes found
on the site before and during construction shall be provided on the
plans. These details shall be approved by the Township Engineer.
[k]
Stormwater management impoundment facilities
(detention ponding, etc.) shall be constructed with an impermeable
liner (man-made or impermeable soil). If a soil liner is used, it
shall be at least 12 inches thick. All liners shall line the bottom
and side slopes of the facility.
[l]
All stormwater improvement facilities shall
contain an impervious low-flow channel from all pipes outletting onto
the facility to the outlet structure. This shall be either a concrete
channel with an impervious soil liner underneath or other impervious
low-flow channel approved by the Township Engineer.
[m]
Where pavement is to be placed within six inches
of exposed or excavated limestone bedrock, then a bed of at least
six-inch thick (compacted) dense-graded aggregate shall be placed
over the rock prior to paving.
[n]
Water supply and other pressurized utility lines
intended to transport liquids beneath the ground surface are equipped
with flow alarms or automatic shutdown mechanisms to detect breaks
which would allow water or other liquids to escape.
[o]
Site grading and blasting has been minimized
insofar as is reasonably practicable.
[p]
Specific details have been shown, describing
the design concepts as well as the construction and operational procedures
that will be used to protect the surface and subsurface water from
potential contamination, as well as a specific timetable schedule
and sequence of construction for the development, as these items relate
to the method to minimize or eliminate the occurrence of sinkholes,
has been submitted.
[q]
Specific details have been shown describing
the construction inspection procedures intended to disclose potential
hazards as well as the possible means for remediating any potential
karst-related hazard that might be encountered during construction.
(c)
Notification to lot owner. The approving authority
shall require, as a condition of final major subdivision or site plan
approval for any development to which this chapter applies, that there
be stated on the final plat and included in a deed (to be recorded)
for each involved lot the following statement:
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"In accordance with the Carbonate Rock District
Development Regulations of the Township of Washington, the owner of
this lot is advised that geologic mapping shows all or part of this
lot to be underlain by formations of limestone or dolomite. Areas
underlain by these geologic formations may be unstable and may be
susceptible to subsidence and surface collapse. This instability may
be enhanced by the alteration of drainage patterns through development
activities. The exact kinds or locations of sinkholes and/or subsidence
which may occur are not always predictable; therefore compliance with
any measures required by the Carbonate Rock District Regulations represents
no warranty or assurance that a sinkhole and/or subsidence will not
occur, and the Township assumes no liability in this regard. The lot
owner should always make independent investigations of these matters
prior to using the lot for construction or any activity which alters
drainage patterns or the soil and bedrock materials."
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A.
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:
(1)
Halt construction activities which would impact the
geologic hazard and divert any stormwater away from the hazard area.
(2)
Report the occurrence of the hazard to the Township
Clerk within 24 hours of discovery.
(3)
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 GTC.
(4)
After obtaining approval from the township, 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.
(5)
Repair any damage to improvements and restore ground
cover and landscaping.
B.
In those cases where the hazard cannot be repaired
without adversely affecting the site plan or subdivision, or without
requiring a change or modification of the approved site plan or subdivision,
the applicant shall file an amended application for a site plan or
subdivision approval in compliance with the provisions of this chapter
and other applicable provisions of this Code.
A.
The approving authority when acting upon applications involving applicable development activity, shall have the power to grant exceptions from the design and performance standards of this chapter in the same manner and under the same standards as exceptions may be granted from the design and performance standards in Article IV, Design and Performance Standards, of Chapter 64, Development Regulations, of this Code, pursuant to § 64-10 of this Code.
B.
If during construction of the development, the developer
fails to comply with any of the design and performance standards of
this chapter which are applicable to the involved development, the
township may issue a stop-work order and may withhold certificates
of occupancy and refuse to issue additional construction permits for
the development until there is compliance. Remedial and corrective
measures may be mandated by the Township Engineer and/or GTC 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.
