This Article XII of the Land Development Chapter shall be known and may be cited as the Mount Arlington Critical Areas Development Control Article.
It is the purpose of this Article to protect the health, safety and welfare of people and property within the Borough of Mount Arlington from improper construction, building and development on steep slope and hillside areas in the Borough and more particularly, but without limitation, to reduce the peculiar hazards which exist in hillside areas by reason of erosion, siltation, flooding, soil slippage, surface water runoff pollution of potable water supplies from nonpoint sources, and destruction of unique and predominant views. It is a further purpose of the Article to encourage appropriate planning design and development sites within hillside areas which preserve and maximize the best use of the natural terrain and maintain ridgelines and skylines intact.
a. 
Applicability to Major Projects.
(1) 
This Article shall apply to all applications for major developments in the Borough of Mount Arlington.
(2) 
The Planning Board shall approve all plans submitted under this Article as part of any application for major site plan approval or major subdivision approval.
(3) 
The Borough Engineer, after referral to and recommendation by the Planning Board in appropriate cases, shall approve all applications for building permits for compliance with this Article.
a. 
Applications and Applicability.
(1) 
Applicants for site plan approval, subdivision approval or a building permit shall submit to the Planning Board Clerk all information and documents (exhibits) required by this Article.
(2) 
The Planning Board Clerk shall process all exhibits submitted under this Article in the same manner as applicators for subdivision approval or site plan approval. The Planning Board may refer exhibits to qualified experts for review including but not limited to the Soil Conservation Service and/or the Borough Engineer.
(3) 
If the application for a building permit involves land where development is proposed only on slopes of 15% or less, the Planning Board may waive application of this Article.
a. 
Submissions.
(1) 
For all sketch plats, sketch site plans and applications for building permits, the following exhibits shall be submitted.
(a) 
Topography map at a scale not less than 1" = 50' showing existing contours at two foot intervals.
(b) 
Areas clearly identified showing the following: (1) slopes as measured between contour lines: Area 1, 30% or higher; Area 2, 21%-29%; Area 3, 16%-20%; Area 4, 0%-15%; (2) flood hazard areas based on Department of Environmental Protection or other reliable source; (3) wetlands based on National Wetlands Inventory or survey by qualified expert; (4) bodies of water.
(c) 
Calculations, in square footage and acres, of amount of area in the various categories listed above.
(2) 
Only where a major development is proposed on slopes greater than 15%, as part of preliminary subdivision approval or preliminary site plan approval the following additional exhibits, prepared by a qualified individual or firm, as determined by the Planning Board, may be required to be submitted.
(a) 
Extent and erodibility potential of exposed soils.
(b) 
Length, steepness and surface roughness of exposed slopes.
(c) 
Resistance of soil to compaction and stability of soil aggregates.
(d) 
High-water table, water infiltration capacity and capacity of soil profile.
(e) 
Chemical, physical and biological nature of subsurface soils.
(f) 
Type and location of construction activity, including the amount of site grading.
(g) 
The time period of exposure of erodible soils during construction.
(h) 
The area and density of woodlands and forests, within the construction site and on contiguous lands for a distance of 500 feet. All significant tree specimens, eight inches in diameter, measured four and one-half (4-1/2) feet above the ground; dogwoods, two inches in diameter, within the work area shall be indicated on development plans as well as physically marked on the construction site.
(i) 
The extent of impervious surface to be constructed.
(j) 
Location of construction access roads.
(k) 
Calculation of amount of site grading, to include a cut-and-fill balance sheet, including cross-sections, and indicating, where applicable, the volume of a source of off-site fill.
a. 
Standards for Development Plans and Improvements.
(1) 
The Planning Board or Borough Engineer, as the case may be, shall review and approve only those applications where development plans and necessary improvements accomplish the following:
(a) 
Control velocity and rate of runoff so that such velocity and rate are no greater after construction and development than before and all other provisions of the Mt. Arlington Stormwater and Flood Plain Regulations Article have been complied with.
(b) 
Minimize stream turbidity and changes in flow.
(c) 
Stabilize exposed soils both during and after construction and development.
(d) 
Prevent soil slippage.
(e) 
Minimize number and extent of cuts to prevent groundwater discharge areas.
(f) 
Preserve maximum number of trees and other vegetation on the site and avoid the critical upland forest areas.
(g) 
Avoid disturbance of critical areas.
(2) 
The Planning Board or the Borough Engineer, as the case may be, may impose such conditions upon any approval as said Board or Engineer deems necessary to achieve the above-stated goals. All permanent improvements necessary to achieve the above criteria shall be bonded in the same manner as set forth in Article IV, Development Procedures, for subdivisions and site plans.
(3) 
Any approval may be subject to the condition that the applicant provide and adhere to a detailed construction schedule, copies of which shall be supplied to the Borough Engineer and the Borough Construction Official for the purpose of monitoring the progress of the work and compliance with the construction schedule. Said approval may be further conditioned upon submission of periodic certifications by the applicant as to compliance with the construction schedule, and, in the event of noncompliance, written assurance as to the nature and time when steps will be taken to achieve compliance with the construction schedule.
(4) 
If the applicant becomes unwilling or unable to comply with the construction schedule or any other requirement or conditions attached to the approval of the Construction Official certifies such unwillingness or inability to the Planning Board, the Planning Board may thereupon revoke approval of the application, after notice and hearing to the applicant, and no further work may be performed on such site with the exception of temporary measures necessary to stabilize the soil and to protect the site from stormwater damage or other hazards created by construction activity on the site.
a. 
Modification of Standards.
(1) 
To meet the purposes, goals and standards set forth in this Article, the applicable provisions of Article VIII, Zoning, relating to lot sizes and density of development shall be modified in areas of slopes greater than 15%, flood hazard areas, wetlands, and bodies of water.
(a) 
The modification shall be determined by multiplying the total land area in the various categories by the following factors. Where categories overlap, the more restrictive factor shall be used.
CRITICAL AREA CATEGORY
Factor
Flood Hazard Areas
0.0
Wetlands
0.0
Bodies of Water
0.0
Slopes
30 or greater
0.0
21-29
0.2
16-20
0.5
0-15
1.0
Land within the Borough will be classified into the following slope areas:
0 - 14.9
0% to 15%
15 - 19.9
16% to 20%
20 - 29.9
21% to 29%
30 and over
30% or greater
(b) 
For classification purposes, slope areas shall be computed for the various slope categories between two foot contours. The percent of slope, rise in 100 foot run, shall be established by measurement of run perpendicular to the contours.
(c) 
Density Modification Formula. The maximum number of dwelling units or nonresidential floor area allowed on any tract shall be computed as follows:
(Acreage of land with 30% or more slopes × 0.0)
= ______
+(Acreage of land with 21%-29% slopes × 0.2)
= ______
+(Acreage of land with 16% to 20% slopes × 0.5)
= ______
+(Acreage of land with 0% to 15% slopes × 1.0)
= ______
(Acreage of Flood Hazard Areas × 0.0)
= ______
(Wetlands × 0.0)
= ______
(Bodies of Water × 0.0)
= ______
=Total Acreage available for development (TLD)
= ______
(d) 
For residential development the following formula shall be used:
TLD
Minimum lot area required/d.u. = Total number of dwelling units on tract
(e) 
For nonresidential development, the following formula should be used:
TLD × FAR = Maximum permitted floor area
(2) 
Within any area containing slopes of 30% or greater, no subdivision shall be created or site plan approved except in conformance with the following regulations:
(a) 
All slopes of 30% or greater located on a tract of land shall be protected from disturbance and preserved in a natural state, except as provided hereafter.
(b) 
All areas of a tract of land containing slopes of 30% or greater shall be delineated on a plan showing the proposed site plan or subdivision. Slope delineation shall be in accordance with this Chapter.
(c) 
Roadways shall be designed to follow natural terrain. Natural slopes of 30% or greater shall not be disturbed for road construction.
(d) 
At the Planning Board's discretion, slopes 30% or greater may be disturbed provided that the slope of 30% or greater is man-made or represents an isolated topographic condition, the disturbance of which will not result in significant modification to the drainage capabilities or visual character of the property.
(e) 
Development shall be designed in accordance with the following standards:
[i] 
Structures shall be located in areas that do not include the top of ridge lines.
[ii] 
Structures shall be located on the edges of fields and in wooded areas to minimize the visual impact of development.
[iii] 
Building envelopes shall not include wetlands, transition areas and flood plains.
[iv] 
Not more than 50% of the building envelope shall contain slopes 30% or greater.
(3) 
Applicants shall be encouraged to concentrate development on lesser slopes. The Planning Board, in appropriate cases and with adequate safeguards, may authorize development on lots smaller than permitted in the zone, in accordance with the provisions of the Zoning Sections in Article VIII regulating cluster developments, provided the total number of dwelling units does not exceed the maximum allowed after application of the density modification formula.
All land required to be maintained as permanent open space shall be indicated as such on any approved plans.