Report 4 13 2026

​ENSURPLAN, INC.​ ​ ww.Ensurplan.​​net​ w ​ ivil Engineers & Land Surveyors C Ph: (732) 469-0400​ ​Certificate of Authorization 24GA27997700​ ​STORMWATER DRAINAGE REPORT​ ​04/13/26​ ​Minor Subdivision 15 Ridgeway Ave West Orange, NJ​ ​Introduction and Major Stormwater Justification​ ​ his report has been prepared to demonstrate that the runoff from the proposed improvements​ T ​to the site, which result in an increase of impervious coverage, is properly mitigated in accord​ ​with the Township of West Orange requirements for a major stormwater project, and will pose no​ ​negative impact to any surrounding downstream properties.​ ​ o ensure that the design complies with the requirements and goals of the Township Stormwater​ T ​Ordinance a detailed analysis of the site condition was performed. A soils evaluator tested​ ​various areas of the site to identify both seasonal high water levels and the ability of the soil to​ ​infiltrate runoff. Additionally areas allowing for use of low impact development were identified;​ ​including potential preservation of large deciduous trees, lessening the slope of surfaces and​ ​elongation of drainage paths. This study focused the design on the area of the site which​ ​would allow for use of infiltration.​ ​ small scale sub-surface extended detention infiltration basin (a system allowing for infiltration​ A ​and controlled release) was chosen as the green infrastructure BMP to provide infiltration,​ ​recharge and reduction of runoff quantity. The basin is located at the area of the site where the​ ​soils evaluation determined an acceptable infiltration rate for design (A factor of safety was​ ​applied to the analysis by utilizing ½ of the measured infiltration rate in all calculations).​ ​ he basin shall be a shared system, accepting runoff from both lots, therefore an easement​ T ​allowing for common use and maintenance shall be established. Operations and maintenance​ ​requirements and responsibilities shall be filed with the record owner deeds.​ ​ ermeable

e an easement​ T ​allowing for common use and maintenance shall be established. Operations and maintenance​ ​requirements and responsibilities shall be filed with the record owner deeds.​ ​ ermeable pavement, another green infrastructure BMP, is specified for all driveway surfaces.​ P ​This system is rated for 80% total suspended solids reduction providing water quality treatment​ ​for the site.​ ​ he analysis shows that the runoff from the developed portion of the site directed towards the​ T ​infiltration basin when combined with the runoff rate from the developed portions of the site​ ​which bypass the system, has been reduced to no more than 50% of the two year storm rate.​ ​75% of the 10 year storm rate and 80% for the 100 year storm rate from what would have​ ​occurred if the design area were an undeveloped wooded lot.​ ​2​ ​Mailing Address: Post Office Box 4304, Warren, NJ 07059​