Groundwater Recharge (GWR) Spreadsheet Review Tool

An interactive guide for Municipal Engineers to evaluate N.J.A.C. 7:8 permit applications, focusing on the counterintuitive depth parameters for Pervious Pavement and Bioretention Systems.

The "Opposite Depth" Mystery Calculator

This section deconstructs the NJGRS variables: d_BMP, d_BMPu, and d_EXC. Use the calculator to simulate applicant inputs and visualize the correct values. The chart highlights the common 250% overestimation error where applicants confuse stone depth with effective storage depth.

System Parameters

d_BMPu (Top Depth)
3.0"
Water stops at bottom of pavement.
d_BMP (Storage Depth)
4.8"
Equivalent void space.
d_EXC (Excavation)
15.0"
Total depth to bottom.

The 250% Overestimation Error (Pervious Pavement)

Cross-Section Logic Model

Pavement (3") - Water level stops here
Stone Reservoir (12")
Only 40% is storage!

Regulatory Defensibility Checklist

This section provides a four-step framework for municipal reviewers. It outlines the mandatory checks required to confirm an applicant's GWR spreadsheet values align with N.J.A.C. 7:8 standards and site testing. Click each item to view specific review strategies.

1. Check Rainfall Factors

🌧

County-specific precipitation adjustments.

2. Verify Soil Testing

🌱

Match spreadsheet to Chapter 12 Soil Logs.

3. The 72-Hour Rule

Infiltration BMPs must drain within 72 hrs.

4. SHWT Separation

Maintain 2-foot separation from water table.

Phase 0: Deep Research Agent Prompt

This section provides a specialized prompt designed to trigger a deep technical simulation by an AI regulatory assistant. Use this to verify complex permit math and identify discrepancies between manual versions.