3-Bethelview Trailhead Improvements-Percolation Test Report.pdf

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January 8, 2024

HEATH & LINEBACK ENGINEERS, INC.

2390 Canton Road Building 200 Marietta, Georgia 30066

Attention: Patrick T. Peters, P.E.

Director of Active Transportation

Subject: Report of In-Situ Percolation Testing – Bethelview Road Trailhead Improvements

FORSYTH BIG CREEK GREENWAY – SEGMENT 3

Forsyth County, Georgia NOVA Project Number 10102-2023112

Dear Mr. Peters:

NOVA Engineering and Environmental, LLC (NOVA) has completed the authorized percolation tests for the above referenced located in Cumming, Forsyth County, Georgia. Our services were performed in general accordance with NOVA Proposal Number 10102-2023112 dated July 24, 2023.

PROJECT INFORMATION

As part of Bethelview Road Trailhead Improvements, infiltration facilities are planned to be constructed at subject property (parking lot) located at 5120 Bethelview Road in Cumming, Georgia. The proposed construction of the facilities will include the following:

Northwest/Northeast Perimeter Grass Channel Western Enhanced Dry Swale with Underdrain/Western Bioretention Area with

Upturned Underdrain

Eastern Enhanced Dry Swale with Underdrain.

The approximate locations of planned facilities are shown in the following Figure 1 – Proposed Infiltration Facilities.

Bethelview Road Trailhead Improvements – In-Situ Percolation Testing January 8, 2024 Forsyth Big Creek Greenway – Segment 3, Cumming, Georgia NOVA Project Number 2023112

Figure 1 – Proposed Infiltration Facilities Source:Parking Lot Configuration prepared by Jacobs dated February 02, 2023 and Google Earth

SCOPE OF SERVICES

For the planned infiltration facilities as indicated in the Project Information Section, Mr. Patrick Peters requested NOVA to perform a total of three infiltration tests. The approximate locations of three infiltration tests were provided to NOVA by Mr. Patrick James via email correspondence dated December 18, 2023. In addition, per Mr. Patrick James, NOVA also understands that the invert of the planned facilities is anticipated to be approximately 2 to 5 feet below the final grades.

A total of three percolation tests were performed on December 21 and 22, 2023 at the approximate locations shown on the following Percolation Test Location Plan. Testing was performed in general accordance with the procedures described in the US Public Health Service’s “Manual of Septic Tank Practice”, Publication No. 526, 1969. The results of the percolation tests were converted to infiltration rates using the Porchet method.

Proposed Percolation/Infiltration Test Locations

Scale: Not to Scale Source: Google Earth

FINDINGS

The following table summarizes the measured percolation rate and the calculated infiltration rate at three test locations.

LOCATION

APPROXIMATE TEST

DEPTH BELOW

GROUND SURFACE

(feet)

MEASURED

PERCOLATION

RATE

(inches/hour)

CALCULATED

INFILTRATION

RATE

(inches/hour)

I-1 4 32.6 22.2

I-2 4 7.7 6.7

I-3 4 5.9 2.5

APPROXIMATE LOCATION OF PERCOLATION/INFILTRATION TESTS

We note that actual percolation/infiltration rates may vary, as soil conditions may differ in between test locations, and larger amounts of soil will be affected in the area of the permeable pavers. Infiltration rates may differ at other locations and depths/elevations across the site.

In addition, we note that construction activities may affect final infiltration rates. Therefore, additional infiltration testing should be performed once grading is complete and prior to placement of permeable pavers/and or underground stormwater management systems, if anticipated.

CLOSING

We appreciate your selection of NOVA and the opportunity to be of service on this project. If you have any questions, or if we may be of further assistance, please do not hesitate to contact us.

Respectfully Submitted, NOVA ENGINEERING & ENVIRONMENTAL, LLC

Georgia Engineering License No. PEF005170

Naveen S. Thakur, P.E. Daniel C. Brahana, P.E.

Senior Geotechnical Engineer Principal Engineer GA P.E. License 051185 GA P.E. License 018053