TRI Environmental Rainfall Erosion Testing of APS Series 700 Siltstop and Soilworks Soiltac using Site Specific Soil (TPD2106019)

June 21, 2021

Mr. Scott Stoneman Golder Associates, Inc.

18300 NE Union Hill Road, Suite 200 Redmond, WA 98052

E-mail: Scott_Stoneman@golder.com

REPORT: Rainfall Erosion Testing (via ASTM D7101) of APS 710 Silt Stop and

Soilworks Soiltac Polymers Using Site Specific Soil

The testing reported herein was performed in general accordance with ASTM D7101 using a site specific soil, Sample ID: “NW – Pit Sample, 5-7-21”, and two unique polymer tackifier products: APS 710 Silt Stop and Soilworks Soiltac. The tested tackifier products were applied in accordance with the manufacturer’s recommendations and exposed to the simulated runoff. The APS 710 Silt Stop application rate was 20 lbs of product in 3000 gallons of water per acre. The Soilworks Soiltac application rate was 290 gallons of product in 2600 gallons of water per acre.

The testing established the following performance characteristics (Soil Loss Ratio “SLR” and C-Factor) for the tested tackifier products by comparing product-protected soil loss to an unprotected or control scenario using the same site specific soil. A higher SLR value and lower C-Factor value represent better performance in controlling soil erosion under the tested conditions.

C. Joel Sprague, P.E. Technical Director TRI-South Carolina

James E. (Jay) Sprague, CPESC Laboratory Director

TRI-South Carolina

Bench-scale Slope Testing Report Evaluation of Erosion Control Products

TEST PROGRAM OBJECTIVES

Bench-scale “indexed” performance tests are a class of tests that have been developed to focus on testing the erosion control product (ECP) / soil system under carefully controlled “standard” conditions.   Since performance of an ECP relies on the complex interaction of the ECP structure with the soil and the water impact/flow, it is helpful and beneficial to be able to examine the effects of the product/soil system under relevant conditions. Bench- scale testing offers relevant conditions for evaluating relative product performance and comparing products while still facilitating lower costs and quicker testing than full-scale outdoor testing.

TESTING EQUIPMENT AND PROCEDURES

Overview of Test and Apparatus

The testing reported herein was performed at TRI Environmental, Inc.’s (TRI’s) erosion and sediment control testing facility located at the Roads to Rivers Research Institute in Greenville, SC. The testing reported herein was performed in accordance with ASTM D7101, on 3:1 slopes using a site-specific soil sample provided by the client; “NW-Pit Sample 5/7/21”. Simulated target rainfall intensities of 2, 4, and 6 in/hr were applied in sequence for 30 minutes each. The sediment loss from the ECP-protected slopes was compared to that from unprotected “control” slopes to characterize performance.

Test Soil

The test soil used in the test plots had the following characteristics.

Table 1. Test Soil Sample “NW-Pit Sample 5/7/21” Characteristics

Tested Product

There were two erosion control products, commonly called tackifiers, evaluated in this test program. Both products were provided by the client and are described as follows:

• Soilworks Soiltac Vinyl Copolymer Soil Stabilizer & Dust Control Agent. The Soilworks Soiltac application rate was 290 gallons of product in 2600 gallons of water per acre.
• Applied Polymer Systems, Inc. APS 710 Silt Stop. The APS 710 Silt Stop application rate was 20 lbs of product in 3000 gallons of water per acre.

Setup and Preparation of the Test Slopes

Test method ASTM D 7101, “Standard Index Test Method for Determination of Unvegetated Rolled Erosion Control Product (RECP) Ability to Protect Soil from Rain Splash and Associated Runoff under Bench-Scale Conditions” was followed in this program. This test method evaluates the ability of an ECP’s to protect soil from rain splash and immediate runoff- induced erosion. The critical element of this protection is the ability of the ECP to absorb the impact force of raindrops, thereby reducing soil particle loosening through “splash” mechanisms. The test method utilizes containers of both bare and ECP-protected soil that are exposed to simulated rainfall and immediate runoff for 30 minutes in the test apparatus. It is a sloped table enclosed by a curtain. Rainfall is simulated using a laboratory drip-type simulator capable of creating uniform drops with a median diameter of 3.0 to 3.5 mm from a drop height of 2.0±0.1 m and producing rainfall intensities as high as 150 mm/hr. The amount of soil that splashes or is washed out of the containers is collected, vacuum filtered, dried and weighed. From this data, an appropriate soil loss ratio (SLR) can be calculated by comparing the ECP-protected soil loss to the control. The inverse of the SLR is comparable to the C-factor which is more commonly used to relate to field performance.

Product Installation on Test Slope

The two erosion control products evaluated in this test program were installed per the instructions provided by the client. Both products were diluted in water at the recommended dilution ratio and applied to the surface of the individual soil cores using a pipette in an effort to uniformly apply the hydrated product at the recommended application rate. Both products were allowed to cure for 24 hours after application and prior to initiation of simulated rainfall event.

Specific Test Procedure

All three scenarios, Control or unprotected soil, soil protected with APS 710 Silt Stop and soil protected with Soilworks Soiltac, were subjected to unique rainfall simulations of 2”/hour, 4”/hour and 6”/hour for thirty minutes. The rainfall simulations were conducted using the prescribed test apparatus as outlined in ASTM D7101 “Standard Index Test Method for Determination of Unvegetated Rolled Erosion Control Product (RECP) Ability to Protect Soil from Rain Splash and Associated Runoff under Bench-Scale  Conditions.” All runoff was collected for each rainfall event. The collected runoff was vacuum filtered using a Whatman Grade 3 filter paper. The filtered soil runoff was then dried and mass of dry soil runoff determined. Pictures of test apparatus and setup are shown in Figures 1 and 2.

Figure 1 ASTM D7101 Test Apparatus                Figure 2 Close-up of Ramps and Collection

Test Results

The testing established the following performance characteristics (Soil Loss Ratio “SLR” and C-Factor) for the tested erosion control polymer products by comparing product soil loss to an unprotected or control scenario using the same site specific soil. A higher SLR value and lower C-Factor value represent better performance in controlling soil erosion under the tested conditions.

The detailed test results, including figures and tables are included in the appendix along with additional pictures of the testing.

Discussion

The experimental results of the   test   program   present   clear   evidence   that   the tested products performed very differently under the test conditions. The Soilworks Soiltac provided significant erosion protection when compared to an unprotected scenario while the APS 710 SiltStop did not provide any   significant   erosion protection under the conditions evaluated in this test program.

Appendix

Data and Figures

Erosion Control Product Testing Summary

ASTM D 7101:

STANDARD INDEX TEST METHOD FOR the DETERMINATION of UNVEGETATED ROLLED EROSION CONTROL PRODUCT (RECP) ABILITY TO PROTECT SOIL

FROM RAIN SPLASH AND ASSOCIATED RUNOFF UNDER BENCH-SCALE CONDITIONS

* soil loss ratio = soil loss of unprotected surface (I.e. control) divided by soil loss with protected surface = 1 / C-Factor

Corporate Lab: 9063 Bee Caves Road, Austin, TX 78733 / www.geosynthetictesting.com.com Southeast Labs: 112 Martin Rd., Greenville, SC 29607 / www.erosiontest.com

Control Test Using “NW Pit Sample 5-7-21” Test Soil

Tested Products

Soiltac Application

Silt Stop After 6″ Rain Event

Soiltac After 6″ Rain Event

Silt Stop Floc Formation on Filter Paper

Corporate Lab: 9063 Bee Caves Road, Austin, TX 78733 / www.geosynthetictesting.com.com Southeast Labs: 112 Martin Rd., Greenville, SC 29607 / www.erosiontest.com

RECP Slope Simulation Test

Corporate Lab: 9063 Bee Caves Road, Austin, TX 78733 / www.geosynthetictesting.com.com Southeast Labs: 112 Martin Rd., Greenville, SC 29607 / www.erosiontest.com

RECP Slope Simulation Test

Corporate Lab: 9063 Bee Caves Road, Austin, TX 78733 / www.geosynthetictesting.com.com Southeast Labs: 112 Martin Rd., Greenville, SC 29607 / www.erosiontest.com

Revision No. 2

Revision Date: 08/29/17

ASTM D422

S&ME Project #:

Project Name:

1426-19-038 (Ph. 10)

TRI Environmental On-Call Lab Testing

Report Date:

Test Date(s):

5/17/21

5/14 – 5/17/21

Sample Description:                 silty SAND (SM) – yellow brown, medium to fine

Revision No. : 1 Revision Date: 07/25/17

S&ME Project #: 1426-19-038 (Ph. 10)

Report Date:            5/17/21

Test Date(s): 5/15/21

Boring #: N/A

Log #: 51g

Sample Date: sub. May 2021

Type:                 Bulk

Depth: N/A