Conservation Commission Meeting Agenda/Materials 109R and 131 Clark Lane Exhibit List (linked)

February 22, 2023
Dear Conservation Commission
The enclosed are documents Table 1, Table 2, Table 3 supporting the reports Carya Documents already
submitted on 01/26/23 and 02/09/23 and in support of oral testimony.
From: Sigrun Gadwa of Carya Ecological Services LLC
C-22-14
109R & 131 CLARK LANE
PUBLIC HEARING 01-26-23
EXHIBIT #59

Table 1: Observed and Calculated Settling Velocities for Various Particle Sizes
(after Yousef et al. 1991, USEPA 1986, TRB 1980)
Average Settling Velocity
‘cni/sec)
4,96
2 3d
0059-0070
i e 0008-0018 :
— 0.0005 :
00007
a — 0.00027 _
0.00008
Note:” Silt settles at a rate of 0.006 inches per minute to 2.7 inches per minute in a water column.
References
Yousef A. Yousef et al. 1991. Final Report on Maintenance Guidelines for Accumulated Sediments in Retention/Detention
Ponds Receiving Highway Runoff. Florida Department of Transportation, Tallahassee, Florida.
Sartor & Boyd. 1972. Water Pollution Aspects of Street Surface Contaminants. EA-R2-72-081, EPA Washington, D.C.
USEPA 1986. Methodology for Analysis of Detention Basins for Control of Urban Runoff Quality. USEPA 440/5-87-001.
Washington, D.C.

Table 2: Soil Textural Classifications
(after Donahue et al. 1977)
Soil Classification or Separate Diameter Range (microns)
Gravel 2000
| Very coarse sand 8 4000 2000
Coarse sand 500-1000
Medium sand e 80 500
| Fine sand _ 100-250
| Very fine sand oo 50 2 100
Silt : : 2-50 c
Ce 8 8 8
— 5
Notes: Corresponds to USDA particle size ranges

Table 3: Percentages of Suspended Solids in Urban Runoff
per Particle Size Categories
(After Rexnord, Inc, 1984 as reported in Yousef et al 1991)
Particle Size Category (microns) % Suspended Solids? % finer
>250 AD oo
88-250 oe 8753
44-88 _ i : 78.45
i average of mean values from four separate studies in Wisconsin, Pennsylvania, California and North Carolina
References
Yousef A. Yousef et al. 1991. Final Report on Maintenance Guidelines for Accumulated Sediments in Retention/Detention
Ponds Receiving Highway Runoff. Florida Department of Transportation, Tallahassee, Florida.