NCG140453 - Carolina Ready Mix South Asheville Plant (3)

•
NARRATIVE REPORT
for
NPDES General Permit NCG140000
for
Carolina Ready Mix and Builders Supply, Inc.
Fletcher Facility
BEA PROJECT #446517
Issue Date: March 2, 2017
Prepared for:
CAROLINA READY MIX AND BUILDERS SUPPLY, INC.
608 Old U.S. 70
Swannanoa, North Carolina 28778
[phone]
Prepared by:
a /
32
i
1
BROOKS ENGINEERING ASSOCIATES
17 Arlington Street
Asheville,NC 28801
[phone]

PROJECT DESCRIPTION
This project consists of the permitting of stormwater and wastewater discharge from a concrete
ready mix plant located near Fletcher,North Carolina.
SITE DESCRIPTION
The site is located on a mostly cleared 2.9 acre parcel located at 264 Mills Gap Road,near
Fletcher,North Carolina. The site currently consists of a level graded site area. Site topology is
slightly sloping from Mills Gap Road to rear of property. The site slopes from the northeast to
southwest. The lowest area is along the southeastern property line. Hoopers Creek, a Class C
watercourse,is the receiving waterbody and lies to the southeast of the subject property.
Stormwater discharge from the site to receiving waterbody is routed through ephemeral drain-
ways.
PURPOSE
The purpose is to obtain a NPDES General Discharge Permit NCG 140000 to discharge
stormwater and wastewater under the National Pollutant Discharge Elimination System(NPDES)
and to obtain an Authorization to Construct(ATC)to implement the necessary infrastructure to
comply with NPDES requirements.
PROCEDURES
To discharge stormwater/process wastewater under the NPDES a Notice of Intent(NOI)
application is to be submitted to the North Carolina Department of Environment and Natural
Resources(NCDENR). Engineering plans and other pertinent data are to be submitted as
designated in the NOI application.
FINDINGS
To comply with NPDES requirements,Brooks Engineering Associates,PA(BEA)has provided
engineering plans sealed March 2,2017 that depicts the current existing conditions. Effluent
limits for the current site configuration can be achieved through a recycle system and a water
mass balance. The truck washdown area has been graded to allow all site process wastewater to
be collected in a single small basin area; all other surface water will bypass the wastewater basin
and be treated as stormwater. The stockpile areas are located within an isolated area and consist
of material that has already been washed and will not be wetted down. The truck washdown area
will collect all material from the truck and drum washdown into a ramped wastewater collection
basin that will allow all heavy material and settable solids to settle out. The settling basin fmal
bay can store 7767 gallons at full capacity. Wastewater from the settling basin final bay will be
pumped by manual control panel operation to the existing concrete production system. The
existing settling basin meets storage requirements from calculations for the 25 year,24 hour
storm event and maximum daily water use classified as wastewater. Calculations have been
provided as Attachment"A". From the calculations provided there is a water balance surplus of
601 gallons. The settling basin can accommodate surplus water until it can be recycled into plant
operations. All total suspended solids and pH are contained on site and reused for concrete. A
Stormwater Pollution Prevention Plan(SPPP)will be written as required by the NPDES permit in
concurrence with the proposed plan.

ATTACHMENTS
The following attachments have been included as part of the requirements set forth in the NOI.
Attachment"A"-Wastewater System Calculations
Attachment"B"-NOAA Rainfall Data
Attachment"C"-USGS Quadrangle Site Location Map

ATTACHMENT A

Project Name: Carolina Ready Mix-Fletcher
Project#: 446517
Date: 3/1/2017
MPRIV
Sheet: 1 of 1
TV
BROOKS ENGINEERING ASSOCIATES
Daily Water Use Calculations
Daily Maximum Number of Trucks: 7 trucks
Wash down Water Usage: 15 gallons/truck
7 trucks x 15 gallons/truck = 105 gallons
Rainfall Volume Calculations
Note: The precipitation estimate(in.)for a 25 year, 24 hour storm for 35.43 N, 82.48 W(subject site)
is 5.95 in. (0.496 ft) per the"Precipitation- Frequency Atlas of the United States" NOAA Atlas
14,Volume 2, Version 3.
Wastewater Basin Area: 1600 ft2 (see site plan for further detail)
Wastewater Basin Volume (V) = 1600 ft2 x 0.496 ft 794 ft3
or 5936 gal
Total V=Wash down Volume+ Rainfall Volume= 105 gallons+ 5936 gallons
Total Volume to Recycle System = 6041 gallons
Total volume to System: 6041 gallons
Total Storage Provided: 7767 gallons
%Storage Used: 78% %
% Storage Freeboard: 22% %
Concrete Production Water Usage Calculation
Average Daily Production of Concrete (yds.) 160 yds.
Water Required per yd. of concrete(gallons) 34 gallons
Average Daily Production Water Use: 5440 gallons
Water Balance Calculation (For a 25 year, 24 hour storm event and Average Daily Production)
Total Water=Total Volume to Recycle System-Average Daily Production Water Use
6041 gallons - 5440 gallons - 601 gallons
Recycle Time: 0.1 days

ATTACHMENT B

Precipitation Frequency Data Server http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?tat=35.4300...
NOAA Atlas 14,Volume 2,Version 3
Location name: Fletcher,North Carolina,USA*
Latitude:35.43°,Longitude:-82.48° •uta
Elevation:2081.52 ft** I
"source ESRI Maps '4,; s°
"source USGS
POINT PRECIPITATION FREQUENCY ESTIMATES
G M Bonnin,D Martin,B Lin,T Parzybok,M Yekta,and D Riley
NOAA National Weather Service,Silver Spnng,Maryland
PF tabular I PF graphical I Maps & aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence en_ ce_in__te_r_v_a_ is (in in_ches)1
Average recurrence interval(years)
Duration 1 2 1 5 L 10 -25 50 J 100 200 1 500 1000
0.367 0.437 0.524 0.590 0.676 0.741 0.8070.873 I 0.958 1 1.03
5-min (0_332-0 408)(0_395-0 485)1(0 473-0 581) (0 531-0 652)1(0 604-0 747),(0.658_0 819);(0 713-0 893);0 766-0 968)1(0 831-1 07) (0 882-1 15)
0.587 0.699 1 0.839 0.944 ' 1.08 1.18 ( 1.28 1 1.38 I 1.52 i' 1.62
10-min (0 530-0 651):(0 633-0 775)1(0 757-0 930) (0 848-1 04) (0 962-1.19) (1 05-1 30) j (1 13-1 42) (1 22-1 53) I (1 31-1 69)1 (1 39-1 82)1
•
15-min 0.734 1 0.879 1 1.06 1, 1.19 1.36 1.50 1.62 1.75 1 1.91 2.03 ;
1 ;(0 662-0 814) (0 795-0 975)' (0 957-1 18)I (1 07-1 32) (1 22-1 51) (1 33-1 65) (1 43-1 79) (1 53-1 94) (1 66-2 13) (1 74-2 28)I
' 30-min 1.01 1.21 1 1.51 1.73 2.02 2.25 2.48 2.72 1 3.04 3.29 ,
(0 908-1 12) (1 10-1 35) 1 (1.36-1 67) (1 55-1_91) (1 81-2 23) (2 00-2 49) ' (2 19-2 75) (2 39-3 02) (2 63-3.39) (2 82-3 69):
60-min 1.25 1.52 1 1.93 1 2.25 2.69 3.05 ! 3.42 3.81 4.36 4.80
(1 13-1 39) (1 38-1 69)j (1 74-2 14) • (2 02-2 49) (2 41-2 98) (2 71-3 37) , (3 02-3 79) (3 35-4 23) (3 78-4 86) (4 12-5 39),
2-hr 1.47 1.78 1 2.25 2.63 3.15 3.58 4.03 4.52 5.20 5.75
1
1 (1 32-1 63) (1 61-1 97) 1 (2 02-2 49) (2.35-2 90) (2 81-3 48) (3 17-3.96) (3 54-4 47) (3 93-5 01) (4.47-5 79) (4 90-6 45)
1.57 1.902.38 2.78 3.36 3.84 I 4.36 4.92 5.73 6.41 '
1 3-hr (1 42-1 75) (1 71-2 11) (2 14-2 64) (2 49-3 08) (2 99-3 72) (3 40_4 26) i (3 82-4 84) (4 26-5 48) ; (4 90-6 42)1 (5 41-7 22)
1 1.97 2.35 2.90 1 3.37 4.06 4.64 5.28 5.97 1 6.98 7.83
6-hr
(1 80-2 17) (2 14-2 58) (2 64-3 18) (3 06-3 70) (3 65-4 45) (4 __ . ..09) (4 66 5 80) (5 21-6 58) (5 74) (6 64_8 73)
1 12-hr 2.48 2.96 1 3.64 1 4.18 4.94 5.57 6.21 1 6.90 ( 7.85 1 8.62
(2 28-2 71) (2 72-3 24) 1 (3 33-3 97) ' (3 82-4 57) (4 49-5 40) (5 04-6 08) I (5 59-6 80) 1 (6.16-7 58) 1 (6 94-8 69) (7 54-9 60);
24-hr 2.96 3.55 1 4.38 1 5.04 lf- 6.69 7.45 8.25 1 9.36 : 10.2
1 (2 74-3 21) (3 29-3 86) 1 (4 06-4 75) • (4 66-5 46) I i; 8.48-6,A'"' (6 14-7_25)„' (6 80-8 07) (7 48-8 94) I (8 42-10 2)' (9 14-11.1)
3.52 I 4.21 5.14 I 5.88 6.90 7.72 8.57 9.45 j 10.7 11.6
2-day (3.27-3 80) (3 90.4 54) I (4 77-5 55) (5 44-6 35) (6 37-7_45)__ (7.09-8 34) , (7 84-9 26) (8 59-10 2)] (9 61-11 6)' (10 4-12 7)!
3-day 3.75 4.48 5.43 1 6.18 7.20 8.01 8.84 1 9.69 10.9 11.8
: (3 49-4 04) (4 17-4 82) (5 04-5 84) (5 73-6 64) (6 65-7 74) (7 37-8 62) , (8 11-9 53) 1 (8 84-10 5) , (9.83-11 8), (10 6-12 8),
4-da 3.99 4.75 I 5.71 I 6.47 7.49 8.29 1 9.10 9.93 11.1 12.0
y ! (3 71-4 28) (4 43_5 10) 1 (5 32-6 13) 1 (6 01-6 94) (6 93-8 04) (7 65_8 90) , (8 37-9 79) (9.10-10 7) (10 1-11 9) (10 8_13.0)
7-day4.64 5.51 1 6.62 7.49 8.68 9.62 10.6 11.6 12.9 14.0
L(4 33-4 98) (5 15-5 92) 1 (6 17-7 10) ; (6 97-8 04) (8 05-9 30) (8 89-10 3) (9 75-11 3) (10 6-12 4) (11 7-13 9) (12 6-15 1)
10-day 5.31 6.28 1 7.46 8.39 9.65 10.6 � 11.6 12.7 14.0 I 15.1
(4 99-5_65) (5 91-6.70) 1 (7 01-7 95) (7 88-8 93) (9 03-10 3) (9 93-11 3) ; (10 8-12 4) (11 7-13 5) (12_9-15 0)' (13 8-16 2)
1 7.19 1 8.45 1 9.84 1 10.9 12.3 13.3 14.4 15.4 16.7 17.7
i 20-day (6 79-7 60) 1 (7 99-8 95) 1 (9 29-10 4) ; (10 3-11 5) (11 6-13 0) (12 5-14 1) (13 5-15 2) (14 4-16 3) I (15 6-17 7), (16 4-18 8)
1 8.82 1 10.3 1 11.8 13.0 14.4 15.4 ' 16.4 ( 17.4 18.6 19.4 1
30 day j (8 37-9 30) (9 81-10 9) (11 2-12 5) , (12 3-13 7) (13 6-15 2) (14 6-16 3) j (15 5-17 3) 1 (16 3-18 4) 1 (17 4-19 6) (18 1-20 6)
l 11.2 13.1 1 14.8 l 16.0 17.4 18.5 19.4 20.3 1 21.4 22.1 '
45-day 1 (10 6-11 8) I (12 4-13 8)____1 (14 0-15 5) (15 2-16 8) (16 6-18 4) (17 5-19 5) ' (18 4-20 5) (19 2-21 4) 1 (20 2-22 6)1 (20 8-23 4)
60-day 13.4 15.6 1 17.5 18.8 20.4 21.5 , 22.5 23.4 24.5 1 25.3
(12.8-14 1) (14 9-16 5) 1 (16.6-18 4) I (17.9-19 8) (19 4-21 5) (20 4-22 7) j (21 4-23 8) (22 2-24 8) j (23 2-25 9) (23 8-26 8)
1 Precipitation frequency(PF)estimates in this table are based on frequency analysis of partial duration series(PDS)
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90%confidence interval The probability that precipitation frequency estimates 1
(for a given duration and average recurrence interval)will be greater than the upper bound(or less than the lower bound)is 5% Estimates at upper bounds '
are not checked against probable maximum precipitation(PMP)estimates and may be higher than currently valid PMP values
Please refer to NOAA Atlas 14 document for more information
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ATTACHMENT C