20160191 Ver 1_Environmental Impact Statement Comments_20071205

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MICHAEL F. EASLEY
GOVERNOR
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STATE OF NORTH CAROLINA ��ST��w,,.
DEPARTMENT OF TRANSPORTATION �A'� Rx�,.�
LYNDO "I7PPETT
SECREfARY
December 5, 2007
Memorandum To: David Wainwright, NC Division of Water Quality, Transportation
Permitting Unit �i'�
From:
Subject:
Colin Mellor, NCDOT, PDEA — Natural Environment Unit
Addendum to the Indirect and Cumulative Impact Water Quality
Report for the Greenville Southwest Bypass, Pitt County, TIP R-
2250
Attached is the addendum to Indirect and Cumulative Impacts Water Quality RepoR.
The addendum addresses the questions raised by NCDWQ in a Memorandum dated June
13, 2007, and further discussed at a meeting of NCDOT and NCDWQ on September 12,
2007.
Please call (715-1426) or email (cmellor(a�,dot.state.nc.us) me if you have any questions.
cc:
Chris Underwood,
Bob Deaton,
Beth Smyre,
MAILINO ADDRESS:
NC DEYMTMENf OF TRr1N5PORT�TqN
PRQIECT DEVELOVMEM AND ENVIRONMEM�L AN�LYSIS
NATUML ENVIRONMEM UNR
1598 MNL SERVICE CENi£R
RLLE�GH NC 2789&1598
Natural environment Unit
Human Environment Unit
Project Development
Te�ev�wHe: 91 &775-1335 w 919-7157334
FAX: 91&7151501
WEeS�7e www.NCD0T.0/tG
LOCATION:
TRANSPORTATqN BUIIpNG
1 $OUfX WILMINCTON $TREET
RueioH NC

GREENVILLE SOUTHWEST BYPASS
INDIRECT AND CUMULATIVE IMPACT WATER QUALITY STUDY UPDATE
Comments from the NCDWQ staff on the report submitted by NCDOT regarding the
Indirect and Cumulative Impacts (ICI) associated with the Greenville Southwest Bypass
(Greenville Bypass) in Pitt County, North Carolina (TIP R-2250) included concerns about
the assumptions regarding septic tank failure rates in the original watershed modeling
analysis. Concerns were also raised in regards to the geographic extent of stream
buffers projected in the watershed model to meet requirements of the Neuse River NSW
strategy. Over and above the concerns raised by NCDWQ, changes in land use patterns
projected to result from development of the Greenville Bypass have occurred since the
ICI study was completed as a result of the elimination of one of the roadway
interchanges in the bypass design (Figure 1). In order to address NCDWQ comments
and account for the impacts of these land use changes, additional model runs were
performed. This memo, which serves as an addendum to the original Greenville
Southwest Bypass ICI Water Quality Report (NCDOT 2006b), contains the model results
as well as a discussion regarding the impacts of adding streams shown on the Pitt
County Soil Survey. �
NEW MODELING SCENARIOS
The Generalized Watershed Loading Function (GWLF) model was .used to simulate
long-term loading of nonpoint source pollutants. Two additional runs of the model were
completed in order to address septic tank failure rates and the elimination of an
interchange. Full details on the previous model assumptions and parameters can be
found in the original report (NCDOT, 2006b).
Septic Ta�/r Fai/ure Rates � ,
The GWLF model incorporates four different septic tank `types' in order to account for
septic tank failure. `Normal' systems conform to EPA guidelines, in which nitrogen
entering surface water is assumed to be a factor of plant uptake or its ability to infiltrate
groundwater and subsequent discharge to streams. Phosphorus is assumed to be
completely absorbed by soils in this scenario. In `short-circuit' systems, the septic tanks
are assumed to be in close-proximity to streams, and therefore phosphorus absorption
by soil is assumed to be negligible. `Ponded' systems describe septic tanks with
hydraulic failure, resulting in the surfacing of tank effluent which enters surface water via
overland flow. `Direct discharge' systems are illegal systems which discharge tank
effluent directly to surtace water. .
Septic tank failure rates are applied in the GWLF model by adjusting the percent of the
population which uses each `type' of septic system. In the model performed for the
original ICI study, 100% of the septic-using population was assumed to be using the
`normal' septic system.
Statistical data on septic system malfunction in North Carolina is very limited. Data
obtained for this study from the Pitt County Management Information Systems Office on
septic repair permits resulted in a calculated septic failure rate of less than one percent.
This is likely a gross underestimation of failure rate given the limited time period of
recorded failures (4 years) and that some systems with failure are never reported.
Instead, a septic tank failure rate was assumed based on a state-wide survey performed
by the North Carolina.Office of State Budget and Management in 1981. In this citizen
survey, 11.4% reported septic system malfunction or failure in the preceding year
(NCDEH, 2000).

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Greenville Southwest Bypass
ICI Water Quality Study Update
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Figure t. Project Study Area
ICI Water QualiTy Study
Greenville Soutwest Bypass
TIP No. R�2250, PiV Counry. NC
�� �'�� Notlh Carolina
� Department oi Transpotlation
Pitt Count
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L

Greenville Southwest Bypass
ICI Water Quality Study Update
Given that the failure rate reported was based on homeowner observation, the most
accurate representation of this failure in the GWLF model . is the `ponded' system
scenario. It is assumed that no illegal `direct discharge' systems are present in the
watershed. Using inputs developed for the Build scenario of the original ICI report,
88.6% of the population on septic systems was input as using `normal' septic systems
and 11.4% on `ponded' systems. The GWLF model was used to generate 10 years of
annual total nitrogen (TN) and total phosphorus (TP) loads in the watershed. These
loads were aggregated into 10-year . pollutant loads of TN and TP for each
subwatershed. The results are presented by pollutant in Table 1.
Table 1. Ten-year Total Loads (tonnes) for All Subwatersheds in the `Normal' and
`Normal + Pondin ' Se tic Failure Scenarios
Total Nitro en Total Phos horus
Normal + % Change . Normal + % Change '
Subwatersheds Normal Pondin Over NormaC ' Normal Pondin Over Normal
U F2 147 147 0% 9.06 10.52 16%
UF1 58 58 0% 11J2 11.81 1%0
UE1 133 133 0% 724 8.64 19%
UD1 17 17 0% OJ5 0.91 21 %
UC1' 73 73 0% 3.53 4.22 20%0
UB1 30 - 30 0% 1.23 1,50 22%
UA3 165 165 0%0 8.65 10.39 20%
UA2 59 59 0% 10.51 10.73 2% -
UA1 55 55 0% 6.85 7.16 5%
SC8 63 63 0% 9.47 9.59 1%.
SC7 53 53 0% 6.55 6.82 4%
SC6 59 59 0% 10.58 10.64 1%
SC5 67 67 0% 11.32 11.48 1%
SC4 151 151 0% 14:23 15.41 8%
SC3 79 79 0% 14.38 14.39 0%
SC2 58 58 0% 10.58 10.69 " 1%
SCi 92 92 0% 17.42 17.42 0%
PB4 122 122 0% 5.81 7.07 22%
P63 70 70 0% 3.63 4.35 � 20%
PB2 43 43 0% 329 3.68 12%
PB1 53 53 0% 9.77 9.83 1%
Total 1646 1646 0% 177 187 6%
The septic tank failure scenario demonstrated a 6% increase in TP loading in the entire
study area watershed, with loading increasing between 0 and' 22% among the
subwatersheds (Table 1 and Figure 2). No change in TN loading was observed between
the two scenarios. This is not surprising given the dynamics of the model and nature of
the nitrogen cycle. In the model performed for the original ICI study, 100% of the septic-
using population was assumed to be using the `normal' type of septic system. In this
system, nitrogen from septic tanks loads to surface water via infiltration to groundwater
and its subsequent discharge to sfreams.
In a conventional septic tank and drainfield system organic nitrogen �in household wastes
is transformed into ammonia products in the anaerobic conditions of the septic tank, a
process referred to as ammonification. When these products exit the septic tank and
encounter the aerobic conditions in the drainfield, the ammonia products are .
3

Greenville Southwest Bypass
ICI Water Quality Study Update
biochemically transformed primarily into nitrates, referred to as nitrification (Washington
State DOH, 2005). In the 'ponding' septic scenario, the nitrogen travels quickly to the
surface, rather than entering the drainfield where nitrification would occur, and almost all
of the nitrogen is lost to the atmosphere through the volatilization of ammonia.
Phosphorus, on the other hand, adsorbs to soils, and in the 'ponding' scenario is
available for loading to surface water via runoff and overland flow. The largest increases
in TP loading were observed in subwatersheds with a high percentage of very low
density residential land use.
Figure 2. Mean Annual Total Phosphorus Loading Rates
2.00
1.80
1.60
1.40
T 1.ZO
r 1.00
Y 0.80
0.60
0.40
0.20
0.00
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Greenville Southwest Bypass
ICI Water Quality Study Update
NC-903/nte�change Hemo�a/ � .
Since the ICI study was completed in May of 2007, the previously planned NC Highway
903 interchange has been eliminated. To account for this design change, the Build
scenario was re-evaluated (Figure 3 Project Subwatersheds). County officials had
expected commercial and light industrial growth in this area as a. result of the
interchange (Figure 4a Original Future Build Land Use/Land Cover Scenario). In
addition, higher density residential housing was anticipated in the area around the
interchange. These predicted land uses have been replace,d with the Residential — Low
Density category which is consistent with the No-Build scenario. A revised Future Build
Land Use/Land Cover Scenario has been created to depict these changes (Figure 4b
Revised Future Build Land Use/Land Cover Scenario).
To model the above scenario, the land use changes in the three subwatersheds affected
by the interchange elimination (UF2, UE1, SC4) were incorporated into the previous
model run developed to include septic tank failure rate. The'GWLF model was then used �
to generate time series reflecting 10 years of annual TN, TP, and sediment loads, which
were aggregated to 10-year pollutant loads. The results are presented in Table 2. A 1%
decrease in TN loading was observed in subwatersheds UF2 and UE1, with a 3%
decrease in SC4, resulting in a study area decrease in TN loads of less than one percent
(Figure 5). TP loads were decreased by 4%, 4%, and 8% in subwatersheds UF2, UE1,.
and SC4 respectively (Figure 6). The total reduction in TP loading in the study area was
approximately 1%. Sediment loads also decreased as a result of the change in, land use
in the three subwatersheds. Loads were decreased by 5%,� Z%, and 11 % in each of the
respective subwatersheds, with a total study area decrease in sediment loads of
approximately 1 % (Figure 7). !
5

Greenville Southwest Bypass
ICI Water Quality Study Update
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♦ WeatherStation Municipalities
Ayden ETJ �CI Water Quality Study - Gfeenville Bypass
L___ � Motlel Subwa�er5hetls TIP No. R�225o, Pin Caunry. NC
�'�.� Impaired Strearns Greenville ETJ ..
� Streams Greenville Proposed ETJ � Nonh Carolina
- Water Bodies W�ntervi�le ETJ +��' Depahment oi Trensportation
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Greenville Southwest Bypass
ICI W ater Quality Study Update
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iC� Water �uaiii Stud
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— Paved Foatl with Righ� ol Way (fi1 %) � Greenvtlle Proposed ETJ
Weliantl Winierville Proposetl ETJ
7

GREENE
Greenville Southwest Bypass
ICI Water Quality Study Update
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� SoleCtetl Allematrve
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- Resitlential Medwm High Oonsiiy (17%) ^ Streams p �
- Resitlentiai Medium Low Densiry (�3%) � Walershetl Bountlary ` Notlh Camlina
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- Pavea Road witn Right ot Way (61 %) � Greanville Proposed ETJ
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Greenville Southwest Bypass
ICI Water Quality Study Update
Table 2. Ten-year Total Loads (tonnes) for All Subwatersheds in the Revised Septic and
Revised Se tic with Land Use Chan e Scenarios
�, Total Nitro en � Total Phos horus � Total Sediment �
� � , >
a�
N Revised � .� Revised � .� Revised � �
� Revised Septic + � � Reuised Septic + � � � � Revised Septic + � �
� Septic LU .c � Septic LU �� Septic LU ��
� Change o • Ghange o C'hange o
� � � o
UF2 147 145 -1%� 11 10 -4% 468. 495 -5%
UF1 58 58 0% 12 12 0% 748 748 0%
UE1 133 132 -1% 9 8 -4% 422 , 454 -7%
UD1 17 17 0% 1 1 0% 170 170 0%
UC1 73 73 0% 4 4 0% 362 362 0%
UB1 30 30 0% 1 1 0% 201 201 0%
UA3 165 165 0% 10 10 0% 483 483 0%
UA2 59 59 0% 11 11 0% 802 802 0%
UA1 55 55 0% 7 7 0% , 557 557 0%
SC8 63 63 0% 10 10 0% 620 620 0%
SC7 53 �3 0% 7 7 0% 327 327 0%
SC6 59 59 0% 11 11 0% 667 667 0%
SC5 67 67 0% 11 11 0% 707 707 0%
SC4 151 146 -3% 15 14 -8% 626 700 -11 %
SC3 79 79 0% 14 14 0% 1004 1004 0%
SC2 58 58 0% 11 11 0% 852 852 0%
SC1 92 92 0% 17 17 0% 1312 1312 0%
PB4 122 122 0% 7 7 0% 424 424 0%
PB3 7.0 70 0% 4 4 0% 243 243 0%
P62 43 43 0% 4 4 0% 185. 185 0%
PB1 53 53 0% 10 10 0% 771 771 0%
Total 1646 1639 -0.4% 187 ' 185 -1 % 11951 12084 -1 %

Greenville Southwest Bypass
ICI Water Quality Study Update
Figure 5. Mean Annual Total Nitrogen Loading Rates
� 6 ■ Build
� ■ Revised Septic
14
�� ❑ Revised Septic + LU Change
12
10
i.
m 8
r
rn
Y
6
4
2
0
UF2 UE7
Figure 6. Mean Annual Total Phosphorus Loading Rates
1.4
■ Build
� 2 ■ Revised Septic
j❑ Revised Septic + LU Change
1 i
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A
t
y O.6
0.4
0.2
0
UF2
SCA
10
uEi SC4

Figure 7. Mean Annual Total Sediment Loading Rates
■ Build
60 — -
■ Revised Septic
50 � ��vi,ed Septir. +
LU Ch„nqe:
4�
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r 30
Y
20
10
0
N
7
STREAMS AND STREAM BUFFERS
Greenville Southwest Bypass
ICI Water Quality Study Update
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Comments from NCDW� included concern over the quantity of streams, and therefore the
amount of stream buffer, depicted on the land use scenarios. There was concern that the
addition of streams would enable more of a constituent (nitrogen, phosphorous, and sediment)
to enter the stream. Blue-line streams found on USGS topographic quadrangles were depicted
on an overlay of the land use scenarios. Additional streams found on the Pitt County Soil Survey
were not included in this overlay in the original study.
GWLF models runoff in a block by block manner. Each block represents a subwatershed.
Nutrient loads from different land uses within each subwatershed are based on the volumes of
flow and the associated flow pathways (overland and seepage), the amounts of soil eroded, and
concentrations that express the amount of nutrient load per unit volume of water flow or
sediment erosion from each land use. As noted, the only two flow pathways are overland flow
and seepage. GWLF does not model streamflow as a flow pathway, and therefore the amount
of streams found within the subwatershed is irrelevant as it will not affect the model outputs.
The quantity of streams depicted does have an impact on land use within the subwatersheds.
Specifically, the fifty-foot buffers that were created for each USGS blue-line stream were
classified as urban greenspace. Urban greenspace is modeled as a rural land use with low
concentrations of dissolved nitrogen and phosphorous. Eliminating these buffers would lead to
greater amounts of urban land uses which would increase the nutrient loads in the system.
Since the streams/channels depicted on the soil survey were not taken into account when
developing the land use scenarios, the amount of buffer, and therefore urban greenspace, is
most likely an underestimation. To illustrate this, additional streams/channels that appear on the
soil survey in seven subwatersheds were digitized. Stream length was calculated, as well as the
area of urban greenspace that the buffer would have occupied (Table 3). Results show that
adding the soil survey streams lead to an increase of between 40 and 80% of stream length,
11

Greenville Southwest Bypass
ICI Water Quality Study Update
depending on the watershed. This additional stream length leads to an increase of urban
greenspace in each watershed ranging from 1.85% to 5.6% of the subwatershed area.
I able 3. U5U5 tilue-line 5treams anci 5on 5urve 5treams
Additional Soil Buffer Area (hectare)
Subwatershed USGS Stream Survey Stream (using additional soil Percent of
Length (feet) Length (feet) survey streams) Watershed
PB1 22,086 15,563 14.46 1.85%
PB2 14,108 11,856 11.01 2.79%
PB3 24,435 � 16.698 15.51 2.76%
P64 53,562 43,870 40.76 3.8%
UA1 10,084 14,658 13.62 1.85%
UA2 7,236 28,161 26.16 � 3.67%
UA3 39,925 69,884 64.92 5.6%
Adding this urban greenspace area to the scenarios would lower the nutrient loads within the
subwatersheds, and additionally would increase the nutrient removal associated with these
buffers. This study aims to model a realistic scenario using conservative assumptions, therefore
the additional streams were not included. The addition of these streams is further shown to be
unnecessary since the resulting increase in urban greenspace would occur in both the Build and
No-Build scenarios.
Adding additional streams could increase the amount of buffer impacted by the proposed
bypass. However, jurisdictional streams have already been determined in the field for the entire
construction corridor. The jurisdictional streams (depicted in the Indirect and Cumulative Impact
Assessment on Figure 6 Water Resources (NCDOT 2006a)) that are affected by Alternate 4
closely match the USGS streams with the exception of one stream. A review of the soil survey
depicts five additional streams in the corridor.,However, these streams, most likely drainage
ditches, are not jurisdictional. � �
CONCLUSIONS
The new model results show that the effects of septic system failure are minimal in the
watershed. There is very little� data on septic system failure and as such, this could be an
underestimation of the impacts on water quality. However, there are less than 200 additional
septic systems in the Build scenar.io compared to the No-Build Scenario which contains over
7,000 septic systems. This is less than a 3% increase in septic systems. Therefore, impacts to
water quality as a result of failing septic systems may occur irregardless of construction of the
new roadway..
The original USGS streams and associated buffers used for modeling purposes depict a
conservative scenario for the study area. Adding more streams would not alter the conclusions
reached in the original ICI study.
12

Greenville Southwest Bypass
ICI Water Quality Study Update
REFERENCES
North Carolina Department of Transportation (NCDOT). 2006a. Final Technical Memorandum.
Greenville Southwest Bypass Indirect and Cumulative Impact Analysis. Prepared for NCDOT by
Lochner. May 2006.
North Carolina Department of Transportation (NCDOT). 2006b. Greenville Southwest Bypass
Indirect and Cumulative Impact Water Quality Study Report. Prepared for NCDOT by Stantec.
December 2006.
Washington State Department of Health. 2005. Nitrogen Reducing Technologies for Onsite
Wastewater Treatment Systems. Report to the Puget Sound Action Team. DOH Pub 334-083.
13

STATE OF NORTH CAROLINA
DEPARTMENT OF TRANSPORTATION
����on�d
JUL 2 3 2007
DENR - WATER �UALITv
WETLANDS AND STOR61YYq1 ER 9RA)!CH
MICHAEL F. EASLEY LYNDO TIPPETT
GOVERNOR � SECRETARY
]UlY 2�, 20�%
Memorandum To: David Wainwright, NC Division of Water Quality, Transportation
Permitting Unit
From:
Colin Mellor, NCDOT, PDEA — Natural Environment Unit ����
Subject: DWQ comments regazding the Indirect and Cumulative Impact
Water Quality Report for the Greenville Southwest Bypass, Pitt
County, TIP R-2250
The following responses refer to your comments on the above referenced report, received
June 29, 2007.
Comment 1: Current and projected sewer infrastructure aze discussed in Sections 2.3.3,
4.2.2, and Figure 4.2.2. Section 4.6.4 states how future septic inputs were estimated
using pazcels outside of probable future sewer serviced areas. SepUc systems were then
estimated based on projected lot densities and an average number of people per housing
unit. Unless there are specific data regazding the failure of septic systems, as an
assumption, "normal" septic systems (assume functioning) seems reasonable.
Comment 2: The modeling performed for this study quantifies the indirect and
cumulative changes in land use expected to be caused by the construction of the Bypass,
and how these changes will effect the transport of selected constituents to the streams
within the established study area. In order to effectively model the in-stream fate of these
constituents the entire Little Contenmea Ck. and Swift Ck. watersheds would need to be
analyzed. This type of analysis is significantly outside the scope of this ICI modeling
study.
Comment 3: The seepage co-efficient was selected because it was appropriate for the
soils of the study area. It yielded a result consistent with published pazameters. Given
that this loss is only 3% of the water balance, altering the coefficient to yield a 1/: or 1%
change would not produce significantly different results. Note that the 2.5 to Scm/yr
infiltration (-2 to 3% of the water balance) comes from a study specific to the North
Carolina coastal plain.
MAIIJNG ADDHESS:
NC DEGRRTMENT OF TqANSPORTRTqN
PPOJECT DEVELOPMENT AND ENVIRONMFNTRL ANALY515
N�TUflM ENVIPONMENT UNR
1 S98 MRR SERVICE CEMER
Rn�eicH NC 27699-1598
TElEaeor+e: 919-715-1335 or 91 9-71 54 334
FAX: [phone]
WEBSITE: WWW.NCDOT.ORG
�ocanorr:
TRRNSPORTATION BUILOING
1 $OIRH W ILMNGTON STREEi
MLEqH NC

Response to DWQ comments on the R-2250 ICI Water Quality Report
Page 2
Comment 4: The overall general conclusion of growth occurring with or without the
bypass was extensively re-researched for this study at the behest of John Hennessey,
following the results of the 2006 ICE document. This conclusion is supported by the data
presented in the report, which was retrieved from published sources and local planners in
the municipalities and counties within the study area (e.g. Sect. 2.3.3 para. 3; Sect. 2.3.4
para. 2). I agree, the statement on page 4-6, Section 4.2.2.1 is a little misleading, and
should probably read "The Build scenario is essentially the same as the No-Build for the
Greenville...". I wish we had caught that when editing the drafts. However, comparison
of Figures 4.2.3 and 4.2.4 shows that the model inputs were exactly as you say, with the
intersections of the Bypass with Forelines Rd., NC 903, and NC 102 showing more
intense (Commercial/Heavy Industrial, Residential-MultiFamily, and Residential High
Density) development.
Comment 5: If there are substantially more (or any) streams indicated on the NRCS
soils maps for the county then the model input should have produced a conservative
result.
If these responses do not adequately address your comments we should probably schedule
a meeting at your earliest possible convenience. Please do not hesitate to call (919-715-
1426) or email ([e-mail]) if you have further questions.

�"�'"'�._�'
Michael F. Easley, Governor
William G. Ross Jr., Secretary
North Carolina Department of Environment and Natural Resources
June 13, 2007
Alan W. Klimek, P.E. Director
Division of Water Quality
MEMORANDUM
To: Colin Mellor, NCDOT
Through: John Hennessy, Supervisor, NC Division of Water Quality, Transportation Permitting Unit
From: David Wainwright, NC Division of Water Quality, Transportation Permitting Unit
Subject: Comments regarding the Indirect and Cumulative Impact Water Quality Study Report for the
Southwest Greenville Bypass, Pitt County, TIl' R-2250.
In response to your correspondence dated February 2007 in which you requested comments for the ICI for
the referenced project, the Division of Water Quality has reviewed the document and provides the
following comments:
Section 5.2 discusses pollutant loading. The text states that the model assumes no phosphorous
export for properly functioning septic systems. However, potential nutrient loading from failing
and faulty septic tank systems is not discussed. In some cases, this loading can be significant..
It appears that the model inputs regarding septic tanlcs are estimated based on existing septic
tanks. It is stated that sewer service is a limiting factor with regard to growth and development,
but future development in areas that will not be sewered and will utilize septic tanks does not
appear to be considered. A map showing future sewered areas is not shown, making it difficult to
deternune how much development (especially residential) will occur outside of sewered areas.
2. Based on the results provided in the report, the DWQ believes that an in-stream model needs to
be developed far watersheds UE1, LTF2, UF1, SC2, SC4, and SC6. The modeling results indicate
the largest increases in flow, nitrogen, phosphorous, and sediment occurs within these
watersheds. Watersheds,LTEl, UF2, and LTF1 discharge either directly or indirectly into Little.
Contentnea Creek, which is listed on the 303(d) list for low dissolved oxygen and biological
integrity. Increases of nitrogen and phosphorous could increase algal growth (especially nitrogen,
which appears to be the limiting nutrient), which in turn could result in decreased dissolved
oxygen due to eutrophication. An inerease in sediment could lead to excessive sedimentation and
an increase in turbidity, thereby disrupting the biological integrity of Little Contentnea Creek.
Watersheds SC2, SC6, and SC4 discharge into Swift Creek, listed on the 303(d) list for biological
integrity. As with Little Contentnea Creek, an increase in sediment loading could alter the
biological integrity of the stream.
Modeling will be necessary to show that projected impacts from the bypass will not further
violate water quality standards and any TMDLs that may be developed in the future. The DWQ
is willing to discuss this further if necessary.
NorthCarolin
Transportation Permitting Unit �lit6fPC1��1,�
1650 Mail Service Center, Raleigh, North Carolina 27699-1650
2321 Crabtree Boulevard, Suite 250, Raleigh, North Carolina 27604
Phone: [phone] FAX [phone]/ Internet: h#tq:!/h2o.enr.state.nc.usincwefiands
An Equal Opportunity/Affirmative Action Employer— 50% Recycled110% Post Consumer Paper

Section 4.4.2 discusses the seepage coefficient. It is stated that typically, 2.5 to 5 cm of the
annual precipitation, or two to three percent, infiltrates to the deep aquifer. A coefficient of 0.015
was used, resulting in a 3 percent loss to the aquifer. It is not clear how sensitive the model is to
this coefficient, but would it have been more appropriate for a two percent loss, which would
haue been more conservative? Or, since the parameter is site specific, perhaps using a coefficient
resulting in a 2.5 percent loss (average for the state) would also have been appropriate. Please
provide more information about model sensitivity to this parameter or rerun the model with the
more conservative input value.
4. The document suggests that for the Greenville area (including the ETJ area) the build and no
build scenarios are the same with respect to development, and that current growth trends indicate
growth regardless of bypass construction. The DWQ does not deny that growth in these areas
will occur if the bypass is not constructed. However, it is assumed that a high-speed, four-lane,
divided highway with full-control of access with links to major arterial roads would be appealing
to commercial and industrial businesses. This would lead one to conclude that more commercial
and industrial development would occur in the close proximity to the roadway, especially near
intersections, than would if the roadway were not built. If this were allowed to happen the build
and no-build scenarios presented would not be the same: According to Table 4.2.5,
office/institutional/light industrial land uses and commerciaUheavy industrial land uses have some
of the highest impervious areas (53 and 71 percent, respectively), leading to more stormwater
runoff and pollutant loading. Please rerun the model with more appropriate land use change
information.
5. Section 4.7.1 discusses the Neuse River Nutrient Sensitive Waters Management Rules. The last .
sentence indicates that a fifty-foot buffer was applied around all streams found on USGS stream
coverage map. It is assumed that this was done to comply with the Neuse River Buffer Rules. It �
should be noted that the rules also state that streams indicated on the paper series of the NRCS
• soils maps for the county of interest are also subj ect to buffer protection as well. The DWQ
requests that the NCDOT rerun the model, imposing the fifty-foot buffer on all streams shown on
both the USGS maps and the NRCS Soils Survey maps.
Thank you for requesting our input at this time. The DWQ will be willing to schedule a meeting to
discuss the requests being made or any other items of concern. If you have any questions, require
additional information, or would like to schedule a meeting, please contact David Wainwright at (919)
715-3415.

Chapter 3: Establishing Tieatmenf System Perfvrmance Re�quireinents �
Table 3-7. Constituent mass loadings and concentrations in typical residential wastewater'
Constltuent Mass loading Concentration°
(grams/persoNday) (mglL)
Total solids (1
Volatile solids
Total suspended solids (TSS)
Volatile suspended solids
5-day biochemical o�rygen demand (BODs)
Chemical oxygen demand (COD)
Totai nitrogen (TN)
Ammonia (NH,)
Nitrites and nitrates (N0� N; N0,-N)
Total phosphorus (TP)`
Fats, oils, and grease
Volatile organic compounds (VOC)
Surfactants
Total coliforms (TC)°
Fecal coliforms (FC)°
65-85
35-75
25-60
35-65
11 �r150
6-17
1-3
<1
1-2
12-18
0.02-0.07
2-4
280-375
155-330
11 �265
155-286
500-660
26-75
4-13
<1
Cr12
7�105
0.1-0.3
9-18
10e_� ��o
1 �°-10°
' Fortypical residemial dwellings equipped wllh standard water-using tiztures and appllances.
' Milligrams per liter, assumed wa�er use of 60 gallonypersoNday (2271iters/personfday).
` The delergent industry has iowered ihe TP concentrafions since eady IiteraWre studies; therefore, Sedlak (1991) was used PorTP dafe.
° Concentrafions presented In Mast Pro6able Numberof organisms per 100 mi�liters.
Source: Adapted from Bauer et al., 1979; Bennett and Linstedt,1975; Laak, 1975, 1986; Sedlak, 7991; Tchobanoglous and Burton, 1991.
Table 3-8. Residential wastewater pollutant contributions by source' °
Paremeter Garhage disposal Toilet Bathing, sinks, Approximate total
(gpcd)` (gpcd)` appliances (gpcd)`
(gpcd)`
BODs mean 18.0 16.7 28.5 632
range 10.9-30.9 6.9-23.6 24.5-36.8
% of total (28%) (26%) (45%) (100qo)
Total suspended mean 26.5 27.0 172 707
solids range 15.8�3.6 12.5-36.5 10.8-22.6
%OftOtal (37%) (38%) (24%) (100%)
Total nitrogen
Total phosphorus°
mean
range
% 0� t0�8�
mean
range
% of total
0.6
0.2-0.9
(5%)
0.1
(4%)
8.7
4.1-16.8
(78%)
1.6
(59%)
1.9
1.1-2.0
(17%)
1.0
(37%)
112
(100%)
2.7
(100%)
' Adapled Irom USEPA, 1992.
' Means and ranges tor BOD, TSS, and TN are results reporled in Bennett and Linstadt,1975; Laak 1975;Ligman et al., 7974; Olsson et a1.,1968; and Siegrisi et a1.,1976.
` Grams per capita (parson) par day.
' The use of low-phosphale detergenls in recenl years has lowered Ihe TP concenVatlons since eatty IUeraWre sludies; Iherefore, Sedlak (1991) was used for TP daU.
USEPA Onsife Wastewater Treatment Systems Manual 3-11

Chapter 3: Estab/ishing Treatment System Per/ormance Re'quiremenls ,
Table 3-16.Typical wastewater pollutants of concern
Pollutant
Reasonforconcern
Total suspended solids In surface waters, suspended solids can result in ihe development of sludge deposits that smother benthic
(TSS) and turbidity (NTU) macroinvertebrates and tish eggs and can contribute to benthic enrichment, toxicity, and sediment oxygen
demand. 6ccessive turhidity (colloidal solids that interfere wflh light pe�etration) can block sunlight, harm
aquatic life (e.g., by blocldng sunlight needed by plants), and lower the ability of aquaUc plants to increase
dissolved oxygen in fhe water column. In drinking water, turbidiry is aestheUcally displeasing and interferes
with disinfection.
Biodegradable organics Biological stabilization of organics in the water wlumn can deplete dissolved o�rygen in surface waters,
(BOD) creaiing anoxic conditions harmfui to aquatic life. O�rygen-reducing conditlons can also result in taste and
odor problems in drinking water.
Pathogens Parasites, bacteria, and viruses can cause communicable dlseases through dlrecWndirect body contact or
ingestion of contaminated water or shelKish. A particular threat occurs when partially treated sewage pools
on ground sur(aces or migrates to recreational waters. Transport distances o( some pathogens (e.g., viruses
and bacteria) in ground water or surtace waters can be significant.
Niirogen Niirogen is an aquatic plant nutrient that can conhibute to eutrophication and dissolved oxygen loss in
surface waters, especialty In lakes, estuaries, and coastal embayments. Algae and aquaiic weeds can
contribute trihalomethane (THM) precursors to the water column that may generate carcinogenic THMs in
chlorinated drinking water. Excessive nitrate-nitrogen in drinking water can cause methemogbbinemia in
infants and pregnancy complications tor women. Livestock can also suHer healih Impacts from drinking
water high in nitrogen.
Phosphorus Phosphorus is an aquatic plant nutrient that can contribute to eutrophication of infand and coastal surface
waters and reductlon of dissolved oxygen.
Toxic organics Toxic organic compounds present in household chemicals and cleaning agents can interfere wiih certain
biological processes in altemative OWTSs. They can be persistent in ground water and contaminate
downgradient sources ot drinking water. They can also cause damage to surface water ecosystems and
human health through ingestlon of contaminated aquatic organisms (e.g., flsh, shellfish).
Heavy metals Heavy metals like Iead and mercury in drinking water can cause human health problems. In the aquatic
ecosystem, they can also be to�tic to aquatic life and accumulate in fish and shellfish thal might be
consumed 6y humans.
Dissolved inorgenics Chloride and sulfide can cause taste and odor problems in drinking water. Boron, sodum, chlorides, sulfate,
and other solutes may limit treated wastewater reuse options (e.g., irrigation). Sodium and to a lesser extent
potassium can be deleterious to soil structure and SWIS performance.
Sowce: Adapletl In part from Tchobanoglous antl Bunon,1991.
Table3-17. Examples of soil infiltration system pertormance
Parameter Applled concentratlon Percent removal Reterences
in milligrams per liter
BODs 136-150 90-98 Siegrist et al., 198fi
U. Wisconsin,1978
Total nitrogen
Total phasphoms
G5''�'
8-12
10-4D
85-95
Fecal coliforms NA' 99-99.99
Fewl ooftortns are rypically measured in oiher uniLs, e.g., colony-forming units per 700 mllliiilers.
Source: Adapted from USEPA, 7992.
Reneau 7977
Sikora et a1.,1976
Sikora et a1.,1976
Gerba,1975
USEPA Onsite Wastewater Treatment Systems Manual 3-23

Table 3-18. Case study: septic tank effluent and soil water quality °
Parameter Statlstics Septic tank ettluent Soil water Soil water
(units) quality quality ° at Ouality' at
0.6 meter 1.2 meters
80D Mean 93.5 <1 <1
(mg�l.) Range 46-156 <i <1
# sampies 11 6 6
TOC
(mg�L)
TKN
(mgll.)
N0,-N
(mg2)
TP
(mglt.)
TDS
(mgll)
CI
(mg/L)
F. Coli
(log B per
100 mL)
F. strep.
(log # per
100 mL)
Mean
Range
# samples
Mean
Range
# samples
Mean
Range
# sarnples
Mean
Range
� samples
Mean
Range
# samples
Mean
Range
� sampies
Mean
Range
# samplas
Mean
Range
# samples
47.4
31-68
11
442
19-53
11
0.04
0.01-0.16
11
8.6
7.2-17.0
11
497
354--610
11
70
37-110
11
4.57
3.�5.4
11
3.60
1.9-5.3
ti
7.8
3.7-17.0
34
o.n
0.46-1.40
35
21.6
1.7-39.0
35
0.40
0.01-3.8
35
448
184-&20
34
41
9-85
34
nd `
<1
24
nd
<1
23
8.0
3.1-25.0
33
0.77
0.25-2.10
33
13.0
2.0-29.0
32
0.1 S
0.02-1.80
33
355
200-592
32
29
9-49
31
nd
�1
21
nd
<1
20
' The soll malra consisled ol a fine sand;lhe waslewater loading rste wes 3.1 cm per dey over 9 monlhs. TOC = total organk ca�bon; TKN = tohal K�eldahl nihogen;
TDS �btal dissohred wlids; CI =chlondes;
F. coY =1oca1 co6fortns; F. strep = fecal streptaaai.
' So0 walerqualily measured In pan tysimeters al unsalurated soil depihs of 21eet (0.6 mMe� and 4 feel(12 meters).
'nd=none dafeded.
Saurce: Adapled tmm Mderson et a1.,1994.
cause cloudiness in surface waters. TSS in direc[
discharges to surface waters can result in the devel-
opment of sludge layers that can hazm aquatic
organisms (e.g., benthic macro invertebrates).
Systems that fail to remove BOD and TSS and are
located neaz surface wate� or drinking water wells
may present additiona] problems in the form of
pathogens, toxic pollutants, and other pollutants.
Under proper site and ope[ating conditions, how-
ever, OWTSs can achieve significant remova] rates
(i.e., greater than 95 percent) for biodegradable
organic compounds and suspended solids. The risk
of ground water contamination by BOD and TSS
3-28
(and other pollutants associated with suspended
solids) below a propedy sited, designed, con-
structed, and maintained SWIS is siight (Anderson
et al., 1994; Universiry of Wisconsin, 1978). Mosc
setdeable and floatable solids aze removed i� the
sep[ic [ank during preVea[men[. Mos[ p�ticulate
BOD remaining is effectively removed at the
infiltrative surface and biomat. Colloidal and
dissolved BOD [hat might pass through the bioma[
are removed through aerobic biologica] processes
in the vadose zone, especially when uniPorm dosing
and reoxygenation occur. If excessive concentra-
tions of BOD and TSS migrate beyond the tank
because of poor main[enance, [he infilVative
USEPA Onsite Wastewater Treafinenf Systems Manual

solution chemistry, organic matter content of the
soil, and rate of degadation by soil microorganisms.
Soils with high organic matter should favor
retention of surfactants because of the lipophilic
componen[ of surfactan[s. Surfactants are readily
biodegraded under aembic conditions and are more
sta61e under anaerobic conditions. Substantial attenua-
tion of LAS in unsaturated soil beneath a subsurface
infiltration system has beeu demolvs[nted (Anderson
ct al., 1994; Robertson et al., 1989; Shunp et al.,
1991). Cafionic surfactants snongly sorb to cation
exchange sites of soil particles and organic matter
(McAvoy et al., 1991). Thus, Gne-textured soils and
soils having high organic matter con[en[ will gener-
ally favor retention of these surfuctants.
Some investigations have identified the occuaence
of inethylene blue active substance (MBAS) in
ground water (Perlmutter and Koch, 1971; T6nnuan
et al., 1986). The type oF anionic surfactant was not
specifically identified. However, it was surmised
that the higher concentrations noted at the time of
the study were probably due to use of alky]-
benzenesulfonate (ABS), which is degraded by
microorgauisms�at a much slower rate than LAS.
There has also been reseazch demonstraflng that all
types of surfactants might be degraded by microor-
ganisms in sahuated sediments (Federle and
Pas[wa, 1988). No inves[iga[ions have been found
that identify cationic or nonionic surfactanu in
ground water that originated from subsurface
was[ewater infiltration systems However, because
of concerns over the use of allcylpheuol
polyethoxyla[es, s[udies of fate and transport of this
class of endocrine dismpLers are in progress.
Summary
Subsurface wastewater infiltration systems are
designed to provide wastewater treatmen[ and
dispersa] [hrough soil purification processes and
ground water recharge. Satisfacrory performance is
dependen[ on the [reaVnent efficiency of the
pretreatment system, the me[hod of wastewa[er
distribuuon and loading to the soil inFiltrative
surface, and the properties of the vadose and
samrated zones underlying the infiltra[ive surface.
The soil should have adequate pore characteristics,
size dishibu[ion, and continuity [o accept the daily
volume of wastewater and provide sufficient soil-
wa[er contact and retention time For treaVnent before
the effluent percolates into the ground wa[er.
Ground water monitoring below properly sited,
designed, constructed, and operated subsurface
infiltration systems has shown carbonaceous
biochemical oxygen demand (CBOD), suspended
solids (TSSj, fecal indicators, metals, and surfactants
can be effectively removed by the first 2 to 5 feet
of suil under uosa[urated, aerobic conditions.
Phosphorus and metals can be removed through
adsorption, ion exchange, and precipitation reac-
tions, bu[ the capacity of soil [o retain these ions is
finite and varies with soil mineralogy, organic
conten[, pH, reduction-oxidalion potential, and
cation exchange capacity. Nitrogen removal rates
vary significanUy, but most conventional SWISs do
not achieve drinking water standazds (i.e., 10 mgJL)
for nitrate concenhations in eftluent plumes.
Evidence is growing that some types of viruses are
able to leach with wastewater from subsurface
infiltration sys[ems to ground watec Longer
retenuon [imes associated with virus removal aze
achieved with fine-texture soil, low hydraulic
loadings, uniform dosing and resting, aerobic sub-
soits, and high temperamres. Toxic organics appeaz
to be removed in subsoils, but further study of the
fate and transpori of these compounds is needed.
Subsurface wastewater infiltra[ion sys[ems do
afFect ground water quality and therefore have the
potential [o affect surface water quality (in azeas
with gaining streams, lazge macropore soils, or
karst terrain or in coastal regions). Smdies have
shown that after the treated percolate enters ground
water i[ can remain as a dislinct plume for as much
as several hundred feeL Concentrations of niVa[e,
dissolved solids, and other soluble contaminants
can remain above ambient ground water concenua-
tions within the plume. Attenuation of solute
concentrations is dependent on the quantity of
natural rechazge and travel distance from the
source, among other facrors. Organic bottom
sediments of surface waters appear to provide some
retention or removal of wastewater contaminan[s if
the ground water seeps through those sediments to
enler the surface watec These bo[tom sediments
migh[ be effective in removing trace organic
compounds, endotoxins, nit��ate, and pathogenic
agents through biochemica] acfivity, but few data
regarding the effectiveness and significance of
removal by bottom sediments aze available.
Public health and environmental risks from prop-
erly sited, designed, construc[ed, and operated
USEPA Onsite Wastewater Treatment Systems Manual 3-39

� . � , � ' Chapter 3: Esfablishing ir���i�fLn��ist�m�l�effo�;,�an�'��������€'�����'�
surface can clog and surface seepage of wastewater
or plumbing fixture backup can occur.
Nitrogen
Nitrogen in raw wastewater is pri.mazily in the
form of organic matter and annmonia. After the
sepfic tank, it is primarily (more than 85 percent)
ammonia. After discharge of the effluent to the
inE%ltrative surtace, aerobic bacteria in the uioiria�
and upper vadose zone aonvert the amriionia in the
effluent almost entirely to nitrite and then to rutrate.
Nitrogen in its nitrate form is a significant ground
water pollutant. It has been detected in urban and
rural ground water nationwide, sometimes at levels
exceeding the USEPA drinking water standard of 10
mg/L (USGS, 1999). High concentrations of nitrate
(greater than 10 mg/L) can cause mefhemoglobin-
emia or "blue baby syndrome," a disease in infants
that reduces the bTood's ability to carry oxygen, and
proUlems during pregnancy. Nitrogen is also an
important plant nutrient that can cause excessive
algal growth in nitrogen-limited inland (fresh)
waters and coastal watezs, which are often limited in
available nitrogen. High algal productivity can block
sunlight, create nuisance or harznfui algal blooms,
and significantly altez• aquatic ecosystems. As algae
die, they �ue decomposeci by bacteria, �vhich can
deplete available.dissolved oxygen in surface waters
and degrade habitat conditions. .
Nitrogen contamination of ground water below
infiltration fields has been documented by many
investigators (Anderson et a1., 1994; Andreoli et
al., 1979; Ayres Associates, 1989, 1993b, c; Bouma
et al., 1972; Carlile et al., 1981; Cogger and
Taple 3-19.�Vastew��ter corTs�ituents of concern at�d re}�reserttative cortcentrations in ;fte eftlue��t o( various ire�t;nent utiits
Constituents o( Fxample direct �arik-based treatment unit effluent concentratiorFs SYViS percolate
concern or indirect Domestic STE into ground water
measures Domestic STE' with N-removal Aerobia.unit Sand filter Foam or textife at 3 to 5 ft depth
(Units) recyclex effluent effluent ,� filter effluent (°/, removal)
Oxygen demand BODS (mg/L) 140-200 . 80-120 5-50 �. 2=15 � 5-15 >90%
Parliculate so{ids TSS (mg/L.) . 50-100 50-80 5-i00 5-20 5-10 >90%
Nitrogen Tatal N(mg 40•900 .10-30 25-60 10-50 ' 30•60 1 p-20%
N/L)
Phosphorus
Bacteria (e.g.,
Clostddium
pe�fringens,
Salmonella,
Shigella)
�rus (e.g.,
hepatitis, polio,
echo, coxsackie,
coliphage)
Organic
chemicals (e.g.,
soivents, petro-
chemicals,
pesticides)
Heavy metats
(e.g., Pb, Cu, Ag,
Hg)
Total P (mg .
P/L)
Fecal coliform
(organisms per
100 mL)
Specific virus
(pfu/mL)
• Specific
organics or
totals (pglL)
Individual
metals {pg/L)
5-15 5-15 410 <i-10' 5-15' 0-100%
108-10° 108-10e 10'-10` 10'-10' 10'-103 >99.99%
0-105 0-105 (episodically 0-10` 0-105 0-105
(episodically presentathigh (episodically '(episodically (episodically
present af high levels) present at high present at high present at high
levels) levels) fevels) levels)
0 to trace leve(s 0 to trace levels 0 to trace levels 0 to trace levels 0 to trace levels
(?) . (?) (?1 (?) (?)
0 to trace levels 0 to trace levels 0 to trace levels 0 to trace levels 0 to trace levels
>99.9%
>99°/0
>99%
' Septic tankeHluent (STE) concentraHons given are for domestic wastewater. However, restaurant STE is markedly higher particulady in BODd CO�, and suspended solids while
concentrations in graywater 5TE are noticeabiy lower in total nitrogen.
'N-removal accomplished by recycling STE through a packed bed for nftrificallon with dlscharge inw the tnfluent end of the sepUc tank for denitrification. .
' P•removal by adsorpUonlpredpitatian is highly dependent an med(a ppacity, P loading, and system operaHon.
Source: Siegrist, 2001(afler Siegrist et al., 2000)
Source: Siegrist, 2001(atter Siegrist et a1., 2000).
USEPA Onsife Wastewafer Treatment Systems Manual 3-29

Cazlile, 1984; Ellis and Childs, 1973; Erickson and
Bastian, 1480; Gibbs, 7977a, b; Peavy and
Brawner, 1979; Peavy and Groves, 1978; Polta,
1969; Preul, 1966; Reneau, 1977, 1979; Robertson
et al., 1989, 1990; Shaw and Turyk, 1994; Starr
and Sawhney, 1980; Tinlcer, 1991; Uebler, 1984;
Vrnraghavan and Waznock, 1976a, b, c; Walker et
al., 1973a, b; Wolterink et al., 1979). Nitrate-
nitrogen concentrations in ground water were
usually found ro eaceed the dcinking wa[er standard
of 10 mg/L neaz the infiltration field. Conventiona]
soil-based systems cao remove some nitrogen from
sepvc tank effluent (table 3-19), but high-density
installation of OWTSs can cause contamination of
ground or surface water resoumes. When nitcate
reaches the ground water, it moves free]y wiffi little
retazdation. Denitrificauon has been found to be
significant in the saturated zone only in raze
instances where cubon or sulfur deposits aze
presenL Reduction of nitra[e concentrations io
ground water occurs primarily through dispersion
or rechazge of ground water supplies by precipita-
tion (Shaw and'h�ryk, 1994).
Nitrogen can undergo several transformations in
and below a SWIS, inciuding adsorption, volatil-
ization, mineralizaUon,' nitrificauon, and denitrifi-
cauon. NiVification, the conversion of ammonium
nitrogen to nih-ite and then nitrate by bacteria
under aerobic conditions, is the predominant
transformation that occurs immediately below the
infiltration zone. The negaavely chazged nitrate ion
is very soluble and moves readily with the percolat-
ing soil water.
Biological denitrification, which converts niVate to
gaseous forms of nitrogen, can remove nitrate from
percolating wastewater. Denitrificauon occurs
under anaerobic conditions where available elecQon
donors such as carbon or sulfur aze present. Deni-
Vifying bacteria use nitrate as a substimte for
oxygen when accepting electrons. It has been
generally thought that anaerobic conditions with
organic matter seldom occur below soi] infiltration
fields. Therefore, it is has been assumed that all the
nitrogen applied to infiltratiou fields ultimately
leaches ro ground water (Brown et al., 1978;
Walker et al., 1973a, b). However, several s[udies
indica[e tha[ deni[rifica[ion can bc significan[.
Jenssen and Siegrist (1990) found in their review
of several labora[ory and field smdies that approxi-
mntely 20 percent of nitrogen is lost from waste-
water percolatlng through soiL Factors found to
favor deniuificauon are fine-grained soils (silts and
clays) and layered soils (altemating Fne-grained
and coarser-grained soils with distinct boundaries
between the texmrally different layers), particularly
if [he fine-grained soil layers contain organic '
material. Jensseo and Siegrist concluded [ha[
nitrogen romoval below the infil7auon Cield can be .
enhanced by placing the system high in the soil
profile, where organic matter in the soil is more
likely to be present, and by dosing septic tank
eftluent onto the infiltrative surface to create .
altemating wetting and drying cycles. Denitrifica-
aon can also occur if ground water enters surface
water bodies through orga�io-rich bottom sedi-
ments. Niuogen concentrations in ground water
were show'n to decrease to less than 0.5 mg/L after
passage through sedimen[s in one Canadian study
(RobeRson et al., 1989, 1990).
It is difficult to predic[ removal rates for wastewa-
ter-borne uitrate or other nitrogen compounds in
the soil matrix. In general, however, [ria�ate con-
centrations in SWIS effluent can and often do
exceed the 10 mg/L drinking water standard. Shaw
and Turyk (1994) found nitrate concenvauons
ranging from 21 to 108 mg2 (average of 31 to 34
mg/L) in SWIS effluent plumcs analyzed as pazt of
a study of 14 pressure-dosed drain fields in sandy
soils of Wisconsia The limited ability of conven-
tional SWISs to achieve enhanced nitrate reduc-
flons and die difficulty in predicting soil nivogen
removal rates means that systems si[ed in drinkiog
water aquifers or neaz sensitive aquatic azeas should
incorporate additional nitrogen removal technolo-
gies prior [o final soil discharge.
Phosphorus
Phosphorus is also a key plant nutrient, and like
nitrogen it contributes to eutrophication and
dissolved oxygen depletion in surface waters,
especially fresh waters such as rivers, lakes, and
ponds. Monitoring below subsurface infi][ration
systems has shown [hat [he amoun[ of phosphorus
leached to ground water depends on several facrors:
the characteristics of the soil, the thickness of the
unsaturated zone through which the wastewater
percola[es, [he applied loading rate, and the age of
the sys[em (Bouma et al., 1972; Brandes, 1972;
Carli]e et al., 1981, Childs et al., 1974; Cogger and
Carlile, t984; Dudley and Stephenson, 1973; Ellis
and Childs, 1973; Erickson and Bastian, 1980;
Gilliom and Patmont, 1983; Harki� et al., 1979;
3•30 USEPA Onsite Wastewater Treatment Syst�ms Manual

Chapter 3: Establishing Treatment System Performance Requirements �
Jones and Lee, 1979; �i'helun and Barrow, 1984).
The amount of phosphorus in ground water varies
from background concenVa[ions fo concentralions
equal to that of septic tank efFluent. However,
removals have been found to continue within
ground water aquifers (Cazlile et aL, 1981; Childs
et al., 1974; Cogger and Cazlile, 1984; Ellis and
Childs, 1973; Gilliom and Pa[mont, 1983; Rea and
Upchurch, 1980; Reneau, 1979; Reneau and Pettry,
1976; Robertson et al., 1990).
Retardation of phosphorus contamination of surface
watecs from SWISs is enhanced in fine-textured
soils without continuous macropores that would
allow rapid percolation. Inereased distaoce of the
system from surface waters is also an important
factor in limiting phosphorus discharges because of
greater and more prolonged contact with soil
surfaces. The risk of phosphorus contanunaaon,
therefore, is greatest in karst regions and coazse-
textured soils without significant iron, calcium, or
aluminum concentrations located neaz surface waters.
The fate and transport of phosphorus in soils are
controlled by sorption and precipitation reactions
(Sikora and Corey, 1976). At low concentrations
(less [han 5 mg/L), the phospha[e ion is chemi-
sorbed onto the surfaces of iron and aluminum
minerals in strongly acid to neutral systems and on
calcium minerals in neutcal to alkaline systems. As
phosphorus concenuations increase, phosphate
precipitates form. Some of the more important
precipitate compoimds formed are strengite,
FeP0q2Hz0; varisci[e, AIP0a2HZ0; dicalcium
phosphate, CaHPOa 2H2O; octacalcium phosphate,
CaaH(POe)33H2O; and hydroxyapati[e, Ca�o
(PO4)6(OHZ). In acidic soils, phosphate sorption
probably iovolvcs the aluminum and iron com-
pounds; in calcareous or alkaline soils, calcium
compounds predominate.
Estimates of the capacity of the soil to retain
phosphorus are often based on sorption iso[herms
such as the Langmuir model (Ellis and Erickson,
1969; Sawney, 1977; Sawney and Hill, 1975;
Sikora and Corey, 1976; Tofflemire and Chen,
1977). This method significanfly uoderes[imates
the to[al retention capacity of [he soil (Anderson et
aL, 1994; Sawney and Hill, 1975; Sikora and
Corey, I)76; Toftlemire and Chen, 1977). This is
because the test measures the chemi-sorpuon
capacity bu[ does not [ake into account the slower
precipitation reacdons that regenerate the chzmi-
sorption sites. "Phese slower rcactions have bccn
shown to increase the capacity of the soil to retain
phosphorus by LS to 3 times the measured capacity
calculated by the isotherm test (Sikora and Corey,
1976; Tofflemire and Chen, 1977). In some cases
the total capacity has been shown to be as much as
six times greater (Tofflemire and Cheu, 1977).
These reactions can take place in uusaturated or
samrated soils (Ellis and Childs, 1973; Jones and
Lee, 7977a, b; Reneau and Pettry, 1976; Robertson
et aL, 1990; Sikora and Corey, 1976).
The capaci[y of the soil to retain phosphoms is
finite, however. With continued ]oading, phospho-
rus movement deeper into the soil profile can be
expec[ed. The uLtimate retention capacity of the
soil depends on several factors, including its
mineralogy, particle size distribution, oxidaaon-
reduction potential, and pH. Fine-[ex[ured soils
theorefically provide more sorption sites for
phosphorus. As uoted above, iron, aluminum, and
calcium minerals in the soil ailow phosphorus
precipitation reactions to occur, a process that can
lead to additional phosphorus retention. Sikora and
Corey (1976) estimated that phosphorus penetration
into lhe soil below a SWIS would be 52 centime-
ters per yeaz in Wisconsin sands and 10 centimeters
per yeaz in Wisconsin silt loams.
Nevertheless, knowiug the re[en[ion capacity of the
soil is not enough to pcedict the [ravel of phospho-
ms from subsurFace infiltration systems. Equally
important is an estimate of the total volume of soil
[hat the wastewater will contact as it percolates to
and through the ground water. Fine-textured,
unstructured soils (e.g., clays, silty clays) can be
expected to disperse the water and cause contact
with a greater volume of soil than coazse, granulaz
soils (e.g., sands) or highly structured fine-textured
soils (e.g., clayey silts) having lazge continuous
pores. Also, the rate of water movement and the
degree to which the water's elevation fluctuates are
importan[ factors.
There are no simple methods for predicting phos-
phorus removal rates at the site level. However,
several landscape-scale tools that provide at least
some estimation of expected phosphorus loads from
clusters of onsi[e sys[ems are available. The
MANAGE assessment method, which is profiled in
secuon 3.9.1, is designed to estimate existing and
projected future (build-out) natrient loads and to
idenufy "hot spots" based on land use and cover
USEPA Onsite Wastewater Treafinent Systems Manual 3-31

�
Chapfer 3: Fstabl shing Treafinent S stem Perfor:mance Re uiremenfs '' p I i ;� ��.
� � � �� g� � u �� I
(see http://www epa.gov/owow/watershedJ
ProceecUjoubert.html; http://www.edc.uri.edu/
cewq/manage.html). Such estimates provide at
least some guidance in siting onsite systems and
considering acceptable Ievels of both numbers and
densities in sensitive areas.
Pathogenic microorganisms
PAthogenic microorganisms found in domestic .
wastewater include a number of different bacteria,
vir�ses, protozoa, and pazasites that cause a wide
range of gastrointestinal, neurological, respiratory,
zenal, and other diseases. Infection can occur �
through ingestion (drinking contaminated water;
incidental ingestion while bathing, skiing, or
fistung), respiration, or contact (table 3-2U). The
occurrence and concentration of pathogenic micro-
organisms in raw wastewater depend on the sources
contributing to the wastewater, the existence of
infected persons in the population, and environ-
mental factors that influence pathogen survival
rates. Such environmental factors include the
following: initial-numbers and types o£ organisms,
temperature (microorganisms survive longer at
lower temperatures), hunnidity (survival is longest
at high humidity), amount of sunlight (solar �
radiation is detrimental to survival), and additional
soil attenuation factors, as discussed below. 'Y'ypical
ranges of survival times are presented in table 3-21.
Among pathogenic agents, only bacteria have any
potential to reproduce and multiply between hosts
(CIiver, 2000). If temperatures are between 50 and
80 degrees Fahrenheit (10 to 25 degrees Celsius)
Tabte 3 20. Waterborne pathogens found 'in human waste and associated diseases
?ype Organism
Bacteria Escir�edchfa coli
� enterapathogenic) , �
Leglonella pneumophila ,
Leptospira �
Salmonelia fyphi�
` Sa/monella
Shigella
�bdo cholerae
Yerslnia enterolitica
Pratozoans Balantidium coli
Cryptosporidium
Entamoeba hisfolytica
GiardJa lambia
Naegleria fowleri
V(Nses Adenovirus
(31 types)
Enterovirus
(67 types, e.g., polio-, echa-,
and Caxsaclde viruses)
Hepatitis A
Notwalk agent
Reovirus
Rotavirus
Source: USEPA,1999.
Disease
Gastroenteritis
Legioneflosis
Leptospirosis
Typhoid fever
Salmonellosis
Shigellosis
Cholera
Yersinosis
Balantidiasis
Crypotosporidiosis
Ameobiasis
(amoebic dysentery)
Giardiasis
Amebic
Meningoencephalitis
Conjunctivitis
Gastroenteritis
Infectious hepatitis
Gastroenteritis
Gastroenteritis
Gastraenteritis
Effects -
Vomiting, diarrhea, death in susceptibte populations
Acute respiratory illness
Jaundice, fever (Vllell's disease)
High fever, diarrhea; ulceration of fhe small_ Intestine
Diarrhea, dehydration
Bacillary dysentery �•
Extremely heavy diarrhea, dehydration
Diarrhea
Diarrhea, dysentery
Diarrhea
Prolonged diarrhea with bleeding, abscesses of the liver
and small intestine
Mild to severe diarrhea, nausea, indigestion a
Fatal disease; inflammation af the brain
Eye, other infections
Neart anomalies, meningitis
Jaundlce, fever
Vomiting, diarrhea
Vomiting, diarrhea
Vomiting, diarrhea
�
;
3-32 USEPA Onsite Wasfewafer Treafinenf Sysiems Manual �

Chapter 3: Establ�shing Treatment m Perfo e; Requirements �
3.7.1 Wastewater pollutants of concern
Environmen[al pm[ection and public health agen-
cies are becoming increasingly concemed about
ground water and surface water contamination
from �vas[ewater pollu[ants. Toxic compounds,
excessive nu[rients, and pathogenic agents aze
among the potential impacts on the emironment
from onsite wastewater systems. Domestic waste-
water contains several pollutaots that could cause
significaut human heal[h or environmen[al risks if
not [reated effec[ively before being released to the
receiving environment.
A conven[ional OWTS (septic tank and SW[S) is
cnpable of neazly complete removal of suspended
solids,�biodeg�adable organic compounds, and fecal
coliforms if properly desigued, sited, installed,
operated, and maintained (USEPA, 1980a, 1997).
These wastewater cons6tueots can becomc pollut-
ants in ground water or surface waters if treatment
is incomplete. Reseazch and moni[oring studies
have demonstrated removais of these typically
found constituents to acceptable levels. Moce
recently, however, other pollutanis present io
wastewater aze caising concerns, including nutrien[s
(e.g., nitrogen and phosphorus), pathogenic
parasi[es (e.g., Cryptosporid�me parvmn, Giariiia
lmnb[ia), bacteria and virnses, toxic organic
Flgure 3•8. Plume movement through the soil to the seturated zone.
compounds, and metlls. Their potentia] impacts on
ground water and surfacc water resources are
suuunazized in table 3-16. Recently, concems havc
been raised over the movement and fa[e of a
variety of endocrine disrupters, usually from use of
phazmaceuticals by residents. No data have been
developed to confirm a risk at this time.
3.7.2 Fate and transport of pollutants
in the environment
When pxopedy designed, sited, constructed, and
maintained, conven[ional onsite wastewa[er treat-
men[ technologies effeclively reduce or eliminate
most horoan heaith or environmental threats posed
by pollu[ants in wastewater (table 3-17). Most
vaditional systems rely primazily on physical,
biological, and chemical prncesses in the septic
tank and in the biomat and unsamrated soil zone
Uelow tl�e SWIS (commonly referred [o as a leach
field or drai� field) to sequester or atteuuate
pollutants of concem. Where point dischazges to
surface waters are permitted, polfutan[s of concem
should be removed or treated to acceptable, permit-
specific levels (levels permitted under the National
Pollutant Dischazge Elimination Sys[em of tl�e
Clean Water Act) before discharge.
Source: Adapled Irom NSFQ 2000.
3-22 USEPA Onsite Wasfewater Treatment Systerns Manual

Pitt County, North Carolina - DP-5. Housing Characteristics: 1990
Subject Number
1970 to 1979 6,593
__. _..__....--------- .............._.._....-..........__._........_...----........._.....-----._......___..._.._._--._.....------------. _...----................_.._._.._........_....._.._....-----........._...__....._.._.._.__.._ __._...._..---------
1960 to 1969 3,277
1959 or earlier � � 2,614
------......___.�.��_._� _. _.._�__.._.�__T__________....____�.______..
TELEPHONE �N
--------------------- ---------------------- -------------- --
No telephone in unit _ � 3,307
VEHICLES AVAILABLE �m
None _.� � _..� �._..._ __e -_--- 4,665
1 13,333
2 � � 15,182
3 or more ' 7,311
MORTGAGE STATUS AND SELECTED MONTHLY OWNER COSTS
• S ecified owner-occu ied housin units 16 563
With a mortgage 11,387
Less than $300 644
- -------------------------------- ------.A. -------------...._..- ----......_
$300 to $499 2,253
$500 to $699 � 3,354
$700 to $999 3,142
$1,000 to $1,499 � 1,477
$1,500 to $1,999 �� � 332
$2,000 or more 185
Median (dollars) 669
Not mortgaged 5,176
Less than $100 182
$100 to $199 1,833
$200 to $299 2,252
$300 to $399 647
$400 or more I� 262
I
Median (dollars) ' 221
SELECTED MONTHLY OWNER COSTS AS A PERCENTAGE OF HOUSEHOLD INCOME IN 1989
S�ecified owner-occupied housing units 16,563
Less than 20 percent 9,336
20 to 24 ercent 2,498
25 to 29 ercent 1,651
30. to 34 percent 895
35 ercent or more 2,086
Not computed 97
GROSS RENT
Specified renter-occupied housing units ___ _ 16,622
Less than $200 2,199
$200 to $299 � 3,344
$300 to $499 7,822
$500 to $749 1,997
_... _....--------...---.._...---- ------------------._._......- -- --- -----------
$750 to $999 203
$1,000 or more 35
No cash rent 1,022
_ ...__. ..--..- - - -------T.........-- ---
Median (dollars 350
GROSS RENT AS A PERCENTAGE OF HOUSEHOLD INCOME IN 1989 _ _
S ecified renter-occupied_housing_units_��� ___ _ 16,622
Less than 20 percent 4,872
20 to 24 ercent 1,870
25 to 29 percent 1,429
30 to 34 percent 1,259
35 ercent or more 5,895
Not com uted � 1,297
(X) Not applicable
Source: U.S. Bureau of the Census, 1990 Census of Population and Housing, Summary Tape File 3(Sample Data)
Matrices H1, H4, H6, H7, H23, H24, H25, H28, H30, H31, H35, H37, H42, H43, H43A, H51, H52, H52A, H58, H64.
Page 2 of 3
http://factfinder.census.gov/servlet/QTTable? bm=n&_lang=en&qr_name=DEC_1990_STF3_DPS&ds_... 7/24/2007

Piu County. N�>rth Carolina - DP-�. Housing Characteristics: 1990
�� • •
:.� � •
�`'�� ,�irierican FaceFindeY � •
�.m � ..
P�ge 1 of3
DR5. Housing Characteristics: 1990
D2t2 SBt: 1 �g[I gll�nm�'.Yy T;.O4' FiF 3� ST� � I� 3;=�n'-ple da[a
Geographic Area: Pitt County, North Carolina
NOTE: For infortnation on confdentiality, sampling ertor. nonsampling error, and definitions, see
I,L;.� ;:�:u�n�iercen=_us.gov,Rieme�eii'datanotes�exp5t�390.htm.
Subject
Total housing units _
YEAR STRUCTURE BUILT _
1989 to March 1990
1985 to 1988 _
7980 to 1984
1970 to 1979
1960 to 7969
1950 to 1959
1940 to 1949
1939 or earlier
BEDROOMS
� No bedroom
1 bedroom
2 bedrooms
3 bedrooms
. 4 bedrooms
5 or more bedrooms
SELECTED CHARACTERISTICS
Lacking complete plumbing facilities
Lacking compiete kitchen facilities
Condominium housing units
SOURCE OF WATER
Public system or private company
Individual drilled well
Individual dug well
� Some olher source
�
SEWAGE DISPOSAL
�h Public sewer
I Seplic tank or cesspool
Other means
Occupied housing units
�HOUSE HEATING FUEL
Utility gas
Boltled, tank, or LP gas
Eiectricity
Fuel oil, kerosene, elC.
Coal or coke
Wood
Solar energy
Other fuel
No (uel used
YEAR HOUSEHOLDER MOVED INTO UNIT
1989 to March 1990
1985 to 1988
1980 to 1984
Number
43,070
1,835
6,095�
11,922
7p28
4.821
2.142
3,005
445
4,337
14,734
18.990
3,840
724
728
553
1,615
37,231
4,594
1,136
109
27.121�
15,350I
599
40,491
5,527
5.272
20,322
7.777
20
1.577
0
70
46
10,518
12.048
5,441
�' �
. Z lr /./ il {u-Se:
' �• � C, I ,l" c
http:llfactfinder.census.gov/servlet/QTTablc?_bm=n&_lang=en&yr_naine=DEC_1990_STF3_DPS&ds_... 7124/'2007

Neuse Rive'r Basin Subbasin 03-04-02
Assessment lmpaired Year
Waferbody and Description Unit (AU) Class Subbasin Use Listed Cafegory and Reason for Listing Potenfial Source(s) Miles orAcres
Swift Creek 27-43-(1)a WS-III 03-04-02 6 ��� 2.6 FW Miles
NSW
From source to confluence with Williams Creek O 1998 6 Impaired biological integrity Land Development
Agriculture
Urban Runoff/Storm Sewers
Swift Creek 27-43-(1)b WS-III 03-04-02
NSW
From confluence with Williams Creek to backwaters of Lake Wheeler
Sycamore Creek (Big Lake) 27-33-9
From source to Crabtree Creek
Toms Creek (Mill Creek) 27-24a
From source to Browns Lake
Toms Creek (Mill Creek) 27-24b
From Browns Lake to Neuse River
B NSW 03-04-02
C NSW 03-04-02
C NSW 03-04-02
Walnut Creek 27-34-(1.7) C NSW 03-04-02
From dam at Lake Johnson to backwaters of Lake Raleigh
Walnut Creek 27-34-(4)a C NSW 03-04-02
From dam at Lake Raleigh to UT 0.6 miles west of I-440
6
AL 1998 6 Impaired biological integrity
[�]
0
5
1998 5 Aquatic Weeds (Hydrilla sp.)
6
1998 6 Impaired biological integrity
6
AL 1998 6 Impaired biological integrity
0
0
6
1998 6 Impaired biological integrity
6
1998 6 Impaired biological integrity
Urban Runoff/Storm Sewers
Package Plants (Small Flows)
Non-urban'development
Urban Runoff/Storm Sewers
Urban Runoff/Storm Sewers
5.5 FW Miles
61.8 FW Acres
1.6 FW Miles
1.5 FW Miles
1.4 FW Miles
6.4 FW Miles
Williams Creek 27-43-2 WS-III 03-04-02 6 2.6 FW Miles
NSW
From source to Swift Creek O 1998 6 Impaired biological integrity Urban Runoff/Storm Sewers
Construction
North Carolina 303(d) Lisf- 2006 Tuesday, June 19, 2007
Neuse Basin 03-04-02 Page 56 of 925

AU NUMBER
18-74-(47.5)
18-74-63
18-74-63-2
18-76-1
18-87-(11.5)
18-87-(23.5)b
18-87-(23.5)c
18-87-11.7b
18-87-11.7c
18-87-11.7f
18-87-19a
18-87-19b
18-87-22a
18-87-22b
18-87-23
18-87-24-3
18-87-25.7b
18-87-25.7c
18-87-25.7d
18-87-26a
18-87-26b
18-87-28
18-87-29
99-(3)b
99-(3)c
Stream Name
Northeast Cape Fear River
Smith Creek
Burnt Mill Creek
Greenfield Lake
Intracoastal Waterway
Intracoastal Waterway
Intracoastal Waterway
Topsail Sound and Middle Sound ORW Area
Topsail Sound and Middle Sound ORW Area
Topsail Sound and Middle Sound ORW Area
Futch Creek
Futch Creek
Pages Creek
Pages Creek
Howe Creek
Banks Channel
Masonboro Sound ORW Area
Masonboro Sound ORW Area
Masonboro Sound ORW Area
Hewletts Creek
Hewletts Creek
Whiskey Creek (Purviance Creek)
Everett Creek �
Atlantic Ocean
Atlantic Ocean
County
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER
NEW HANOVER

AU NUMBER
15-(1)d
15-(1)e
15-(18) �
15-25-1-(16)a ,
15-25-1-(16)b
15-25-1-(16)c
15-25-1-18-(2)
15-25-1-19
15-25-1=20
15-25-1-21
15-25-2-(10)a
15-25-2-(10)b
15-25-2-(10)c
15-25-2-(10)d
15-25-2-11-(2)
15-25-2-12-(2)
15-25-2-14
15-25-2-15-(3)
15-25-2-16
15-25-2-16-1-(2)
15-25-2-16-4-(2)
15-25-3
15-25-4
15-25-5
15-25d
15-25f
15-25g
15-25i
15-25j
15-25k
15-251
15-250
15-25q
15-25r
15-25s
15-25u
15-25v
18-(63)a
18-(71)a
18-(87.5)a
18-(87.5)c
18-(87.5)d
18-77
18-81
18-88-8-4
18-88-8-4-1
18-88-9-1-(1.5)
18-88-9-2-(1)
18-88-9-2-(2)
18-88-9-2-3
- 18-88-9-2-4
18-88-9-2-5
18-88-9-2-5-1
18-88-9-3-(2.5)
18-88-9-3-(4)
18-88-9-3-3
18-88-9a
18-88-9b
99-(1)
99-(2)
99-(3)a
Stream Name
WACCAMAW RIVER
WACCAMAW RIVER
WACCAMAW RIVER
Lockwoods Folly River
Lockwoods Folly River
Lockwoods Folly River
Mill Creek
Mullet Creek
Lockwoods Creek
Spring Creek
Shallotte River
Shallotte River
Shallotte River
Shallotte River
The Mill Pond
Sams Branch
The Swash
Shallotte Creek
Saucepan Creek
Jinnys Branch
Goose Creek
Big Gut Slough
Kilbart Slough
Gause Landing Creek
Intracoastal Waterway
Intracoastal Waterway
Intracoastal Waterway
Intracoastal Waterway
Intracoastal Waterway
Intracoastal Waterway
Intracoastal Waterway
Intracoastal Waterway
Intracoastal Waterway
Intracoastal Waterway
Intracoastal Waterway
Intracoastal Waterway
Montgomery Slough
CAPE FEAR RIVER
CAPE FEAR RIVER
CAPE FEAR RIVER
CAPE FEAR RIVER
CAPE FEAR RIVER
Brunswick River
Town Creek (Rattlesnake Branch)
Bald Head Creek
Fishing Creek
Beaverdam Creek
Elizabeth River
Elizabeth River Shellfishing Area
Denis Creek
Piney point Creek
Molasses Creek
Coward Creek �
Dutchman Creek
Dutchman Creek Shellfish Area
Dutchman Creek Outlet Channel
Intracoastal Waterway
Intracoastal Waterway
Atlantic Ocean
Atlantic Ocean
Atlantic Ocean
County
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSW ICK
BRUNSWICK
BRUNSW ICK
BRUNSWICK
BRUNSWICK
BRUNSW ICK
BRUNSW ICK
BRUNSW ICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSW ICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSW ICK
BRUNSWICK
BRUNSW ICK
BRUNSW ICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSW ICK
BRUNSW ICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSW ICK
BRUNSW ICK
BRUNSW ICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
BRUNSW ICK
BRUNSWICK
BRUNSWICK
BRUNSWICK
5` � 1/ 4 �'°`T S

�.;�
.�
prescribed standard designs sometimes copied from
jurisdicUons in vas[ly differen[ geoclimaUc re-
gions. In addition, these laws ofren depended on
minimally trained personnel [o oversee design,
permitdng, and installaflon and mosdy untrained,
uninformed homeowners to operate and maintain
the systems. During the 1950s s[ates began to adopt
laws upgrading onsite system design and installa-
tion practices to ensure proper functioning and
eliminate the threats posed by waterborne patho-
gens (Kreissl, 1982). Despite these improvements,
many regulations have not considered cumulative
ground water and surface watec impacts, especially
in areas with high system densifles aad significant
wastewater discharges.
ICieissl (1982) and Plews (1977) examined changes
in state onsite wastewater treatment regulauons
prompted by the publication of the first U.S. Public
Heal[h Service Mmmal of Septic-Tnnk Practice in
1959. Plews found significant code revisions under
way by the ]ate 1970s, mosdy because of local
experience, new research information, and the need
to nccommodate housing in azeas not suited for
conventional soil infiltradon systems. Kreissl found
[hat states were gradually inereasiug required
septic tank and drainfield sizes but also noted that
32 states were still specifying use of the percola-
tion test in system sizing in 1980, despite its proven
shortcomings. Other differences noted among state
codes included sepazalion dis[ances between [he
infiltration trench bottom and seasonal ground
water tables, minimum trench widths, horizontal
setbacks to potable water supplies, and maximum
allowable land slopes (I{reissl, 1982).
Although state ]awmakers have continued ro revise
onsi[e system codes, most revisions have failed to
address the fundamental issue of system perfor-
mance in the con[ext of risk management for both a
site and the region in which it is located. Prescdbed
system designs require that site conditions fit
system capabilities rather than the reverse and aze
sometimes incorrectly based on the assumption Ihat
cen[ralized wastewater collection and [reatment
services will be available in the future. Codes that
emphasize prescriptive standazds based on empiri-
cal relationships and hydraulic performance do not
necessarily protect gcound water and surface water
resources from public health threats. Devising a
new regime for protecting public health and the
environment in a cost-effective manner will require
increased focus on system performance, pollutant
transport and fatc and resulting environmental
impacts, and integration of the planning, design,
siting, installation, maintenance, and management
functions to actueve public health and environmen-
tal objectives.
1.4 Onsite wastewater treatiment
system use, distribution, and
failure rate
Accocding to [he U.S. Census Bureaa (1999),
approximately 23 percent of the estimated 115
million occupied homes in the United States are
served by onsite systems, a proportion that has
changed little since 1970. As shown iu figure ]-3
and table 1-2, [he dis[ribution and density of homes
with OWTSs vary widely by state, with a high of
about 55 percent in Vermont and a low of azound 10
percent io California (U.S. Census Bureau, 1990).
New England s[a[es have [he highest proporflon of
homes served by onsite systems: New Hampshire
and Maine both report that abou[ half of all homes
aze served by individual wastewater treatment
systems. More than a third of the homes in the
sou[heastern sta[es depend on [hese systems,
including approximately 48 percent in North
Cazolina and about 40 percent in both Kentucky
and South Carolina. More [han 60 million people
depend on decen[ralized sys[ems, including the
residents of about one-third of new homes and
more than half of all mobile homes nationwide
(U.S. Census Bureau, 1999). Some communities
rely completely on OWTSs.
A number of systems relying on outdated and
underperforming technologies (e.g., cesspools,
drywells) still exist, and many of them are Gsted
among failed systems. Moreover, about half of the
occupied homes with onsite trea[men[ systems aze
more than 30 years old (U.S. Census Bureaa, 1997),
and a significant number report system problems. A
sdrvey conducted by [he U.S. Census IIureau
(1997) estimated [hat 403,000 homes experienced
septic system breakdowns within a
3-month period during 1997; 31,000 reported four
or more breakdowns at the same home. Swdies
reviewed by USEPA cite failure rates rauging from
10 to 20 perceot (USEPA, 2000). System failure
surveys rypically do not include systems that might
be contaminatiug surface or ground water, a
situaaon that often is detectable only through si[e-
i-4 USEPA Onsite WastewaterTreafinent Systems Manual

t: � • '
� ' • � � Chapter i: Background and Use otOnsiteWaste�raterTrearir�entSystems �
Figure 1-3. Onsite treatment system distribution in the United 5fates
Source: U.S, Cerisus Bureau,1990,
level monitoring. Figure 1-4 demonstrates ways
'' that effluent water from a septic system can reach
ground water or surface waters.
Compreherisive data to measure the true extent of
septic system'fai�lure are not currently collected by
any single organization. Although estimates of
system failure rates have been collected from 28
states (table 1-3), no state had directly measured its
own failure rate and definitions of failwre vary
(Nelson et al., 1999). Most available data are the
result of incidents that directly affect public health
or are obtained from homeownerS' applications for
permits to z�place or repair failing systems. The 20
percent failure rate from the Massachusetts time-of-
transfer inspection program is based on an inspec-
tion of each septic system prior to home sale, which
is a comprehensive data collection effort. However,
the Massachusetts program only identifies failures
according to code and does not track.ground water
contamination that may result from onsite system
failures. ,
In addition to failures due to age and hydraulic
overloading, OWTSs can fail because of design,
installation, and maintenance problems. Hydrauli-
cally functioning systeins can create health and
Y
y ..
�e of state
using onsite
ar systems
25% ❑
�i0% �
40% �
' ecological risks when multiple 'treatment units are'
installed at densities that exceecl tlie capacity o£
local soils to assimilate pollutant loads. System
owners are not likely to repair or replace aging or
otherwise failing systems unless sewage backup,
septage pooling on lawns, or targeted monitoring
that identifies health risks occurs. Because ground
and surface water contamination by onsite systems
has rarely been confirmed through targeted moni-
toring, total failure rates and onsite system impacts
over time are likely to be significantly higher than
historical statistics indicate. For example, the
Chesapeake Bay Program found that 55 to 85 percent
of the nitrogen entering an onsite system can be
discharged-into ground water (USEPA, 1993). A
1991 study concluded that conventional systems
accounted for 74 percent of the nitrogen entering
Buttermilk Bay in Massachusetts (USEPA, 1993).
1.5 Problems vuith exl�ting onsite
wastewater management
programs
Under a typical conventional system management
approach, untrained and often uninformed system
owners assume responsibility for operating and
USEPA Onsite Wastewater Treatmenf Systems Manual i-5

STATE OF NORTH CAROLINA
DEPARTMENT OF TRANSPORTATION
MICHAEL F. EASLEY
GOVERNOR
MEMORANDUM TO:
FROM:
SUBJECT:
June 4, 2007
John Hennessy
Division of Water Quality
Colin Mellor �% ' .
PDEA — Natural Environment Unit
R-2250 ICI Water Quality Study Report
LYNDO TIPPETT
SECRETARY
Attached is a copy of the Indirect and Cumulative Impact Water Quality Study Report for
R-2250, the Greenville Southwest Bypass. Please contact me by phone [phone]) or
email (cmellor(c�dot.state.nc.us) if you have any questions or comments. An elech�onic
copy will also be fonvarded through NCDOT's file transfer system.
Cc:
Chris Underwood,
Bob Deaton,
Beth Smyre,
David Wainwright
MAILING ADDRESS:
NC DEPARTMENT OF TRANSPORTATION
PROJECT DEVELOPMEM ANO ENVIRONMEMAL AN4LVSIS
NATURFL ENVIRONMENT UNIT
1598 MAI� SERVICE CENtER
RnLE1GN NC 27699-1598
Natural environment Unit
Human Environment Unit
Project Development
Division of Water Quality (w/ electronic attachment)
TELEPHONE: 9i9-��$-�33$ Of J1 9-71 5 7 334
FAX: [phone]
WEBS/TE: WWW.NCDOT.ORG
������b� r:
��
JUN 0 7 200)
WE1tANDSANOST R�41ER9PuU,�i:�
LOCATION:
TRANSPoRTATION BUILDING
1 SOIITH W IIFANGTON STREET
RALEIGH NC

GREENVILLE SOUTHWEST BYPASS
PITT COUNTY, NORTH CAROLINA
TIP PROJECT NO. R-2250
INDIRECT AND CUMULATIVE IMPACT
WATER QUALITY STUDY REPORT
PREPAREDFOR:
North Carolina Department of Transportation
Division of Highways
Project Development and Environmental Analysis Branch
oF �vR�n C�R�
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May 2007

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Prepared by:
�
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Stantec
Stantec Consulting Services Inc.
801 Jones Franklin Road, Suite 300
Raleigh, NC 27606

;;'
Greenville Southwest Bypass
ICI Water Quality Study
Table of Confents
1 � Introduction :......................
...... ....... ......... . ......... ................. ...1-1
.... .... ........ .... ....
1.1 Transportation Project Overview .......:...........................:.............................1-1
1.2 ICI Modeling Study Descripfion ....:..:...............
........... ................:.:........ 1-1
......
2 Existing Water Quality Conditions ..............:.....:.:........:.....:.:....................:.. 2-1
2.1 Impaired Waters ................................... ................ 2-1
..........................:............
2.2 Neuse Riyer Basin Water Quality Initiatives ...................,............................2-1
2.2.1 Neuse River NSW Management Strategy ..............:................:................... 2-2
2.2.2 Neuse River Estuary TMDL .............................:...:....:::........�.:......:..:............ 2-2
2.3 Notable Features and Development Considerations ........:..................:.........2-3
2.3.1 Surface Water Resources ....................:......................::......:....................... 2-3
2.3.2 Protected Species ...........:..:.....:......:....:....:.................:........ .... 2-3
....................
2.3.3 Infrastructure .....................................:..................................................:...... 2-3
2.3.4 Development Trends ........:................
.......................................................... 2-4
2.4 Stormwater Management ....................:............................. ..... 2-5
.....................
2.4.1 NC Session Law 2006-246 and NPDES Phase ll .............:................:...
..... 2-5
2.4.2 Neuse River NSW Management Strategy ....................:.:............................ 2-5
3 Watershed Modeling Approach ...................................:................................ 3-1
3.1 Objectives and Model Selection .....................:............................................ 3-1
3.2 The GWLF Model ..........::............................................. ....... 3-1
........................
3.2.1 Hydrology ..:...:................:....... ..... 3-2
................................................................
3.2.2 Erosion and Sedimentation .............:.......:.........::................................:........ 3-2
3.2:3 Nutrient Loading ............::................................ ..:......... 3-3
................................
3.2.4 Input Data Requirements ......:.................:................................................:...3-3
4 GWLF Model Development .........., ......:....................................................... 4-1.
4.1 Delineation of Subwatersheds .............:................:......................................4-1
4.2 Land Use Scenarios ..............:...:......:..::......................:............................... 4-1
4,2.1 . Existing Land Use ...............:...........::................:................:.,..........,............4-3
4.2.2 Future. No Build and Build Scenarios .:............................................:............ 4-4
4.2.3 Scenario Comparisons :...................:................:..........:................:.....:........ 4-9
4.2.4 Modellmperviousness ......................................:................:.........................4-13
4.3 Surface Water Hydrology ....................................................:..........:.....:...... 4-15
4.3.1 Precipitation .....:.............................:...........................::....:........,:.....:...;.......4-15
4.3.2 Evapotranspiration Cover Coefficients :................:........:.............................. 4-16
4.3.3 Antecedent Soil Moisture Conditions :............:................:....:..........:.....:...... 4-16
4.3.4 Runoff Curve Numbers .:..........:.......:.........................::...............:.......:........4-16
4.4 Groundwater Hydrology .....................:.
.............:................:..........::.........:... 4-16
4:4.1 Recession Coefficient .............:.....:..:......:......:..:.............:...:.:....:.....:...:.:.....4-16
4.4:2 Seepage Coefficient ...:.......:............................:...:...:.........:...:........:..:::.. .....4=17
4.4.3 Available Soil Water Capacity ..........................:.......................................:.. 4-.18
4.4.4 Initial Saturated and Unsaturated Storage ..........:..............:.......:.......:..:...,:4-18
4.5 Erosion and Sediment Tcansport .....................:.......:.......................:..:.......:. 4-19
� 4.5.1 Soil Erod'ibility (K) Factor :..........:.......:.:..............:.: ......4-19
................................
4._5.2 . Length-Slope (LS) Factor ...:....:...........:...: .......: .�.....:,.....:. 4-19: . .
...........................
4:5.3 . Cover (C.) and.Management Practice (P) Factors .........:.:...:..........:.:...: ....4-19
4.5.4 Sediment Delivery. Ratio ....,...:...:.... �
. ..:..:...:...................................................4-19 .
4.5.5 : Sedimentation from U�ban Land Uses :...........................:................:.:......:..4-20
� 4.6 Nutrient Loading ..........:.....:..........:...................:............:................::........... 4-21
4.6.1 Solid Phase Nutrients ..:.::..................�.......:..........:.....::...:.....:....:.....:...-...,...: 4-21
. ..
� -. - .

4.6.2
4.6.3
4.6.4
4.7
4.7.1
4.8
5
5.1
5.2
5.3
5.3.1
5.3.2
6
6.1
6.2
7
8
9
9.1
9.2
Greenville Southwest Bypass
ICI Water Quality Study
Dissolved Groundwater Nutrients ......:.............................................:...........4-21
Runoff Concentrations and Build-up Rates ..............:.................................. 4-21
Septic System Loading ................................................................................4-23
Consideration of Existing Environmental Regulations .........:..........:.:...:......4-24
Neuse_ River Nutrient Sensitive Waters Management Rules ......:...........,.... 4-24
Model Implementation ..........:...... .... 4-25
.............................................................
GWLF Model Results and Discussion ......................................................... 5-1
Hydrology........................................:.......................:................................... 5-1
PollutantLoading ......................................................................................... 5-1
Verification of Model Results .....................................:.................................5-6
Pollutant Loading Comparison ................................:................................... 5-6
Streamflow Comparison ........:..............:. ........... 5-6
..........................................
Stream Erosion Risk Analysis ..................................................................... 6-1
TechnicalApproach .....................................................................................6-1
Resu Its ...................... .............. ............ ............................................ ...... ...... . 6-2
Conclusions..................................................................:.............................. 7-1
References......................................................................:........................... 8-1
Appendix
Land Use Scenarios .................................................................................... 9-1
Runoff Volume Analysis ..................................................:..............:............ 9-3
�

,� i . . . ' . . � . . . .
� � �
Greenville Soutbwest.Bypass
j�-��,. ICI Water Quality Study
�, .
r-I Tables
�__� Table 4.2.1 Land Use Categories and Density ..............:......... . ....4-1
. .................................
Table 4.2.2 Existing Land Use/Land Cover Conversion Table ...:......:..:............:............4-10-
��'� Table 4.2.3 Future Land Use/Land Cover Conversion Table ................................:........4-10
' Table 4.2.4 Estimates of Imperviousness from the Literature
�� . :' ..............:......................... 4-13
Table 4.2.5 Land Use Categories and Estimated Imperviousness ...............:....::........... 4-14
� Table 4.3,1 Surface Water Hydrology Input Parameters ........:................:............:.........4-15
�-,
'� Table 4.3.2 Curve Numbers for Land Use and Soil Hydrologic Groups ....:.....:.....:....:... 4-17
Table 4.4.1 Groundwater Input Parameters ........................:........:...........:..................... 4-18
�--, Table 4.5.1 Rural Sediment Transport Input Parameters ........:................:..................... 4-20
;� Table 4.5.2 Cover (C) and Management Practice (P) Factors :..:...:.......................:....... 4-20
Table 4.6.1 Nutrient Loading Input Parameters ..:...............::................................:....:.... 4-22
r,
Table 4.6.2 Nutrient Runoff and Buildup Rates for Existing Land Uses .:....................... 4-23
� Table 4.6.3 Septic System Input Parameters .:........4-24
.......................................................
__� Table 5.2.1 Ten-Year Total Loads (tonnes) for All Subwatersheds .................:.............. 5-3
Table 5.2.1 Comparison.of Model Loading Rates to the Literature .........:...................... 5-7
�;
Table 6.2.1 Storm Flow Volumes (cubic meters) for the One=Year, 24-Hour Storm ...... 6-2
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Greenville Southwest Bypass
ICI Water Quality Study
Figures
Figure 1.1.1 Project Vicinity .............................................................................................1-1
Figure 32.1 Schematic of GWLF Model Processes (taken from Dai et al., 2000) .......... 3-2
Figure 4.1.1 Model Subwatersheds .................................................................................4-2
Figure 4.2.1 Existing Land Use / Land Cover .............................................:.....:..............4-5
Figure4.2.2 Proposed ETJ .............................................................................................4-6
Figure 4.2.3 Future No Build Land Use/Land Cover Scenario .................:...................... 4-1_1
Figure 4.2.4 Future Build Land/Land Cover Scenario ............................................:........ 4-12
Figure 5.1.1 Mean Monthly Water Balance for the UB1 Subwatershed (No Build
Scenario) 5-2 �
Figure 5.2.1 Mean Annual Total Nitrogen Loading Rates ........................................::...:.. 5-4
Figure 5.2.2 Mean Annual Total Phosphorus Loading Rates .......................................... 5-4
Figure 5.2.3 Mean Annual Sediment Loading Rates ....................................................... 5-5
Figure 5.2.4 Total Nitrogen (TN), Total Phosphorus (TP), and Sediment Loading Over
the Ten-Year Model Simulation Period ........................................................................ 5-5
� iv

Greenville Southwest Bypass
ICI Water Quality Study
Executive Summary
The North Carolina Department of Transportation (NCDO� 2006-2012 Transportation
Improvement Program (TIP) includes transportation improvements for the Stantonsburg
Road (US 264 Business)/Memorial Drive (NC 11) corridor in Pitt County, North Carolina,
This project is referred to as the Greenville Southwest Bypass (TIP Project No. R 2250)
and is proposed as a four-lane, median-divided, full control of access facility.' The
approximate length of the project is 13 miles (34 kilometers) with 11 miles on new
location (bypass alfernate 4).
An Indirect and Cumulative Effects (ICE) Analysis was completed in May 2006 to
provide an assessment of the potential long-term, induced impacts of the proposed
project (NCDOT, 2006a). In response to NC Division of Water Quality (NCDWQ)
comments on the ICE.Assessment and.in preparation for an Individual Section 401
Water Quality Certification, a water quality modeling analysis has been conducted to
quantify the project's indirect and cumulative impacts (ICIs) on water resources.. The
focus of the analysis is on the potential increases in stormwater runoff and nonpoint
source loads of nitrogen, phosphorus, and sediment resulting from a future development
scenarios associated with the roadway.
Two modeling tools were used to quantify impacts on water resources: the Generalized
1Natershed Loading Function (GWLF) watershed model and the SCS Curve N,umber
Method. The GWLF model (Haith and Shoemaker, 1987; Haifh et al., 1992) was
selected to simulate long-term loading of nonpoint source pollutants, An additional
parameter, runoff from the one-year,.24-hour storm event, was evaluated using the SCS .
Curve Number Method (SCS,: 1986) to assess the potential risk of downstream channel
erosion.
Predictions from the modeling analyses suggest that if fhe roadway is constructed (Build
scenario) storm event runoff volume and nutrient loading would increase slightly relative
to the No Build scenario (see figure summarizing results on next page). The overall
increases under both scenarios are in part mitigated as a result .of the existing (and
expected) regulations governing the jurisdictions (Neuse Nutrient Sensitive Water rules
and NPDES Stormwater Rhase II). Individual subwatershed increases ranged from less
than 1 % to 22%. . :
These results have important implications for. the potential increases in predicted
pollutant loads to two local streams, Swiff Creek and Little Contentnea Creek, which
have been designated as impaired by NCDENR. While development in the area will
result irr increases in pollutant, loads to these waterbodies, .the increases suggested by
the modeling analysis do not appear to be influenced significantly by #he new roadway.

�I �soo
1600
1400
1200
d 1000
c
C
� $��
600
400
I 200
I �
Tf�l TP
Greenville Southwest Bypass
ICI Water Quality Study
' ■ No Build
� Build
Sediment X 10
Total Nitrogen (TN), Total Phosphorus (TP), and Sediment Loading Over the Ten-Year
Model Simulation Period
vi

Greenville Southwest Bypass
ICI Water Quality Study
INTRODUCTION
1.1 Transportation Project Overview
The North Carolina Department of Transportation (NCDOT) 2006-2012 Transportation
Improvement Program (TIP) includes transportation improvements for the Stantonsburg
Road (US 264 Business)1Memorial Drive (NC 11) corridor in Pitt County, North Carolina.
This project is referred to as the Greenville Southwest Bypass (TIP Project No. R-2250)
and is proposed as a four-lane, median-divided, full control of access facility. The
approximate length of the project is 13 miles (34 kilometers) with 11 miles on new
location (bypass alternative 4). Figure 1.1.1 shows the vicinity of the proposed project.
The project begins at an interchange with NC 11 near Jacksontown Road south of the
Town of Ayden. There are interchanges proposed at NC 102, NC 903, Forli�es Road,
and US 13/264 Alt. The project ends at the existing interchange at US 264
Bypass/Business. The purpose of and need for this project is to ease congestion on
existing Memorial Drive (NC 11 and Stantonsburg Road (US 264 Business).
1.2 ICI Modeling Study Description
An Indirect and Cumulative Effects (ICE) Assessment was developed to provide
comprehensive information on the potential long-term, induced impacts of the proposed
project (NCDOT, 2006a). The assessment was conducted in accordance with federal
Council on Environmental Quality (CEQ) regulations and follows the systematic
1-1

� Greenville Southwest Bypass
ICI WaterQuality.Study
procedures contained in Guidance for Assessing Indirect and Cumulative Impacts of
Transportation Projects in No'rth Carolina.(NCDOT, 2001).
Findingsfrom the ICE stated'that growth in Greenville has been spurred by the regional
medical center_ and East Carolina University and that transportation improvement
projects have been constructed to ease congestion: The report found tfiat since the
plans to build a bypass have been around since the 1970s, local regulations and officials
have been targeting growth along the major feeder roads in anticipation of construction.
Even without the bypass, areas around the planned bypass will continue to grow. The
construction of the bypass will enhance this trend. The bypass will increase access and
mobility and thus increase the potential for highway-related development. The study
found water service was not a limiting growth factor as it is already available in much of
the study area and . new extensions are .allowed buf sewer service was found _ta be a
more limiting growth factor. This issue is further assessed in the Section 2.3.4.
In response to NC Division of Water Quality (NCDWQ) comments on the ICE
Assessment and in preparation for an Individual Section 401 Water Quality Certification,
the NCDOT contracted with, Stantec #o conduct watershed modeling_ to quantify the
project's indirect and cumulative impacts (ICIs) on water resources. The focus of the
analysis is potential increases in stormwater runoff and nonpoint source loads of
nitrogen; phosphorous and ''sediment resulting from a future development scenario
associated with the roadway.
The present analysis focuses�,on an area confined to the Neuse River Basin and draining
to Little Contentnea Creek and Swift Creek, the two impaired waters located within the
previously defined ICE study, area (Figure 1.2.1.). Twenty-one subwatersheds covering
169 kmz (65 mi2) were delineated for watershed modeling purposes. The model study
area contains portions of the following jurisdictions: Greenville, Winterville, Ayden,.and
Pitt County.
The Generalized Watershed Loading Function (Haith and Shoemaker, 1987; Haith et al.,
1992) model was selected for the purposes of simulating nonpoint source loads of
nitrogen, phosphorous and sediment. An additional parameter, storm event runoff, was
evaluated using a separate �assessment tool, the SCS Curve Number Method (SCS,
1986), to assess the risk of downstream .channet erosion.
A particular focus in the analysis was the potential increase in predicted pollutant loads
to Swift Creek and Little Contentnea Creek, which have. been designated as impaired by
the NC Department of Environment and Natural Resources {NCDENR). Little
Contentnea Creek is impaired for low dissolved oxygen and biological integrity. Swift
Creek is impaired for biological integrity. In addition the project area is approximately 30
miles from the Neuse Estua,ry,. which is impaired .for chlorophyll a and is subject of a total
maximum daily load (TMDL) for nitrogen. .
�
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, 1-2

Greenville Southwest Bypass
ICI Water Quality Study
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ICI Water Quality Sludy
Greenville Souhvest Bypass
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1-3

Greenville Southwest Bypass
ICI Water Quality Study
2 EXISTING WATER QUALITY CONDITIONS
2.1 Impaired Waters
Two water bodies in the immediate vicinity of #he project, Swift Creek and Little
Contentnea Creek, have been designated as impaired by the NC Department of
Environment and Natural Resources (NCDENR). Little Contentnea Creek is impaired for
low dissolved oxygen and biological integrity. Swift Creek is impaired for biological
integrity. In addition the project area is approximately 30.miles from the Neuse Estuary,
which is impaired for chlorophyll a and is subject of a total maximum daily load (TMDL)
#or nitrogen.
Little Contentnea Creek drains the southwestern corner of Pitt County, north of the Town
of Farmville and also portions of northeastern Wilson and northern Greene counties.
Swift Creek is a large tributary to the Neuse River. The watershed of Swift Creek drains
the agricultural areas of southeastern and south central Pitt County and the suburbs of
the southern part of the City of Greenville. Potential sources of impairment to both
streams are primarily agricultural (NCDWQ, 2006a).
There are no NCDWQ ambient monitoring sites, biological monitoring stations or USGS
gages located within the model study area. Two sites are located near the study area: a
benthos station on Little Contentnea Creek at US 264A and a fish community station on
Swift Creek located several miles downstream of the study area boundary. An ambient
monitoring site (J7739550) is located on Little Contentnea Creek at SR 1125 near the
study area. None of the parameters sampled during the. most recent assessment
exhibited violations of water quality standards except for iron. Iron concentrations
exceeded action level water quality standards. The cause of the elevated levels was not
identified (NCDWQ, 2006b). The next closest station is located 9 miles south of the
study area on Contentnea Creek (J7810000).
At the US 264A benfhos monitoring station (B-5), Little Contentnea Creek has. swamp-
like characteristics: tannic water and. a slightly braided channel NCDWQ (2006). The
substrate was mostly sand with some silt. Like many of the streams in the area, variety
in pool size was lacking. This site has been sampled for macroinvertebrates in 2000,
2001, .and 2005, all three times rated as Fair. The creek may have been channelized
more than 50 years ago according to NCDWQ.. �
Swift Creek is a shallow, sandy bottom, entrenched stream that has been channelized
and is maintained as a channelized waterbody. The fish community station (F-1) at SR
1753 had the second lowest habitat score of any fish community site in the Coastal Plain
in 2005. Swift Creek is currently impaired from its source to the Neuse River because it
received a Fair bioclassification rating after macroinvertebrate sampling. Habitat
degradation is the most likely cause of impairment according to the 2002 Basinwide
VUater Quality Plan (NCDWQ, 2002a). There were few pools and a silty substrate was
noted by sfate monitoring personnel.
2.2 Neuse River Basin Water Quality Initiatives
Water quality in the Neuse River estuary has been a concern for over a century.
Nitrogen loading has been increasing in the Neuse River Basin, corresponding witti
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Greenville Southwest Bypass
ICI Water Quality Study
increases in chemical fertilizer use in the early 1960's and animal feeding operations in
the 1970's_(Stow et al., 2001): Total nitrogen concentrations increased in the river until
about 1990 but more recently have been declining. Elevated nutrient levels have led to
frequent algal blooms, hypoxic conditions and fish kills in the estuary. As a result, the
Neuse River Basin was listed as impaired by chlorophyll a on North Carolina's 303(d) list
in the early to mid-1990's.
2.2.1 Neuse River NSW Management Strategy
Water quality research in the Neuse River Basin expanded after extensive fish kills in
1995. Low dissolved oxygen levels associated with eutrophication were determined to
be a probable cause. Although, a number of fish kills were also attributed to a
dinoflagellate known as �esteria piscicida; thought to thrive in poor water quality
situations (NCDWQ, 2002a). In 1997, the North Carolina Environmental Management
Commission (EMC) adopted a mandatory plan, the Neuse River Nutrient Sensitive
Waters (NSV1n Management Strategy, to control both point and nonpoint sources of
pollution in the Neuse River basin (NCDWQ, 2002b). With the exception of the riparian
buffer rules, these rules became effective in 1998. The buffer rules became effective in
2000. The overall goal of these rules was to reduce average annual load of nitrogen (a
key nutrient contributing to excess algal growth) delivered to the Neuse River Estuary by
30% by the year 2001.
The Neuse River NSW Management Strategy is made up of a number of rules regulating
various items such as waStewater discharges, urban stormwater management,
agricultural nitrogen reduc#ion, nutrient management, and protection and maintenance of
riparian areas (NCDWQ, 2002b). NCDWQ is responsible for administering and enforcing
these rules.
2.2.2 Neuse Riyer Estuary TMDL
A TMDL (total maximum daily load) is defined as a calculation of fhe maximum amount
of a pollutant that a waterbody can receiye and still meet water quality standards, and an
allocation of that amount to the pollutant's sources. The first phase of the TMDL for Total
Nitrogen to the Neuse River estuary was conditionally approved in July 1999. The
second phase was completed by DWQ and approved by the EPA in 2001. The premise
for developing the TMDL is that a portion of the Neuse River is impaired for chlorophyll
a, an indicator of excessive eutrophication as a result of nutrient loading. The Neuse
River TMDL supported the nitrogen reduction goal set forth by the earlier Neuse River
NSW Management Strategy. A declining trend in nitrogen is attributed to the
implementation of the 1997 Neuse River NSW. Management Strategy outlined. above
(Harned, 2003). . . .
2-2 -
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Greenville Southwest Bypass
ICI Water Quality Study
2.3 Notable Features and Development Considerations
This section discusses the most notable.features and development considerations.of the
project study area and vicinity.
2.3.1 Surface Water Resources
The model study area lies within the Neuse River Basin, eight-digit Hydrologic Units
03020202 and 03020203. The western and northern portions of the study area drain to
Pinelog Branch and various unnamed tributaries of Little Contentnea Creek.
Waterbodies in the eastern portion of the study area include Gum Swamp, Horsepen
Swamp, Nobel Canal, Simmon Branch, and various unnamed tributaries that flow into
Swift Creek
NCDWQ classifies all the named sfreams in the project study area as Class C waters
(NCDWQ 2005c), which are best suited for aquatic life survival and propagation, fishing,
wildlife, secondary recreation, and agriculture. These streams have also been assigned
the supplemental classifications of nutrient sensitive waters (NSV1/) and swamp waters
(Sw). NSWs require limitations on nutrient input and are included in the Neuse River
NSW Management Strategy. Swamp waters are designated as such due to their low
velocities and other natural characteristics that are different from adjacent streams.
2.3.2 Protected Species
Under the Endangered Species Act (ESA) of 1973, four species are listed as
endangered or threatened for Pitt County: bald eagle (Haliaeetus leucocephalus), West
Indian manatee (Trichechus manatus), red-cockaded woodpecker (Picoides borealis),
and Tar River spinymussel (Elliptio steinstansana) (USFWS, 2006). According to the
Natural Heritage Program, there are no records of occurrences or known populations of
any of these species located within the model study area. Spinymussel populations exist
in. the Tar River drainage in Nash, Franklin,.Warren, Halifax and Edgecombe Counties.
There are ten Federal Species of Concern (FSCs) listed for Pitt County, of which only
one, the Henslow's sparrow (Ammodramus henslowii) is on record as being seen during
the last 20 years.
2.3.3 Infrastructure
The Tar River serves as the primary water source for Greenville. Ayden, and Winterville.
Private water systems in Pitt County draw water from groundwater aquifers, primarily the
Black Creek aquifer. Water service is generally available throughout.the study area.
Access to sewer service is .currently limited to the municipal boundaries and portions of
the extraterritorial jurisdictions (ETJs) of Greenville, Ayden and Winterville. Greenville is
served by a 17.5 million gallon per day (mgd) wastewater treatment plant (WVVfP). The
Contentnea Metropolitan Sewerage District (CMSD) serves the towns of Ayden, Grifton,
and Winterville. Both plants have surplus capacity.
The ICE contains a.summary of Greenville Utilities Commission's (GUC) regulations
regarding sewer exfension. The regulations state that sewer extension outside of the city
limits or outside of the current ETJ can only occur after the property owner has filed for
2-3
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Greenville Southvirest Bypass
ICI Water Quality Study
voluntary annexation with the City of Greenville. It also states that in-city waste or sewer
extensions will be given priority over out-of-city extensions: The ICE concludes that
sewer is.therefore a limiting factor to growth in the study area. Upon further investigation
and conversation with the City of Greenville, it was found thaf sewer is likely to expand
throughout Greenville's ETJ and beyoncl as long as developers request it (Harry
Hamilton/Greenville Planning; personal communication). This is common as many
developers in the area prefer to develop at a higher density than allowed with
conventional septic systems. Sewer lines have already been extended throughout the
southwest portion of Vision Area E in preparation for new developments that will be
annexed by the city. Greenville is divided into vision areas for planning purposes. Vision
Area E contains the southwest portion of the City of Greenville and its ETJ and is bound
by Green Mill Run and Forbes Run to the north; Seaboard Coastline railroad to the east;
Greenville ETJ to the south and west. The southwest portion of Vision Area E coincides
with a portion of tfie model study area (in and around subwatershed SC1).
;_ ; Winterville and Ayden currently only have sewer senrice within the town limits of each
municipality. The ICE states that Winterville and Ayden have no policies or ordinances
�� that restrict the extension of water or sewer utilities although further discussion with the
j" municipalities revealed that Ayden requires annexation for extensions.
2.3.4 Developmenf Trends
Between 1990 and 2000 Pitt County. experienced a 24% increase in population. The
population in the study area grew by 49.1 %. Greenville and Winterville both had positive
growth, 32.1 % and 56.2% respectively, while Ayden saw a 5.6% decrease. The
expected population increase in the county and in the study area between' 2000 and
2010 is 14.4% and 26.8% respectively, assuming the .study area captures the same
percentage of the county's growth as it did between 1990 and 2000 (NCDOT, 2006a).
As the population grows land continues to be developed in the study area, especially the
portions within the Greenville and Winterville ETJs. The primary growth areas . in
. Greenville have been towards the south and southwest (Greenville, 2004). Most of the
- growth in this area has been residential although there has been some commercial and
institutional growth including a high school. In 2006 Greenville produced a study
� focusing on the portion of Vision Area E contained in the study area (in and around
__a subwatershed SC1) that predicts full build out of the area in finrenty years. Growth has
been attributed to the availability of municipal, county, and GUC services and facilities
� now available in the area (SW Area Report 2006). According to the report "estimates of
� future build-out are based on existing zoning patterns and anticipated future rezoning of
- existing RA20 district properties as recommended by the Horizons Plan and Future Land
Use Plan Map (2/04). The projected densities for future development areas are based on
� current and historical residential trends and continued application of current regulatory
standards" (SW Area Report 2006). Although existing and future transportation systems
were considered along with adjoining land uses patterns and environmental constraints,
� Greenville Planning staff believe that growth will eontinue as projected even if the
_� Southwest Bypass is not constructed (Harry Harriilton/Greenville Planning, personal
communication).
Between 2000 and 2004 Pitt County approved over 50 developments in the portion of
the study area under county jurisdiction. .Most of the developments will contain between
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Greenville Southwest Bypass _
ICI WaterQuality.Study ' I
i�
6 and 40 houses although there are two preliminary piats for developments with over 60 ,
houses each. � � � � � �
� � l�
2.4 Stormwater Managemeni
2.4.1 NC Session Law 2006-246 and NPDES Phase 11
Session Law 2006-246 was, approved by the NC L.egislature and signed into law in late
summer of -2006. The act provides for the implementation of the federal Phase II
stormwater program and additional stormwater management provisions.
I�
Beginning July 2007, any new development that cumulatively disturbs one acre or more ;;
of 'land located in Pitt County or municipalities contained therein must comply with the '—f
standards set forth in Section 9 of Session Law 2006-246. Under Section 9, programs
are deemed compliant where the Neuse River NSW Management Strategy is being � �
implemented. For fhe study area, this includes Pitt County and Greenville. In addition, �_�
Greenville, Ayden, and Winterville will be issued Phase II NPDES permits.
� `i
Ayden and Winterville were contacted about new requirements expected to be installed ��
as a result of the new law. Both municipalities expect to adopt requirements similar to �
the County, which recently adopted the stormwater provisions contained within the ;,
Neuse rules (Chris Padgett/Ayden and �Ilie Gay�nterville, personal communication). j�
2.4.2 Neuse River NSW Management Sfrategy
The Neuse stormwater rules require the development of stormwater management plans
for each of the fifteen largest local governments within the basin, including the City of
Greenville. Pitt County has also opted to implement the rules within its jurisdiction.
The local government stormwater plans must be consistent with the overall 30% nitrogen
reduction goal of the Neuse River NSW Management Strategy (NCDWQ, 2002b). The
rules require that each new development must meet a nitrogen export performance
standard with a provision for mitigation offset payments. The Neuse NSW stormwater
management program imposes a 4.0 kg/ha/yr (3.6 pounds per acre per year or Ib/ac/yr)
nitrogen loading limit on new development. Nitrogen load from new developments that
exceed this performance standard may be offset by payment of a fee to the Wetlands
Restoration Fund provided, however, that no new residential development can exceed
6.7 kg/ha/yr (6.0 Ib/ac/yr) and no new nonresidential development can exceed 11.2
kg/ha/yr (10.0 Ib/ac/yr).
The rule also requires presenration of fifty-foot riparian buffers on perennial and
intermittent streams. Further, all new development must control water runoff so that
there is no net increase in the peak discharge from the predevelopment conditions for
the 1=year, 24-hour storm.
2-5
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Greenville Southwest.Bypass
ICI Water Quality Study
3 WATERSHED MODELING APPROACH
� 3.1 Objectives and Model Selection
The objective of this modeling analysis is to quantify the changes in long term pollutanf
loads resulting from potential land use changes induced within the project study area by
construction of the Greenville Southwest Bypass. Two land use scenarios, referred to
from here out as the Build and No Build Scenarios, were developed for this study. The
analysis will quantify changes relative to a land use scenario predicted to develop
without construction of the roadway.
The parameters of interest in this study are sediment, total nitrogen (TN), total
phosphorus (TP), and storm event runoff volume. The Generalized Watershed Loading
Function (Haith and Shoemaker, 1987; Haith et al., 1992) model was selected to
simulate long-term nutrient and sediment loads from catchments draining the project
study area. Storm event runoff was evaluated using a separate assessment tool, the
SCS Curve Number Method (SCS, 1986) to assess the risk of downstream channel
erosion.
The Generalized Watershed Loading Function (GWLF) is a continuous simulation model
�" i with a complexity in the mid-range of watershed models, falling between detailed
j_1 mechanistic models like the Soil & Water Assessment 'fool (Neitsch et aL, 2001) or the
Hydrologic Simulation Program — Fortran (Bicknell et al., 1985) and simpler, empirical
methods such as export coefficient- or event mean concentration-driven such as PLOAD
', (USEPA, 2001). The model does not contain instream transport or transformation
algorithms.
GWLF is applicable as an assessment tool with or without formal calibration, the process
of adjusting a model's parameters to fit an observed data set. This featuce of the model
is important for the present study given that water quality and flow data were not
available from the study area to allow comparisons of observed and predicted values.
GWLF has been utilized in several successful applications to watershed studies,
including some in coastal North Carolina (Dodd and Tippett, 1994; Swaney et al., 1996;
Lee et al., 1999; CH2M Hill, 2003; NCDOT, 2005c; NCDOT, 2006b) and was. used for
the watershed modeling component of the Jordan Reservoir Nutrient TMDL (NCDWQ,
2005a).
r�'� ' The BasinSim 1.0 version of GWLF was selected for this modeling analys'ts. BasinSim is
_' an updated version of GWLF developed by a team of researchers at the_ Virginia lnstitute
of Marine Science with a grant from NOAA Coastal Zone Management (Dai et al., 2000j.
;-^; The updates consist primarily of an improved graphical user interface and the addition of
;� numerous software utilities to edit input and manage and display GWLF results.
f,
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3:2 The GWLF Model
This section provides an overview of the mathematical basis used in GWLF. The
discussion is a summary, largely drawn from the GWLF Version 2.0 User Manual (Haith
et aL, 1992). Figure 3.2.1 is a schematic illustration of the structure of the GWLF model
from. Dai et al.. (2000): �.
,--. 3-1
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Greenville Southwest Bypass
ICI Water Quality Study
GWLF provides the ability to simulate continuously runoff, sediment, and nutrient (N and
P) loading from a watershed given variable-size source areas (i.e., agricultural, forested
and developed land). The model uses daily steps for weather data and water balance
calculation. The model is considered a combined distributed/lumped parameter
watershed model. For surface loading, it is distributed in the sense that it allows multiple
land use/cover scenarios, but each area is assumed to be homogenous with regard to
various attributes considered by the model. The model does not spatially distribute the
source areas, but simply aggregates the loads from each area into a watershed total; in
other words there is no spatial routing. For sub-surface loading, the model also acts as a
lumped parameter model using a water balance approach.
3.2.1 Hydrology
GWLF estimates surface runoff using the Soil Conservation Service (SCS) Curve
Number (CN) approach with daily weather (temperature and precipitation) inputs. Daily
water balances are calculated for unsaturated and shallow saturated zones. Infiltration to
the unsaturated and shallow saturated zones equals the excess, if any, of rainfall and
snowmelt less runoff and evapotranspiration. The product of a cover factor dependent
on land use/cover type and potential evapotranspiration gives daity evapotranspiration.
The latter is estimated as a function of daylight hours, saturated water vapor pressure
and daily temperature. Percolatio� occurs when unsaturated zone water exceeds field
capacity. Streamflow consists of runoff and discharge from groundwater.
3.2.2 Erosion and Sedimentation
Precipi[ation Evapotranspaation
Land Surface - SCS Cune
Number Sinulation
Unsaturated Zone
Shallow Saturoted Zone
Deep Seepage
Loss
Erosion
(USLE)
Runoff
DissoMed Nutrients
Groundwater
(Shallow)
Septic System Loads
Particu late
Nutrients
�Loading to
SVeam
Figure 3.2.1 Schematic of GWLF Model Processes (taken from Dai et al., 2000)
3-2

Greenville Southwest Bypass
ICI Water Quality Study
Erosion and sediment yield from rural land uses are estimated using monthly erosion
calculations based on the Universal Soil Loss Equation (USLE) algorithm (with monthly
rainfall-runoff coefficients) and monthly composite of soil erodibility (K), topographic
factor (LS), crop management (C), and conservation practice (P) values for each source
area. A sediment delivery ratio, which is based on watershed size, and a transport
capacity, which is based on average daily runoff, are then applied to estimate the
sediment yield for each source area.
Sediment load from urban land uses are not included in the current BasinSim
application. For the present study, sediment from urban sources was modeled using the
same accumulation and washoff functions from the model substituting sediment
accumulation rates for particulate nutrient accumulation in the nutrient data file. A similar
approach was used by Schneiderman et a/. (2002) in an update to the original
application of GWLF on the Cannonsville watershed by Haith and Shoemaker (1987).
Note that GWLF and the current study do not predict short term sedimentation from
construction sites.
3.2.3 Nutrient Loading
Surface nutrient losses are determined by applying dissolved nitrogen (N) and
phosphorus (P) coefficients to surface runoff from each agricultural source area. Point
source discharges can also contribute to dissolved losses and are specified in terms of
kilograms per month. Manured areas, as well as septic systems, can also be considered.
Urban nutrient inputs are all assumed to be solid-phase; the model uses exponential
accumulation and washoff function for these loadings. Sub-surface losses are calculated
using dissolved N and P coefficients for shallow groundwater contributions to stream
nutrient loads. The sub-surface sub-model considers only a single, lumped parameter
contributing area.
3.2.4 Input Data Requirements
For execution, the model requires three separate input files containing transport,
nutrient, and weather-related data. The transport file defines the necessary parameters
for each source area to be considered (e.g., area size, curve number) as well as global
parameters (e.g., initial storage, sediment delivery ratio) that apply to all source areas.
The nutrient file specifies the various loading parameters for the different source areas
identified (e.g., number of septic systems, urban source area accumulation rates,
manure concentrations). The weather file contains daily average temperature and total
precipitation values for each year simulated.
3-3

Greenville Southwest Bypass
ICI Water Quality Study
4 GWLF MODEL DEVELOPMENT
The following sections provide a discussion of the data sources, parameter inputs; and
assumptions utilized in this watershed modeling analysis.
4.1 Delineation of Subwatersheds
The study area was delineated into twenty-one subwatersheds covering 169 kmZ (65
mi2). Subwatersheds ranged.in size from 2.6 to 12.5 km2 (1.O to 4.8 mi2). A 6-meter (20-
foot) digital elevation model (DEM), a raster grid of regularly spaced elevation values
derived from recent Light Detecting and Ranging (LIDAR) data and obtained from
NCDOT (2005b), was used to develop a preliminary delineation with a hydrology
modeling extension developed for ArcGIS (ESRI, 2005). Field reconnaissance was
conducted to identify man-made alterations to flow paths and directions of drainage
aided in refining the delineation. The size of each subwatershed in hectares is shown in
Figure 4.1.1.
4.2 Land Use Scenarios
No-Build and Build land use scenarios (Figures 4.2.3 and 4.2.4 respectively) were
developed using fhe categories presented in Table 4.2.1. The scenarios were based on
zoning, future land use maps, special studies, and personal communication with various
town and county planners.
Table 4.2.1 Land Use Categories and Density
LAND USE NAME 'GWLF CODE DENSITY
Agriculture/Residential — Very Low Density . RVL greater than 2 acres per
dwelling unit
Residential — Low Density RLL 1.5-2 acres per d.u:
Residentiaf— Medium Cow Density RML 1-1.5 acres per d.u.
Residential — Medium High Density RMH 0:5-1 acres per d.u.
Residential — High Density RHH 0.25-0.5 acres per d.u.
Residential — MultifamilyNery High Density RVH less than 0.25 acres per d:u.
Office/Institutional/Light Industrial OFF N/A
Commercial/Heavy Industrial COM N/A
Paved Road with Right of Way ROAD N/A
Urban Green Space/Forest UGR N/A
Wetlands WET N/A
Water WAT N/A
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Greenville Southwest Bypass
ICI Water Quality Study
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— selected_corridor �_ _� Rrver Basin Bountlary Figure 4.1.1. Project Subwatersheds
♦ Weather Station " ,_ Counry Boundary
�___ ICI Water �uality Study - Greenville Bypass
.� _� Model Su6watersheds Mumcipalities
TIP No R-2250, Pitl Counry. NC
• � Impaired Streams Ayden ETJ _
"�-���- -� Sfreams Greemille ETJ North Carolina
_ Water Botlies Greenville Proposed ETJ ���� Department oi Transportation
� i Railroads Nhntervilte ETJ �
0 O S 1 2 3 Miles
Roads N/nterville Proposed ETJ
4-2

Greenville Southwest Bypass _ _
ICI Water Quality Study �'
�i
4.2.1 Existing Land Use
Existing land uses were identified before producing the land use scenarios. All existing
developed land was then tagged in the land use scenarios as their modeled loading
rates are different due to regulations governing new development in .the study area
(discussed further in Section 4.7). The existing land use layer as well as the land use
scenarios are GIS layers or datasets. Each GIS layer was created as described below
and in the following section and then depicted on the figures in this section.
The existing land use GIS layer (Figure 4.2.1 Existing Land Use/Land Cover) is based
on a compilation of existing land use maps provided by Greenville, and Pitt County.
Winterville has a developed parcels layer that was used in conjunction with the zoning
layer to determine land use. Ayden existing land use was based on zoning and 2004
aerial imagery. Land use classes and zoning categories from the different jurisdictions
were assigned to each of the model categories according to information provided by
each jurisdiction (Table 4.2.2)_ Undeveloped land could also be assigned to the
additional classes of row crop (ROV1� and forest (FOR). All references of aerial imagery
refer to the 2004 true color aerial imagery provided by the GUC. -
The Greenville existing land use map was created in 2004. The commercial and
industrial land uses were assigned to the Commercial/Heavy Industrial category. The
office and institutional land uses were assigned. to the Office/Institutional/Light Industrial
category, There was one cemetery that was labeled open space. Utility land uses wece
checked using aerial imagery and then assigned to Open Space or Office depending on
the type of utility. The one recreation parcel had a building and parking lot and was
therefore defined as Office/Institutional/Light Industrial. The duplex, multi-family, mobile
home, mobile home park, and single family residential land uses were placed into
categories depending on parcel size and number of units per parcel. All residential
parcels greater than five acres in size were examined using aerial imagery to quantify
the number of houses or units per parcel, determine density, and then assign the parcel
to a residential category. All vacant land was assigned to Row Crop, Forest,_ or _Open
Space depending on land cover as determined using aerial imagery. Finally, a current
parcel map (September 2006) provided by Pitt County was combined with the existing
land use map to bring.it up to date. The parcel map contains information on building
values. If the building value is greater than 0 on a new parcel, it is assumed that the
parcel has been developed. If the building value is zero, the parcel has been created
and reaorded but the building has not been constructed. Therefore, new parcels from the
parcel layer, with a current building value greater than zero, were assigned fo a category
based on zoning and then on parcel size if considered residential. New parcels from the
parcel layer, with a current building.value of zero, were assigned to a category based on
aerial imagery.
The Pitt County existing land use map was created .in 2002. Commercial and industrial
land uses were assigned to the Commercial/Heavy Industrial category. The institutional
land use was assigned to the : Office/Institutional/Light Industrial category.
Government/utility facilities and recreation .land uses were checked using aerial imagery
and then assigned to Open Space or Office depending on the type of utility or recreation
use. Residential land uses were assigned to land use categories based on parcel size.
The remaining undeveloped/agricultural land use areas were examined with aerial
imagery. Areas were divided, into forest, open space, and :agriculture based on land
4-3
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'j
4
Greenville Southwest Bypass
ICI Water Quality Study
cover. In addition the 2006 county, parcel layer was joined with the land use to reflect all
new parcels from 2002 to 2006. All parcels with the attribute "heated square feet>0" and
an area of less than five acres in size were assigned a residential category. Land use for
those parcels greater than five acres were verified using aerial imagery:
The Winterville developed parcels layer contains land use attributes. These land uses
were assigned to model categories as follows: commercial assigned to
Commercial/Heavy Industrial, church and institutional assigned to
Office/Institutional/Light Industrial except for finro parcels assigned to Open Space, and
government utility assigned to Office/Institutional/Light Industrial or Open Space. All
residential land uses including mobile home parks were placed into residential
categories depending on parcel size and number of units per parcel. All areas not
included _in the developed parcels layer were checked using aerial imagery. All parcels
with the attribute "heated square feet>0" and an area of less than five acres in size were
assigned a residential category. Those greater than five acres were divided into forest,
agriculture, and open space according to land cover. .
Ayden has a zoning layer that was used to assign categories to all developed parcels as
reflected on the 2004 aerial imagery. In addition, the county parcel layer was used to
identify any new development that occurred befinreen 2004 and 2006. The business (B-1
and B-2) and heavy industrial zones were assigned to Commercial/Heavy Industrial and
the light industrial and office/institufional zones were assigned to the
Office/Institutional/Light Industrial category. The conservation zone was assigned to
Forest and Open Space as that .is the current land use. All residential zones were
assigned to residential categories based on parcel size and number of units per parcel.
Any parcel greater than five acres was checked visually and then divided befirveen
forest, agriculture, and open space based on land cover. _
4.2.2 Future No Build and Build Scenarios
Existing land uses were identified separately in the land use scenarios GIS layer as their
modeled loading rates are different from new development due to regulations governing
that new development in the study area (discussed Section 4.7). All existing land areas
that had been classified as developed were put in their same categories in the future
scenarios with the exception of a few parcels in �ntenrille that were residential and
were then classified as Commercial/Heavy Industrial in the No-Build and Build
scenarios. These low density residential parcels on Old NC 11 are located in an .area
zoned as commercial and will most likely be replaced with commercial 6uildings in the
future. _ It_ was assumed that existing wetlands as depicted on the existing land use map
would remain as wetlands. All other areas were assigned to categories according to
future land use maps, other studies.and information, and personal communication with
each jurisdiction.
4-4

� I '_-.; I. -�
�
Greenville Southwest Bypass
ICI Water Quality Study
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O`AN' Selttted Attemalive - Resitlenllal MuuUamilyNery Mqn Densiiy
� Streams - Resitlenllal High Density
� Counry eoundary _ Resieential Metlium High �ensiry
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Ealsllng Contlitions
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Resitlenhal Very Low Oensrty
_ Fwest
_ Pavetl Road wNh Right ol Way
4-5
► - '. 1 1' / 1.-.
k < �- = � _
Figure 4.2.1 Existing Land Use/Land Cover
ICI Wa[er Qualiry Swdy - Greenville Southwest Bypass
TIP No. R-2250, Pitt Counry, NC
�Norih Carolina
� �epartment of Transportation
0 0.5 1 2 3 Miles

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Greenville Southwest Bypass
ICI Water Quality. Study
4.2.2.1 Greenville
The Greenville future land use map was used to develop fhe build and no-build
scenarios GIS layer for the area currently under Greenville jurisdiction and the area
between the existing ETJ and a newly proposed ETJ. Greenville and Winterville have
proposed an expansion of their ETJs to extend out beyond the proposed Southwest
Bypass corridor (Figure 4.2.2 obtained from the City of Greenville). This proposed ETJ
boundary was used for both scenarios as it is not dependent on construction of the
proposed Southwest Bypass. If the county does not approve the ETJ expansion, both
municipalities plan on offering sewer to new developments and then annexing the land
so it is likely the area or parts of the area will fall under the municipalities jurisdiction and .
therefore under their land use plans regardless of changes in the ETJ. Greenville's
future land use plan was developed with a finro mile buffer around its existing boundary
for this reason.
For the No-Build scenario, all currently undeveloped land was assigned a model
category based on the future land use map classes. Commercial and industrial land
uses were both placed in the Commercial/Heavy Industrial category and
office/institutional/multi-family land use were assigned the Office/Institutional/Light
Industrial category. The only residential land uses in the study area are high density
residential and medium density residential Greenville Land Use classes. These
Greenville land use classes would both fall into the Residential Very High Density model
land use category based on parcel size as explained in Horizons, Greenville°s
Community Plan. A more detailed study of land use has been undertaken by the
Greenville planning department for the southwest portion of Vision Area E, which
coincides with a portion of the model study area (in and around subwatershed SC1). The
plan predicts 3,102 dwellings in the undeveloped portions of the area, approximately 680
acres (Greenville, 2006). This works out to be 0.22 acres per dwelling although this does
not take into account associated roadways. Finally all conservation/open space was
labeled as Forest or Open Space dependent on land cover.
The Build scenario is the same as fhe No-Build for the Greenville (including . the
proposed ETJ) portion of the study area except for the addition of the road. Past and
current growth trends indicate growth regardless of road construction (Greenville, 2004;
Greenville, 2006). The land use plan already allows focus areas which can contain
nonresidential land uses. Portions of these focus areas are found on fhe existing land
use map and further expansion is expected with or without the bypass. The focus areas
include two large commercial and office areas along Dickinson Road and Memorial DriVe
and a small area at the intersection of Frog Level and Davenport Farms Rd. The
Dickinson Rd commercial and office focus area contains the Southwest Bypass
interchange with Dickinson Rd. In addition there. is an industrial park that is promoted by
the city and county. Greenville has no plans to allow commercial or office development
in any other areas. The Forlines Rd interchange falls on Greenville's proposed ETJ line.
Although Greenville's future land .use plan would not allow for commercial growth in this
area, #he.county is likely to allow it if it remains under their jurisdiction. Therefore a small
� amount of commer.cial growth was added to the interchange for the build scenario..
4-6

Greenville Southwest Bypass
ICI Water Quality Study
Figure 4.22 Proposed ETJ Expansion (map obtained from the City of Greenville)
Growth Areas and Boundary Map for the
Ciry of c�reenville, and Town of Winterville
� y , , j! r _
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Ayden
4-7

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Greenville Southwest Bypass
ICI Water Quality Study
4.2.2.2 Winterville
The Winterville future land use map was used to develop the Build and No-6uild
scenarios GIS layer for the area currently under Winterville jurisdiction and the area
between the existing ETJ and a newly proposed ETJ, as described above. For the No-
Build scenario, all currently undeveloped land was assigned a model category based on
the future land use map classes. Commercial and industrial land uses were both placed
in the Commercial/Heavy Industrial category and the office & institutional land use was
put in the Office/Institutional/Light Industrial category. Recreational/cultural as well as
land uses government/utility were assigned to Open Space. The four Winterville
residential land uses were assigned to residential model categories based on.#he lot size
as described in the Winterville Horizon Land Use Plan (high density = RVH; medium
density = RHH, low density = RMH, ag/res = RLL — based on a mixture of houses and
agricultural lands): The commercial/residential transition land use was divided between
Office/Institutional/Light Industrial category and the RVH category, with the former
placed adjacent to Commercial parcels and the latter filling in the rest of the area. The
undeveloped area between the current ETJ and the proposed ETJ was assigned to the
RMH category on the west side _of Winterville and .RLL on the east side of Winterville
(personal communication, Alan Lily). -
, The Build scenario is almost the same as the No-Build. The town expects residential
, growth to occur regardless of the . bypass. They do expect some commercial
' development along NC903 as a result of the bypass especially at the intersection with
__ � Frog Level Rd. This intersection will see more traffic and will therefore be more suitable
� for a small commercial center rather than s'ingle family homes (personal communication
' � Alan Lily):
4.2.2.3 Ayden
The Ayden future. land use map was used to develop the Build and No-Build scenarios
GIS layer for the Town of Ayden and its current ETJ. The map was developed without
considering construction of the Southwest Bypass therefore it was used as the base for
the no-build scenario. All of the currently undeveloped land. was assigned a model
category based on the town's future land use classes: The area labeled as mixed
use/downtown future land use is already fully developed. The industrial and commercial
land use areas were placed in the Commercial/Heavy Industrial category. The residential
land uses were assigned to categories based on lot size as described in the future.land
use map documentation and the zoning map. High density residential includes 6,000
square foot lots, mobile homes, and multi-family buildings which are all considered to be
RVH. Mediurn density residential includes 8,000, 10,000, and 12,000 square foot lots
which is a mixture of RVH and RHH. All of these parcels were labeled as RVH as most
of the area is zoned for 8,000 or 10,000 square foot lots and there are very few 12,000
square foot areas. Low density residential includes 20,000 square foot lots. These areas
were assigned to the RLL category since it is unlikely all of the land will develop without
the bypass. Undeveloped land that falls into the_conservation land use was left with the
designation assigned in the existing Jand use layer (either Forest or.Open Space). �-
The Build scenario for this portion of the study differs from the No-Build scenario: The
town expects an increase in development after the.bypass is constructed as it_will be
convenient for commuters. An increase in commercial_ development could occur around
4-8 ..

-�
� '�
Greenville Southwest Bypass
ICI Water Quality Study ' ,
�
the interchange with NC102. Commercial and industrial development is already
proposed for the interchange.at NC11. Higher density residential growth is_expected to � 1
the west of the bypass. Sewer could be expanded to this area as needed to serve new -�
developments.
4.2.2.4 Pitt County
� ,�
I'
;I
� _�
The Pitt County future land use map was used for the remaining portions of the study �-�
area that were not in a developed category for the existing land use/land cover map. The �
No-Build scenario GIS layer is based on the future land use map. The Bell Arthur `1
Crossroads and Ballards Crossroads are both crossroad communities where a small
portion of parcels were assigned to Office/Institutional/Light Industrial. There are no new I�
commercial or industrial areas planned for this part of the county. The suburban 1-�
residential land use class was assigned to the RLL category to reflect a mix of
development on lots at least 25,000 square foot in size and continued agricultural uses. �
The rural residential/agricultural land use was assigned to the RVL category to reflect a _,
smaller amount of development on lots at Ieast 25,000 square foot in size and a larger
amount of agricultural use. Residential development in this portion of the county is �
expected as shown in the planned development map produced by Pitt County that _ ��
covers the years 2000 to 2004 and shows many new developments in the study area.
The Build scenario GIS layer for the county will differ from the No-Build scenario at the
NC903 interchange. The county plans to allow for commercial and light industrial around
the entire interchange. Higher density housing is expected around the interchange
although the area will still be served by septic and therefore a 25;000 lot minimum will be
required. RML was chosen for the residential density to reflect an increase in the number
of 25,000 square foot lots and a decrease in agricultural and wooded land.
4.2.3 Scenario Comparisons
Graphical depictions of the Build and No-Builci .scenarios are presented in Figures 4.2.3 �
and 4.2.4. Commercial and heavy industrial land use increases by almost 78 hectares I
(8.7%) more in the Build scenario compared to the No Build scenario. This development 1---
is expectecl to occur at the NC903 interchange, the Forlines Road interchange, and the
Frog Level/NC903 intersection. Office/institutional%light industrial land uses actually �
decrease in the Build scenario due to the new roadway and associated right of way.
Residential - Low Density area in the Build scenario decreased by. 643 hectares relative
to _No-Build due to the increase in commercial land use and higher density residential �-
areas including RML in the county and RHH and RVH in the Town of Ayden. The land
use scenarios for each subwatershed can be found in the Appendix.
- � �}
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4-9

I _ , __ � _ �� .. _.. � __ _� � _�
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� J - � - - - --- - -- - - = -- - � � -- � -- -
Greenville Southwest_ Bypass
ICI Water Quality Study
Table 4.2.2 Existing Land Use/Land Cover Conversion Table
Category � Ayden (zoning)* , Greenville (land use) Winterville (developed ' Pitt County' (land use)
arcels � -
Commercial/Heavy Business (B-1 & B-2), Commercial, Industrial Commercial, Industrial Commercial, Industrial
Industrial Hea Industrial
Institutional/Office/Light Light Industrial, Institutional, Office, Church, Institutional,
Industrial Office/Institutional Recreation; Utility Government/Utility; Governmental/Utility
Institutional ' Facilities, Recreation
Residential (different RA-20, RA-20A, R-12, R- Duplex, Multi-family, Mobile Home Park, Single- Residential Development
categories based on 10, R-8, Multi=Family, Mobile Home, Mobile Family Residential, Two-
�density) Manufactures Housing, Home Park, Single Family Family Residential,
Rlanned Unit Develo ment Residential Multifamil Residential
Open Space Conservation Cemetery, Utility, Church, Governmental/Utility
. Conservation Open Space GovernmenUUtility, Facilities, Recreation
Institutional
Row Cro Vacant Undevelo ed Undevelo ed/A ricultural
Forest Vacant Undevelo ed Undevelo ed/A ricultural
* all parcels were observed using aerial imagery to determine if was developed or undeveloped
Table 4.2.3 Future Land'Use/Land Cover Conversion Table
� ,g-ry ,. ' . Ayden (future land use .Greenville (future land use Winterville (future land use Pitt County:(future land �
Cafe�"o
_ . _ . . � . ma - . , . , ma . � ma . . use ma ".
Commercial/Heavy Commercial, Mixed Commercial, Industrial Commercial, Industrial Commercial/ Light
Industrial. Use/Downtown, Industrial Industrial
Institutional/O�ce/Light Office/Institutional/Multi- Office & Institutional, Rural Commercial/
Industrial �. family Commercial/Residential. Crossroad Community .
Transition
� Residential (different . High Density Residential, High Densify Residential, Commercial/Residential Suburban Residential,
� ' categories based on Medium Density Medium Density Residential Transition, High Density . Rural Residential/
density) Residential, Low Density . Residential, Med Density Agricultural
: Residential Residential, Low Density
Res, A ri/Residential
� Open Space - Conservation Conservation Open Space Government/Utility, Agricultural/ Open Space/
Recreational/cultural Natural Resource
' 4-10

��
Greenville Southwest Bypass
ICI Water �uality Study
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Future No Bulltl Contlltlons Wetlantl
(. Impervlousness) Water
- Open SpaceB Forest /�/ Roaas Figure 4.2.3 Future No Build
- CommerciallHeavy Intlustrial Q2%) Land Use/Land Cover Scenario
l\/ Railroatls
Office/InslitutianaVLight IntluSVial �53 %� B�y'� Selected Aliemalive ICI water Oualiry Study
- Re5i4en�ial MultBamilyNery Hiqh �¢n5ity (42%) '�. � Sireams Greenville 5outhwes� Bypass
_ ResiEential Hign Densiry (24 /) � County Bountlary TIP No. R-2250, Pitt County, NC
_ Resitlen�ial Medium Hgh �anstty (i7 %) � Waters�ed Bountlary � NoRh Carolin2
- ResideMial Metllum Low Ornsily (73 %) � Aytlen ETJ .�. DepdAmenl Of Tf2n5pOft36on
Resitlenlial Low Denstly (11%) � Greenville Propose0 ETJ �� ^^
AgncuHurelResitlential Very Low Densiry (5%) Wmterville Proposed ETJ 0 0.5 1 2 Mi18S
_ Pavea ftoaG wM Rghl IN Way (61 k) �

Greenville Southwest Bypass
ICI Water Quality Study
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Future Bulld Conditlons Waler
(% Impervlousness) i Open Space 8 Fores� Figure 4.2.4 Future Build
� CommercialfHeavy lndusfnal p2%) �✓ SelecteG Altematrve Land Use/Land Cover Scenario
OKcellnstiWlionaULight InEustrial (53% )
�} Inrerchange ICI Water Quality Slutly
- Resitlential Multi/amilyNery Hign Densiry (42%) ^� RoaAs Greerrville Southwesl Bypa55
- Reskential High Densiry (24%) y�J RaAroads TIP No. R-2250, Pitt County, NC
_ Resitlenhal Metlium High Densiry (17 %) "�. : Streams
_ Reswenlial Medium Low Denslry (13 %) � yyatershetl Bountlary North Camlina
�, Depatlment of Transportation
ResWenlal �ow Oensily (11%� � County Boundary .„
AgnculWrelResiEenlial Very Low �ensity (5%) � I q�en ETJ
-Pavetl Roatl with Ri nt ol Wa 61 % 0 0.5 1 2 3 MileS
9 Y l 1 � Greenville Pmposetl ETJ
Wetland Wnterville Proposea ETJ
4-12

Greenville Southwest Bypass
ICI Water Quality Study
4.2.4 Modellmperviousness
The intensity of imperviousness increases as development density increases, which
directly affects the velocity and volume of runoff, as well as the quantity of pollutant
export. Site-specific impervious factors were not readily available for the study area.
Therefore, literature-based estimates were adapted to the watershed.
Table 4.2.4 below shows values from three literature sources: Soil Conservation Service
(SCS 1986), Hunt and Lucas (2003), .and Cappiella and Brown (2001). Impervious
estimates from Hunt and Lucas (2003) and Cappiella and Brown (2001) are close in
value, whereas estimates from SCS (1986) are high in comparison, particularly for small
residential lots.
Table 4.2.4 Estimates of Imperviousness from the Literature
Land Use Category Percent Impervious
Reference Hunt and Lucas Cappiella and SCS (1986)
(2003) Brown (2001)
Location Tar-Pamlico River Chesapeake Bay, National Estimate
Basin, NC Va/Md
Regression Equation y=0.148x o.aa y_14.669x °'42 y=17.895x o.s�o�
RZ 0.98 0.98 0.98
Residential 1/8 acre lot 38 33 65
Residenfial 1/4 acre lot 30 28 38
Residential 1/2 acre lot 22 21 25
Residential 1 acre lot 14 14 20
Residential 2 acre lot 11* 11 12
MultiFamilylTownhome 41-44 65
Institutional 34
Light Industrial 53
Industrial 72
Commercial 72 85
* Calculated with rearession eauation.
The imperviousness values selected for this study are presented in Table 4:2.5: Single
family residential values selected for this study are based on Hunt and Lucas (2003)
since they were derived from North Carolina. data. Single family residential yalues were
calculated using the power equation shown in the table above; which suggests a strong
relationship between average lot size and imperviousness. The mid-point of the range in
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Greenville Southwest Bypass
ICI Water Quality Study
lot size is used to calculate the percent impervousness. Values for multifamily and non-
residential land uses are taken from Cappiella and Brown (2001). The Multifamily/Very
High Density category is based on the average of a 1/8 acre lot (35%) and the
Multifamily value of 44%. The assumed imperviousness for roads with right of way is
61 % based on semi-rural highways studied in Wu et al. (1998).
Table 4.2.5 Land Use Categories and Estimated Imperviousness
LAND:USE NAME GWLF CODE PERCENT IMPERVIOUS
Very Low Density Residential/Agriculture RVL 5% .
(greater than 2 acres per dwelling unit)
Residential — Low Density RLL 11 %
(1.5-2 acres per d.u.)
Residential — Medium Low Density . RML. 13%
(1-1.5 acres per d.u.)
Residential — Medium High Density RMH 17%
(0.5-1 acres per d.u.)
Residential — Fiigh Density RHH 24%
(0.25-0.5 acres per d.u.)
Residential — Multifamily/Very High Density RVH 42%
(less than 0.25 acres per d.u.)
Office/Institutional/Light Industrial OFF 53%
Commercial/Heavy Industrial COM 72%
Paved Road with Right of Way � ROAD 61%
Urban Green Space UGR 0%
Row Crop ROW 0°/a
Forest FOR 0%
Wetlands WET 0%
Water WAT N/A
The RVL category includes a mix of low density residential housing and agricultural land
uses. The proportion of each land use-is not known but would be expected to result in a
very low impervious surface coverage when averaged across the area. An average of
5% impervious surtace coverage is assumed across the RVL category. Note however
that agriculture land uses, both row crops and pasture operations, often have higher
curve numbers (less infiltration) and greater nutrient runoff concentrations than a low .
density residential development. For the purposes of this analysis, the RVL category is
modeled as a residential development category without adjusting the curve numbers or
runoff concentrations upward. Since no differences in agricultural land use are assumed
in the build and nobuild scenarios, the assumption.will not affect the differences in loads
between the scenarios.
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G�eenville Southwest Bypass
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4.3 Surface Water Hydrology
Table 4.3.1 provides a summary of several of the surFace water inputs and assumptions
utilized in the GWLF modeling analysis. The individual parameters are discussed below.
Table 4.3.1 SurFace Water Hydrology Input Parameters
_
INPUT BASELINE COMMENTS/ �
DESCRIPTION UNIT LITERATURE REFERENCE
PARAIVIETER VALUE' RqNGE �
Precipitation Daily rainfall cm Annual Min Ten years of data Data from
= 98.7 (April 1996 — Greenville
Max = 159.2 March 2006) used COOP Station
Mean = for simulation and 313638, State .
134.4 assumed to be Climate Office
uniform for the of NC
study area
Evapo- Cover coefficient _ none Values Rural land uses: Haith et al.. .
transpiration for estimating ET range from Default values (1992)
(ET) Cover 1.0 for derived based on
forest to land use.
0.15 for high Urban land uses:
intensity 1 - impervious
urban fraction
Antecedent Moisture for up to cm 0 Unknown and Haith et al.
Soil Moisture five days prior to therefore (1992) .
Conditions initial step. assumed in
accordance with
manual to be zero
Runoff Curve . Parameter for none Ranges Site dependant SCS (1986)
Numbers converting mass from 57 to based on soil type
rainfall to mass 98 in the and land use.
runoff. current
study.
4.3.1 ,Precipitation .
Daily rainfall records for the study area were obtained from the North Carolina State
Climate Office for COOP 8tation 313638, located approximafely 8 miles from the center
of the study area (Figure 4.1.1). Data for a ten-year period was assembled (1996-2006).
Missing values in the time series .were filled in using the average for that month.
Tlie mean rainfall over the ten-year simulation period is within 7 percent of the long-term
average (125 cm) at station 313638 indicating that the model simulation period
represents average hydrologic conditions for the area. Rainfall was assumed uniform
throughout the study area. �
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Greenville Southwest Bypass
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4.3.2 Evapotranspi�ation Cover Coefficients
The.portion of rainfall returned to the atmosphere through evapotranspiration (E� is
determined by temperature and the density of vegetative cover, which varies by land use
and by season (g�owing and dormant). For rural land uses, evapotranspiration cover
coefficients were determined from seasonal values provided in the GWLF inanual (Haith
et aL, 1992). For urban land uses, the coefficients were . set equal to one minus the
impervious fraction: Monthly values were determined by watershed on an area-weighted
basis.
4.3.3 Antecedenfi Soil Moisture Conditions
Antecedent soil moisture conditions are a function of rainfall levels up to five days prior
to the day on which modeling begins. Antecedent soil moisture conditions were unknown
and were assumed to be zero as per guidance provided in the GWLF inanual (Haith et
al., 1992).
4.3.4 Runoff Curve Numbers
The frac#ion of precipitation that becomes surface water runoff in GWLF is calculated on
the basis of the SCS Curve Number Method as presented in the TR-55 Manual (SCS,
1986). Curve numbers are derived based on impervious cover and soil hydrologic group.
Soil hydrologic groups for the soils present within the study area were determined using
a the Natural Resource Conservation Service (NRCS) detailed soil survey geographic
(SSURGO) database. Each spatial association between a given soil group and a land
use category was deemed a hydrologic response unit (HRU) and each HRU was
assigned a curve number according to the values presented in Table 4.3.2. For each
land use within a watershed, an area-weighted curve number is assigned based on the
HRUs.
___ The curve numbers.in Table 4.3.2 are interpolations of curve numbers given in SCS
'� (1986). Forest, wetland, and urban g�een space curve numbers are based on Woods-
�- � Good, Woods-Poor, and Pasture-Good hydrologic conditions, respectively.
i � 4.4 Groundwater Hydrology
� Table 4.4.1 provides a summary of several of the groundwater inputs and assumptions
� utilized in the G1NLF modeling analysis. The individual parameters are discussed below.
J 4.4.9 Recession Coefficient -
The rate at which groundwater is. discharged to s#reams is a function of the recession
coefficient. In theory, provided that flow.data are available, this factor can be determined
through analysis of the hydrograph. However, no flow data were available within the
study area: GWLF modeling studies by Lee et al. (1999) coastal Maryland have shown
that the. GWLF model results are sensitive to the recession .coefficient and that the
coefficient is strongly correlated .with drainage area.. Through model calibrations and
regression analqses on numerous watersheds Lee et al. (1999) developed the following.
relationship between recession coefficient (R) and drainage area (DA in km2): .
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Greenville Southwest Bypass
ICI Water Quality Study
R= 0. 0450 + 1.13 "(0.306 + DA)''
This equation was used to calculate individual recession coefficients for each of the
GWLF subwatersheds simulated. Results ranged in value from 0.13 to 0.43.
Table 4.3.2 Curve Numbers for Land Use and Soil Hydrologic Groups
LAND,USE NAME LUCODE GROUP GROUP GROUP GROUP COMBINED
A B C D GROUP B& D
Agriculture/
Residential — Very RVL 42 62 75 80 71 -
Low Density
Residential — Low RLL 45 65 77 82 73
Density
Residential —
Medium L.ow RML 47 65 77 82 74
Density
Residential —
Medium High RMH 49 67 78 83 75
Density
Residential — High RHH 53 70 80 85 77
Density
Residential — Very RVH 63 76 84 88 82
High Density
Office/Light OFF 70 81 87 90 85
Industrial
Commercial/Heav COM 75 84 89 91 87
y Industrial
Paved Road with ROAD 81 88 91 93 94
Right of Way
Urban
Greenspace/Open UGR 39 61 74 80 71
Space
Forest FOR 30 55 70 77 66
Wetlands WET 45 66 77 83 75
Water WAT 98 98 98 98 98
4.4:2 Seepage Coefficient
GWLF simulates three subsurface zones: a shallow unsaturated zone, a shallow
saturated zone (aquifer), and a deep aquifer zone. The deep seepage coefficient is the
portion of groundwater in the shallow aquifer that seeps down to the deep aquifer and
does not return as surface flow, thereby removing it from the water. balance of the
watershed. In eastern North Carolina, 2:5 to 5 cm per year typically infiltrates through to
deep groundwater aquifers, representing about 2 to 3% of the water balance (Evans et
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Greenville Southwest Bypass
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al., 2000). The seepage coefficient was set to a value of 0.015, which produced_ a 3%
loss to deep groundwater over the entire. study area,
Table 4.4.1 Groundwater Input Parameters
INPUT BASELINE COMMENTSI; "
PARAMETER DESCRIPTION UNIT VALUE LITERATURE . REFERENCE
� � RANGE �
Baseflow - Groundwater day -' Min = 0.13 Drainage area= Lee et al.
Recession seepage rate Max = 0.43 dependant and (1999)
Coefficient (r) Mean = calculated �
0.20 accorcling to
Lee et al. (1999)
Seepage (s) Deep seepage day -' 0.015 Site dependant; , Haith et al.
coefficient Goal to (1992);
generate 3% Evans et�al. .
deep seepage . (2000) _
overthe
simulation
period
Unsaturated Interstitial storage cm Min = 12.4 . Determined Haith et al.
Soil Water Max =15.5 from SSURGO (1992)
Storage Mean = soils data
Capacity 13.5
Initial Initial amount of cm 10 GWLF Manual Haith et al.
Unsaturated water stored in default (1992)
Storage (IUS) unsaturated zone
Initial Saturated Initial amount of cm 0 GWLF Manual Haith et al.
Storage (ISS) water stored in default (1992)
saturated zone
4.4.3 Available Soil Water Capacity
Water stored in the soil may evaporate, be transpired by plants, or percolate down to
groundwater below.the rooting zone, The amount of water that can be stored in the soil
in the region where it is. still available for evapotranspiration is the available soil_water
capacity (AWC), which varies according to soil type and rooting depth. Volumetric AWC
values (cm/cm) were extracted from the Soil Survey Geographic (SSURGO) Database
for the study area. Assuming a 100 cm rooting depth and #he volumetric AWC, the AWC
values ranged from 12.4 to 15.5 cm (Haith et al., 1992).
4:4.4 Initial Saturated and Unsaturated. Storage
When the initial amounts of water stored in the saturated shallow aquifer and the
unsaturated zone are unknown, the GWLF inanual advises using default values of zero
and 10 cm, respectiVely (Haith.�ef a/., 1992): It should be .noted that these parameters
have only a minimal impacf on modeling results; they only affect.the water balance.for .
the first three months of simulation (Lee et al.; 1999). _ . � _
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Greenville Southwest Bypass
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4.5 Erosion and Sediment Transport
Table 4.5.1 provides a summary of several of the erosion and sediment transport inputs
and assumptions utilized in the GWLF modeling analysis. The individual parameters are
discussed below.
Sediment erosion in the GWLF model is simulated through application of the USLE,
which uses four input factors (K, LS, C and P). The first of these four is soil erodibility or
(K) factor, which is a measure of a given soil's propensity to erode when struck by water.
4.5.1 Soil Erodibility (K) Factor
K factors in this .analysis were obtained from the SSURGO database. For the four soil
groups distributed within the study area, area-weighted K factors ranged from 0.275 to
0.316.
4.5.2 Length-S/ope (LS) Factor
Erosion potential varies with slope as much as with soil characteristics, so the second
element in the USLE equation is the length-slope (LS) factor, which is the average
length (L) that runoff travels from the highest point of any flow path within a watershed to
the point at which it reaches concentrated flow multiplied by the slope (S), which
represents the effect of slope steepness on erodibility for each soil type. LS factors for
this modeling analysis were generated by GIS spatial analysis using the USLE Sediment
Tool included in the US Environmental Protection Agency (USEPA) Watershed
Characterization System (Tetra Tech, 2000). Area-weighted values ranged from 0.105 to
0.185.
4.5.3 Cover (C) and Management Practice (P) Factors
The mechanism by which soil is eroded from a land area and the amount of soil eroded
depends on soil treatment resulting from a combination of land uses (e.g., forestry
versus row-cropped agriculture) and the specific manner in which land uses are
managed (e.g., no-till agriculture versus non-contoured row cropping), which are
represented by cover and management factors in the USLE. Cover and management
factors for non-agricultural land uses in this study are from Haith et al. (1992). Factors
for row crop agricultural were taken from the North Carolina Revised USLE Manual
(USDA, 1995). The resulting factors are summarized in Table 4.5.2. C and P factors are
not required for the urban land uses, which are modeled in GWLF via a buildup-washoff
formulation rather than the USLE.
4.5.4 Sediment Delivery Ratio
In GWLF, the sediment delivery ratio accounts for trapping of sediments and sediment-
bound pollutants that occurs befinreen the edge of the field (origin) and the watershed
outlet (delivery point). The BasinSim version of GWLF utilized in this analysis includes a
software utility that calculates the sediment delivery ratio on the basis of the drainage
area of the subwatershed being simulated. Sediment delivery ratios for this study ranged
from 0.21 to 0.29.
4-19
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Greenville Southwest Bypass
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Table 4.5.1 Rural Sedimenf Transport Input Parameters.
INPUT � �BASELINE COMMENTS/ �
DESCRIPTION UNIT LITERATURE REFERENCE
PARi4METER � - VALUE ,,RqNGE
Rainfall Kinetic energy MJ- 0.16 (cool Rainfall erosivity Haith et al.
Erosivity (R) of rainfall Mm/ha season) may vary (1992) for
0.28 (warm seasonally and is Wilmington,
season — Apr _ estimated by. NC .
thru Oct) geographic
� region
Soil Erodibility Soil e�osion None. Area-weighted Derived from County level
Factor (K) potential soils GIS data soils data for
_ Min = 0.275 (function of soil the study�area
� Max = 0.316 texture and
composition}
Length-Slope Sediment None . Varies by Derived from USEPA
Factor (LS) transport Subwatershed DEM as function Watershed
potential based of slope and Characterizati
on topography overland runoff on System
(Tetra Tech,
2000)
Sediment Portion of None Varies by Empirically BasinSim
Delivery Ratio Eroded Material Subwatersfied estimated as a Utility
(SDR) that is function of (Dai et al.,
transported to subwatershed. 2000).
receiving waters
Table 4.5.2 Cover (C) and Management Practice (P) Factors.
LAND USE:NAME C P �
Residential — Very Low Density 0.0100 1.000
Wetlands 0.0020 1.000
Forest 0.0020 1.000
Row Crop 0.0940 0.600"
Pasture 0.0900 1.000
Urban Grass 0.0065 � 1.000 :
4.5.5 Sedimentation from Urban.Land Uses
For urban land uses, the GWLF model calculates particle loads associated with
particulate nutrients without calculating sediment load. For the present study, sediment
from urban sources was modeled using the same accumulation and washoff functions
from the model substituting sediment accumulation rates_ for particulate nutrient
accumulation rates.. A similar_ approach was used:by Schneiderman ef a/. (2002) in an
update to the original application of GWLF on the Cannonsville watershed by Haith and
Shoemaker (1987): .
_ 4-20 .

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Greenville Southwest Bypass --,
ICI Water Quality.Study. . ;
In the model application, sediment accumulation rates by land use ranged from 1.66 to
3.24 kilograms per hectare per day (kg/ha/day). These rates were based on suspended
solids accumulation rates from Kuo et al. (1988) as cited in Haith et al. (1982). Rates for
residential land uses ranged from 1.66 to 3.24 kg/ha/day, with values increasing with
residential imperviousness. Accumulation rates for nonresidential land uses including
commercial and officel categories were 2.24 to 1.8.6 kg/ha/day, falling in between the
rates for various densities of residential land use. Based on these data, fihere does not
appear to be a linear relationship befinreen imperviousness and accumulation rates
across all land uses.
The accumulation rate (1.8 kg/ha/day) for roads was taken from the modeling analysis
for NC 43 (NCDOT, 2006b) and. based on an export rate of 185 kg/ha/yr. The export rate
is based on the average of the North Carolina value from FHWA (1990) and regional
event mean concentration values in USEPA (2001).
4.6 Nutrient Loading
Table 4.6.1 provides a summary of several of the nutrient inputs and assumpfions
utilized in the GWLF modeling analysis. The individual parameters are discussed below.
4.6.1 Solid Phase Nutrients
Sediment bound nutrient loads to streams are driven by the soil nutrient concentrations ���,
within the watershed. In the absence of study area specific information, the soil � �
concentration of total nitrogen and total phosphorus in this . analysis was set at 1400 �-�
mg/kg and 352 mg/kg; respectively, based on guidance from the GWLF Manual (Haith et
a/., 1992) and regional observations provided by Mills et al. (1985). ; I
4.6.2 Dissolved Groundwater Nutrients
� ��
The GWLF model applies average groundwater nitrogen and phosphorus concentrations 1',
to flow from the saturated zone to the stream channel. Based on the nutrient {-�
concentration values reported by Spruill et al. (1998) in a study of water quality in the __
Albemarle-Pamlico Drainage Basin, groundwater nutrient concentrations in this modeling � j
ana lysis were se t a t 0. 4 2 mg/ L for T N a n d 0. 0 4 m g/ L f o r T P: �--'
4.6.3 Runoff Concenfrations and Build-up F?ates
(�
l_ .
In GWLF, nutrient loads from different land uses are based on the volumes of flow and
the associated flow pathways (overland or seepage), the amounts of soil eroded, and r-
concentrations that express the amount of nutrient load per unit volume of water flow or ��
sediment erosion from each land use. The GWLF model uses buildup/washoff
relationships to predict nutrient loads for urban (developed) and runoff concentrations to -.
predict nutrient loads from rural and agricultural land uses. These processes vary based
on the interactions between soil types and land uses, and are definecl by a range of �
parameter values (Table .4.6.2). Except for roadways and urban greenspace, runoff
concentrations and build up/wash off rates are based on those used in .the Jordan Lake �'
��
Watershed Model (Tetra Tech, 2003). , _
��
�_�
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Greenville Southwest Bypass
ICI Water Quality Study
Table 4.6.1 Nutrient Loading Input Parameters
INPUT � BASELINE COMMENTS/
.PARAMETER DESCRIPTION UNIT VALUE LITERATURE REFERENCE ,
� REVIEW
Solid Phase Nutrient Loading
Nutrient Total Nitrogen mglkg 1400 Varies Haith et al.
concentration Concentration regionally and (1992)
in sediment by site; 500-900 Mills et al.
from rural based. on (1985)
sources literature;
multiplied by a
mid range
enrichment ratio
of 2.0
Total mg/kg 352 Varies Haith et al..
Phosphorous regionally and (1992)
Concentration by site; less Mills et al.
than or equal to (1985)
400; multiplied
P205
conversion
factor and
enrichment ratio
(2.0)
. Dissolved Nutrient�in Groundwater
Nutrient Total Nitrogen mg/L 0.42 Median value Spruill et al.
concentration Concentration for the inner (1998)
coastal plain
Total mg/L 0.04 Median value Spruill et al. .
Phosphorous for the inner (1998)
Concentration coastal plain
Nutient runoff concentrations and build-up rates are from Tetra Tech (2003). The rates
were re-evaluated for use in this study and.were found to be within the range of the
GWLF nutrient inputs used in recent studies focused on coastal plain watersheds except
for nitrogen build-up (NCDOT, 2005; CH2M Hill; 2003; Lee et al., 1999; Dodd and
Tippett, 1994).
Nitrogen build-up rates used in the Jordan Lake study and the present study are fiigher
(abouf double) than default model values and the coastal plain studies cited above.
Buildup rates in the Jordan Lake study were derived based on event mean concentration
values from Line et al. (2002), CH2M HILL (2000), Greensboro (2003), and U.S. EPA _
(1983). Those rates were found to be in general agreement with export coefficients
reported in the literature (CDM, 1989; Hartigan et al.; 1983; USEPA, 1983; Beaulac and
Reckhow, 1982; Frink, 1991). The Jordan Lake values are probably more appropriate
given that their origin is primarily in North Carolina research.
4-22

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� �
Greenville Southwest Bypass
ICI Water Quality Study ; �
�,
Table 4.6.2 Nutrient Runoff and Buildup Rates for Existing Land Uses
RUNOFF CONCENT.RATIONS
RURAL LAND USES �DISSOLV.ED �N (mglL) DISSOLVED P
(mg/L)
Pasture 2.770 0.250
Row Crop 2.770 0.250
Forest 0.190 0.006
Wetlands 0.190 0.006
Urban Greenspace 0.190 0.006
Residential — Very Low Density 0.230 0.007
MASS BUILDUP RATES .
URBAN LAND'USES N BUILDUP (kglha/day) P BUILDUP.(kg/ha/day)
Residential — Low Density 0.214 0.040
Residential — Medium Low Density 0.242 0.040
Residential — Medium High Density 0.242 0.040
Residential — High Density 0.219 0.037
Residential — Very High Density 0.201 0:033
Office/Light Industrial 0.158 0.025
Commercial/Heavy Industrial 0.191 0.029
Roadways 0.067 0.009
Accumulation rates for roadways were taken from NCDOT (2006) and based on TN and
TP export rates of 5.5 and 0.7 kg/ha/yr (FHWA, 1990; USEPA, 2001). Urban greenspace
land uses were assigned values befinreen very low density residential and forest land
uses.
4.6.4 Septic System Loading
The septic system component of the model simulates dissolved nutrient loads to
streamflow from a variety of system types. For normal systems, the type simulated here,
effluent nitrogen is converted to nitrate. The nitrogen is removed by plant uptake or
transported to surface waters via groundwater discharge. Phosphates in the effluent is
absorbed and retained in the soil.
Inputs required by the model are presented in Table 4.6.3 and include the number of
people on septic systems by subwatershed, the per capita effluent load, and the rate of
plant uptake. The population of septic was estimated using the number of parcels on
septic (not in a future sewer service area), lot density, and an average number of
persons per hoiasing unit: Subwatersheds that did not have a change in land use
between scenarios were assigned the same population on septic.
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Greenville Southwest. Bypass
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Table 4.6.3 Septic System Input Parameters
•INPUT PARAMETER UNIT VALUE COMMENTS REFERENCE -
Population Using Persons Ranges from Based on census- US Census
Septic 21 to 2,304 based average Bureau (2005)
� per persons per housing
subwatershed unit
Nitrogen Septic Tank Grams/day 12:33 Based on Neuse River Buetow (2002)
Effluent basin data
Phosphorus Septic Grams/day 1.75 Based on Neuse River Buetow (2002)
Tank EfFluent basin data
Nitrogen Plant Grams/day 1.6 Growing season Model default
Uptake Rate
Phosphorus Plant Grams/day 0.4 Growing season Model default
Uptake Rate
4.7 Consideration of Existing Environmental Regulations
4.7.1 Neuse River Nutrient Sensifive Waters Management Rules
The Neuse NSW stormwater management program imposes a 4.0 kg/ha/yr (3.6 pounds
per acre per year or Ib/ac/yr) nitrogen loading limit on new development. Nitrogen load
from new developments that exceeds this performance s#andard may be offset by
payment of a fee to the Wetlands Restoration Fund provided, however, that no new
residential development can.exceed 6.7 kg/ha/yr (6.0 Ib/ac/yr) and no new nonresidential
development can exceed 11.2 kg/ha/yr (10.0 Ib/ac/yr). �
All existing development,was assigned loading rates shown in Table 4.6.2.
Rates for future residential and nonresidential development were determined using the
iterative process described in section 4.5.5 targeting TN export rates of 5.8 and 4.0
kg/ha/yr for nonresidential and residential land uses, respectively. The export rate caps
for nonresidential land uses were adjusted assuming the offset provision would be used
in approximately 25% of cases. While the offset provision is used less than 5%
presently, there will likely be an increase in its use as development in the Neuse area of .
Greenville continues (Lisa Kirby/Greenville, personal communicafion).
Reductions in nitrogen loading will. be accompanied by reductions in TP and TSS
(NCDWQ, . 2004 and 2005). A concomitant reduction of 30% in both constituents,
adjusted in terms of accumulation, is assumed and implemented in the model
simulations.
An additional feature of the Neuse rules requires no net increase in peak flow leaving a
newly developed site compared to predevelopment conditions for the one-year, 24-hour
storm. This feature was not explicitly incorporated into the model simulation for finro
reasons. Since many traditional BMPs convert little runoff to infiltcation, mitigating peak
flows will have little impact on long-term runoff rates or volumes. In addition, BMPs for
water quality provide some control . of peak flow,. so. some . of this required control, is
.
4-24

Greenville Southwest Bqpass
ICI Water Quality Study
considered implicitly. This is a conservative assumption since control of peak flows may
be expected to provide additional control of runoff. However, note that control of peak
flows is required regardless of the development scenario. Therefore, the change in the
peak of the hydrograph or difference between the two scenarios should be insignificant
since nearly aIF of the new development would require control:
In both land use scenarios, a fifty-foot buffer on all perennial and intermittent sfreams
identified on the USGS-based stream coverage was classified as urban greenspaee.
4,8 Modellmplementation
Based on the series of inputs discussed in the following section, a series of transport
and nutrient model input files were developed to execute individual model runs
simulating the Build and No-Build scenarios in each of the GWLF subwatersheds
presented in Figure 4.1.1. All model runs relied on the same weather file that contains
precipitation and air temperature data for climate years 1996 through 2006. The climate
year for GWLF is defined as April 1— March 31.
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Greenville Southwest Bypass
ICI Water Quality Study
5 GWLF MODEL RESULTS AND DISCUSSION
5.1 Hydrology
Components of the hydrologic cycle illustrated in Figure 3.2.1 include precipitation,
evapotranspiration, runoff, and deep groundwater seepage. In eastern North Carolina,
rainfall typically ranges from 112 to 152 cm (44-60, in). A study by Evans et al. found that
evapotranspiration (ET), runoff (surface and subsurface) and deep groundwater outflow
range from 81 to 102 cm (32-40 in), 30 to 51 cm (12-20 in), and 3 to 5 cm (1-2 in),
respectively (Evans et al., 2000). In other words, the water balance breakdown would be
comprised of 65 to 71 % evapotranspiration, 26 to 32% runoff, and about 3% deep
groundwater outflow.
In addition, a comprehensive study of hydrology of forested lands in eastern North
Carolina found that annual outFlow or runoff from forested sites ranged from 17 to 45% of
rainfall (Chescheir et aL, 2003). �Ider et al. (1978) cited 68% of the water balance as
ET for northeastern NC. The predicted hydrologic components of the model are
comparecl to these literature values. Since the li#erature values are based on hydrology
in an undisturbed watershed; one of the most undeveloped subwatersheds in the model,
UB1, was chosen for comparison. In the No-Build scenario this watershed has
agriculture and low-density residential land uses.
Runoff from UB1 comprised 38% of the water balance over the simulation period for the
No-Build Scenario, which is within the range of the Chescheir et al. but higher fhan
Evans et al. ET comprised 60% of the water balance, lower than the average proportion
cited by �Ider et al. and Evans et al. The lower percentage of ET is likely due to the
greater amount of development compared to a mass balance based on a more rural
setting as described in Evans et al. (2000). Urbanization is accompanied by a decrease
in vegetation available to produce evapotranspiration as well as a greater proportion of
surface runoff (versus subsurface runoff in shallow groundwater). For the study area as
a whole, ET and runoff were 52 and 45% of total rainfall for the No Build scenario.
The seasonal change in hydrologic conditions in the UB1 subwatershed is shown in
Figure 5.1.1. As expected, evapotranspiration decreases in. winter due to lower
temperatures and dormant yegetation resulting in a higher proportion of runoff:
5.2 Pollutant Loading
For each land use scenario, GWLF model output time series were generated reflecting
10 y.ears of annual total nitrogen (TN), total phosphorus (TP) and. sediment loads:
Annual loads were.aggregated into 10-year pollutant loads for each parameter_ and each
subwatershed and the results are presented by pollutant in Table 5.2.1: _
The Build Scenario resulfed in changes in TN and TP loads ranging from -3% to 8%0.
Sediment loads increased in 7 of 21 subwatersheds. The average sediment load across �
all subwatersheds increased 2% when, comparing the Build and No-Build scenario, �
though most of the increase is a result of one subwatershed (UF1). -
Model subwatersheds UF1, UF2, UE1, and SC4 saw the greatest changes in land use
between scenarios. These subwatersheds also`had some of the largest :increases in
5-1 . .
.

Greenville Southwest Bypass
ICI Water Quality Study
constituent loads. The greatest increase in sediment loading occurs in UF1 where there
were large differences in RHH (high density residential) and RLL (low densiry residential)
land use categories between scenarios.
In UF2, the model simulated an increase in nitrogen but no change in phosphorus. This
result is influenced by the septic system inputs and resulting loads. While there is
increased nitrogen export associated with the greater number of septic systems in the
Build scenario, the model assumes no phosphorus export for normally functioning
systems.
25 i —
20
15
E
U
��
f Precipitalion (cm) �
—a— E�apotranspiration (cm)
—�-- Subsurtace Runoff (cm)
�� Su�iaceRunoff(cm)
�—Total Runofl(cm)
� — — —
Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar
Figure 5.1.1 Mean Monthly Water Balance for the UB1 Subwatershed (No Build
Scenario)
In some cases, the loading is predicted to decrease slightly. For exampie, the results
show that nutrients decrease in subwatershed SC6. The decrease is caused by a
number of factors: the No-Build scenario has a greater population on septic and the new
roadway in the Build scenario has a lower nutrient accumulation rate than many of the
other developed uses.
Nutrient and sediment export by subwatershed is presented in Figures 5.2.1 through
5.2.3. Patterns are similar for all three constituents. Subwatershed UB1 had the lowest
area-based expoR of nutrients due to its lower intensity development. The highest export
rates for nitrogen occurred in subwatersheds with the greatest numbers on septic
5-2

Greenville Southwest Bypass
ICI Water Quality Study
systems: UE1, UA3, and UF2. For phosphorus and sediment, high intensity land use
and significant amounts of existing development caused SC1 to have the highest rates,
though there is no change in land use between Build and No-Build.
In sum, nonpoint source loading is increased slightly in the Build scenario relative to the
No-Build, though the increases are mitigated to some extent by the existing (and
expected) regulations governing the jurisdictions (e.g., Neuse rules) (Figure 5.2.4). While
sediment had the greatest increase on a percentage basis (2.4%), a conservative
assumption of 30% reduction as a byproduct of the Neuse stormwater rules suggests
the increase could be lower.
Table 5.2.1 Ten-Year Total Loads (tonnes) for All Subwatersheds
� Total Nitrogen > pho pholrous > Total Sediment �
r O o O v O v
N N '� N '� N '�
N mm mm mp7
R
3 No zz No tz No rz
a Build U Build U Build c�
� Build o Build � Build o
<
UF2 142 147 3% 9 9 0% 469 495 6%
UF1 57 58 3% 11 l2 5% 614 748 22%
UE1 123 133 S% 7 7 2% 428 454 6%
UD1 17 17 0% 1 1 0% 170 170 0%
UC1 73 73 0% 4 4 0% 362 362 0%
U61 30 30 0% 1 1 0% 201 201 0%
UA3 165 165 0% 9 9 0% 483 483 0%
UA2 59 59 -1% 11 11 -1% 806 802 -1%
UA1 55 55 0°/a 7 7 -2% 549 557 1°/a
SC8 63 63 0% 9 9 0% 620 620 0%
SC7 53 53 0% 7 7 0% 327 327 0%
SC6 6� 59 -3% 11 11 -1% 657 667 2%
SC5 67 67 0% 11 11 0% 707 707 0%
SC4 145 151 4% 14 14 2% 645 700 9%
SC3 79 79 0% 14 14 0% 1,001 1,004 0%
SC2 58 58 1% 10 11 2% 829 852 3°/a
SC1 92 92 0% 17 17 0% 1,312 1,312 0%
P84 122 122 0% 6 6 0% 424 424 0%
P83 70 70 0% 4 4 0% 243 243 0%
P62 43 43 0% 3 3 0% 185 185 0%
P61 53 53 1% 10 10 0% 771 771 0%
Total 1,626 1,646 12% 176 177 0.5% 11,804 12,084 2.4%
5-3

Greenville Southwest Bypass
ICI Water Quality Study
Figure 5.2.1 Mean Annual Total Nitrogen Loading Rates
Figure 5.2.2 Mean Annual Total Phosphorus Loading Rates
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Greenville Southwest Bypass
ICI Water Quality Study
Figure 5.2.3 Mean Annual Sediment Loading Rates
1800
1600
1400
1200
d 1000
c
c
F 800
600
400
200
0
— ! s No Build I
■ Build I
TPl
TP Sediment X 10
Figure 5.2.4 Total Nitrogen (TN), Total Phosphorus (TP), and Sediment Loading Over
the Ten-Year Mode� Simulation Period
5-5

Greenville Southwest Bypass ---
ICI Water Quality Study , '
,,
5.3 Verification of Model Resu/ts
No stream flow or water quality data within the study area were available for model
calibration. Though the current model application can only provide a coarse
approximation of pollutant loads for the study area, it still remains highly useful for 1
purposes of comparing relative degrees of change befinreen different watershed �
management strategies or land use regimes. Further, the uncertainty in the difference
between the model results of two alternatives is typically much smaller than the ��
uncertainty in the absolute results (Reichart and Borsuk, 2002). '�__I
Nonetheless, it is appropriate to determine if, at a minimum, the results are reasonable
and within physically defensible ranges. One approach for judging the validity of results
is by comparison of predicted pollutant load outputs to those reported in other studies.
5.3. 9 Pollutant Loading Comparison
Table 5.3.1 presents predicted pollutant loads from the current GWLF analysis as well
as those from the five GWLF modeling studies in North Carolina and additional literature
values. The subwatershed ranges of reported values from the modeling studies were
standardized to aerial load rates for purposes of comparison.
Four of the five GWLF modeling analyses received some limited calibration. The
exception is CH2M HILL (2003), which lacked local flow and constituent data to formally
calibrate the model as in this study.
When evaluating the reported load values in Table 5.3.1 consideration should be given
to the differences in study area characteristics. For example, the studies described in
CH2M HILL (2003) and RTI (1995) were pertormed on rural watersheds and hence
reflect the impact of significant areas of agricultural land. The Morgan Creek study by
Tetra Tech (2004) encompassed the Town of Chapel Hill. The most similar study is the
NCDOT study (2006b) that was also located on the inner Coastal Plain in an urbanizing
watershed although it was a smaller watershed.
Evaluation of the load values presented in Table 5.3.1 reveals that the maximum values
of sediment loads from the current GWLF analysis are lower than most of the other
studies. This largely stems from the representation of reductions in loading associated
with the Neuse rules and the lack of agriculture land uses. Elevated sediment loading in
CH2M Hill (2003) and RTI (1995) is derived mostly from row crop agricultural land uses.
Phosphorus and nitrogen values from the current study are within the range of many of
the citations.
5.3.2 Streamflow Comparison
Another effective means by which to judge the validity of results from a modeling
analysis . of this nature is to compare the predicted . stream flow to that from a nearby
USGS stream gage with similar drainage area characteristics.
The nearest USGS gage with a reasonably small drainage area is the gage on Chicod i�
Creek at State Road 1760, station number 02084160. The Chicod Creek gage, located _
approximately 13 miles east of the study area has a reported. drainage area of 117 km2
�
1 i
L_�
5-6 -

Greenville Southwest Bypass
ICI Water Quality Study ,
and an average daily flow of 54 cubic feet per second or 1.5 cubic meters per second
(m3/s), based on data from 30 years (1975). This time period coincidentally represents
average_.hydrologic conditions based on state-wide annual precipitation data.
Table 5.3.1 Comparison of Model Loading Rates to the Literature
Study Location Watershed Total N Total P: Sediment'
. , ; Land Use (kg/halyr} (kgfha/yr), (kg/ha%yr)
Min Max Min �Max Min �Max
Current Inner Coastal Plain
Study* NC urban 6.2 14.3 0.3 1.7 40. 131
NCDOT Inner Coastal Plain
(2006b)* NC urban 3.3. 9.8 0.7 1.9 42 127
CH2M HILL Inner Coastal Plain
(2003)" NC rural 2.5 8.0 0.7 1.9 , 29 361
Tetra Tech P�edmont NC
(2003)" �ordan Lake mixed 1.8 . 26.9 0.3 2.8 -- --
Watershed
Tetra Tech Piedmont NC
(2004)" Morgan Creek mixed 3.7 16.1 0.3 1.9 -- --
Watershed
Coastal Plain and
RTI (1995)* Piedmont NC . rural 1.6 2.7 0.1 0.3 25 355
Tar-Pamlico River
Basin
Compilation
of Literature Various various 0.7 28.0 0.01 3.8 -- --
Export
Coefficients '"*
" GWLF Modeling Study
** A compilation of literature export coefficients for nutrients was presented in bofh Line et a1.
(2002) and Tetra Tech (2003).
In order to provide.a standardized comparison, the flows from the GWLF subwatersheds
were converted into annual m3/ha yields: The 10-year average annual yields from the 21
subwatersheds (No Build Scenario) ranged fcom.5,007 to 7,656 m3/ha/yr, cesulting in
percent errors of 7 to 64% and an overall average of 29%0, when compared to the
average.annual yield form the Chicod Creek gaging station (4,676 m3/ha/yr). Fercent
errors in annual mean yalues were calculated by the following formula:; [(simulafed -
observed) / observed] x 100% (Zarriello, 1998): However, the watershed for Chicod
� Creek watershed is rural which has implications for its water balance: .less streamflow is
.
5-7. . .

Greenville Southwest Bypass
ICI Water Quality Study
expected due to greater evapotranspiration (more vegetation) and less runoff (less
impervious surfaee). When comparing the three least developed subwatersheds (UB1,
UC1, UD1) in the study area to the Chicod Creek gage, the.percent errors average 9%
suggesting the model does a good job of simulating the long term water balance and
stream response.
If this were a comparison of simulated values and actual observed values measured
within the watershed, an average percent ecror of 10% in annual predictions would
represent a"Good" calibration according to Donigian's (2000) general calibration targets
for watershed modeling. The comparison indicates that the predicted stream flows from
the GWLF modeling results are reasonable.
5-8

'i - . ' . . . . ' ' ' . . . " . . . . . . '
� � . . . ' " " . . " ' . � . . ' . . . . . . � .
. . . . . . . . . . . . . . . . . . "
_ : _� � . Greenville Southwest Bypass
�� . ICI 1Nater Quality Study .
'� E . � -
6 STREAM EROSION RISK ANALYSIS
�.
The proportion of impervious surface 'increases as the intensity of development
-- increases, which also increases the volume and velocity of stormwater runoff.- The
;�
resulting increase in frequency and magnitude of high flow events in receiving streams
�' has the propensity to increase hydraulic shear stress, in turn raising fhe risk level foc
_ � stream erosion and sedimentation, potentially leading to deg�adation of aquatic habitat.
�� In order to examine the potential for increased risk levels for these phenomena, a simple .
° analysis was used to predict the degree of change in storm flow volume associated with
the Build scenario relative to that of the No Build scenario. The analysis was pertormed
i° through application of the SCS Curve Number Method as presented in `Urban Hydrology
' for Small Watersheds (SCS, 1986). The technicaf approach to the analysis and the
results are described' below:
�+
� 6.1 Technical. Approach . . .
,
The Curve Number Method - represents a well-established means to _ estimate runoff
j�r volume from a given rainfall event. The method inVolves three equations, the first of
'� _; which is used to determine the potential maximum retention after runoff begins (S) for
each land use type through:
r�-, .
I �u S� _ (4000 / CN�) - 10. .
,- , Where: CN� = Runoff Curve Number for Land Use Type U
The portion of runoff contributed by each land use type within a given watershed is
,_ caleulated by:
.
y
� Q� _ (P - 0.2 ".S�)2 / (P +. 0. 8 * Su)
Where: Q� = Flow Volume contributed by Land Use Type U .
, P = rainfall
-r The total tlow volume is then estimated with the equation:
i
�-- � � �� � � -� � QTOTAL ' ��U �AU *.QUI � �
, r Where: QTOTA� = Total Flow Volume contributed by all Land Uses within .the viratershed
[ -'� evaluated .
A� = Area of Land Use Type U
;; �
�' The runoff curve numbers utilized in this analysis are identical to those used in the
GWLF modeling analysis and are presented in Table 4.3.2. The storm event. selected
-, for the analysis was the one-year, 24-hour storm in order to approximate the amount of .
� rainfall that would result in banKfull flow conditions in the receiving streams. The greatest -.
potential for channel erosion occurs for storms with a recurrence interval of one to two
years. The rainfall volume_for the one-year, 24-hour storm is approximately 9 cm or_3.5 .
� � inches.(USDC, 1961). . -. .
�_� �
� , _.
' -` . .
- 6=1 -

�r i
� _ - �_ �
Greenville Southwest Bypass --
ICI Water Quality.Study � �
Note that runoff volume is caiculated for each land use and then summed rather than ���
producing a single.area-averaged curve number from which to calculate runoff. This . '
approach avoids underestimation of runoff derived from the fact that runoff is not a linear �'
function with respeet to curve number. ,
��
6.2 Results �--�
The above equations and assumptions were executed on the Build and No-Build land . P
use scenarios presented in Section 4.2 and the results comparing the finro scenarios for (_ !
the 21 GWLF subwatersheds are presented in Table 6.2.1.
�
The analysis suggests that development of the Build scenario would have a no impact I_ J! .
on storm event flows .volumes for the one-year, 24-hour storm in 15 of the 21
subwatersheds. However, some impact is expected in six of the subwatersheds with the -,
greatest in UF1. ;
Table 6:2.1 Storm Flow Volumes (cubic meters) for the One-Year, 24-Hour Storm l!
. ._ � I
Sub- % "Change Sub- % Change.
No Build Build ; Over No No �Build Build Over No
watershed � . watershed ��
Build ' Build ! � .
I�
PB1 297,640 297;640 0% SC8 279,322 279,322 0%
PB2 100,031 . 100,031 0% UA1 255,244 255,538 0% ;-r
P63 147,659 147,659 0% UA2 296,449 295.590 0% ��
�_ v
PB4 288,594 288;594 0% UA3 295,576 295,576 0%
SC1 435,359 147,659 0% UB1 104,687 104,587 0%
- -,
SC2 309,883 315,949 2%. UC1 194,049 190,049 0% {�
SC3 380,874 381,668 0%. UD1 50,556 50,556 0%
SC4 371,644 383,740 3% UE1 250,223. 258,465 3% i
SC5. 286,987 286,987 0% UF1 281,132 307,862 10% �'
SC6 271,245 281,558 4%, . UF2 281,663 287,345 2%
SC7 194,777 194,777 0% Total - 5,373,494 5,442,821 1.3%u �-
�
;=-�
�4
i
_ . � � � �
�-�
_ I_ �
(�i
I �
. � f
i_ �
;� ��
. 6-2 � .. ,
-. � `i
i�

Greenville Southwest Bypass
ICI Water Quality Study
7 CONCLUSIONS
The project referred to as the Greenville Southwest Bypass (TIP Project No. R-2250) is
proposed as a four-lane, median-divided, full control of access facility in Pitt County. A
qualitative I.CE Analysis was completed in . May 2006 to provide an assessment of the
potential long-term, induced impacts of the proposed project (NCDOT, 2006).
In. response to NC Division of Water Quality (NCDWQ) comments on the ICE
Assessment and in preparation for an Individual Section 401 Water Quality Certification,
a water quality modeling analysis was conducted to quantify fhe project's ICIs on water
resources. The focus of the analysis is on the potential increases in stormwater runoff
and nonpoint source loads of nitrogen, phosphorous and sediment resulting from a
future development sceriario associated with the roadway.
Predictions from the modeling analyses suggest that while storm event runoff volume
and nonpoint source pollutant loading would increase in the Build Scenario �elative to
the No Build Scenario, the increases are small, due in part to the existing (and expected) .
regulations governing the jurisdictions, and that significant development will occur with or
without the roadway.
These results have important implications for the potential increases in predicted �
pollutant loads to two local streams, Swift Creek and Little Contentnea Creek, which
have been designated as impaired by NCDENR. While development in the area will
result in increases in pollutant loads to these waterbodies, the increases suggested by
the modeling analysis do not appear to be influenced significantly by the new roadway.
7-1

_ �
Greenville Southwest Bypass
ICI Water Quality Study !
�`,
,
J�
7-2 � � ,

��' �
Greenville Southwest Bypass
ICI Water Quality Study
8 REFERENCES
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ICI Water Quality Study ,
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-i�
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�; .
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� - _
:. . : :. : : : .
,- , � . 8-3 _ �
� � : _

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ICI Water Quality Study
Prepared for NCDOT by Lochner. May 2006. (referred to in text as Indirect and
Cumulative Effects Analysis)
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Water Quality. Raleigh, NC. August 1999..
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North Carolina Division of Water Quality (NCDWQ). 2005b. Updated Draft Manual of
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8-4
;'�

Greenville Southwest Bypass
ICI Water Quality. Study
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-
8-5

Greeriville Southwest Bypass
ICI Water Quality Study
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Data, p. 7-163 to 7-170.
:.
;'
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, , 9 APPENDIX
�,
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9.1 Land Use Scenarios
� I 9.2 Runoff Volume Analysis
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Greenville Southwest Bypass
ICI Water Quality. Study

Appendix 9.1 Land Use Scenarios
Land Use PB1 P62 P63 P64 SC1 SC2 SC3
No BuilcJ Build No Build Build No Build Build No Build Build No Build Build No Build Build No Build Build
COM 19.87 19.87 0.00 0.00 0.00 0.00 0.00 0.00 49.29 49.29 2.85 20.88 70.85 70.85
GOMe 3.20 3.20 0.00 0.00 0.57 0.57 2.39 2.39 102.46 102.46 8.81 8.81 53.45 53.45
FOR 153.18 153.18 95.15 95.15 19.46 19.46 111.17 111.17 60.60 60.60 106.87 100.60 82.60 80.70
OFF 17.08 17.08 0.00 0.00 0.00 0.00 1.93 1.93 88.61 88.61 56.19 55.84 49.19 49.19
OFFe 6.87 6.87 0.08 0.08 0.59 0.59 1.66 1.66 50.68 50.68 38.30 38.30 42.01 42.01
OPN 30.94 30.94 36.12 36.12 19.36 19.36 22.06 22.06 26.61 26.61 18.35 18.28 31.19 31.19
RHH 0.18 0.18 0.00 0.00 0.00 0.00 0.20 0.20 20.25 20.25 7.45 7.45 18.55 18.55
RHHe 49.09 49.09 1.32 1.32 7.93 7.93 13.01 13.01 48.00 48.00 15.55 15.55 55.88 55.88
RLL 20.99 20.99 165.32 165.32 195.49 195.49 316.43 316.43 0.00 0.00 0.00 0.00 59.43 58.67
RLLe 6.68 6.68 1.28 1.28 5.75 5.75 1.22 1.22 8.64 8.64 4.39 4.39 10.44 10.44
RMH 1.03 1.03 0.96 0.96 0.45 0.45 8.95 8.95 8.83 8.83 3.51 3.51 134.58 134.58
RMHe 67.50 67.50 5.21 5.21 19.76 19.76 21.46 21.46 46.89 46.89 27.63 27.63 33.98 33.98
RML 0.47 0.47 b.49 0.49 0.40 0.40 0.96 0.96 1.49 1.49 0.00 0.00 1.04 1.04
RMLe 10.97 10.97 2.92 2.92 5.18 5.18 4.21 4.21 15.86 15.86 7.45 7.45 22.13 22.13
ROAD 77.24 77.24 6.04 6.04 27.19 27.19 53.94 53.94 56.17 56.17 34.19 51.91 74.30 76.95
RVH 309.80 309.80 71.53 71.53 13.75 13.75 0.00 0.00 360.37 360.37 354.36 325.31 164.78 164.78
RVHe 0.23' 0.23 0.00 0.00 ' 0.22 0.22 1.18 1.18 42.06 42.06 19.52 19.52 33.10 33.10
RVL 0.00 0.00 0.00 0.00 229.04 229.04 490.64 490.64 0.00 0.00 3.43 3.43 0.00 0.00
RVLe 3.20 3.20 3.15 3.15 12.41 12.41 11.13 11.13 17.59 17.59 14.44 14.44 26.16 26.16
WAT 3.49' 3.49 4.85 4.85 4.25 4.25 1.48 1.48 0.00 0.00 0.00 0.00 0.00 0.00
WET 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.48 0.48
Land Use SC4 SCS SC6 SC7 SC8 UA1 UA2
No Build Build No Build Build No Build Build No Build Build No Build Build No Build Build No Build Build
COM 0.00 19.56 98.28 98.28 90.54 111.24 13.55 13.55 0.24 0.24 12.80 10.40 115.98 110.83
COMe 4.57 4.57 14.21 14.21 23.73 23.73 6.40 6.40 14.37 14.37 0.41 0.41 25.54 23.80
FOR 62.24 62.24 9.83 9.83 19.23 19.20 108:52 108.52 140.44 140.44 132.20 132.20 114.99 114.99
OFF 0.00 0.00 0.16 0.16 0.00 0.00 0.00 0.00 0.00 0.00 117.99 106.10 0.00 0.00
OFFe 1.53 1.53 14.20 14.20 28.41 28.41 0.77 0.77 10.07 10.07 0.16 0.16 0.00 0.00
OPN 17.35 17.35 19.31 19.31 16.b2 15.65 4.49 4.49 72.38 72.38 34.14 34.14 30.20 30.20
RHH 31.94 31.94 43.94 43.94 17.55 17.55 2.01 2.01 11.22 11.22 0.00 0.00 0.00 0.00
RHHe 7.55 7.55 25.09 25.09 28.54 28.54 8.01 8.01 53.96 53.96 3.16 3.16 0.43 0.43
RLL 534.18 403.00 157.97 157.17 302.51 274.06 249.78 249.78 337.66 337.66 22.95 22.95 90.17 90.17
RLLe 7.38' 7.38 3.90 3.90 2.63 2.63 5.97 5.97 0.00 0.00 3.55 3.55 0.63 0.63
RMH 332.64 316.65 206.87 206.87 4.83 4.83 144.58 144.58 39.70 39.70 1.38 1.38 0.00 0.00
RMHe 46.50 46.50 22.00 22.00 31.84 31.84 5.14 5.14 24.01 24.01 10.08 10.08 1.53 1.53
RML 2.80 111.33 1.25 1.25 0.00 0.00 0.00 0.00 0.00 0.00 0.89 0.89 0.00 0.00
RMLe 21.91 21.91 14.17 14.17 9.30 9.30 3.36 3.36 6.12 6.12 5.72 5.72 2.54 2.54
ROAD 35.86 55.01 67.69 67.69 61.05 69.19 28.56 28.56 74.31 74.31 18.96 33.25 16.87 23.76
RVH 61.52 61.46 69.67 69.67 36.16 36.16 11.89 11.89 119.01 119.01 194.85 194.85 309.81 309.81
RVHe 0.01 0.01 14.29 14:29 29.55 29.55 0.31 0.31 51.22 51.22 0.07 0.07 0.00 0.00
RVL 0.00 0.00 2.83 2.83 0.00 0.00 0.00 0.00 0.00 0.00 167.69 167.69 0.00 0.00
RVLe 14.50 14.50 15.48 15.48 7.00 7.00 25.24 25.24 13.21 13.21 8.21 8.21 4.15 4.15
WAT 0:93 0.93 0.39 0.39 0.00 0:00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0:00
W ET 70.00 70.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
hn napiananun ui mnu usa wuns is pruv�aeu m i aoie y.c.-i
area is in heactares, e= existing
9-1
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Land Use UA3 U81 UC1 UD1 UE1 UF1 UF2 �.
No Build Build No Build Build No Build Build No Build Build No Build Build No.Build Build No Build Build .
. COM 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 16.27 123.06 132.63 0.00 4.63
COMe . 7.22 7.22 0.30 0.30 13.56 13.56 0.00 6.74 . 6.74 4.40 4.40 4.75 3.16
� FOR 1'12.90 112.90 16.18 16.18 29.50 29.50 1.48 1:.48 17.92 17.92 6.88 6.88 63.85 63.85
�' OFF 3.34 3.34 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 ' 0.00 0.00 . 0.00 0.00
OFFe ". . 1.42. " 1.42 1.27 . 1.27 0.00 0.00 0.00 0.00 0.65 . 0.65 .. 4.26 4.26 1.85 1.85
OPN . 11.50 11.50 8.67 8.6Z 97.90 17.90 14.41 14.41 14.97 14.97 41.59. 41.59. 38.45 38.16 '
RFIH 0.40 0.40 0.00 0.00 0.00 0.00 020 0.20 0.15 0.15 3.38 180:81 0.34 0.34
RHHe 9.57. 9.57 . 1'.48 . 1:48 3.43 3.43 0.75. 0.75 OJ2 ' 0.72 3.90 3.90 5.95, 5.95
RLL �' 525.04 525.04 1.25 1.25 82.22 82.22 1.51 1:51 426.96 310.48 540.43 289.41 657:84 542.63
� RLLe 4.59 4.59 3.38 3.38 2.06 . 2.06 2:26 2.26 1.86 1.86 2.80 . 2.80 : 3.74 ' 374 �
RMH 16.22 16.22 0.32 0.32 0.00 0.00 1.78 1.78 5.79 5.79 1.87 1.87 1.57 1.57
. RMHe 32.72 32:72 5.79 5.79 15.Ofi 15.06 7.97 7.97 11.66 11.66 21.45 21.45 13.59 13.36
RML � 1.60 1.60 0.03 0.03 1.78 1.78 0.00 0.00 2.82 97.59 0.00 0.00 0.00 96.32 .
RMLe 4.20 ' 4.20 ' 2.30 ' 2.30 5.09 5.09 3.33 3.33 6.86 6:86 7.64 7.23 5.04 4.67
�; ROAD • 31.91 31.91 12.15 12.15 : 13.85 13.85 6:67 6,67 16.53 . 21.97 ,27.00 42.59 26.78 44.08
RVH 9.05 9.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 35.57 ' 84.39 0.00 0.02
RVHe ; 0.61 0,61 0.53 0.53 0.00 0.00 0.01 . 0.01 0.25 0.25 0.84 0.84 0.33 0.33
RVL 360.22 360.22 408.41 . 408.41 630.55 630.55 206.62 206.62 361.87 361.87 , 48.62 _ 48.62 249.75 24975
RVLe 5.61 5.61 6.54 6.54 18.99 18.99 12.53 12.53. 24.41 24.41 3.74 3.74 9.47 8.91
WAT 2.33 2.33 � 2.25 2.25 0.00 0.00 3.93 3.93 0.27 0.27 0.00 0.00 ' 1.14 1.14
' WET . 14.73 14.73 4.31 ' 4.31 0:00 0.00 0.00 0.00 0.00 0.00. 0.00 0.00 0.00 0.00
� . � � , � An�explanation of land use codes is provided.inTable 42.1 � � . � . � � . . . . . . � . . � .
�. . area is In,heacfares, e=�existing . . . � �- � � � .
9-2

Appendix 9.2 Runoff Volume Analysis
Sub- 6and No Build CN No CN S fact-No S fact- Q(in) no Q(in) No Build
watershed Use Ha Build Ha Build Build build build build build m^3 Build m^3
PB1 COM 19.87 19.87 89 89 1.257815 1.257815 2.341712 2.341712 11817.73 11817.73
PB1 COMe. 3.20 3.20 90 90 1.099258 1.099258 2.456811 2.456811 T999.77 1999.77
PB1 FOR 153.18 153.18 70 70 4.36Z098 4.367098 0.986451 0.986451 38380.92 38380.92
PB1 OFF 17.08 17.08 80 80 2.515767 2.515767 1.629189 1.629189 7066.20 7066.20
PB1 OFFe 6.87 6.87 87 87 1.474034 1.474034 2.195504 2.195504 3828.44 3828.44
P61 O.PN 30.94 30.94 72 72 3.836604 3.836604 1.136735_ 1.136735 8932.06 8932.06
PB1 RHH 0.18 0.18 70 70 4.237652 4.237652 1.021113 1.021113 45:79 45.79
P61 RHHe 49.09 49.09 72 72 3.965114 3.965114 1.098265 1.098265 13693.53 13693.53
PB1 RLL 20.99 20.99 65 65 5.273589 5.273589 0.774648 0.774648 413024 4130.24
PB1 RLLe 6.68 6.68 66 66 5.126414: 5.126414 0.805699 0.805699 1366.47 1366.47
PB1 RMH 1.03 1:03 74 74 .3.569235 3.569235 1.221428 1.221428 318.37 318.37
PB1 RMHe 67.50 67.50 71 71 4.04842 4.04842 1.074059 1.074059 18415.32 18415.32
P81 RML 0.47 0.47 69 69 4.412651 4.412651 0.974542 0.974542 115.72 115.72
PB1 RMLe 10.97 10.97 . 70 70 4.355602 4.355602 0.98948 0.98948 2758.01 2758.01
PB1. ROAD 77.24 7724 86 86 1.669357 1.669357. 2.073085 2.073085 40672.15 40672.15
P61 RVH 309.80 309.80 82 82 2.185728 2.185728 ''1.787355 1.787355 140645.23 140645,23
PB1 RVHe 0.23 0.23 83 83 2.112979 2.112979 1.824608 1.824608 107.91 107.91
PB1' RVL 0.00 0.00 . 0.00 0.00
P61 RVLe 3.20 3.20 61 61 6.510347 6.510347 0.554748. 0.554748 450.45 . 450.45
PB1 WAT . 3.49 3.49 98 98 0.204082 .0.204082 3.266471 3.266471 2895.65 2895.65
PB1 WET 0.00 0.00 0.00 0.00
PB2 COM 0.00 0.00 0.00 0.00
PB2 COMe 0.00 0.00 � 0.00 0.00
PB2 FOR 95.15 95.15 62 62 6.135379 6.135379 0.614415 0.614415 14849.24 14849.24
P62 OFF 0.00 0.00 0.00 0:00
PB2 OFFe 0.08 0.08 90 90 1.130227 1.130227 2.433773 2.433773 51.57 51.57
PB2 OPN 36.12 36.12 69 69 4.451575 4.451575 0.964482 0.964482 ' 8847.76 8847.76
PB2 RHH 0.00 0.00 0.00 0.00
P82 RHHe 1.32 1.32 67 67 4.847244 4.847244 0.867968 0.867968 291.30 291.30
P62 RLL 165.32 165.32 69 69 4.556289 4.556289 0.937937 0.937937 39385.92 39385.92
P62 RLLe 128 1.28 65 65 5.384615 5.384615 0.751989 0.751989 244.79 244.79
PB2 RMH 0.96 0.96 67 . 67 4.925373 4:.925373 0.85008 0.85008 207.53 207.53
PB2 RMHe 5.29 5.21 64 . 64 5.544302 5.544302 0.720508 0.720508 954.12 g54,12
P62 RML 0.49 0.49 59 59 7.086661. 7.086661 0.473045 0.473045 58.99 58.99
P62 RMLe 2.92 2.92 64 64 5.581359 5.581359 0.713383 0.713383 529.69 529.69
PB2 ROAD 6.04 6.04 86 86 1.657856 1.657856 2.080055 2.080055 3188.86 3188.86
P62 RVH 71.53' 71.53 78 78 2.837578. 2.837578 1.490359 1.490359 27077.73 27077.73
P62 RVHe 0.00 0.00 0.00 0.00
PB2 RVL 0.00 0.00 0.00 0.00
PB2 RVLe 3.15 3.15 57 57 7.69756 7.69756 0.39796 0.39796 317.99 317.99
PB2 WAT 4.85 4,85 98 98 0.204082 , 0.204082 3.266471 3.266471 4025.08 4025.08
PB2 WET 0.00 0.00 0.00 0.00
P63 COM 0.00 . 0.00 0.00 0.00
PB3 COMe 0.57 0.57. 90 90 1.142819 1.142819 2.424485 2.424485 352.16. 352.16
PB3 FOR 19.46 19.46 74 74 3.539628 3.539628 1.231214 1:231214 6087.18 6087:18
PB3 AFF 0.00 0.00 0.00 0.00 .
PB3 OFFe 0.59 0.59 . 83 83 2.023089 2.023089 1.871924 1.871924 282.34 282.34
PB3 OPN 19.36 _ 19:36 69 69 4.409651. 4.409651 0.975322 0.975322 479729 4797.29
P63 RHM 0.00 0.00 0.00 - 0.00
PB3 RHHe 7.93 7.93 74 74 3.551098 3.551098 1.227413 1.227413 2472.44 2472.44
PB3 RLL 195.49 195.49 68 ' 68 4.631385 4.631385 0.919355 0.919355 45649:17 45649.17
P83 RLLe 5.75 5.75 88 68 4.692076 4.692076 0.904608 0.904608 1321:01 1321.01
P63 RMFi 0.45 0.45 67 67 4.925373 4.925373 0.850U8 0.85008 96.93 96.93
PB3 RMHe 19.76 19.76 70 70 4.353725 4.353725 0.989976 0.989976 4969.41 ' 4969.41
PB3 . RML :. 0.40 0.40 65 . 65 5.384615 .5.384615: 0.751989 0.751989 76.86 . 76.86
PB3 RMLe 5.18 5.18 69 69 4.568833 4.568833 0.934807 0.934807 1229.77 1229.77
PB3 , ROAD 27.19 27:19 85 85 1.738013 1.738013 2:0320fi 2.03206 14034.02 14034.02
P63 RVH 13.75 13.75 77 77 2.955373 2.955373 1.442943 1.442943 5039.39 5039.39
PB3 RVHe 0.22 0.22 79 79 2.586763 2.586763 1.59733 1.59733 88.39 88.39
PB3 RVL 229.04 229.04 69 69 4.496771 4.496771 0.952932 0.952932 55438.19 . 55438:99
PB3 RVLe 12.41 12.41 64 64 5.666352 5.666352 0.697293 0.697293 2197.27 2197.27
P63 WAT 4.25 4.25 98 98 0.204082 0.204082 3.266471 3.266471 3527.02 3527.02 ,
PB3 W ET 0.00 0.00 0.00 . 0.00
GICG III IlCIiIGICJ . . .
9-3

� .
i. �. � � � �
Sub- Land No Build _. CN No GN S fact-No S fact-. Q(in) no Q(io) No Build
watershed Use . Ha Build Ha Build Build build build build build m^3 .'�Build m^3
PB4. . COM 0.00 0.00 0.00 . 0:00
PB4 COMe 2.39 2.39 87 87 1.559635 1.559635 2.140782 2:140782 1298.07 1298.07
PB4 FOR 111:17 111.17 74 74 3.604857 3.604857 1.209765 1.209765 34159.06 . 34159.06
PB4 OFF - 1.93' 1.93 82 82 2.196032 2.196032 1:782151 '1.782151 872.39 872.39
PB4 OFFe 1.66 1.66 84 84 1.933191 1.933191 1.920721 1.920721 809.14 809,14
P64 OPN 22.06' ' 22.06 73 73 3.718683 3.718683 1.17329 1.17329 657425 6574.25
P64 RHH 0.20 0.20 78 78 2.841913 2.841913 1.488589 1.488583 76.03 76.03
P64 RNHe 13.01 13.01 73 Z3 3.611358 3.611358 1.207649 1.207649 3989.34 3989.34
PB4 RLL 316.43 316.43 68 68 4.706363 4.706363 0.901171 0.901171 72429.99 72429.99
PB4 RLLe . 1.22.. 1.22 71 . 71 4..167907 4.167907 1:040306.1.040306 32224 322.24
PB4 . RMH 8.95 8.95 73 73 3.642776 3.642776 1.197481 1.197487 272276 2722.76
P64 RMHe 21.46 21.46 72 ,- 72 3.963774 3.963774 1.098659 1:098659 5989.69 5989:69
PB4 RML 0.96 0.96 77 77 2.987013 2.987013 1.430497 1.430497 349.85 349.85
PB4 RMLe 4.21 4.21 71 71 4.155379 4.155379 1.043792 1.043792 1114.90 1114.90
PB4 ROAD 53.94 53.94 86 86 1.588122 1.588122 2.122947 2.122947 29088.65 29088.65
PB4 RVH 0.00 0.00 ' 0.00 0.00
PB4 RVHe . 1.18 1.18 79 79 2.613976 2.613976 1:585309 1.585309 474.30 474.30
PB4 RVL 490.64 490.64 70" 70 4.328246 4.328246 0.996727 0.996727 124214.02 124214.02
PB4 . RVLe 11.13 11.13 70 70 4250812 4.250812 1.017533 1.017533 287Z:24 2877.24
PB4 WAT 1.48 1.48 98 98 0.204082 0.204082 3.266471 3266471 1231.88 1231.88
PB4 WET A.00 0.00 0.00 0.00.
SC1 COM 49.29 49:29 9T 91 1.006715 1.006715 2.52734 2.52734 31643.45 31643.45
$C1 COMe 102.46 102.46 91 91 1.038765 1:038765 2.502623 2.502623 65130.10 65130.10
SC1 FOR 60.60 60.60 65 65 5.404381 5:404381 0.748023 0.748023 11519.72 11513.72
SC1 OFF 88.61 88.61 84 84 1.947634 1:947634 1.912779 1.912779 43053.11 43053.11
SC1 OFFe 50.68 50.68 83 83 2.023481 2.023481 1.871715 1.871715 24094.03 24094.03
SC1 OPN 26.61 26.61 70 70 4.388483 4.388483 0.980842 0.980842 6628.63 6628.63.
SC1 RWH 2O.25 " 20.25 77 77 3.037049. 3.037049 1.41106 1.41106 7258.64 7258.64
SC1 RHHe 48.00 48.00 75 75 3.359305 3.359305 1.292678 1.292678 15759.40 15759.40
SC1 RLL 0.00 0.00 0.00 0.00
SC1 RLLe 8.64 8.64 71 71 4.182773 4.182773 1.036184 1.036184 2273.63 2273.63
SC'I RMH 8.83 8.83 76 76 3.200524 3.200524 1.349577 1.349577 3026.02 3026.02
SC1 RMHe 46.89 46.89 74 74 3.588043 3.588043 1.215255 1.215255 14474.79 14474.79
SC1 RML 1.49. 1.49 76 76 3.213833 3:213833 1.344703 1.344703 509.19 509.19.
SC1 RMLe 15.86 15.86 69 69 4.473859 4.473859 0:95877 0.95877 3861.96 3861.96
SC1 ROAD 56.17 56.17 86 86 1.569895. 1.569895 2.134338 2.134338 30452.23 30452.23
SC1 RVH 360.37 360.37 81 81 2.400678. 2:400678 1.682411 1:682411 153997.50 153997.50
SC1 RVHe 42.06 42.06 80 80 2.485398 2.485398 1.643041 1.643041 17552.01 17552.01
SC1 RVL 0.00 0.00 0.00 0.00
SC1 RVLe 17.59 17.59 68 68 4.609372 4.609372 0.924763 0.924763 4130.84 4130.84
SC1 WAT 0.00 0.00 0.00 0.00
SC1. " WET. 0.00 0.00 0.00 0.00
SC2 COM 2.85 20.88 90 ': 92 1.124725: 0.811586 2.437846 2.684841 1765.21 14235.89
SG2 COMe 8.81 8.81 90 90 1.14756T 1.147567 2.420994 2.420994 5418.03 5418.U3
SC2 FOR 106.87. 100.60 73 73 3.675566 3.717073 1.186966 1.173797 32221.72 29994.27
SC2 OFF 56.19 55.84 � 86 86 1.576332 1.57939 2.130307 2:128394 30403.99 3018626
SC2 OFFe 38.30 38.30 81 81 2.296256. 2.296256 1.732461 1:732461 16853.66 16853:66
SC2 OPN 18.35 18.28 75 - 75 3.274118 3.277504 1.32287 1.321655 6167.00 6136.13
SC2 RHH 7.45 � 7.45 79 79 2.632604 2.632604 1,57714 1.57714 2983.49 2983:49
SC2 RHHe 15.55 15.55 77 77 3:b21587 3.021587 1.417035 1.417035 5595.23 5595.23
SC2 RLL 0.00 0.00 0.00 0.00
SC2. RLI:e . 4.39 4.39 77 77 2.982815 . 2:982815 . 1.432142 1.432142 1598.07 1598.07
SC2 RMH 3.51 3.51 75 75 3.245808 3.245808 1.333074 1.333074 1189.36 1189.36
SC2 - RMHe 27.6& 27.63 74 74 3.468592 3.468592 1.25504 1.25504 8808:93 8808.93
SC2 RML 0.00 ' 0.00 : 0.00 0.00
SC2 RMLe 7.45 . 7.45 74 . 74 3.515709 3.518709 1.238179 1.238179 2343.25 ' 2343.25.
SC2 ROAD 34.19 51.91 87 . 88 1.476542 1.376121 2.193876 2.260251 1905:1.11 29799.60 '
SC2 RVH 354.36 325.31 82 82 2.144687 2.176425 1:808259 1.792068 162755.05 148077.59
SC2 RVHe 19.52 19.52 SO 80 2.560632 2.560632 1.608972 1:608972 7978.12 7978.12
SC2 RVL: 3.43 3.43 68 68 4.764343 4.764343 0.887356 0:887356 773.04 773.04 -
SC2 RVLe 14.44 14.44 71 71 4:011917 4.011917 1.084596 9.084596 8977.93 3977.93
SC2 WAT 0.00 A.00 0.00 . 0.00.
SC2 WET 0.00 ' 0.00 0:00 . 0.00 ..
area in hecta�es .
I I _
_.
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i �� � _ .
9-4 ' .

Sub- Land No Build CN No CN S fact-No S fact- Q(in) no Q(in) No Build
watershed Use Ha Build Ha Build Build build . build build build m^3 Build m^3
SC3 COM 70.85 70.85 90 90 1.104485 1.104485 2.452903 2.452903 44145.25 44145.25
SC3 COMe 53.45 . 53.45 91 91 0.998315 0.998315 2:53387 2.53387 34403.22 34403.22
SC3 FOR 82.60 80.70 72 72 3.830413 3.828544 1.138624 1.139195 23889.89 23352.13
SC3 OFF 49.19 49.19 84 84 1.905537 1.905537 1.936039 1.936039 24187.48 24187.48
SC3 OFFe 42.01 42.01 83 83 2.009163 2.009163 1.879385 1.879385 20052.22 20052.22
SC3 OPN 31.19 31.19 72 72 3.945918 3.945918 1.103924 1.103924 8746.60 8746.60
SC3 RHH 18.55 18.55 76 76 3.231797 3.231797 1.338156 1.338156 _ 6306.56 6306.56
SC3 RHHe 55.88 55.88 77 77 3.053382 3.053382 1:404779 1.404779 19938.21 19938.21
SC3 RLL 59.43 58.67 71. 71 4.078256 4.086977 1.065526 1.063045 16083.72 15843.06
SC3 RLLe 10.44_ 10.44 67 67 5.036683 5.036683 0.82522 0.82522 2187.87 2187.87
SC3 RMH 134.58 134.58 70 70 4.258504 A.258504 1.015446 1.015446 34710.89 34710.89
SC3 RMHe 33.98 33.98 72 72 3.907116 3.907116 1.115455 1.115455 9628.35 9628:35
SC3 RML 1.04 1.04 73 73 3.609983 3.609983 1.208096 1.208096 319.02 319.02
SC3 RMLe 22.13 22.13 71 71 4.138432 4.138432 1.048528 1.048528 5894.06 5894.06
SC3 ROAD 74.30 76.95 86 86 1.577464 1.56623 2.129598 2.136637 40187.86 41760.19
SC3 RVH 164.78 164.78 81 81 2.40936 2.40936 1.678326 1.678326 70247.04 70247.04
SC3 RVHe 33.10 33.10 81 81 2.291764 2.291764 1:734653 1.734653 14584.16 14584.16
SC3 RVL 0.00 0.00 0.00 0,00
SC3 RVLe 26.16 26.16 65 65 5.282594 5.282594 0.772786 0.772786 5135.57 5135.57
SC3 WAT 0.00 0.00 0.00 0.00
SC3 W ET 0.48 A.48 83 83 2.048193 2.048193 1.858564 1.858564 226.42 226.42
SC4 COM 0.00 19.56 89 1.242629 3.5 2.352435 0.00 11686.44
SC4 COMe 4.57 4.57 90 90 1.070407 1.070407 2:478525 2.478525 2874.48 2874.48
SC4 FOR 62.24 62.24 72 72 3.844905 3.844905 1.134208 1.134208 17931.80 17931.80
SC4 OFF 0.00 0.00 0.00 0.00
SC4 OFFe 1.53 1.53 84 84 '1.84954 1.84954 1:96751 1.96751 766.09 766.09
SC4 OPN 17.35 17.35 68 68 4.764575 4.764575 0.887301 0.887301 3910.06 3910.06.
SC4 RHH. 31.94 31.94 75 75 3.284152. 3.284152 1.319274 1.319274 10704.39 10704.33
SC4 RHHe. 7.55 7.55 72 72 3.974235 3.974235 1.095587 1.095587 2100.10 2100.10
SC4 RLL 534.18 403.00 72 72 3.889217 3.900672 1.120816 1.117382 152074.48 114377.81
SC4 RLLe 7.38 7.38 71 71 4.083947 4.083947 1.063906 1.063906 1994.01 1994.01
SC4 RMH 332.64. 316.65 69 69 4.538119 4.543349 0.942489 0.941176 79632.81 75697.43
SC4 RMHe 46.50 46.50 70 70 4.263148 4.263148 1.014189 1.014189 11979.42 11979.42
SC4 RML 2.80 111.33 71 72 4.131084 3.851924 1.050589 1.132075 746.93 32012.99
SC4 RMLe 21.91 21.91 70 70 4.231795 4.231795 1.022711 1.022711 5690.29 5690.29
SC4 ROAD 35.86 55.01 85 86 1.747146 1.637941 2.026678 2.092195 18459.96 29231.69
SC4 RVH 61.52 61.46 82 82 2.248254 2.248254 1.756053 1.756053 27441.13 27414.37
SC4 RVHe 0.01 0.01 76 76 3.157895 3.157895 1.365318 1.365318 3.71 3.71
SC4 RVL 0.00 0.00 0.00 0.00
SC4 RVLe 14.50 14.50 69 69 4.408485 '4.408485 0.975625 0.975625 3592.29 3592.29
SC4 WAT 0.93 0.93 98 98 0.204082 0.204082 3.266471 3.266471 775.43 775.43
SC4 W ET 70.00 70.00 81 81 2.277463 2.277463 1.741653 1.741653 30966.96 30966.96
SCS COM 98.28 98.28 90 90 1.10544 1.'10544 2.45219 2.45219 61212.92 612'12.92
SC5 COMe 14.21 14.21 90 90 1.100641 1.100641 2.455776 2.455776 8862.35 8862.35
SC5 FOR 9.83 9.83 68 68 4.76491 4.76491 0.887222 0.887222 2215.77 2215.77
SC5 OFF 0.16 0.16 81 81 2.283128 2.283128 1.738876 1.738876 70.44 70.44
SC5 OFFe 14.20 14.20 83 83 2.057846 2.057846 1.853457 1.853457 6683.58 6683.58
SC5 OPN 19.31 19.31 . 71 71 4.01574 4.01574 1.083488 1.083488 5314.55 5314.55
SC5 RHH 43.94 43.94 76 76 3.166171 3.166171 1.362246 1.362246 15205.22 15205.22
SC5 RHHe 25.09 25.09 76 76 3.142878 3.142878 1.370912 1.370912 8737.29 8737.29
SC5 RLL 157.17 157.17 66 66 5.193057 5.193057 0.791492 0.791492 31598.16 31598.16
SC5. RLLe 3.90 3.90 68 68 4.718736 4.718736 0:898205 0.898205 890.14 890.14
SC5 RMH 2O6.87 206.87 73 73 3.77039 3.77039 1.15711 1.15711 60799.56 60799.56
SC5 RMHe 22.00 22.00 73 73 3.736126 3.736126 1.167805 1.167805 6524:40 6524.40
SC5 RML 1.25 1.25 66 66 5.243589 5.243589 0.780882 0.780882 . 248.70 248.70
SC5 RMLe 14.17 14.17 70 70 4_197111 4.197111 1.032224 1.032224 3715.35 3715.35
SC5 ROAD 67.69 67.69 86. 86 1.643508 1.643508 2.088793 2.088793 35911.53 35911.53
SC5 RVH 69.67 69.67 80 . 80 2.524122 2.524122 1.625402 1.625402 2876211 28762:11
SC5 RVHe 14.29 14.29 81 81 2.370152 2.370152 1.696866 1.696866 6160.55 6160.55
SC5 RVL 2.83 2.83 58 58 7.283408 7.283408 0.447654 0.447654 322.28 322:28
S.C5 RVLe 15.48 15.48 67 67 4.824928 4.824928 0.873145 0.873145 3432.34 3432.34
SC5 WAT 0.39 0.39 98 98 0.204082 0.204082 3.266471 3.266471 320.07 320:07
SC5 W ET 0.00 0.00 0:00 0.00
area in hectares
9-5

Sub- Land No Build CN No CN S fact-No S fact- Q(in) no Q(in) No Build
watershed Use Ha Build Ha Build Build build build build build m^3 Build m^3
SC6 COM 90.54 111.24 90 90 1.112002 1.076715 2.447297 2.473756 56281.93 69898.82.
SC6 COMe 23.73 23.73 91 91 1.004443 1.004443 2.529104 2.529104 15242.80 15242.80
SC6 FOR 19.23 19.20 76 76 3.198336 3.195907 1.35038 1.351272 6595.71 6590.13
SC6 OFF 0.00 0:00 0.00 0.00
SC6 OFFe 28.41 28.41 84 84 1.945732 1.945732 1,913823 1.913823 13810.56 13810.56
SC6 OPN 16.02 15.65 77 77 3.063127 3.048569 1.401047 1.406827 5701.50 5592.78
SC6 RHH 17.55 17.55 76 76 3.158893 3.158893 1.364947 1.364947 6085.53 6085.53
SC6. RHHe 28.54 28.54 76 76 3.171232 3.171232 1.360371 1.360371 9860.00 9860.00
SC6 RLL 302.51 274.06 71 71 4.055153 4.054857 1.072127 1.072212 82380.43 74639.06
SC6 RLLe 2.63 2.63 67 67 4.817655 4.817655 0.874839 0.874839 584.35 584.35
SC6 RMH 4.83 4.83 75 75 3.322078 3.322078 1.305778 1.305778 1603.18 1603.11
SC6 RMHe 31.84 31.84 73 73 3.696248 3.696248 1.180385 1.180385 9544.93 9544.93
SC6 RML 0.00 0.00 0.00 0.00
SC6 RMLe 9.30 9.30 71 71 4.111925 4.111925 1.055981 1.055981 2493.65 . 2493.65
SC6 ROAD 61A5 69.19 86 86 1.598245 1.582341 2.116654 2.126552 32821.41 37373.37
SC6 RVH 36.16 36.16 79 79 2.581715 2.581715 1.599571 1.599571 14693.23 14693.23
SC6 RVHe 29.55 29.55 79 79 2.645312 2.645312 1.571595 1.571595 11795.66 11795.66
SC6 RVL 0.00 0.00 0.00 0.00
SC6 RVLe 7.00 7.00 70 70 4:372529 4.372529 0.985024 0.985024 1750.53 1750.53
SC6 WAT 0.00 0.00 0.00 0.00
SC6 W ET 0.00 0.00 0.00 0.00
SC7 COM 13.55 13.55 91 91 0.975238 0.975238 2.551922 2.551922 8780.89 8780.89
SC7 COMe 6.40 6.40 89 89 1.250831 1.250831 2.346636 2.346636 3813.90 3813.90 -
SC7 FOR 108.52 108.52 76 76 3.219126 3.219126 1.342771 1.342771 37012.69 37012.69
SC7 OFF 0.00 0.00 90 90 1.111111 1.111111 2.447961 2.447961 0.27 0.27
SC7 OFFe 0.77 0.77 89 89 1.280963 1.280963 2.325485 2.325485 452.13 452.13
SC7 OPN 4.49 4.49 69 69 4.412161 4.412161 0.974669 0.974669 1112.30 1112.30
SC7 RHH 2.01 2:01 76 76 3.118114 3.118114 1.380191 1.380191 704.33 704.33
SC7 RHHe 8.01 8.01 76 76 3.234083 3.234083 1.337325 1.337325 2719.53 2719.53
SC7 RLL 249.78 249.78 70 70 4.372716 4.372716 0.984975 0.984975 62492.17 62492.17
SC7 RLLe 5.97 5.97 76 76 3.220198 3.220198 1.342379 1.342379 2037.05 2037.05
SC7 RMH 144.58 144.58 74 74 3.5829Y4 3.582914 1.216935 1.216935 44688.58 44688.58
SC7 RMHe 5.14 5.14 68 68 4.663319 4.663319 0.911565 0.911565 1189.59 1189.59
SC7 RML 0.00 0.00 0.00 0.00
SC7 RMLe 3.36 3.36 77 77 2.999994 2.999944 1.425445 1.425445 1215.86 1215.86
SC7 ROAD 28.56 28.56 87 87 1.534111 1.534111 2.15692 2.15692 15646.31 15646.31
SC7 RVH 11.89 11.89 79 79 2.730345 2.730345 1.53506 1.53506 4635.61 4635.61
SC7 RVHe 0.31 0.31 80 80 2.495293 2.495293 1.638513 1.638513 130.04 130.04
SC7 RVL 0.00 0.00 0.00 0.00
SC7 RVLe 25.24 25.24 74 74 3.422875 3.422875 1,270638 1.270638 8146.19 8146.19
SC7 WAT 0.00 0.00 0.00 0.00
SC7 W ET 0:00 0.00 0.00 0.00
SC8 COM 0.24 0.24 93 93 0.748353 0.748353 2.738614 2.738614 165.82 165.82
SC8 COMe 14.37 14.37 89 89 1.174249 1.174249 2.401498 2.401498 8767.98 8767.98
SCS FOR 140.44 140.44 75 75 3.403294 .3.403294 1.277382 1.277382 45565.55 45565.55
SCS OFF 0.00 0.00 . 0.00 0.00
SC8 OFFe 10.07 10.07 84 84 1.940524 1.940524 1.916684 1.916684 4900.86 4900.86.
SCS OPN 72.38 72.38 65 65 5.402399 5.402399 0.74842 0.74842 13759.32 13759.32
SC8 RHH 11.22 11.22 73 73 3.671268 3.671268 1.188339 1.188339 3386.61 . 3386.61
SC8 RHHe 53.96 53.96 72 72 3.797251 3.797251 1.148798 1.148798 15745.38 15745.38.
SC8 RLL 337.66 337.66 66 66 5.244934 5244934 0.780601 0.780601 66948.85 66948.85
SCS RLLe 0.00 0.00 0.00 0.00
SCS RMH. 39.70 39.70 60 60 6.529118 6.529118 0.551903 0.551903 5565.76 5565.76
SC8 RMHe 24.01 24.01 69. 69 4.52494. 4.52494 0.945805 0.945805 5769.01 5769.01 .
SC8 RML 0.00 0.00 0.00 0.00
SC8 RMLe 6.12 6.12 66 66 5.145662 5.145662 0.801571 0.801571 1245.87 1245.87
SC8 ROAD 74.31 74.31 85 85 1.737739 1.737739 2.032222 2.032222 38358.07 38358.07
SC8 RVH 119.01 119.01 79 79 2.684986 2.684986 1.554427 1.554427 46988.26 46988.26
SCS RVHe 51.22 51.22 78 78 2.808804 2.808804 1.502207 1.502207 19541.78 19541.78
SC8 RVL 0.00 0.00 � 0.00 0.00
SC8 RVLe 13.21 13.21 . 66 66 .5.255071 5.255071 0.77849 0.77849 . 2612.40 2612.40
SC8 WAT 0.00 0.00 0.00 0:00
SC8 WET 0.00 0.00 0.00 0.00 .
area in hectares
9-6

Sub- Land No Build CN No CN S fact-No S fact- (� (in) no Q(in) No Build
watershed Use Ha Build Ha Build Build build build build build m^3 Build m^3
UA1 COM 12.80 10.40 90 90 1.051553 1.07054 2.492847 2.478424 8103.43 6546.13
UA1 COMe 0.41 0.41 94 94 0.638298 0.638298 2.835628 2.835628 292.64 292.64
UA1 FOR 132.20 132.20 66 66 5.053018 5.053018 0.821633 0.821633 27589.88 27589.88
UA1 OFF 117.99 106.10 86 86 1.645819 1.66889 2.087383 2.073367 62560.44 55876.98
UA1 OFFe 0.16 0.16 87 87 1.494253 1.494253 2.182424 2.182424 87.25 87.25
UA1 OPN 34.14 34.14 70 70 4.270823 4.270823 1.012114 1.012114 8776:56 8776.56
UA1 RHH 0:00 0.00 0.00 0.00
UA1 RHMe 3.16 3.16 73 73 3:760487 3.760487 1.16019 1.16019 932.28 932.28
UA1 RLL 22.95 22.95 70 70 4282549 4.282549 1.008952 1.008952 5881.73 5881.73
UA1 RLLe 3.55 3.55 76 76 3.176857 3.176857 1.358291 1.358291 1223.11 1223.11
UA1 RMH 1.38 1.38 70 70 4.204773 4.204773 1.030115 1.030115 361.99 361.91
UA1 RMHe 10.08 10.08 67 67 4.93524 4.93524 0.847847 0.847847 2171.66 2171.66
UA1 RML 0.89 0.89 76 76 3.146577 3.146577 1.369531 1.369531 309.22 309.22
UA1 RMLe 5.72 5.72 72 72 3.931799 3.931799 1.108105 1.108105 1608.98 1608.98
UA1 ROAD 18.96 33.25 86 87 1.577914 1.42956 2.129317 2.224622 10255.06 18790.13
UA1 RVH 194.85 194.85 81 81 2.31008 2.31008 1.725736 1.725736 85408.20 85408.20
UA1 RVHe 0.07 0:07 88 88 1.363636 1.363636 2.268677 2.268677 39.61 39.61
UA1 RVL 167.69 167.69 68 68 4.782296 4.782296 0.883121 0.883121 37615.40 37615.40
UA1 RVLe 8.21 8.21 69 69 4.424112 4.424112 0.971569 0.971569 2026.47 2026.47
UA1 WAT 0.00 0.00 0.00 0.00
UA1 WET 0.00 0.00 0.00 0.00
UA2 COM 115.98 110.83 92 92 0.906053 0.908321 2.607047 2.605215 76797.77 73336.44
UA2 COMe 25.54 23.80 92 92 0.922785 0.891977 2.593575 2.618451 16823.66 15830.82
UA2 FOR 114.99 114.99 65 65 5.49585 5.49585 0.729925 0.729925 21319.71 21319.71
UA2 OFF 0.00 0.00 0.00 0.00
UA2 OFFe 0.00 0.00 0.00 0.00
UA2 OPN 30.20 30.20 75 75 3.256403 3.256403 1.329245 1.329245 10197.76 10197.76
UA2 RHH 0.00 0.00 0.00 0.00
UA2 RHHe 0.43 0.43 77 77 2.978305 2.978305 1.433911 1.433911 156.30 156.30
UA2 RLL 90.17 90.17 69 69 4.438016 4.438016 0.967974. 0.967974 22170.16 22170.16
UA2 RLLe 0.63 0.63 69 69 4.482409 4.482409 0.956587 0.956587 151.90 151.90
UA2 RMH 0.00 0.00 0.00 0.00
UA2 RMHe 1.53 1.53 70 70 4.327073 4.326871 0.997038 0.997092 387.78 387.67
UA2 RML 0.00 0.00 0.00 0.00
UA2 RMLe 2.54 2.54 71 71 4.044873 4.044873 1.075078 1.075078 694.83 694.83
UA2 ROAD 16.87 23.76 88 87 1.391153 1.476517 2.250156 2.193893 9644.51 13240.11
UA2 RVH 309.81 309.81 81 81 2.282395 2.282395 1.739235 1.739235 136865.27 13686527
UA2 RVHe 0.00 0.00 . 0.00 0.00
UA2 RVL 0.00 0.00 0.00 0.00
UA2 RVLe 4.15 4.15 73 73 3.71049 3.71049 1.175875 1.175875 1238.99 1238.99
UA2 WAT 0.00 0.00 0.00 0.00
UA2 W ET 0:00 0.00 0.00 0.00
UA3 COM 0.00 0.00 0.00 0.00
UA3 COMe 7.22 7.22 88 88 1.315112 1.315112 2.301805 2.301805 4219.08 4219.08
UA3 FOR 112.90 112.90 " 68 68 4.799291 4.799291 0.879131 0.879131 25210.27 25210.27
UA3 OFF 3.34 3.34 84 84 1.964343 1.964343 1.903641 1.903641 _ 1615.02 1615.02
UA3 OFFe 1.42 1.42 84 84 1.926935 1.926935 1.924174 1.924174 692.17 692:17
UA3 OPN 11.50 11.50 70 70 4.257612 4.257612 1.015688 1.015688 2966.69 2966.69
UA3 RHH 0.40 0.40 79 79 2.647789 2.647789 1.570517 1.570517 160.79 160.79
UA3 RHHe 9.57 9.57 74 74 3.599298 3.599298 1.211577 1.211577 2945.95 2945.95
UA3 RLL 525.04 525.04 70 70 4.230231 4.230231 1.023138 1.023138 136446.96 136446.96
UA3 RLLe 4.59 4.59 72 72 3.947554 3.947554 1.10344 1.10344 1286.48 1286.48
GA3 RMH 16.22 16.22 73 73 3.785469 3.785469 1.152436 1.152436 4748.14 4748.14
UA3 RMHe 32.72 32.72 70 70 4.381608 4.381608 0.982642 0.982642 8167.19 8167.19
UA3 RML 1.60 1.60 74 74 3.57134 3.57134 1.220735 1.220735 496.25 496.25
UA3 RMLe 4.20 4.20 74 74 3.517879 3.517879 1.238456 1.238456 1322.19 1322.19
UA3 ROAD 31.91 31.91 86 86 1.568354 1.568354 2.135304 2.135304 17305.22 17305.22
UA3 RVH 9.05 9.05 79 79 2.638764 2.638764 1.574449 1.574449 3619.56 3619.56
UA3 RVHe 0.61 0.61 82 82 2.248976 2.248976 1.755696 1.755696 271.26 271.26
UA3 RVL 360.22 360.22 66 66 5.091421 5.091421 0.813258 0.813258 74410.71 74410.71
UA$ RVLe 5.61 5.61 72 72 3.797062 3.797062 1.148856 1.148856 1637.67 1637.67
UA3 WAT 2.33 2.33 98 98 0.204082 0.204082 3.266471 3.266471 1931.74 1931.74
UA3 W ET 14.73 14.73 80 80 2.499017 2.499017 1.636812 1.636812 6122.56 6122.56
area in hectares
9-7
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, L
f

Sub- Land No Build . CN No CN S fact-No S fact-. Q(in) no Q(in) No Build
watershed Use Ha Build Ha Build Build build build build build m^3 Build m^3
UB1 COM 0.00 0.00 0.00 0:00
UB1 COMe 0.30 0.30 92 92 0.822137 0.822137 2.676004 2:676004 203.19 203.19
UB1 FOR 16.18 16.18 60 60 6.747412 6.747412 0.519753 0.519753 2135.60 2135.60
UB1 OFF 0.00 0.00 0.00 0.00
UB1 OFFe 1.27 1.27 85 85 1.705684 1.705684 2.051253 2.051253 662.00 662.00
U61 OPN 8.67 8.67 64 64 5.509521 5.509521 0.727256 0.727256 1601:94 1601.94
UB1 RHH 0.00 0.00 0.00 0.00
U61 RHHe 1.48 1.48 75 75 3.359636 3.359636 1.292562 1.292562 484.67 . 484.67
U61 RLL 1.25 1.25 77 77 2.987013 2.987013 1.430497 1.430497 453.44 453.44
U61 RLLe . 3.38 3.38 75 75 3.382577 3.382577 1.284561 .1.284561 1102.71 1102.71
UB1 RMH 0.32 0.32 66 66 5.068002 5.068002 0.818355 0.818355 . 67.47 67.47
UB1 RMHe 5.79 5.79 69 69 4.584138 4.584138 0.931002 0.931002 1368.52 1368.52
UB1 RML 0.03 0.03 77 77 2.987013 2.987013 1.430497 1.430497 9.96 9.96
UB1 RMLe 2.30 2.30 69 69 4.582192 4.582192 0.931485 0.931485 543.98 543.98
UB1 ROAD 12.15 12.15 86 86 1.623269 1.623269 2.101194 2.101194 6483.57 6483.57
UB1 RVH 0.00 0.00 0.00 0.00
UB1 RVHe 0.53 0.53 82. 82 2.244236 2.244236 1.758045 1.758045 237.47 237.47
UB1 RVL 408.41 408.41 66 66 5.06974 5.06974 0.817976 0.817976 84853.66 84853.66
UB1 RVLe 6.54 6.54 65 65 5.371833 5.371833 0.754565 0.754565 1254.10 1254.10
UB1 WAT 2.25 2.25 98 98.0.204082 0.204082 3.266471 3.266471 . 1867.03 1867.03
UB1 WET 4.31 4.31 72 72 3.800309 3.800309 1.147856 1.147856 1257.21 1257.21
UC1 COM 0.00 0.00 0:00 0.00
UC1 COMe 13.56 13.56 93 93 0.717841 0.717841 2.765066 2.765066 9522.61 9522.61
UC1 FOR 29.50 29.50 64 64 5.623157 5.623157 0.705427 0.705427 5286.54 5286.54
UC1. OFF 0.00 0.00 0.00 0.00
UC1 OFFe 0.00 0.00 0.00 0.00
UC1 OPN 1.7.90 17.90 70 70 4.238955 4.238955 1.020758 1.020758 4640.74 4640.74
UC1 RHH 0.00 0.00 0.00 0.00
UC1 RHHe 3.43 3.43 73 73 3.715077 3.715077 1.174427 1.174427 1023.44 1023.44
UC1 RLL 82.22 82.22 74 74 3.534434 3.534434 1.232939 1.232939 25747.83 25747.83
UC1 RLLe 2.06 2.06 76 76 3.165477 3.165477 1.362503 1.362503 713.16 713.16
UC1 RMH 0.00 0.00 0.00 0.00
UC1 RMHe 15.06 15.06 75 75 3.304695 3.304695 1.311945 1.311945 . 5017.82 5017.82
UC1 RML 1.78 1.78 76 . 76 3.114686 3.114686 1.381482 1.381482 624.02 624.02.
UC1 RMLe 5.09 5.09 76 76 3.169346 3.169346 1.36107 1.36107 1761.39 1761.39
UC1 ROAD 13.85 13.85 87 87 1.54619 1.54619 2.149265 2.149265 7563.36 7563.36
UC1 RVH 0.00 0.00 0.00 0.00
UC1 RVHe 0.00 0.00 0.00 0.00
UC1 RVL 630.55 630.55 66 66 5.191458 5.191458 0.79183 0.79183 126819.64 126819.64
UC1 RVLe 18.99 18.99 72 72 3.94369 3.94369 1.104582 1.104582 5328.67 5328.67
UC1 WAT 0.00 0.00 0.00 0.00
UC1 WET 0.00 0.00 0.00 0.00
UD1 COM 0.00 0.00 0.00 0.00
UD1 COMe 0.00 0.00 0.00 0.00
UD1 FOR 1.48. 1.48 64 64 5.635523 5.635523 0.703089 0.703089 265.13 265.13
UD1 OFF 0.00 0.00 0.00 0.00
UD1 OFFe 0.00 0.00 0.00 0.00
UD1 OPN 14.41 14.41 59 59 7.054269 7.054269 0.477342 0.477342 1747.13 1747.13
UD1 RHH 0.20 -0.20 70 70 4.285714 4.285714 1.0081 1.0081 50.03 � 50.03
UD1 RHHe 0.75 0.75 71 71 4.033424 4.033424 1.078375 1.078375 206.74 206.74
UD1 RLL 1.51 1.51 74 74 3.45545 3.45545 1.259502 1.259502 482.90 482.90
UD1 RLLe 2.26 226 66 66 5.190693 5.190693 0.791992 0.791992 453.84 453.84
UD1 RMH 1.78 1.78 67 67 4.925373 4.925373 0.85008 0.85008 384.27 384.27
UD1 RMHe 7.97 7.97 67 67 4.847256 4.847256 0.867965 0.867965 1756.73 1756.73
UD1 RML 0.00 0.00 0.00 0.00
UD1 RMLe 3.33 3.33 66 66 5.041143 5.041143 0.824239 0.824239 696.37 696.37
UD1 ROAD 6.67 6.67 84 84 1.850855 1.850855 1.966764 1.966764 3330.72 3330.72
UD1 RVH 0.00 0.00 0.00 0.00'
UD1 RVHe 0.01 0.01 84 84 1.907346 1.907346 1.935033 1.935033 7.12 7.12
UD1, RVL .206.62 206.62 64 64 5.73179T 5.731797 0.685136 0.685136 35956.50 35956.50
UD1 RVLe 12.53 12.53 62 62 6.124392 6.124392 0.616247 0.616247 1961.25 1961.25
UD1 WAT 3.93 3.93 98 98 0.204082 0.204082 3.266471 3.266471 3257.24 3257:24
UD1 WET 0.00 0.00 0.00 0.00
area in hectares -
9-8

Sub- Land No Build CN No CN S fact-No S fact- Q(in) no Q(in) No Build
watershed Use Ha Build Ha Build Build build build build build m^3 Build m"3
UE1 COM 0.00 16.27 89 1.264315 3.5 2.337141 0.00 9659:70
UE1 COMe 6.74 6.74 91 91 1.00068 1.00068 2.532029 2.532029 4337.73 4337.73
UE1 FOR 17.92 17.92 72 72 3.964769 3.964769 1.098367 1.098367 5000.81 5000.81
UE1 OFF 0.00 0.00 0.00 0.00
UE1 OFFe 0.65 0.65 81 81 2.345679 2.345679 1.708558 1.708558 280.19 280.19
UE1 OPN 14.97 14.97 65 65 5.368887 5.368887 0.75516 0.75516 2871.16 2871.16
UE1 RHH 0.15 0.15 70 70 4.285714 4.285714 1.0081 1.0081 39.62 39.62
UE1 RHHe 0.72 0.72 71 71 4.178427 4.178427 1.037387 1.037387 189.03 189.03
UE1 RLL 426.96 310.48 73 73 3.722031 3.646384 1.172235 1.196319 127127.62 94342.93
UE1 RLLe 1.86 1.86 70 70 4.23873 4.23873 1.02082 1.02082 482.50 482.50
UE1 RMH 5.79 5.79 68 68 4.799424 4.799424 0.8791 0.8791 1292.19 1292.19
UE1 RMHe 11.66 11.66 68 68 4.741608 4.741608 0.892747 0:892747 2643.90 2643.90
UE1 RML 2.82 97:59 70 73 4.221308 3.701291 1.025578 1.178786 734.19 29220.53
UE1 RMLe 6.86 6.86 70 70 4.208452 4.208452 1.029104 1.029104 1793.08 1793.08
UE1 ROAD 16.53 21.97 86 86 1.64767 1,648471 2.086254 2.085766 8758.32 11638.79
UE1 RVH 0.00 0.00 0.00 0.00
UE1 RVHe 0.25 0.25 82 82 2.20096 2.20096 1.779669 1.779669 113.55 113.55
UE1 RVL 361.87 361.87 69 69 4.433242 4.433242 0.969207 0.969207 89083.76 89083.76
UE1 RVLe 24.41 24.41 67 67 4.940123 4.940123 0.846744 0.846744 5249.98 5249.98
UE1 WAT 0.27 0.27 98 98 0.204082 0.204082 3.266471 3.266471 225.20 225.20
UE1 WET 0.00 0.00 0.00 0.00
UF1 COM 123.06 132.63 93 93 0.793657 0.784286. 2.699946 2.707885 84391.03 91225.96
UF1 COMe 4.40 4.40 92 92 0.813558 0.813558 2.683187 2.683187 2996.18 2996.18
UF1 FOR 6.88 6.88 68 68 4.798755 4.798755 0.879256 0.879256 1535.80 1535.80
UF1 OFF 0.00 0.00 0.00 0.00
UF1 OFFe 4.26 4.26 88 88 1.413581 1.413581 2.235201 2.235201 2420.83 2420.83
UF1 OPN 41.59 41.59 70 70 4.188802 4.188802 1.034517 1.034517 10928.16 10928.16
UF1 RHH 3.38 180.81 76 74 3.115529 3.484534 1.381964 1.24965 1185.45 57390.53
UF1 RHHe 3.90 3.90 67 67 4.991434 4.991434 0.835239 0.835239 828.25 828.25
UF1 RLL 540.43 289.41 69 67 4.483223 4.825597 0.95638 0.87299 131280.98 64172.84
UF1 RLLe 2.80 2.80 71 71 4.044056 4.044056 1.075313 1.075313 765.07 765.07
UF1 RMH 1.87 1.87 63 63 5.834912 5.834912 0.666383 0.666383 316.59 316.59
UF1 RMHe 21.45 21.45 61 61 6.396341 6.396341 0.572312 0.572312 3117.68 3117.68
UF1 RML 0.00 0.00 0.00 0.00
UF1 RMLe 7.64 7.23 68 67 4.754851 4.830452 0.889603 0.871861 1725.47 1602.15
UF1 ROAD 27.00 42.59 85 86 1.708255 1.602164 2.049718 2.114223 14055.15 22874.03
UF1 RVH 35.57 84.39 82 82 2.236614 2.212651 1.761831 1.773797 15916.77 38019.88
UF1 RVHe 0.84 0.84 88 88 1.409646 1.409646 2237816 2.237816 478.55 478.55
UF1 RVL 48.62 48.62 64 64 5.648416 5.648416 0.70066 0.70066 8652.62 8652.62
UF1 RVLe 3.74 3.74 61 61 6.438536 6.438536 0.565754 0.565754 536.96 536.96
UF1 WAT 0.00 0.00 0.00 0.00
UF1 WET 0.00 0.00 0.00 0.00
UF2 COM 0.00 4.63 0 89 1.173318 3.5 2.402174 0.00 2822.71
UF2 COMe 4.75 3.16 93 92 0.810178 0.844623 2.686023 2.657295 3241.96 2130.80
UF2 FOR 63.85 63.85 69 69 4.512414 4.512414 0.948968 0.948968 15391.47 15391.47
UF2 OFF 0.00 0.00 86 86 1.683969 1.683969 2.064269 2:064269 0.51 0.51
UF2 OFFe 1.85 1.85 85 85 1.784998 1.784998 2.004557 2.004557 939.92 939.92
UF2 OPN 38.45 38.16 71 71 4.100186 4.08497 1.059298 1.063615 10344.96 10309.43
UF2 RHH 0.34 0.34 70 70 4.285714 4.285714 1.0081 1.0081 85.93 85.93
UF2 RHHe 5.95 5.95 74 74 3.433098 3.433098 1.267131 1.267131 1915.75 1915.75
UF2 RLL 657.84 542.63 70 70 4.24277 4.26124 1.019719 1.014705 170386.80 139854.20
UF2 RLLe 3.74 3.74 72 72 3.924887 3.924887 1.110158 1.110158 1054.70 1054.70
UF2 RMH 1.57 1.57 70 70 4.26727 4.267545 1.013074 1.012999 402.85 402.77
UF2 RMHe 13.59 13.36 70 70 4.218024 4.234418 1.026477 1.021995 3542.21 3467.28
UF2 RML 0.00 96.32 0 70 4.206096 3.5 1.029751 0.00 25192.14
UF2 RMLe 5.04 4.67 72 72 3.885154 3.874665 1.122037 1.125196 1436.89 1333.60
UF2 ROAD 26.78 44.08 86 87 1.614877 1.54555 2.106363 2.149669 14328.95 24070.68
UF2 RVH 0.00 0.02 0 82 2.195122 3.5 1.78261 0.00 9.33
UF2 RVHe 0.33 0:33 81 81 2.284206 2.284206 1.738348 1.738348 144.38 144.38
UF2 RVL 249.75 249.75 67 67 4.86904 4.86904 0.862941 0.862941 54741.06 54741.06
UF2 RVLe 9.47 8.9'I 72 72 3.809246 3.901262 1.145107 1.117205 2755.88 2528.91
UF2 WAT 1.14 1.14 98 98 0.204082 0.204082 3.266471 3.266471 949.18 949.18
UF2. WET 0.00 0.00 0.00 0.00
area in hectares
9-9