19940203 Ver 1_Complete File_19950613

COMPENSATORY MITIGATION PLAN
N.C. DEPARTMENT OF TRANSPORTATION
US 17 WIDENING, EDENTON TO HERTFORD
TRAFFIC IMPROVEMENT PROJECT (TIP): R-2208A
CHOWAN AND PERQUIMANS COUNTIES, NORTH CAROLINA
Prepared for:
The North Carolina Department of Transportation
Raleigh, North Carolina
Prepared by:
Environmental Services, Inc.
1318 Dale Street, Suite 220
Raleigh, North Carolina 27605
APRIL 1995

State of North Carolina
Department of Environment,
Health and Natural Resources r4**A
Division of Environmental Management
James B. Hunt, Jr., Governor
E H N
Jonathan B. Howes, , Secretary
A. Preston Howard, Jr., P.E., Director
June 13, 1995
Mr. H. Franklin Vick, P.E., Manager
Planning and Environmental Branch
NCDOT-Division of Highways
P.O. Box 25201
Raleigh, NC 27611-5201
Dear Mr. Vick:
Subject: Certification for U.S. 17 Widening, Edenton to Hertford
DEM Project # 94203, TIP # R-2208A
Chowan and Perquimans Counties
The purpose of this letter is to clarify Condition 2 of Water Quality Certification # 2998
which was issued for the subject project on May 25, 1995. The intent of Condition 2 was to
acknowledge that there are sufficient credits in the proposed Dismal Swamp Mitigation Bank as
described in the mitigation proposal dated April, 1995 to compensate for the loss of 21.76 acres
of wetlands impact associated with the subject project. The Division has not made a
determination of the number of credits that exist in the proposed bank nor the number of credits
that will be debited for the subject project. The Division will submit comments on the mitigation
proposal by June 23, 1995. The determination of the number of credits in the bank and the
number or credits to be debited for the subject project will be coordinated with the U.S. Army
Corps of Engineers and other review agencies.
If you have any questions concerning this matter please contact Mr. Ron Ferrell at 919-
733-0026.
Sincerely,
Jo .ney
cc: Ron Ferrell
Gordon Cashion
Corps of Engineers, Washington Field Office
P.O. Box 29535, Raleigh, North Carolina 27626-0535 Telephone [phone] FAX [phone]
An Equal Opportunity Affirmative Action Employer 50% recycled/ 10% post-consumer paper
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Jun 95 9 P. 02'x`02

NORTH CAROLINA
Perguimans, Hertford and Chowan Counties
CERTIFICATION
THIS CERTIFICATION is issued in conformity with the requirements of Section 401
Public Laws 92-500 and 95-217 of the United States and subject to the North -Carolina Division of
Environmental Management Regulations in 15 NCAC 2H, Section .0500 to N.C. Department of
Transportation resulting in 21.76 acres of wetland impact pursuant to an application filed on the 3rd
day of March, 1994 and 15 May 1995 to widen US 17 from Hertford to Edenton. The Application
provides adequate assurance that the discharge of fill material into the waters of Burnt Mill. Bethel
and Raccoon Creeks in conjunction with the proposed road improvement will not result in a violation
of applicable Water Quality Standards and discharge guidelines. Therefore, the State of North
Carolina certifies that this activity will not violate Sections 301, 302, 303, 306, 307 of PL 9?-S00 and
PL 95-217 if conducted in accordance with the application and conditions hereinafter set forth.
Condition(s) of Certification:
That the activity be conducted in such a manner as to prevent significant
increase in turbidity outside the area of construction or construction related
discharge (SO NTUs in streams and rivers not designated as trout waters by
DEM; 25 NTUs in all saltwater classes, and all lakes and reservoirs; 10 NTUs
in trout waters).
2_ Compensatory mitigation for impacts to these wetlands will be accomplished
by the restoration or approximately 483 acres of prior converted wetlands as
described in the draft compensatory mitigation plan for the Dismal Swamp
Mitigation site in Gates and Perquimans Counties dated April 1995 and as
amended in the final plan. The final plan, as-built reports and all monitoring
reports shall be submitted in duplicate to the Division of Environmental
Management at the time of submittal to the US Army Corps of Engineers.
Violations of any condition herein set forth shall result in revocation of this Certification. This
Certification shall become null and void unless the above conditions are made conditions of the
Federal 404 and/or Coastal Area Management Act Permit. This Certification shall expire upon
expiration of the 404 or CAMA permit.
If this Certification is unacceptable to you, you have the right to an adjudicatory hearing upon
written request within sixty (60) days following receipt of this Certification. This request must be in
the form of a written petition conforming to Chapter 150B of the North Carolina General Statutes and
filed with the Office of Administrative Hearings, P.O. Box 27447, Raleigh, N.C. 27611-7447. Unless
such demands are made, this Certification shall be final and binding.
This the 25th day of May, 1995.
ONMENTAL MANAGEMENT
WQC# 2998
NC DELI WO ENVSCI Fax: 919-X15:;-99 9 Jun r '95 9:6-) F. u1/U2
State of North Carolina
Department of Environment,
Health and Natural Resources / • •
Division of Environmental Management
James B. Hunt, Jr., Governor p
Jonathan B. Howes, Secretary F1.
A. Preston Howard, Jr., P.E., Director
Mr. Barney O'Quinn
Planning and Environmental Branch
N.C. Department of Transportation
P.O. BOX 25201
Raleigh, N.C. 27611-5201
May 25, 1995
Post-it' Fax Note 7671 Date Ipages
To ? From
Co.roePC. Ca.
Phone x Phone n -7
Fax it Fax 8
Dear Mr. O'Quinn:
Subject: Certification Pursuant to Section 401 of the Federal
Clean Water Act,
Proposed widening of US 17 from Hertford to Edenton
project # 94203, COE # 199401492, TIP # R-2209A, State Project No.
6.039001T
Perquimans, Hertford and Chowan Counties
Attached hereto is a copy of Certification No. 2998 issued to N.C. Department of
Transportation dated 25 May 1995.
If we can be of further assistance, do not hesitate to contact us.
Attachments
2998.1tr
Sin re ,
eston Howard, Jr.
cc: Wilmington District Corps of Engineers
Corps of Engineers Washington Field Office
Washington DEM Regional Office
Mr. John Dorney
Mr. John Parker, Division of Coastal Management
Central Files
P.O. Box 29535, Rdelgh, North Carolina 27626-0535 Telephone [phone] FAX [phone]
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STATE OF NORTH CAROLINA
DEPARTMENT OF TRANSPORTATION
JAMES B. HUNT, JR. DIVISION OF HIGHWAYS
GOVERNOR P.O. BOX 25201, RALEIGH. N.C. 27611-5201
April 24, 1995
Dr. G. Wayne Wright
Chief, Regulatory Branch
Department of the Army
Wilmington District, Corps of Engineers
Post Office Box 1890
Wilmington, North Carolina 28402-1890
Dear Dr. Wright:
R. SAMUEL HUNT III
SECRETARY
SUBJECT: Dismal Swamp Mitigation Site, Gates and Perquimans Counties, TIP No.
R-2208A, State Project No. 6.039001T, Widening of U. S. 17, from
Hertford to Edenton, Perquimans and Chowan Counties.
Please find enclosed three copies of the Wetland Mitigation Plan for the Dismal
Swamp Mitigation Site in Gates and Perquimans Counties. This document, which is
contained in a loose-leaf binder, was prepared by for the North Carolina Department of
Transportation by our consultant, Environmental Services, Inc.
We are submitting this document to outline our plans for compehsatory mitigation
for R-2208A, and are proposing that the impacts from R-2208A be debited from the
Dismal Swamp Site. Remaining credits in the Dismal Swamp Site are anticipated as "up-
front" mitigation for future projects. R-2208A will impact 2.9 acres of riverine wetlands
and 8.8 acres of nonriverine/interstream wetlands. In addition, there will be impacts
caused by the effects of associated ditches in wetlands adjacent to R-2208A. These latter
impacts are as yet unquantified; a separate report very near completion by Environmental
Services, Inc. will address these impacts and the acreage is proposed to also be debited
from the Dismal Swamp Site.
We request that a permit for R-2208A be issued at the earliest possible date on the
strength of our permit application of February 7, 1994, the enclosed Dismal Swamp
Mitigation Plan, and the NCDOT's commitment to debit appropriate acreage for all three
types of impacts described above.
9
l
2
Thank you for your assistance in reviewing the work that went into the
development of this plan.
Sincerely,,
H. Franklin Vick, P. E., Manager
Planning and Environmental Branch
HFV/ds
Enclosures (3)
cc: (with one copy of enclosure)
Mr. Mike Bell, COE
Mr. Lee Pelej, USEPA
Mr. David Cox, NCWRC
Mr. David Dell, USFWS
Mr. Ron Ferrell, NCDEHNR
Mr. Eric Galamb, NCDEHNR
Mr. Ron Sechler, NMFS
Mr. N. L. Graf, P. E., FHWA; Attn.: Mr. Roy Shelton
Mr. D. R. Morton, P. E., NCDOT, State Highway Engineer - Design
Mr. W. D. Johnson, P. E., NCDOT, State Roadside Environmental Engineer
Mr. A. L. Hankins, P. E., NCDOT, State Hydraulics Engineer

COMPENSATORY MITIGATION PLAN
N.C. DEPARTMENT OF TRANSPORTATION
US 17 WIDENING, EDENTON TO HERTFORD
TRAFFIC IMPROVEMENT PROJECT (TIP): R-2208A
CHOWAN AND PERQUIMANS COUNTIES, NORTH CAROLINA
Prepared for:
The North Carolina Department of Transportation
Raleigh, North Carolina
Prepared by:
Environmental Services, Inc.
1318 Dale Street, Suite 220
Raleigh, North Carolina 27605
APRIL 1995
11
TABLE OF CONTENTS
LIST OF FIGURES .................................................. iii
LIST OF TABLES .................................................. iii
EXECUTIVE SUMMARY ............................................. iv
1.0 INTRODUCTION ...............................................1
2.0 RATIONALE .................................................3
3.0 AFFECTED ENVIRONMENT .......................................4
3.1 Impacted Wetlands ........................................ 4
4.0 MITIGATION GUIDELINES ........................................ 9
4.1 Mitigation Policy ......................................... 9
4.2 Mitigation Sequencing .................................... 10
5.0 MITIGATION SITE .................... 11
5.1 Project Overview ........................................ 11
5.2 Dismal Swamp Mitigation Site History ......................... 11
5.3 Existing Conditions ....................................... 14
5.3.1 Physiography, Topography, and Land Use .................. 14
5.3.2 Soils ............................................14
5.3.3 Hydrogeology ..................................... 18
5.3.4 Plant Communities .................................. 19
5.3.5 Wildlife Communities ................................ 19
5.3.6 Jurisdictional Wetlands ............................... 20
6.0 MITIGATION PLAN ............................................ 22
6.1 Wetland Restoration Modeling ............................... 22
6.1.1 Hydrological Modeling ................................ 22
6.1.2 Reference Forest Ecosystem Modeling .................... 25
6.2 Wetland Restoration Methodology ............................ 30
6.2.1 Hydrological Restoration .............................. 30
6.2.2 Plant Community Restoration ........................... 32
6.2.3 Wetland Soil Restoration .............................. 41
TABLE OF CONTENTS
7.0 MONITORING PLAN ........................................... 43
7.1 Hydrology Monitoring ..................................... 43
7.2 Hydrology Success Criteria ................................. 43
7.3 Vegetation ............................................44
7.4 Vegetation Success Criteria ................................. 44
7.5 Report Submittal ........................................ 45
7.6 Contingency ...........................................45
8.0 MITIGATION CREDIT DETERMINATION ............................. 46
8.1 Wetland Functional Evaluations .............................. 46
8.2 Mitigation Credit Determination .............................. 52
9.0 DISPENSATION OF PROPERTY ................................... 54
10.0 REFERENCES CITED ...........................................55
11.0 APPENDIX
1.1 Hydrogeological Site Assessment for the Great Dismal
Swamp Mitigation Site ...................................... 46
LIST OF FIGURES
Figure 1 - Site Location Map ........................................... 2
Figure 2 - Dismal Swamp Mitigation Site in relation to the
Dismal Swamp National Wildlife Refuge ........................... 12
Figure 3 - Aerial Photograph, Dismal Swamp Mitigation Site .................... 13
Figure 4 - Natural Resource Conservation Service (NRCS)
Dismal Swamp Mitigation Site .................................. 15
Figure 5 - Hydric/Nonhydric Soil Boundaries ............................... 17
Figure 6 - Jurisdictional Wetlands, Jurisdictional Open Waters
and Prior Converted Farmland ..................:............... 21
Figure 7 - DRAINMOD - Estimated Percent of the Growing Season
Wetland Hydrology will Persist ................................. 26
Figure 8 - Estimated Riverine/Floodplain Restoration Area ...................... 33
Figure 9 - Conceptual Model of Target Community Patterns .................... 34
Figure 10 - Community Restoration Map Units ............................ 35
Figure 11 - Wetland Mitigation Design Units ............................... 47
LIST OF TABLES
Table 1 - Wetland Impacts by Type ...................................... 4
Table 2 - Results of DRAINMOD Simulations for Saturation within 12 inches of surface
for Selected Percentages of the Growing Season (Surface Storage = 10 cm) . 24
Table 3 - Reference Forest Ecosystems, Nonriverine Swamp Forest
Plots Summary (Canopy Species) ................................ 28
Table 4 - Inventory of Shrubs and Herbs in Reference Nonriverine Swamp Forests .... 29
Table 5 - Planting Regime - Dismal Swamp Mitigation Site ..................... 38
Table 6 - Expected Functions in Impacted Wetland Classes ..................... 48
COMPENSATORY MITIGATION PLAN
N.C. DEPARTMENT OF TRANSPORTATION
US 17 WIDENING, EDENTON TO HERTFORD
TRAFFIC IMPROVEMENT PROJECT (TIP): R-2208A
CHOWAN AND PERQUIMANS COUNTIES, NORTH CAROLINA
EXECUTIVE SUMMARY
The N.C. Department of Transportation (NCDOT) proposes widening of approximately 8.2
miles of US Highway 17 from immediately north of Edenton to south of Hertford, in Chowan
and Perquimans Counties, North Carolina. The current two-lane roadway will be widened into
a four-lane thoroughfare. Approximately 12 acres of palustrine forested wetlands may be
impacted by road widening. In addition, potential indirect impacts to wetlands associated with
planned ditch construction adjacent to the new roadway are currently being studied. If
wetland impacts are predicted from the ditch impact study, additional impact acreages will be
incorporated into this mitigation plan as a supplemental document.
A wetland restoration area within the Great Dismal Swamp complex of North Carolina has
been selected to provide compensatory mitigation for this project. The mitigation site
encompasses approximately 612 acres of farm and forest land approximately 1.2 miles east
of the town of Sandy Cross and SR 1002 (Folly Road) along the Gates County/Perquimans
County line. This mitigation site provides a contiguous restoration area that is connected to
an eve s Vw d ref fge d r# ?t t r ;• This document is targeted towards
outlining a plan for compensation of wetlands impacted as a result of construction. However,
additional mitigation credit' generated by the project will serve:as-an-NCD07 regional wetland
mitigation bank.
A number of wetland restoration studies and models were performed to ensure success in
wetland restoration efforts. Models include site hydrogeological modeling, generation of an
available water budget, reference forest ecosystem characterizations, analyses of soil-site
relations, and a subjective wetland functional assessment using hydrogeomorphic (HGM)
parameters (Brinson 1993, ESI 1994a, ESI 1994b). Hydrological restoration and community
restoration designs and procedures are outlined in detail with monitoring plans, success
criteria, and reporting programs clearly defined in order to promote wetland restoration
success.
IV
The Dismal Swamp bank site includes approximately 428:<acreFl of etland-,restofatior within
prior converted farmlands. Of this 428 acres, approximately 3,4,
,y will occur within a former floodplain area situated behind a large dike on the
property. The floodplain area to be restored comprises part of a historical stream corridor that
constitutes channelized upper reaches of the Perquimans River. An additionallom
-riverin4'A'inrad enhancement will be facilitated through restoration of overbank flooding
within forested wetlands on the mitigation site. Two upland ridges/knolls totaling
approximately 12 acres will also be restored to promote establishment of coastal fringe
sandhill forest communities. These upland restoration areas provide the opportunity to create
eland/wetla d ecotones whi C1 are con'sWe--wd, amo k',M-est-.div0se and p dive
2
ei i i lii a9 ',for wildlife (Brinson et a/. 1981). Other components of the mitigation plan
include the establishment of fsledwa>ffers adjacent to perimeter canals outside of
the mitigation property 4 res? 'and pne "'I anagement of forested remnants on the
acres).
Proposed improvements to the subject segment of US 17 (R-2208A) will impact approximately
12 acres of wetlands within the same wetland classes as the mitigation site. Based on the
mitigation strategy, modeling results, wetland functional evaluations, and current research, this
mitigation project will provide adequate compensatory mitigation credit for wetland impacts
associated with US 17 widening. Substantial mitigation credit remains from wetland
mitigation activities for projects in the region which impact wetlands of comparable function.
t-m-itisamiewn - it' credit -units for use as a. regional mitigation- bank-,will-.be determh- e`d' dtiting
deutlephitft1 "bf mitigation bank protocol and debiting procedures.

t N tlAw'LahQNF
3I4 _ ;LL?E*Anl'E

94 - L c veLk"'rt

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COMPENSATORY MITIGATION PLAN
N.C. DEPARTMENT OF TRANSPORTATION
US 17 WIDENING, EDENTON TO HERTFORD
TRAFFIC IMPROVEMENT PROJECT (TIP): R-2208A
CHOWAN AND PERQUIMANS COUNTIES, NORTH CAROLINA
1.0 INTRODUCTION
North Carolina General Assembly House Bill 399, ratified in 1989, provides for the
establishment of the North Carolina Highway Trust Fund. Portions of the Highway Trust Fund
are allocated to the intrastate system. This system was established to provided free-flowing,
safe inter-city travel for motorists, and to support statewide growth and development
objectives.
The General Assembly recognized the importance of US Highway 17 (hereafter US 17) to
travel and economic development along the coast of eastern North Carolina, and included this
route in the intrastate system. As part of the North Carolina Department of Transportation
(NCDOT) Intrastate Corridor Program, over 250 miles of a multi-laned US 17 will extend from
the South Carolina border to Virginia.
NCDOT proposes to widen an 8.2 mile segment of US 17 in Chowan and Perquimans County
from Business 17 north of Edenton to Business 17 south of Hertford (Figure 1). Proposed
improvements will be accomplished by constructing a new two-lane section immediately
adjacent to the existing roadway. The environmental impacts of this project were studied in
a State Environmental Assessment (dated 4/25/91) and a Finding of No Significant Impact
(dated 1/6/92). These documents evaluated several alternatives, including a no-build option,
widening to the north, widening to the south, and new location alternatives. Subsequently,
the preferred alternative was selected to avoid and minimize wetland impacts while ensuring
travel safety.
This report examines the wetland encroachment and mitigation strategy for dealing with
anticipated wetland losses associated with development of R-2208A. Information contained
in this report is intended to supplement and support NCDOT's Section 404 permit application
and request for 401 Water Quality Certification. The Section 404 permit application was
submitted on February 7, 1994. This mitigation plan outlines a method to replace wetland
functions lost as a result of road widening, through compensatory mitigation.
1
r Dismal Swamp L
Mitigation Site
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77 P\ a\
Environmental Site Location Figure: 1 ?' s
US 17 Edenton to Hertford,
Se Inr- (R-2208A), and
8ce Street
I Selected Mitigation Site Project: ER94018.7
IL Suite 220 Gates, Perquimans, and
Raleigh, NC 27605 Chowan Counties, NC
Date: 5 April 1995
7
2.0 RATIONALE
Section 404 of the Clean Water Act (CWA) requires regulation of discharges into "waters of
the United States." Although the principal administrative agency of the CWA is the U.S.
Environmental Protection Agency (EPA), the U.S. Army Corps of Engineers (COE) has major
responsibilities for implementation, permitting, and enforcement of provisions of the CWA.
The COE regulatory program is defined in 33 CFR 320-330.
Water bodies such as rivers, lakes, and streams are subject to jurisdictional consideration
under the Section 404 program. However, by regulation, wetlands are also considered
"waters of the United States" (33 CFR 328.3). Wetlands are described as:
those areas that are inundated or saturated by groundwater at a frequency and
duration sufficient to support, and that under normal circumstances do support, a
prevalence of vegetation typically adapted for life in saturated soil conditions.
Wetlands generally include swamps, marshes, bogs, and similar areas (33 CFR
328.3(b), (1986)).
The COE requires the presence of three parameters (hydrophytic vegetation, hydric soils, and
evidence of hydrology) in support of a jurisdictional determination (DOA 1987).
Wetlands within the project corridor were initially mapped and classified in the spring of 1990
by NCDOT personnel as part of the State Environmental Assessment process. Wetlands were
identified based upon parameters outlined in the "Federal Manual for Identifying - and
Delineating Jurisdictional Wetlands (89 Manual)"(FICWD 1989). Subsequently, wetlands were
revisited in 1992 by NCDOT personnel to conform jurisdictional mapping to wetland
parameters enumerated in the "Corps of Engineers Wetland Delineation Manual (87 Manual)"
(DOA 1987). Wetlands were classified using the U.S. Fish and Wildlife Service (USFWS)
manual, Classification of Wetlands and Deegwater Habitats of the United States" (Cowardin
et a/. 1979), and current trends in the classification system.
A Section 404 permit application for this project was submitted to the Wilmington District
Corps of Engineers on February 7, 1994. Design specifications and avoidance/minimization
issues were addressed in this permit application and in the State Environmental Assessment
(EA). Subsequently, this compensatory mitigation strategy has been developed to provide
compensation for impacts to unavoidable wetland resources.
3
3.0 AFFECTED ENVIRONMENT
3,1 Impacted Wetlands
Approximately 12 acres of wetlands may be directly impacted by US 17 widening. Potential
indirect impacts to wetlands associated with planned ditch construction adjacent to the new
roadway are currently being studied. If indirect wetland impacts are predicted from the ditch
impact analysis, additional impact acreages will be incorporated into this plan as a
supplemental document.
Wetland types within the project corridor have been grouped into riverine/bottomland wetlands
and nonriverine/interstream wetlands for descriptive purposes. Wetland types and associated
acreage within the construction limits are listed in Table 1.
TABLE 1: Wetland Impacts by Type
Palustrine forested Palustrine forested Palustrine forested
needle-leaved evergreen broad-leaved deciduous/ broad-leaved deciduous/
Wetland temporarily flooded (needle-leaved evergreen) (needle-leaved deciduous)
Type ditched and bedded temporarily flooded seasonally flooded TOTAL
PF04Ad PF01 A (PF01 /4A) PFO1 C (PFO1 /2C)
Nonriverine/Interstream Nonriverine/Interatream Rivedne/Bottomiand
Area
Impacted 3.3 5.5 2.9 11.702)
(Acres)

Although Wt}uantitative methodology was, employed. to .determine functional values of
„m- s, general wetland functions were evaluated based on best professional
judgement using parameters described in hydrogeomorphic (HGM) functional assessment
technology (Brinson 1993, ESI 1994b). A summary of HGM functions and functional
performance variables considered is presented in Section 8 (Mitigation Credit Determination).
Wetland functions are subdivided into hydrodynamic, biogeochemical, and biotic components
for descriptive purposes. The following wetland types have been identified:
Palustrine forested, broad-leaved deciduous/(needle-leaved evergreen), temporarily flooded
wetlands (PF01 A, (PF01 /4A))
Impacts to npnriverine pine/hardwooW-.,fdfeeted-wetlands;4,5z.5-eefes) represent a majority of
wetland impacts associated with widening of US 17. For descriptive purposes, interstream
wetland types include all nonriverine wet hardwood forests and wet hardwood/pine mixed
forest intergrades. These wetlands are positioned along the center of interstream tracts which
4
are temporarily saturated or inundated during early portions of the growing season.
Interstream wetlands are typically fragmented within farmed landscapes or road networks and
exhibit negligible forest connectivity with riverine/bottomland corridors. Interstream wetlands
exhibit indications of long-term disturbance such as antecedent farming, affected hydrology,
or systematic logging.
Included within this wetland class is minimal acreage of palustrine, shrub scrub, broad leaved
deciduous/needle-leaved evergreen, temporarily flooded wetlands (PSS1 /4A). This community
represents woodland or pine plantation which has been clear cut in the last 10 years. Due to
limited impact acreage, PSS1 /4A wetlands do not warrant separation as a distinct wetland
type.
S ithin interstream wetlands include th ans (Typic Ochraquults), Portsmouth
sms
(Typic umbraquults), and Fanpke (Typic Ochraquults) series (USDA 1986). These soils are
nearly level, poorly drained, with the seasonal high water table at or near the surface. Silty
clays of limited permeability lie a few inches to a few feet below the ground surface.
Relatively low permeability of subsoils may contribute to the presence of wetland hydrology
in these areas. When drained, these soils are well suited for agriculture.
Dominant tree species occurring within these interstream communities include water oak
(Quercus nigra), willow oak (Quercus phe/%s.), swamp chestnut oak (Quercus michauxii), laurel
oak (Quercus laurifolia), sweet gum (Liquidambar styraciflua), black gum (Nyssa bif/ora), and
loblolly pine Onus taeda?. Swamp red bay (Persea palustris), sweet bay (Magnolia virginiana), U L
red maple (Acer rubrum), and sweet pepperbush (Clethra alnifolia) are common
understory/shrub components. Characteristic ground cover species include partridge berry
(Mitchella repens), switch cane (Arundinaria gigantea), netted chain fern (Woodwardia
areolata), false nettle (Boehmeria cylindrica), and infrequent dog hobble (Leucothoe axillaris).
Nonriverine forested wetlands, when compared to riverine systems, appear to exhibit relatively
low value for performance of most physical wetland functions. Expected physical functions
dra 9' ? i t itian of°
include long-t?ertri water storage during periods' of grou?Wr
graun-d tPa `flow/movement within the watershed, and attenuation ofi Surface runoff into
streams a ':agricultural (slppe) areas of lower landscape ;position (Adamus et al. 1991).
Because these wetland functions occur primarily below ground surface, indirect visual
observations of functional performance are required. For instance, the presence of natural,
first order stream corridors extending from interstream wetlands towards bottomland systems
would indicate that near surface groundwater is serving to recharge larger bottomland systems
in downstream areas. Conversion of these surface water outlets into inter-field ditches alters
the effectiveness of interstream wetlands to attenuate stream recharge in the lower
5
watershed. In essence, relatively undisturbed (reference) nonriverine wetlands often act as
"sumps" or collectors of rainfall and possibly groundwater. Stored water is then released in
moderation through subsurface flow or first order stream flow towards downslope areas.
The ability of impacted interstream wetland resources to perform physical wetland functions
appears to be degraded by adjacent land use practices. Extensive ditching and fragmentation
in farm fields surrounding interstream wetlands has accelerated the transport of stored water
and rainfall from these interstream flats, through inter-field ditches, and into area streams.
Ditching has also lowered the seasonal high water table to marginal wetland levels in some
areas. Evidence of above ground hydrology within these systems is limited to isolated, very
small pockets which fill with water during winter and early spring. Therefore, pith
fbncti.e , ," ' ' Cream wetland areas y? b`e a_ i Oo byo Yd es r t i h
are depdorested,etlar?de.iiFsval.
In Chowan and Perquimans Counties, interstream wetlands often provide a large majority of
remaining forested habitat for native wildlife (Adamus and Stockwell 1983). Most uplands and
historical wetland areas in the region are currently farmed. Therefore, the maintenance of
species distributions and abundance is dependent, in part, upon these nonriverine wetlands.
Habitat value of interstream wetlands, when interspersed and connected with bottomland
systems, is considered important to maintenance of characteristic wildlife guilds (USFWS
1981). No net loss of interstream wetland function and connectivity for wildlife in the region
should assist in maintaining species distributions and abundance.
Field evaluations suggest that the wetland fringes potentially impacted by road widening
exhibit relatively low value for wildlife. These areas exhibit negligible connectivity with riverine
corridors and have sustained long-term degradation from human activity. These wetland
fringes immediately adjacent to the existing roadway often serve as household trash, dump
areas for local residents. In addition, the wetland/roadway edge provides an ecotonal fringe
that is considered common habitat throughout eastern North Carolina. As expected, road
widening tends to avoid significant impacts to high value wildlife habitat in nonriverine.systems
as compared to likely impacts associated with new alignment corridors.
Palustrine forested, needle-leaved evergreen, temporarily flooded wetlands, ditched and bedded
(PF04Ad)
Approximately 3L3;_acres. of pine=plantat*o?> within partially drained wetlands may be impacted
by widening of the US 17 corridor. These systems are nonriverine in function and occur along
the center of interstream flats and depressional slopes. Soils consist primarily of the poorly
drained Ptcq> hs ands-Roan t series. Canopy elements are composed entirely of loblolly
pine. Understory elements often form an impenetrable thicket or are periodically maintained
6
through prescribed fire. Characteristic understory elements include red maple, sweet gum,
switch cane, and other disturbance adapted species.
These pine plantations appear to;be rna _)a ,i? lpy ,od n. The relatively short
rotation (approximately 20 years) and the lack of habitat heterogeneity may diminish wildlife
habitat for certain characteristic guilds. Mature wet pine stands (greater than 30 years of
age), which may provide important habitat for certain species, are not located within the
potential impact area.
Physical and biotic wetland functions, in general, are considered similar in nature to the PF01
and PFO 1 /4A wetlands described above.
Palustrine forested, broad-leaved deciduous/(needle leaved deciduous), seasonally flooded
wetlands (PF01 C,( PF01 /2C))
Impacted riverine/bottomland wetlands are concentrated within the Iil
kekyandmse r1(di3r=tFbutaries. Approximately 2.9 acres
of bottomland wetlands may be impacted at these stream crossings. Hydric soil types
occurring in these alluvial systems consist primarily of z :_silt loams (Thapto-Histic
F/uvaquents) (USDA 1986). These are very poorly drained, floodplain soils characteristic of
small streams in the region. Character canopy species include sweet gum (Liquidambar.
styraciflua), red maple (Acer rubrum), willow oak (Quercus phe/%s), laurel oak (Quercus?
t
laurifolia), river birch (Betula nigra), American sycamore (P/atanus occidentalis), with inclusions
of bald cypress (Taxodium distichum), and tupelo gum (Nyssa aquatica).
PF01 C and PF01 /2C wetlands are functionally valuable ecosystems. Because of their position
in the landscape (i.e. interspersed between agricultural fields and stream channels), these
bd ri raACf c unities act as major -receptorg,of, upland runoff (Cooper et aL 1986, Peterjohn
and Correll 1984)). As such, important biogeochemical functions performed by floodplains
which dissect agricultural regions include removal of elements=`ar?d r ds, reamo of"
pa?tcpvfa ediments), and rir?CT f g (Brinson et al. 1994).
Bottomiand wetlands immediately adjacent to the existing roadway are typically channelized
to varying extent to improve drainage. In many cases, channelization has allowed for
conversion of surrounding floodplains to agricultural land. Hydrodynamic functions within a
large majority of impacted bottomland systems have been jeopardized by stream
channelization, encroachment into the floodplain by agriculture, and logging impacts. The
frequency and duration of overbank flooding in most bottomland impact areas has been
reduced with consequent reductions in short-term and long-term surface water storage
capacity. Conversion of wetland/upland ecotones for agriculture has also reduced the
7
wetlands' ability to attenuate groundwater flow or discharge and the ability to reduce the
deleterious impacts of overland runoff from adjacent fields (Karr and Schlosser 1978). In
addition, energy dissipation functions have been jeopardized by reductions in large woody
debris from encroachment and clear-cutting along with changes in surface microtopraphy as
a result of periodic timber harvests.
Bottomland ecosystems provide valuable habitat for biotic resources in the region. Habitat
value of bottomland forests, especially for migration and wintering species, is considered
important to maintenance of characteristic wildlife guilds and migratory species. Vegetational
diversity and aquatic affiliation offers all the necessary components (food, water, cover)
needed to support a variety of mammals and birds. In addition, seasonal inundation provides
ideal habitat opportunities for waterfowl, such as wood ducks, as well as a variety of reptiles
and amphibians. Field evaluations suggest that the diversity and abundance of aquatic
organisms within bottomland impact areas has been jeopardized through channelization,
floodplain reduction, sediment/nutrient loading, and riparian canopy removal. However, aquatic
species adapted to disturbance in stream corridors are expected to persist in these areas.
A large majority of impacts to bottomland wetlands will occur in relatively degraded systems
described above. However, encroachment within floodplain forests of Bethel Creek will impact
limited bottomlands (:r acres) which appear to approach maximum sustainable performance
for a number of wetland functions. At the 1_. cre eigbetfe.Edin:.is
cotrr _ er y of pe.?o gum_With some scattered red maple. Adjacent to existing US
17 at the Bethel Creek crossing, power transmission lines parallel the roadway. These cleared
easements are composed of successional vegetation including red maple, winged sumac (Rhus
copaiiina), and blackberry (Rubus).
Bethel Creek flows in a north/south direction, passing to the west of the town of Bethel before
emptying into the Yeopim River. Near the point of discharge into the Yeopim River, Bethel
Creek is under tidal influence. Coordination with the North Carolina Division of Marine
Fisheries indicates the occurrence of ffo t ected :fishes,. tl a $looback : -4A4b96 '
aestivaiis) am slew fe (A%ap gus} ` within the Bethel Creek system. Both
anadromous fish species are listed by the state of North Carolina as "vulnerable" (Category
3). Upstream migrations of anadromous populations take place between February 15 and May
15 of each year (pers. comm., WRC, 4/12/95). As stated in the State EA, a part of
compensatory mitigation will include a construction moratorium at the Bethel Creek crossing
during this period.
8
4.0 MITIGATION GUIDELINES
4.1 Mitigation Policy
Mitigation for wetland losses from the proposed project is recommended in accordance with
Section 404(b)(1) Guidelines of the Clean Water Act (40 CFR 230), mitigation policy mandates
articulated in the COE/EPA Memorandum of Agreement (MOA; Page and Wilcher 1990),
Executive Order 11990 (42 FR 26961 (1977)), FWS mitigation policy directives (46 FR 7644-
7663 (1981)), and Federal Highway Administration (FHWA) stepdown procedures (23 CFR
777.1-777.11). Mitigation has been defined in National Environmental Policy Act (NEPA)
regulations to include efforts which: a) avoid; b) minimize; c) rectify; d) reduce or eliminate;
or e) compensate for adverse impacts to the environment (40 CFR 1508.22 (a-e)).
Section 404(b)(1) Guidelines, the COE/EPA MOA, and Executive Order 11990, stress
avoidance and minimization as primary considerations for protection of "waters of the United
States." Practicable alternatives must be fully evaluated before compensatory mitigation can
be discussed.
USFWS policy also emphasizes avoidance and minimization. However, for unavoidable losses,
the FWS recommends that mitigation efforts be correlated with value and scarcity of the
habitat at risk. Habitat is classified into four Resource Categories based on decreasing
importance and value, with subsequent decreases in mitigation planning objectives (46 FR
7657-7658). The forested wetlands in the project corridor would be considered Resource
Category 2 (riverine systems) or 3 (nonriverine systems) (high to moderate value), requiring
a mitigation goal of no net loss of habitat (compensation through replacement of lost habitat
function). Methods used to achieve this goal include: the physical modification of replacement
habitat to convert it to the type that is lost, restoration or rehabilitation of previously altered
habitat, increased management of similar replacement habitat so that in-kind value of the lost
habitat is replaced, or a combination of these measures.
FHWA policy stresses that all practicable measures should be taken to avoid or minimize harm
to wetlands which will be affected by federally funded highway construction. A sequencing
(stepdown) procedure is recommended in the event that avoidance is impossible. First,
consideration must be given to providing for mitigation within highway right-of-way limits,
generally through enhancement, restoration, or creation. Mitigation employed outside of the
highway right-of-way must be reviewed and approved on a case-by-case basis. Measures
should be designed "to reestablish, to the extent reasonable, a condition similar to that which
would have existed if the project were not built" (23 CFR 777.9(b)).
9
4 .2 Mitigation Seauencina
Existing policy guidelines on mitigation sequencing have been employed for this project.
Measures to avoid, minimize, reduce, and eliminate wetland impacts have been employed
where feasible. NCDOT's efforts at impact avoidance and minimization are more fully
addressed in the February 7, 1994 permit application.
Avoidance -Total avoidance is not always feasible in eliminating impacts associated with a
proposed project. Road widening cannot be achieved while avoiding all wetland areas. In
addition, the economic and social costs associated with a "no action" alternative are
prohibitive. Current and future traffic problems are not resolved by avoiding needed
improvements.
Although proposed construction may impact approximately 12 acres of wetlands, every effort
has been made to avoid wetland communities whenever possible. Alignment shifts to the
north or south of the existing roadway were designed, in part, to avoid extensive wetland
fringe areas.
Minimization - Impacts on wetlands adjacent to the roadway will be minimized by implementing
erosion control measures such as seeding slopes, installation of silt fences, and the proper use
of sediment basins. Fill slopes through wetland areas have been steepened to the maximum
practical, and lateral drainage ditches will be eliminated where feasible in order to reduce
wetland impacts. Canopy removal will be restricted outside of right-of-way limits in wetland
areas. Bottomland communities will not be used as staging sites. In addition, median widths
have been reduced to 46 feet (14 m ) at wetland crossings, which is the minimum necessary
at this location to provide adequate drainage.
Compensatory mitigation is proposed for all unavoidable impacts resulting from roadway
widening and improvements to the subject segment of US 17. In all cases, replacement of lost
wetland functions is considered paramount.
Mitigation banking - Mvtigation bankibols c?onsid"eyed an integral partof project. After
debiting for R-2208A impacts, remaining credits from the Dismal Swamp site are expected to
be "banked" for future use by NCDOT. Although formalization of a mitigation bank is beyond
the perview of this project, this plan has been formulated under recent guidance for the use
and operation of mitigation banks (60 FR 12286-12293, 1995) in order to facilitate the
banking process. Mitigation banking is recognized as a potential benefit in facilitating the
permit process and providing more effective mitigation for impacted wetlands.
10
5.0 MITIGATION SITE
5.1 Proaect Overview
A portion of fWr *FZ amp in Gates an 1 ?ans Counties, North Carolina, has been
selected for consolidation of wetland impacts from US 17 widening (R-2208A). The Dismal
Swamp wetland restoration, e'eo[`=appFlttiEafi;c?f#arm and forest land
approximately 1.2 miles east of the town of Sandy Cross and SR 1002 (Folly Road), along the
Gates County/Perquimans County line (Figure 1).
The Dismal Swamp site provides a contiguous mitigation area of relatively high potential
wetland value. The Dismal Swamp wetland restoration and enhancement area will provide for
full replacement of wetland function lost as a result of proposed US 17 improvements. In
addition, a Dismal Swamp mitigation bank will subsequently be developed to allow for
consolidation of minor wetland impacts from other roadway/bridge construction projects in the
region. Mitigation banking within Dismal Swamp is considered an important means to restore
prior converted wetlands of regional significance. The location of the mitigation site in relation
to the Dismal Swamp National Wildlife Refuge and natural areas is depicted in Figure 2. Figure
3 illustrates a 1994 aerial photograph of the mitigation area.
Environmental Services, Inc. (ESI) personnel visited the mitigation site in December 1994 to
evaluate existing conditions, ground truth Natural Resource Conservation Service (NRCS) soil
mapping, and to model site hydrology. Adjacent, relatively undisturbed forested areas were
surveyed, sampled, and described to establish a reference forest ecosystem (FIFE) for
restoration planning. Soil samples were evaluated to correlate reference soil systems to the
wetland restoration area. In addition, the USFWS Dismal Swamp National Wildlife Refuge
office and the N.C. Natural Heritage Program (NCNHP) were visited to collect information
pertaining to wetland community-landscape patterns, including Atlantic white cedar
(Chamaecyparis thyoides) distributions, in the Dismal Swamp complex.
Mitigation site hydrology was modeled for pre-mitigation and post-mitigation hydrologic inputs
and outputs to generate an available water budget. Subsequently, conditions were modeled
with DRAINMOD to predict the influence of various site interventions to restore wetland
hydrology.
2 Dismal Swamn Mitigation Site History
The Dismal Swamp mitigation site was originally _ d before Section
404 of the Clean Water Act was implemented in, %. The drainage system was originally
installed by Weyerhauser to facilitate the commercial growth and harvest of pine trees. The
612 acre tract has been utilized primarily for tree plantations in the past, as well as agriculture
activities through 1995.
11

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Environmental Dismal Swamp Mitigation Site Figure: 2 Dismal Swamp Wildlife
0
Services, Inc. in relation to the Refuge and Natural Areas
1318 Dale Street
Suite 220 Dismal Swamp National
Wildlife Refuge Project: ER94018.7 Mitigation Site
Raleigh, NC 27605 and Natural Areas
Date: 7 Apr 1995 0 1 2 3 4 Mlles
12
13
The site is bordered on the north by artificially drained pine plantation owned by Weyerhauser.
The southern and eastern boundaries abut former cultivated lands or active farmfields which
have also sustained impacts from drainage structures. The mitigation bank site is bordered on
the west by upper reaches of the Perquimans River and relatively undisturbed forested'
wetlands which constitute part of the Great Dismal Swamp refuge (Figure 2).
5.3 Existing Conditions
5.3.1 Physiography, Topography, and Land Use
The subject property is located in the Atlantic Coastal Plain Physiographic Province of North
Carolina. The Coastal Plain is comprised of sediments deposited since the Cretaceous Period
during a series of transgressions and regressions of the Atlantic Ocean. The Dismal Swamp
site is situated on the Outer Coastal Plain which extends from the Suffolk Scarp, a paleo-
shoreline, to the Atlantic Ocean. The mitigation site is located approximately 1 mile east of
the western edge of the primary Suffolk Scarp formation (DNR 1985).
Current land use consists of agriculture including 1994 harvests of corn and soybean. A
forested area persists in the southwest section of the site. This stand appears to have been
selectively cut over the last 20 years. Hunting club leases are currently applied in forested
areas. Numerous commercial hunts were observed during field studies.
5.3.2 Soils
The site is located within the southern portion of the Great Dismal Swamp complex. The
gA qF W9 W-04 ItISOIS,
surficial soils encountered were orq ?stosols) and or
Inceptisols?, with two small inclusions of nonhydric soils (Spodosols) in the southern portion
of the tract.
Soils have been mapped by the Natural Resource Conservation Service (NRCS) (USDA 1986,
USDA 1994). Figure 4 depicts NRCS soil map units overlaid upon recent aerial photography.
Soil phases include the Scuppernong/Belhaven series (Terric Medisaprists), the Arapahoe series
(Typic Humaquepts), the Icaria series (Typic umbraquults), the Leon/Lynn Haven series (Aeric
to Typic Haplaquods), and the Echaw series (Entic Haplohumods). Series represented by two
names are typically similar soil map units that occur on either side of the county line.
14
15
Soil texture within most of the site ranges from loam to loamy sand of slow to moderate
permeability. Upland soils include a highly permeable upper soil solum. In undrained condition,
the seasonal high water table varies along the topographic gradient from surface flooding to
more than 4 feet 0.2 m) below the soil surface. NRCS mapping (Figure 4) identifies low-lying
flats associated with upper reaches of the Perquimans River, which support very poorly
drained, organic soils (Medisaprists, Scuppernong/Belhaven Series). A portion of this map unit
exhibits indications of fluvial deposits from infrequent overbank flooding within the adjacent
tributary.
Areas further east of the channelized tributary support poorly drained, mineral soils
(Umbraquu/ts, Icaria Series; Hap/aquods, Leon Series). An isolated knoll maintaining non-hydric
soils is situated in the southeastern corner of the property (Hap/ohumods, Echaw Series). The
soil and landform gradient suggests that several natural forested communities existed on the
site prior to farming and forestry practices. Soil-site relations indicate that riverine/bottomland
swamp forest, nonriverine swamp/peatland Atlantic white cedar forest (organic soil subtypes),
nonriverine swamp hardwood forest (mineral soil subtypes), limited nonriverine wet hardwood
forest edges, and a coastal fringe sandhill forest inclusion may have occurred on the site prior
to farming (soil-forest site classifications are introduced in Schaf ale and Weakley (1990) and
Van Lear and Jones (1987).
Hydric soils are defined as "soils that are saturated, flooded, or ponded long enough during the
growing season to develop anaerobic conditions in the upper soil layer" (USDA, 1987). Hydric
soil boundaries on the site were flagged in December 1994, by the N.C. Department of
Environment, Health, and Natural Resources (NCDEHNR); Division of Soil and Water.
Subsequently, NCDOT personnel mapped hydric soil limits using GPS technology. Figure 5
depicts the hydric/nonhydric soil boundaries identified on the site. Hydric soils include the
Scuppernog/Belhaven, Arapahoe, Icaria , and Leon series. Organic matter content ranges from
a potential maximum of 90% in the control section of Scuppernog/Belhaven soils to a minimum
of 0.5% in the Leon series (USDA 1986, USDA 1994). era rainage are
inWaded by relatively slow pe eabi#i ir_ soils coupled with the presence of clayey
subse atizons of moderate organic content and the lack of topographic slope in the area.
The construction of large canals and feeder ditches has drained most of these soil units to the
extent that hydric conditions in upper soil horizons are currently limited. In addition, artificial
drainage and agricultural production most.likely promoted a reduction in organic matter content
through accelerated decomposition and harvesting. In order to reestablish wetland hydrology
within hydric soil areas, drainage canals require modification to recreate natural subsurface
drainage patterns. Organic matter relations in the soil environment are expected to return to
relict condition over time, once wetland hydrology is restored.
16
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Nonhydric Soil Areas -12 Acres
Hydric Soil Areas - 600 Acres 1 inch = 800 feet
Figure: 5
Environmental Hydric/Nonhydric
Services, Inc. Soil Boundaries
1318 Dale Street Dismal Swamp Mitigation Site Project: ER94018.7
Suite 220 Gates and Perquimans
Raleigh, NC 27605 Counties, NC Dare: 10 Apr 1995
17
The only non-hydric soil on the mitigation site comprises the moderately well drained, Echaw
Series (Entic Haplohumods). This non-hydric map unit occupies a small area in southern
portions of the site (Figure 4) (USDA 1986). The area supports an elevated, sandy knoll with
the seasonal high water table at approximately 3 feet (0.9 m) below the surface. This area
lacks wetland hydrology (as is historically the case). However, this upland inclusion in the
mitigation landscape provides the potential for restoration of an upland/wetland ecotone into
native forest communities. Wetland/upland ecotones are among the most diverse and
productive environments for wildlife (Brinson et al 1981). In addition, a number of physical
wetland parameters are also enhanced by the presence of wetland/upland ecotones on the
mitigation site (ESI 1994a).
5.3.3 Hydrogeology
A detailed hydrogeomorphic site assessment and hydrological restoration report are included
in Section 11.0 (Appendices). A summary of existing hydrogeological conditions discerned
from these studies is provided below.
Regional Hvdrogeolocav
Regional groundwater flow in the Coastal Plain is generally in a down dip direction, which
trends southeast in this area of North Carolina. Rivers flow from northwest to southeast in
the Coastal Plain, roughly paralleling the dip direction. The southern portion of the Great
Dismal Swamp also drains south to southeast into the Perquimans and Pasquotank Rivers,
which drain into the Albemarle Sound. Shallow groundwater usually occurs under unconfined,
water table conditions within 5 feet 0.5 m) of the surface in the region, as evidenced by the
large expanses of hydric soils, and the extensive use of drainage systems.
Local Hvdrogeologv
r
A grcm -.d-v%Vr'f-aae wateilr c i a %> ` 1 Ind on the subject property to
lower near surface hydrology for agricultural production. Systematic ditching has lowered the
groundwater table and redirected groundwater flow towards feeder canals and upper reaches
of the Perquimans River. This below headwater tributary runs from north to south along the
western property boundary.
The dr the, ' . *fTINM E approximately. ewart and drain
south towards a large canal which transects central portions of the site. The drainage ditches
in the so prox mateFy' 50 feet (76 m) apart, and flow either north or south
into canals along both sides of the property boundary. Ditches and canals range from 1 foot
deep in elevated, central portions of the site t*' ti;' J in plMmO . Site
modeling indicates that groundwatep-f#ee w.estwar mass the mitigation area before
entering the channelized Perquimans River tributary.
18
The results of the slug tests indicate that the hydric soils on the site have a moderately low
hydraulic conductivity ranging from a low of 0.017 inches/hour (4.33x10'2 cm/hr) to a high of
1.02 inches/hour (2.58 cm/hr). Groundwater modeling identified two localized high points in
the water table, one is in the southeastern portion of the site in the non-hydric Echaw soils
which is represented as a topographic high. The knoll of non-hydric soils and the access road
function as a drainage divide in the southern tract. Another localized high point is in the
northern tract and appears to be less related to topography.
5.3.4 Plant Communities
A large majority of the Dismal Swamp mitigation site consists of active agricultural fields. Of
the total 612 acres, ap %) have been cone ??,?'e and
?k
support seasonal crops such as corn (Zea mays) and soybeans (Glycine max), along with
intermittent early successional vegetation. Within agricultural areas, numerous in-field ditches
support some hydrophytic plants, and intra-field dirt road berms are invaded by various upland
and invasive species. VfiA q LoG
In the southwestern portion of the site, a; disturbed swamp forest community persists
(Schafale and Weakly, 1990). This fo urea comprises approximate) s-
of the total 612 acre mitigation site. This forested area is similar to a large portion of the
adjacent Great Dismal Swamp. Originally, the Great Dismal Swamp was thought to be
primarily Atlantic white cedar forests (Chamaecyparis thyoides) from which cedar populations
have been declining or eliminated (Schafale and Weakley 1990). Past logging of the cedar and
altered fire regimes may have resulted in a forest now -rubrum),
ar styraciflua), sw r = (Nyssa bifiora), and b Tess
(Taxodium distichum) among infrequent stems of Atlantic white cedar. A number of Atlantic
white cedar stumps to 20 inches (51 cm) in diameter-breast-high (DBH) and standing trees to
10 inches (25 cm) DBH have been documented within forested areas on the mitigation site.
Signs of reproduction such as cedar seedlings or saplings near the cedar population are also
apparent.
5.3.5 Wildlife Communities
Although the original forest tracts on this site have been utilized for large-scale agricultural
purposes, the adjacent swamp forests of Dismal Swamp and associated field edges provide
food, water, and cover for various species of wildlife. In spite of area-wide changes in the
original swamp forest, the Great Dismal Swamp and State Natural Area are still known to
support large mammals such as black bear (Ursus americanus), bobcat (Felis rufus), and white-
tailed deer (Odocoileus virginianus). In addition, the swamp and surrounding lands support
many smaller mammals in a complex food chain of predator and prey elements.
19
Extensive areas of standing water and seasonal wetlands within the refuge provide favorable
conditions for many species of reptiles and amphibians. Character species include red-bellied
water snake (Natrix erythrogaster), eastern cottonmouth (Aglistrodon piscivorus), yellow-
bellied turtle (Chrysemys scripta), spotted turtle (Clemmys guttata), southern leopard frog
(Rana sphenocephala) and marbled salamander (Ambystoma opacum). These and numerous
other reptiles and amphibians are integral components of the wetland food chain.
Seasonal use of the Dismal Swamp refuge can be expected by wading birds and waterfowl,
including great blue heron (Ardea herodias), black-crowned night heron (Nycticorax nycticorax),
mallard (Arras p/atyrhynchos), and wood duck (Aix sponsa). In addition, a high number of
passerine birds, both permanent and summer resident species, nest in hardwood swamp
forest. Among these are several neotropical migrants such as Swainson's warbler
(Limnothlypis swainsonii) and prothonotary warbler (Protonotaria citrea), or forest interior
species such as the wood thrush (Hy/ocich/a mustelina) and Acadian flycatcher (Empidonax
virescens), that require large tracts of contiguous forest (Keller et al. 1993).
Extensive agricultural land on the mitigation site, considered prevalent in the region, provides
limited habitat opportunities for these character species. The restoration of forested wetlands
immediately adjacent to the Dismal Swamp provides the opportunity to restore forested habitat
for these unique wildlife guilds.
5.3.6 Jurisdictional Wetlands
Jurisdictional wetlands were flagged in the field to facilitate restoration planning. Jurisdictional
areas were defined using the criteria set forth in the COE Wetlands Delineation Manual (DOA
1987). Approximately mss,.: ters and f juri - I wetlands were
identified. Figure 6 depicts the location of existing wetland/open water systems. The COE
Special Coordinator for NCDOT projects, Mr. Mike Bell, confirmed jurisdictional determinations
on 9 February 1995.
Jurisdictional wetlands (115 acres) reside within a forested area in the southwestern corner
of the property. These wetlands areas are palustrine in nature, characterized by early to mid-
successional growth of nonriverine swamp forest cover. Dominant species include sweet gum
and red maple, which commonly compose up to 90% of the forest canopy. Infrequent stems
of swamp black gum, cypress, laurel oak, and an inclusion of several Atlantic white cedar
stems are also present. An additional two acres of jurisdictional open waters reside in a large
drainage canal which extends from east to west through the center of the mitigation site. This
drainage canal will be eliminated during hydrological restoration activities.
The remaining acreage on the site ( 495 acres) consists of approximately 483 acres of prior
converted farmland on hydric soils and approximately 12 acres of farmland on non-hydric soils
(Figure 6).
20
® Jurisdictional Open Waters - 2 Acres ® Converted Farmlands
on Nonhydric Soils -12 Acres
Figure: g
Environmental Jurisdictional Wetlands, Jurisdictional
Services, Inc Open Waters, and Prior Converted Farmland
1318 Dale Street Dismal Swamp Mitigation Site Project: ER94018.7
Suite 220 Gates and Perquimans
Ralelgh, NC 27605 Counties, NC
Date: 11 Apr 1995
21
Jurisdictional Wetlands - 115 Acres Prior Converted Farmlands
on Hydric Soils - 482 Acres
6.0 MITIGATION PLAN
6.1 Wetland Restoration Modeling
A number of mitigation design studies have been utilized for restoration planning. These
include hydrogeological modeling, development of available water budgets, soil-site studies,
Reference Forest Ecosystem (RFE) characterizations (EPA 1990), and wetland functional
evaluations.
6.1.1 Hydrogeological Modeling
A hydrogeological site assessment was conducted to determine the existing conditions and
wetland restoration potential of the subject property. A detailed report of hydrogeological
modeling procedures and results is included in Section 11.0 (Appendix). The assessment
included the installation of a series of exploratory soil borings, the conversion of the soil
borings into observation wells, and water level measurements over an approximately two
month period. Hydraulic conductivity testing of the saturated zone and review of existing data
for the region were also performed and incorporated into the hydrological model.
The groundwater modeling software selected as most appropriate for simulating shallow
subsurface conditions and groundwater behavior was DRAINMOD. This model was developed
by Dr. R.W. Skaggs of North Carolina State University (NCSU). The model was originally
developed to simulate the performance of agricultural drainage and water table control systems
on sites with shallow water table conditions. DRAINMOD was subsequently modified for
application to wetland studies by adding a counter that accumulated the number of times that
the water table rose above a specified depth and remained there for a given duration during
the growing season. The model results can then be analyzed to determine if wetland criteria
are satisfied during the growing season, on average, more than half of the years modeled
(usually 30 years).
Dr. George Chescheir of NCSU also participated in the current study by reviewing the site
characterization data and setting up the DRAINMOD model for the study area. Dr. Chescheir
provided input parameters required by DRAINMOD and supplied model results for the study
area. Output from the DRAINMOD model was then applied to the study area to determine
which areas would not achieve wetland hydrology criteria. W s
µr?bgth
s latn tai .`1cinfae :`_:
1 # tC e d ys (5°% of :thee °'9row? a ` and:r3'I nc TS v.e oa is { 12 5r°1? If :the
groves err): For the purposes of this study, the growing season was defined as the period
between 21 March and 19 November (USDA 1986, USDA 1994). Simulations were also
conducted to forecast whether saturation within 12 inches (30 cm) of the surface could be
achieved for 49 and 61 consecutive days ( 20%, and 25% of the growing season,
22
respectively) using conservative model estimates. These additional simulations were
conducted to provide information concerning the expected influence of prolonged soil
saturation on various target plant species populations.
Model Description
DRAINMOD predicts water balances in the soil-water regime at the midpoint between two
drains of equal elevation. The model is capable of calculating hourly values for water table
depth, surface runoff, subsurface drainage, infiltration, and actual evapotranspiration over long
periods of climatological data. The reliability of DRAINMOD has been tested for a wide range
of soil, crop, and climatological conditions. Results of tests in North Carolina (Skaggs, 1982),
Ohio (Skaggs et a/., 1981), Louisiana (Gayle et a/., 1985; Fouss et a/., 1987), Florida (Rogers,
1985), Michigan (Belcher and Merva, 1987), and Belgium (Susanto et a/., 1987) indicate that
the model can be used to reliably predict water table elevations and drain flow rates.
DRAINMOD has been used to evaluate wetland hydrology by Skaggs et a/. (1993).
Model Calibration
The hydrology of various soil-water conditions applicable to the site was simulated using
DRAINMOD. The simulation used the hydric mineral Icaria series, a fine sandy loam, for
portions of the site consisting of prior converted farmlands. Icaria soils represent the most
common series of most intermediate character on the site. Soil input parameters for
DRAINMOD were calculated by the NRCS model, DMSOIL (Baumer and Rice, 1988) using soil
texture data from soil samples collected on site. Soil hydraulic conductivity values were
determined from the slug test data. Simulations were conducted for the time periods from
1951 to 1980 using climatological record from Plymouth, Washington County,.North Carolina.
DRAINMOD simulations were conducted for the range of ditch depths and for the distances
of a midpoint between ditches. Simulations were then run to determine the distance between
ditches predicted for the establishment of wetland hydrology for 5%, 12.5%, 20%, and 25%
of the growing season. T e
j..
. , Mby the process of below ground plant growth, interception of rainfall,
and litter accumulation. An irnperrneable4daye a as,?.,Lp-be present at a depth 9A
i° rtr). A detailed description of model calibration parameters is provided in Section
11.0 (Appendices; Hydrogeological Site Assessment Report).
The depth of depressional storage used in initial DRAINMOD simulations was 1.96 inches (5
cm) assuming no provisions for amelioration of surface storage on farmed land. Based upon
the input data, saturation to within 12 inches (30 cm) of the surface for 25% of the growing
season (61 consecutive days) could not be achieved. The simulations were repeated using a
23
surface storage of 3.9 inches (10 cm), assuming that surface roughing would be used on the
site to increase surface storage. Based on 3.9 inches (10 cm) of surface storage, saturation
for 25 % of the growing season was achieved. The rooting depth function used in the
simulation was a constant depth of 17.7 inches (45 cm), which is typically used for forested
conditions.
Model Results
The DRAINMOD simulations predicted that a very high percentage of the cultivated land would
achieve wetland hydrology criteria. The model predicted that at a maximum of 330 feet (100
m) from the drainage canal, saturation for 12.5% of the growl season could be achieved by
MWateral ditches and assuming surface sto _ge of 3 9 inches (10 c . Table 2 provides the
results of the DRAINMOD modeling study presenting different ditch depths and distances from
the perimeter canals that wetland hydrology would persist for 5%, 12.5%, 20%, and 25°x6 of
the growing season.
TABLE .2
Results of DRAINMOD Simulations for Saturation within 12 inches (30 cm) of surface for
Selected Percentages of the Growing Season (Surface Storage = 10 cm)
Ditch Depth
Percentage
of Growing
Season Number
of Days 30 cm
(1 ft) 60 cm
(2 ft) 90 cm
(3 ft) 120 cm
K ft) 150 cm
(5 ft)
Ditch Spacing (meters)
5 12 25 37.5 50 50 50
12.5 31 37.5 50 75 75 75
20 49 50 75 75 75 100

Wetland hydrology is defined as the conditions that resulted in the
tha?a.i0122CI ifiears. As was expected, wetland hydrology was more likely to occur in the
interior portion of the tract, away from the perimeter canals. Of 483 acres of farmed hydric
soils, approximately
p se ?yason, oe ditches and canals are eliminated. Based on DRAINMOD results,an
24
(_;
additional 28 acres of prior converted farmland would meet the wetland criteria for between
5% and 12% of the growing season. The remaining 57 acres of prior converted farmland in
close proximity to the perimeter canals will support wetland hydrology for less than 5% of the
growing season. This narrow strip along the outer edge of the mitigation property will serve
as a wetland hydrological buffer between canals and the restoration areas. Figure 7 identifies
the location of modeled wetland hydrology map units on the site.
The wetland hydrology results in Table 2 were also used to determine which portions of the
tract would not meet wetland criteria, on average, more than half the time. The issue of
determining if a specific portion of the site will support wetland hydrology was predicted by
comparing the ground elevation at the simulated midpoint to the elevation of the water in the
nearest perimeter canal. Those areas which would not meet wetland criteria include two small
elevated upland islands, comprising approximately 12 acres, in the southern portion of the site.
Wetland hydrology map units presented in Figure 7 were utilized, in part, to model community
restoration potential.
6.1.2 Reference Forest Ecosystem Modeling
In order to restore or create a forested wetland for mitigation purposes, a reference community
endpoint needs to be established. According to Mitigation Site Type Classification (MiST)
guidelines (EPA 1990), the area of proposed restoration should attempt to emulate a Reference
Forest Ecosystem (FIFE) in soils, hydrology, and vegetation. RFEs are composed of relatively
undisturbed woodlands near the mitigation site which support soil, landform, and hydrological
characteristics that restoration activities are attempting to emulate. Although selection of the
RFEs is determined by soil, hydrologic, and landform parameters, there is much variation within
local forested areas that may not be represented in the sample plots. Nearly all potential RFE
sites have been impacted in the past by selective cutting or high-grading, and the species
composition of the plots should be considered as a minimum starting point in restoration
procedures. Therefore, FIFE information, when incorporated into a community restoration plan,
should be modified based on community information obtained from other available resources.
Reference forest data utilized in restoration planning have been modified, where appropriate,
to emulate steady state community structure as described in Classification of the Natural
Communities of North Carolina (Schafale and Weakley 1990). Information obtained from the
USFWS Dismal Swamp National Wildlife Refuge office was also incorporated into community
restoration procedures. In addition, forest ecosystem classification research developed for the
southeastern United States was incorporated (Van Lear and Jones 1987, Jones 1989, Peet
and Christensen 1980, Beals 1984).
Based on soil and landform parameters on the mitigation site, four reference ecosystem types
were considered for reference characterizations. These include riverine swamp forest on
25
I i
_
fll II I IIIIII' I? ?? I Ill??l llllil f- ? .
- --------------------
-OIIY••Pii. i
p r --- -------- r- --•---- k -•-•---------------------------- F -•-•--•-i----- F ---+ ----- ---__;_ _i
=r-
-_
! i ! ! ! air M4 i i I r
! I I 1 j 1 r
ie"r-P I' i i o"16
L?
S I 1 -_
1 inch = 800 feet
W0% - 5% (57 acres) 20% - 25% (44 acres) N
5% - 12.5% (28 acres) >25% (443 acres)
12.5% - 20% (26 acres) ® Nonhydric Soils (12 acres)
Environmental DRAINMOD Figure: 7
Services, Inc. Estimated percent of the growing season
1318 Dale Street that wetland hydrology will persist project: ER94018.7
Suite 220 on the mitigation site
Raleigh, NC 27605 (3.9 inches (10 CM) Surface Storage)
Date: 13 Apr 1995
ItFLOY-
26
organic soils exhibiting fluvial interlayers, nonriverine swamp forest on organic soils
(Scuppernong/Belhaven series), nonriverine swamp/wet hardwood forest on mineral hydric soils
(Icaria series, Leon inclusions), and coastal fringe sandhill forest on moderately well drained,
non-hydric, fine sandy soils (Echaw series).
Systematic surveys were performed in forests surrounding the site to locate sample plot
locations within the four reference vegetation/landform types. Variations in species
composition between forests on the Scuppernong/Belhaven series and Icaria inclusions were
minimal, and these two ecosystem types were combined into one type for reference
characterization purposes. The primary purpose for differentiating between swamp forest soil
subtypes is to target Atlantic white cedar restoration towards organic soil areas.
T eas were identified to characterize thand'Atlantic white cedar
forest restoration areas. These plot locations are situated approximately 15 d-2000
feet northwest of the mitigation property along an adjacent access road (Figure 2). These
steady-state forest sites were sampled using 0.20-acre circular plots (standard forestry
methodology). Plots were randomly established within forested areas supporting target
landform, soil, and hydrological characteristics in an effort to characterize the expected steady-
state composition of the mitigation site after restoration. Ecologists identified and counted all
species of trees (greater than 20 feet (6.1 m) in height); the diameter breast height (DBH) of
each tree was measured from which basal area coverage was calculated. Importance values
(IV) (Brower et al. 1990) were later calculated for the dominants. Composition of shrub and
ground cover strata were also recorded and plants identified to species. Sampling efforts were
concentrated within canopy layers to identify tree species to be chosen for later restoration
planting. Importance values for tree species within swamp forest sample plots is depicted in
Table 3. In addition, Table 4 provides a complete inventory of shrubs and herbs identified in
sample plots and adjacent areas during the study period (December 1994).
Nonriverine swamp forest canopies on Belhaven/Scuppernong soils and Icaria inclusions are
dominated by swamp black gum (IV = 38%), red maple (IV = 18%), and bald cypress (IV =
16%) (Table 3). To a lesser extent, a mixture of sweet gum (IV = 9%), sweet bay (Magnolia
virginica)(IV = 5%), laurel oak (Quercus laurifolia)(IV = 5%), swamp red bay (Persea
palustris), American holly (flex opaca), and ash (Fraxinus sp.) are also found. Infrequent stems
of loblolly pine (Pinus taeda), willow oak (Quercus phellos), and yellow poplar (Liriodendron
tulipifera), although not situated within sample plots, were noted in adjacent areas. Atlantic
white cedar is known from nearby parts of the swamp forest ecosystem and several
reproducing specimens were found within forested portions of the mitigation site. This area
had apparently been cut over some time ago, but several Atlantic white cedar stems were
spared. Disturbance seems to have increased the occurrence of yellow poplar (Liriodendron
tulipifera), loblolly pine, and the maturation of several water oaks (Q. nigra) and American holly
in this area.
27
VI
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TABLE 4
Inventory of Shrubs and Herbs in Reference Nonriverine Swamp Forests
(December 1994)
Shrubs
Red Maple Acer rubrum
Pawpaw Asimina triloba
Sweet Pepperbush Clethra alnifolia
American Holly Ilex opaca
Virginia Willow Itea virginica
Fetterbush Leucothoe racemosa
Sweet Gum Liquidambar styraciflua
Sweet Bay Magnolia virginica
Laurel Oak Quercus laurifolia
Willow Oak Quercus phellos
Smooth Greenbrier Smilax glauca
Laureleaf Greenbrier Smilax Iaurifolia
Blueberry Vaccinium sp.
Swamp Red Bay Persea palustris
Herbs
Switch Cane Arundinaria gigantea
Fern Fern sp.
Virginia Chainfern Woodwardia virginica
Water Hyssop Bacopa sp.
Poison Ivy Toxicodendron radicans
Partridge Berry Mitchella repens
Sedge Carex sp.
29
Based on available information, other species may have occurred within the system before
long-term disturbance from logging. However, these species were not found in RIFE plots or
adjacent areas. Other potential members of the swamp forest/Atlantic white cedar community
include Carolina ash (Fraxinus caroiiniana), pond pine (Pious serotina), and swamp hickory
(Carya aquatica). Overcup oak (Quercus iyrata), tupelo gum, and swamp cottonwood (Popuius
heterophy//a) may have occurred in expected relict floodplains near the large channelized
tributary which borders the western edge of the property.
The upland forest restoration area and riverine swamp forest inclusion were not characterized
by RFE sampling due to the lack of relatively undisturbed, representative sites in the project
area. Upland areas near the mitigation site currently consist of farmlands and pine plantation.
Based on available information concerning soil.and landform features, the upland areas may
have supported coastal fringe sandhill species such as longleaf pine (Pins Pa/ustris), live oak
(Quercus virginiana), turkey oak (Quercus iaevis), dwarf post oak (Quercus ste//ata), scarlet
oak (Quercus coccinea), blackjack oak (Quercus mariiandica), and black gum (Nyssa syivadca)
(Schafale and Weakley 1990, USDA 1994, USDA 1986). Lower positions on the knoll may
have also included character species such as water oak (Quercus pagoda), swamp chestnut
oak (Q. michauxii), and yellow poplar. 'Restoration of the natural forest community will be
implemented along this upland/wetland ecotone to increase habitat diversity across the
mitigation landscape.
6.2.1 Hydrological Restoration
The results of the DRAINMOD modeling study indicate that well hr can be achieved
within approximately . r1'nf prior converted farmland on hydric soils, 9e..
d NO "' 0emoved and the surface de - ted. The 427
acre area includes -acres at saturation for greater than 12.5% of the growing season and
28 acres at saturati n for between 5% and 12.5% of the growing season.
V r
dr ,#q"ithee=, a, ::effectily °be -achie+ ?l fly ,filling the lat"eral-;fieeder- ditt*hd ?'an-d thwl? wo°
drCg* `eanaiw4et. ee}thy"rior?fi?an - sr?utfiern-?rae?s'`af the site. Increasing the
depressional storage an be achieved by limited rowing and bedding when planting specimens
and by scarifying the oils between beds. If bedding is performed, rows will be established
roughly parallel to exi ting topographic contours with 1 foot (.30 m) high beds spaced at
intervals to allow acces by a tractor. Tractor access will allow mowing of the area to prevent
over-topping by pioneer vegetation and to scarify the soils between the beds during the first
two years of restoration, if necessary.
r

30

Recommendations For Filling Drainage Ditches
Restoring wetland hydrology on the site will require the effective filling and sealing of the
lateral feeder ditches and the canals between the northern and southern portions of the site.
Subject ditches can be specifically identified on large scale figures in the detailed
Hydrogeological Site Assessment (Section 11.0; Appendix).
The large canals and lateral ditches will be backfilled in a manner to minimize the former canals
serving as pathways of preferential migration for groundwater. Backfill will be deposited in
lifts of 1 foot (0.30 cm) with each lift compacted to at least 90% of the maximum dry density
determined by the standard proctor test (ASTM D-698). Failure to minimize preferential
migration will allow the former canals to function as french drains and short circuit the
groundwater flow at the site and jeopardize the restoration efforts.
The relatively shallow, lateral ditches may be backfilled in one lift. However, if this method
is selected for implementation, a series of clay dikes will be required across each lateral ditch
to minimize preferential migration and drainage. The clay dikes will be required to extend to
1 foot (0.30 cm) below the existing bottom of the ditch. After implementation of the selected
backfill method, the deposited material will have a hydraulic conductivity of 1.42x 10'8
inches/hour (3.6x104 cm/h) or less.
Fill material is available on-site from the spoil ridge along the western site boundary. This spoil
currently functions as a dike to prevent overbank flooding. Additional fill material is also
available by removing the road between the two tracts and grading a smooth transition from
the north to the south across the former canals and road. Fill material for the ditches and
canal should be low permeability clays or silty clays. However, due to the relative scarcity of
clays in spoil material, bentonite or montmorillonite clay will be mixed with fill material on-site
prior to placement and compaction.
Recommendations for Site Grading and Floodqlain Restoration
Along with backfilling the existing drainage system, portions of the site will be graded to
enhance hydrologic function. Spoil from dredging upper reaches of the Perquimans River is
piled along the stream bank running the length of the western property boundary. This MWOIS?l
has prevented or minimized overbank flooding within lower portions of the mitigation site. The
• ?re?-a?i??#oc fill
material. The western edge of the tract will then be gr e a ton? =feet
( f?lized tributary. A levee ??pr??cirateby-.t?e8 gym) tall
w ,ec aJgrQ_th&-stream bank. This levee will reproduce the functions of a natural
levee by delaying the recession of flood waters back into the channel, thus extending the
period of water storage within the floodplain. An opening in the levee will be constructed near
31
the north end to facilitate the diversion of flood waters onto the site. 1'u0oiVfield
o tions, elevations of flood waters in the field are expected to range between 10 and 11
feet (3.0 and 3.3 m) above msl. This grading and berm construction would facilitate the
restoration of riverine floodplain conditions adjacent to the canal. Estimated area of flood plain
restoration achieved using 11 feet (3.3 m) msl as the maximum elevation is approximately 34
acres. An additional 24 acres of floodplain enhancement would also be realized within low-
lying forested portions of the site. The estimated floodplain restoration and enhancement area
is presented in Figure 8. Acreage of floodplain resulting from restoration activities will be
substantiated by Rlacing a,xeamgauge;irr the adjacent below headwater tributary.
6.2.2 Plant Community Restoration
Restoration of wetland forested communities provides habitat for area wildlife and allows for
development and expansion of characteristic wetland dependent species across the landscape.
Ecotonal changes between community types developed through a landscape approach to
community restoration contribute to area diversity and provide secondary benefits, such as
enhanced feeding and nesting opportunities for mammals, birds, amphibians, and other wildlife.
RFE data and on-site observations, coupled with experience in forest ecosystem classification
and a review of the available literature, were used to develop the primary plant community
associations that will be promoted during community restoration activities. These community
associations include: 1) riverine swamp forest; 2) nonriverine swamp forest: organic soil
variant; 3) nonriverine swamp forest: mineral soil variant; and 4) coastal fringe sandhill forest:
non-hydric soil inclusions. Figure 9 provides a landscape portrayal of target vegetation
communities that will be promoted in the restoration process. Figure 10 identifies the location
of each community on the mitigation site. A summary of community restoration components
is provided.
Restoration of riverine swamp forest wetlands (34 acres) is designed to reestablish the major
component species which facilitate development of the community. The riverine swamp forest
community is targeted to support indicator species such as overcup oak (Quercus iyrata),
swamp cottonwood (Popuius heterophy//a), tupelo gum (Nyssa aquatica), bald cypress
(Taxodium distichum), Carolina ash (Fraxinus caroiiniana), and swamp hickory (Carya aquatica)
The riverine swamp forest community is expected to sustain periodic overbank flooding.
Nonriverine swamp forest community types have been subdivided into an organic soil variant
and a mineral soil variant based on ecological features. The subdivision of swamp forest
restoration areas into two planting regimes has been implemented primarily to target available
stems of Atlantic white cedar to landscape areas which contain soils of high organic content
and exhibit the potential for relatively long term soil saturation (Schafale and Weakley 1990;
32
! i
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i
i o?-ne i i ! i pM-?}3 i i i
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i
N
Estimated Floodplain
Area - 58 Acres
Figure: 8
Environmental Estimated Riverine/Floodplain
Services, Inc. Restoration Area
1318 Dale Street Dismal Swamp Mitigation Site Project: ER94018.7
Suite 220 Gates and Perquimans
Raleigh, NC 27605 Counties, NC
Date: 13 Apr 1995
33
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© Riverine Swamp Forest - 34 Acres
® Nonriverine Swamp/Atlantic White Cedar
Forest - Organic Soil Subtype -136 Acres
14? -
Environmental
Services, Inc.
1318 Dale Street
Suite 220
Raleigh, NC 27605
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Forested Area - 115 Acres N
Nonriverine Swamp Forest -
Mineral Soil Subtype - 315 Acres
Coastal Fringe Sandhill Forest 12 Acres
Figure: 10
Community Restoration
Map Units
Dismal Swamp Mitigation Site Project: ER94018.7
Gates and Perquimans
Counties, NC
Date: 13 Apr 1995
35
pers. comm. Brownlie, FWS Dismal Swamp National Refuge Office). The mineral soil variant
of the swamp forest restoration area may also include intermittent stems of Atlantic white
cedar, if planting sources are available. However, species such as laurel oak, swamp black
gum, willow oak, yellow poplar, and cypress may exhibit higher affinity for these areas.
The target community structure for nonriverine swamp forests is composed of swamp black
gum, cypress and Atlantic white cedar. Intermittent stems or dominating inclusions of laurel
oak, cherrybark oak (Quercus pagoda), green ash, yellow poplar, and willow oak are being
facilitated. Infrequent plantings of swamp hickory, Carolina ash, overcup oak, and tupelo gum
will also be encouraged in the target swamp forest canopy.
Opportunistic species which typically dominate disturbed swamp forests have been excluded
from initial community restoration efforts. Opportunistic species include loblolly pine, sweet
gum, and red maple. In addition,. American sycamore (Platanus occidentalis) has been
excluded due to the perceived low ecosystem value indicated by various natural resource
personnel. Efforts to inhibit early site domination by opportunistic species may be required
during the first several years of tree growth to encourage diversity. However, these species
should also be considered important components-of steady-state swamp forest communities
where species diversity has not been jeopardized.
The survival rate of Atlantic white cedar seedlings has not been fully researched to determine
survivability and causes of mortality. Therefore, this species should not be heavily relied upon
to achieve the success criteria outlined in the Vegetation Monitoring Plan (Section VI).
Evidence indicates that a major cause of mortality in planted seedlings is over-browsing by
deer. Methods to control deer browsing, such as tree shelters, should be considered. The
presence of dense successional thickets around planted seedlings may also limit deer
browsing. However, in some instances, the substantial decrease in growth rates and the
potential for over-topping by weedy species may reduce the benefits of this option. Regular
shrub and herb maintenance coupled with selective use of tree shelters may encourage higher
survival rates and more rapid growth.
The restoration of a coastal fringe sandhill community isolated within the wetland complex has
also been designed. Upland forest restoration plans are designed to enhance wetland functions
and to restore a wetland/upland forest ecotone that is considered rare in the region. The target
forest community is composed primarily of longleaf pine among intermittent stems of live oak,
turkey oak, dwarf post oak, scarlet oak, blackjack oak, and black gum. Additional upland
groundcover and understory elements such as black cherry (Prunus serotina), sassafras
(Sassafras albidum), Vacciniums (Vaccinium spp.), and other species are expected to migrate
from upland roadway edges and berms adjacent to the mitigation site.
36
For upland restoration areas, the planting regime can be modified to allow for maintenance of
food plots or other wildlife management features. Upland restoration efforts will be
coordinated with WRC, USFWS, or other management contingencies.
The following planting plan serves as the blueprint for community restoration. The anticipated
results stated in the Success Criteria are expected to reflect potential vegetative conditions
which may be achieved after steady-state conditions prevail over time.
Planting Plan
A planting plan is proposed for the mitigation areas to reestablish wetland community patterns
across the landscape. The plan consists of: 1) acquisition of available wetland species; 2)
implementation of proposed surface topography improvements; and 3) planting of selected
species on site. The COE bottomland hardwood forest mitigation guidelines (DOA 1993) were
utilized in developing this plan.
The species selected for planting will be dependent upon the availability ofocal seedling
sources at the time of planting. Target planting densities and total sus needed by species
are depicted in Table 5. Based on contacts with tree nurseries, the availability of Atlantic
white cedar and other species is limited. Advance notification to nurseries (1 year) will
facilitate availability of various non-commercial elements. An outline of planting groups is
provided.
1. Riverine/Floodplain Swamp Forest'
A. Overstory
1. Bald Cypress (Taxodium distichum)
2. Tupelo Gum (Nyssa aquatica)
3. Swamp Black Gum (Nyssa biflora)
4. Overcup Oak (Quercus lyrata)
5. Swamp Cottonwood (Populus heterophylla)
6. Green Ash (Fraxinus pennsylvanica)
7. Swamp Hickory (Carya aquatica)
8. Carolina Ash (Fraxinus caroliniana)
9. Laurel Oak (Quercus laurifolia)
'Certain characteristic canopy trees such as sweet gum (Liquidambar styraciflua), red maple (Acer rubrum), and loblolly
pine (Pious taeda) have not been incorporated into this plan because these species are expected through natural recruitment.
37
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B. Understory and Groundcover
Groundcover and understory elements are expected through natural recruitment
from adjacent swamp forest areas and stream banks.
II. Nonriverine Swamp Forest: Organic Soil Variant
A. Overstory
1. Atlantic White Cedar (Chamaecyparis thyoides)
2. Bald Cypress (Taxodium distichum)
3. Swamp Black Gum (Nyssa bif/ora)
4. Laurel Oak (Quercus laurifolia)
5. Green Ash (Fraxinus pennsylvanica)
6. Cherrybark Oak (Quercus pagoda)
7. Willow Oak (Quercus phellos)
8. Carolina Ash (Fraxinus caroliniana)
B. Understory and Groundcover
Groundcover and understory elements are expected through natural recruitment
from adjacent nonriverine swamp forest areas.
Atlantic white cedar plantings will be concentrated within organic soil areas of the
nonriverine swamp forest community as indicated appropriate by reference systems and
available information. However, the survival rate of Atlantic white cedar seedlings has
not been fully researched to determine survivability and causes of mortality. Therefore,
this species should not be heavily relied upon to achieve the success criteria outlined
in the Vegetation Monitoring Plan (Section VI).
Ill. Nonriverine Swamp Forest: Mineral Soil Variant
A. Overstory
1. Laurel Oak (Quercus laurifolia)
2. Willow Oak (Quercus phellos)
3. Cherrybark Oak (Quercus pagoda)
4. Swamp Black Gum (Nyssa biflora)
5. Bald Cypress (Taxodium distichum)
6. Green Ash (Fraxinus pennsylvanica)
7. Yellow Poplar (Liriodendron tulipifera)
39
8. Atlantic White Cedar (Chamaecyparis thyoides)
9. Swamp Chestnut Oak (Quercus michauxii)
B. Understory and groundcover
Groundcover and understory elements are expected through natural recruitment
from adjacent nonriverine swamp forest.
IV. Coastal Fringe Sandhill Forest
A. Overstory
1. Longleaf Pine (Pious Palustris)
2. Live Oak (Quercus virginiana)
3. Water Oak (Quercus nigra)
4. Blackjack Oak (Quercus marilandica)
6. Dwarf Post Oak (Quercus stellata)
7. Scarlet Oak (Quercus coccinea)
8. Black Gum (Nyssa sylvatica)
9. Turkey Oak (Quercus laevis)
10. Mockernut Hickory (Carya tomemtosa)
B. Understory and groundcover
Additional upland groundcover and understory elements such as black cherry
(Prunus serotina), sassafras (Sassafras albidum), vacciniums (Vaccinium spp.),
and other species are expected to migrate from upland roadway edges and
berms adjacent to the mitigation unit.
Coastal sandhill/longleaf pine-oak forest areas represent a small portion of the
acreage to be planted during restoration activities. This planting regime can be
modified to allow for maintenance of food plots within forest interiors. Upland
restoration efforts will be coordinated with the WRC, the FWS, or other
management contingencies.
Planting Program
Bare root seedlings of tree species will be planted on 8-foot (2.4 m) centers (680 trees/acre)
within the specified map areas. In restoration areas, species at the relative densities indicated
in Table 5 will be alternated within adjacent centers whenever feasible. Planting will be
performed between December 1 and March 15 to allow plants to stabilize during the dormant
period and set root during the spring season. Standard tree tube shelters may also be used
40
on select stems to promote survival. Removal or control of competing nuisance vegetation will
be implemented as necessary to ensure adequate survival of target wetland and upland plants.
6.2.3 Wetland Soil Restoration
Land use practices have impacted soil characteristics on the mitigation site. Impacts include
the minimization of hydric conditions in upper soil horizons, the reduction in organic matter
content through accelerated decomposition, the placement of spoil ridges along the site, and
the elimination of surface microtopography by farming activities. The filling of canals and
ditches as proposed during hydrological restoration should-serve to reintroduce hydric soil
conditions and halt the long-term reductions in organic matter content. Further soil
remediation tasks include removal of spoil ridges, reestablishment of surface microtopography,
and construction of a natural levee formation within former floodplains of headwaters to the
Perquimans River.
During hydrological restoration efforts, fill for ditches will be obtained, wherever feasible, from
spoil ridges along the western property boundary and central portions of the tract. Any spoil
ridges which remain after hydrological restoration is complete will be removed from the
mitigation site. Spoil areas will be graded to the elevation of historic surface and landscaped
to produce a smooth transition across the former spoil ridge and adjacent canal.
Reference wetlands within relatively undisturbed portions of the Dismal Swamp exhibit
complex surface microtopography. Small concavities, swales, exposed root systems, and
hummocks associated with vegetative growth and hydrological patterns are scattered
throughout the system. Large woody debris and partially decomposed litter provide additional
complexity across the wetland soil surface. Efforts to advance the development of
characteristic surface roughness will be implemented on the mitigation site. Limited bedding
and rowing to be implemented during planting activities will promote the formation of
hummocks and concavities that act to increase surface storage and provide micro-habitat for
invertebrates, reptiles, and amphibians. Scarification of surface soils between planted trees
will further promote surface microtopography on the mitigation site.
Along the western edge of the property, a spoil ridge has been constructed to prevent or
minimize overbank flooding from upper reaches of the Perquimans River. Soil subhorizons
adjacent to the tributary indicate that deposition of fluvial sediments historically occurred in
the low-lying area (Figure 8). In addition, back-water flooding of this area occurred in
December 1994 as a result of drainage overflow from a perpendicular canal which feeds into
the main channel. Therefore, removal of the spoil ridge should reestablish overbank flooding
and back-water flooding within the soils unit. The western edge of the mitigation site will be
graded down to an elevation of eight feet (2.4 m) at the bank of the canal. A levee
41
approximately 1 foot (.30 cm) tall will be constructed along the canal bank. This levee will
reproduce the functions of a natural levee by delaying the recession of flood waters back into
the channel, thus extending the period of water storage and fluvial deposition of sediments
within the floodplain. An opening in the levee will be constructed near the north end to
facilitate the diversion of flood waters onto the wetland soil unit.
42
7.0 MONITORING PLAN
Monitoring of wetland restoration and enhancement efforts will be performed until success
criteria are fulfilled. Monitoring is proposed for two wetland components, vegetation and
hydrology. Wetland soils currently exist within restoration areas and monitoring is not
considered necessary to verify hydric soil requirements for a jurisdictional determination.
7.1 Hydrology Monitoring
While hydrological modifications are being performed on the site, surficial monitoring wells will
be designed and placed in accordance with specifications in U.S. Corps of Engineers', Installing
Monitoring Wells/Piezometers in Wetlands (WRP Technical Note HY-IA-3.1, August 1993).
Monitoring wells will be set to a depth 24 inches below the soil surface.
pproximate 24 surficial monitoring wells will be imbedded within vegetation sampling plots
to provide representataive coverage within each of the three wetland ecosystem types.
Ecosystem types are depicted as community restoration map units (Figure 10) which support
similar soils, landform, and target community, structure. Hydrological sampling will be
performed throughout the growing season at intervals necessary to satisfy the hydrology
success criteria within each community restoration area (EPA 1990).
In order to substantiate the extent of floodplain restoration along the Perquimans River, a
stream gauge will be placed in the adjacent tributary. Stream gauge data will determine the
elevational reach and frequency of overbank flooding events.
7.2 Hydrology Success Criteria
Target hydrological characteristics include saturation or inundation for at least 12.5% of the
growing season at lower landscape positions, during average climatic conditions. Upper
landscape reaches and areas near perimeter canals may exhibit surface saturation/inundation
for between 5% and 12.5% of the growing season based on well data. These 5%-12% areas
are expected to support hydrophytic vegetation within organic soils of low permeability. If
wetland parameters are marginal as indicated by vegetation and hydrology monitoring,
consultation with COE personnel will be undertaken to determine jurisdictional extent in these
I

tranSlL %J"G areas.
i?Stream gauge data will be utilized, by flood event frequency and the elevation of each flood
event, to substantiate the area of floodplain restoration. Stream gauge monitoring and
floodplain area calculations will require average climatic condition including an average
distribution of peak storm events. 1
43
7 .3 Vegetation
Restoration monitoring procedures for vegetation are designed in accordance with EPA
guidelines enumerated in Mitigation Site Type (MiST) documentation (EPA 1990) and COE
Compensatory Hardwood Mitigation Guidelines (DOA 1993). A general discussion of the
restoration monitoring program is provided.
After planting has been completed in winter or early spring, an initial evaluation will be
performed to verify planting methods and to determine initial species composition and density.
Supplemental planting and additional site modifications will be implemented, if necessary.
During the first year, vegetation will receive cursory, visual evaluation on a periodic basis to
ascertain the degree of overtopping of planted elements by nuisance species. Subsequently,
quantitative sampling of vegetation will be performed between August 1 and September 31
after each growing season until the vegetation success criteria is achieved.
During quantitative vegetation sampling in early fall of the first year, 0.05 acre plots will be
randomly placed with' a ch restored ecosystem type. Due to the homogeneity of the Dismal
Swamp landscape, proximat y 48 plots (2.4 acre total) will be established to provide a
0.5% sample of there ration area. Sample plot distributions will be correlated with
hydrological monitoring locations to provide point-related data on hydrological and vegetation
parameters. In each 0.05-acre sample plot, vegetation parameters to be monitored include
average tree height, species composition, density, and basal area. Visual observations of the
percent cover of shrub and herbaceous species will also be recorded.
7.4 Vegetation Success Criteria
Success criteria have been established to verify that the wetland vegetation component
supports community components necessary for a jurisdictional determination. Additional
success criteria are dependent upon the density and growth of characteristic forest species.
Specifically, a minimum mean density of 320 characteristic tree species/acre must be surviving
for at least 3 years after initial planting. _ rats
CO planting plan along with natural recruitment of sweet gum, red maple,
American sycamore, and loblolly pine. Loblolly pine (softwood species) cannot comprise more
than 10% of the 320 stem/acre requirement. In addition, at least five other character tree
species must be present, and no species can comprise more than 20% of the 320 stem/acre
total. Supplemental plantings will be performed as needed to achieve the vegetation success
criteria.
44
No quantitative sampling requirements are proposed for herb and shrub assemblages as part
of the vegetation success criteria. Development of a swamp forest canopy over several
decades and restoration of wetland hydrology will dictate the success in migration and
establishment of desired wetland understory and groundcover populations. Visual estimates
of the percent cover of shrub and herbaceous species and photographic evidence will be
reported for information purposes.
7.5 Report Submittal
An "as built" plan drawing of the area, including initial species compositions by community
type, and sample plot locations, will be provided after completion of planting. A discussion
of the planting design, including what species were planted, the species densities and numbers
planted will also be included. The report will be provided within 90 days of completion of
planting.
Subsequently, reports will be submitted yearly to appropriate permitting agencies following
each assessment. Submitted reports will document the sample transect locations, along with
photographs which illustrate site conditions.
Surficial well data will be presented in tabular format. The duration of wetland hydrology
during the growing season will also be calculated within each community restoration map unit
(Figure 10).
The survival and density of planted tree stock will be reported. In addition, character tree
mean density and average height as formatted in the Vegetation Success Criteria will be
calculated. A visual estimate and photographic evidence of the relative percent cover of
understory and groundcover species will be generated.
7.6 Contingency
In the event that vegetation or hydrology success criteria are not fulfilled, a mechanism for
contingency will be implemented. For vegetation contingency, replanting and extended
monitoring periods will be implemented if community restoration does not fulfill minimum
species density and distribution requirements.
Hydrological contingency will require consultation with hydrologists and regulatory agencies
in the event that wetland hydrology restoration is not achieved during the monitoring period.
Recommendations for contingency to establish wetland hydrology will be implemented and
monitored until the Hydrology Success Criteria are achieved.
45
8.0 MITIGATION CREDIT EVALUATIONS
Figure 11 depicts mitigation design units generated through integration of mitigation design
studies. Mitigation units identified include riverine wetland restoration (34 acres), riverine
wetland enhancement (24 acres), nonriverine wetland restoration (394 acres), nonriverine
wetland preservation/management (91 acres), upland forest restoration (12 acres), and
wetland buffer restoration/establishment (adjacent to perimeter canals; 57 acres).
Potential mitigation credit for the various design strategies should be determined based on
wetland functional evaluations and a review of available research and literature. A summary
of evaluation techniques and comparison of wetland functions between impacted and
mitigation wetlands is provided.
8.1 Wetland Functional Evaluations
Mitigation planning has been oriented towards replacing wetland functions diminished or lost
due to widening of the subject segment of US 17 (R-2208A). Wetland restoration and
enhancement strategies have been designed to exceed those functions believed to be present
(and eventually lost) within the intended road widening corridor.
A subjective wetland functional evaluation was undertaken on the mitigation site and impact
areas to evaluate functional replacement needs. The study involved visual evaluations of
hydrogeomorphic (HGM) wetland functions outlined in various research and project literature
(Brinson 1994, ESI 1994a, ESI 1994b). Specific wetland functions evaluated are presented
in Table 6. This assessment has been expanded in an effort to categorize functions into three
primary areas: a) hydrodynamics; b) biogeochemical processes; and c) maintenance of biotic
resources. Proposed mitigation seeks both spatial and functional replacement for impacted
wetland resources.
An objective I unctional r ses.Sndh **hWTT40 perform> dinate, through multivariate
analysis, the range of wetland functions that occur within subject wetland classes. Reference
wetland data sets e
p M _ ce" for characteristic wetland functions. In addition, the I
d. In this study, reference wetland systems were
evaluated in the field by ecologists to discern the features present within relatively undisturbed
(reference) wetlands. Subsequently, impacted wetlands and mitigation activities were
subjectively compared to reference conditions as an indicator of differences in existing or
projected wetland functions. Projected performance of wetland functions on the mitigation
site was in -m condit?ortis ewp'? fifer mitigation activities are completed.
ppw
46
© Riverine Floodplain Restoration - Wetland Preservation/Management - N
Wetland Restoration - 34 Acres 91 Acres
etlan Restoration - Upland Restoration - 12 Acres
Wetland d Enhancement - 24 Acres
0 Wetland Restoration - 394 Acres ® Wetland Buffer Restoration - 57 Acres i
aPa-
41 xi? Environmental Wetland Mitigation Figure: 11
Services, Inc. Design Units
1318 Dale Street Dismal Swamp Mitigation Site Project: ER94018.7
Suite 220 Gates and Perquimans
Raleigh, NC 27605 Counties, NC
Date: 13 Apr 1995
47
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49
Reference Forest Ecosystem (RFE) areas within the adjacent Great Dismal Swamp Refuge were
utilized as an indicator of maximum sustainable performance for characteristic wetland
functions. Target functions have been identified based on the types of wetlands to be
impacted; primarily nonriverine/interstream, temporarily saturated wetlands (PFO 1 A, PF01 /4A,
PF04Ad) and riverine/bottomland, seasonally flooded wetlands (PF01 C, PFOI/2C).
Nonriverine/interstream, temporarily saturated wetlands are the dominant wetland type likely
to be impacted by US 17 widening (8.4 acres; Section III, Table 1). These systems currently
provide limited hydrodynamic functions such as subsurface storage of water, moderation of
groundwater flow, and surface water discharge. Limitations are primarily due to adjacent
agricultural practices and the positioning of nonriverine wetlands along broad interstream flats,
with precipitation representing the principal water source entering these wetlands (limited
connectivity with surface waters). Biogeochemical functions (nutrient cycling, removal of
elements from cropland drainage, and particulate retention) are somewhat more important
because these systems may act as sumps which collect overland runoff from adjacent
agricultural fields. However, both functions may have been jeopardized by farmland
encroachment, soil compaction through mechanized logging, extensive ditching, and
surrounding site disturbances. Community maintenance (structural integrity, habitat for
wildlife, interspersion and connectivity with larger systems) is typically an important function
of nonriverine forested wetlands. However, many of the impacted interstream wetlands in the
US 17 corridor exhibit reduced community maintenance functions due to fragmentation and
other impacts from human use.
Mitigation has been proposed to provide spatial and functional replacement - and enhancement
- for these functions. Nonriverine swamp forests will be restored through reestablishment of
area hydrology and active planting on converted farmland at the Dismal Swamp mitigation site.
Due to adjacency and connectivity of nonriverine restoration areas to the Perquimans River,
important hydrodynamic functions expected after mitigation include moderation of
groundwater flow and subsurface storage of water. The transformation of farmland adjacent
to the tributary into seasonally to semi-permanently inundated wetlands will also maximize
biochemical functions such as retention of particulates, removal of elements and compounds,
and nutrient cycling. Retention features in the restored wetlands result primarily from spatial
elimination of agricultural land immediately adjacent to the tributary. Although restored
physical functions exceed those in impacted nonriverine systems, maximum sustainable
performance for hydrodynamic and biochemical functions on the mitigation site may never be
fully realized. Functional performance may be limited due to the presence of large drainage
systems and canals in managed pine plantations upslope of the mitigation area. Diversion of
regional groundwater flow into drainage systems and shunting of resulting surface water into
area streams may decrease the capability of wetlands to store, retain, and filter surface and
50
groundwater components. However, restoration activities are expected to induce substantial
changes in lateral surface/subsurface flow in restored agricultural areas.
Biotic functions in nonriverine wetland restoration areas will include maintenance of habitat
for certain terrestrial and semi-aquatic wildlife guilds. Species populations promoted include
those dependent upon interspersion and connectivity with bottomland areas along with the
need for forest interior habitat. These interstream functions are considered degraded along
interstream wetland fringes impacted by US 17 widening. Habitat value and community
maintenance functions will also be improved by creation and interconnection of four plant
community types along the wetland/upland environmental gradient. Cover will be expanded
and species diversity may be promoted within southern portions of the Great Dismal Swamp
complex.
Riverine/bottomland, seasonally flooded wetlands (PF01 C) represent the second most
impacted wetland type in the US 17 corridor (3.3 acres; Section III, Table 1). Because
bottomiand systems are typically situated immediately adjacent to area streams, these
wetlands have the potential to provide significant hydrodynamic, biochemical, and community
maintenance functions. PF01 C wetlands have the potential to attenuate floodflow, provide
for long-term surf ace/subsurf ace water storage, moderate riparian groundwater discharge, and
retain sediments or other elements. Habitat diversity and resulting species diversity is
generally higher in bottomland wetlands. In the impact area, bottomland functions may have
been compromised by channelization (which has reduced frequency, depth, and extent of over
bank flooding) and through encroachment from agriculture However, these wetlands continue
to represent a valuable resource for the region. Functional replacement is considered
paramount.
Mitigation provides for restoration and enhancement of a contiguous wetland area situated
immediately adjacent to headwaters of the Perquimans river. The entire wetland site will
function as a stream-side management zone (SMZ) with resultant benefits to the riverine
system. Provisions for overbank flooding into relict floodplain areas of the mitigation site will
also be facilitated. Historical drainage patterns and resultant benefits to bottomland systems
will result. Restoration of hydrodynamic and biogeochemical processes in riverine and
nonriverine systems should result in improvements to water quality in the below headwater
tributary. In addition, the presence of contiguous, restored natural communities from upland
sandhill forests to bottomland swamp forests will provide wildlife habitat of greater area-wide
function than the collective sum of narrow crossings of impacted PFO1 C systems in the US
17 widening corridor.
51
8 .2 Mitigation Credit Evaluations
As planned, US 17 (R2208A) construction will affect approximately three acres of
riverine/bottomland wetlands (PF01 C, PF01 /2C) and 9 acres of nonriverine/interstream
wetlands (PF01 /4A, PF04Ad), for a total of 12 acres of expected impacts. Most of these
impacted systems exhibit functional attributes which have been reduced or diminished through
fragmentation, ditching, farm ing/silvicultural activities, or other land use practices.
A ditch impact study is currently underway to determine the indirect affects associated with
construction of drainage ditches along the US 17 alignment. If additional wetland impacts are
found to occur, this additional acreage will also be mitigated at the proposed Dismal Swamp
site under supplemental documentation.
Approximately 612 acres are being offered for R-2208A mitigation needs and as a mitigation
bank for future transportation projects. Restoration and enhancement strategies are designed
to create riverine and nonriverine wetland ecosystems which support an array of native plant
and wildlife communities. Site hydrology will be restored and native wetland communities will
be reestablished. Connectivity with the Great Dismal Swamp complex and adjacency to the
Perquimans River afford opportunities which go beyond enhancement of on-site wetland
functions. Restoration and enhancement strategies will contribute to regional diversity as well.
Integration of wetland and upland interfaces are an important part of this mitigation plan.
Wetland buffers will be restored along remaining canals, offering an ecological gradient from
uplands to wetlands and providing for ecotonal fringes. "gMeMsImemmemwill
re *09 t df,dW car a'n'?iander it"thTag"nxo 1. of pliilIdik -80-4 'g rive"- anks
and _. , ' ra,diths. Without upland restoration/enhancement and wetland
„ -a-
buffer establishment, intrinsic functions in adjacent, restored components may be diminished
or lost.
The acreages for each Dismal Swamp mitigation design/credit map unit (Figure 11) are
summarized in the following table:
Mitigation Strategy
Nonriverine Wetland Restoration
Riverine Wetland Restoration
Riverine Wetland Enhancement
Nonriverine Wetland Preservation/Management
Wetland/Upland Ecotone Restoration
Wetland Buffer Restoration (Adjacent to perimeter canals)
TOTAL
Acreage
394
34
24
91
12
57
612
52
Based on the proposed mitigation strategy, hydrogeological modeling results, subjective
wetland functional evaluations, and current research, this mitigation project is expected to
meet and exceed mitigation needs associated with US 17 widening. After debiting for the R-
2208A project, remaining credits will be available for projects in the region which impact
wetlands of comparable type and function. It is expected that excess credits from the Dismal
Swamp site will be developed into a regional mitigation bank, with appropriate protocols
established for use and debiting of the bank.
53
9.0 DISPENSATION OF PROPERTY
NCDOT is in the process of soliciting conservation groups and natural resource agencies for
final dispensation of properties. Representatives from the N.C. Wildlife Resources Commission
(WRC) and the U.S. Fish and Wildlife Services have visited the site. At present, WRC is
considered the most appropriate recipient of the land for incorporation into the state gamelands
program.
Transfer of the property will occur upon implementation of the proposed mitigation strategy.
The NCDOT will remain responsible for meeting success criteria established in the mitigation
plan. Stipulations will be incorporated into the deed upon transfer to the accepting resource
agency to insure that the property remains as conservation land in perpetuity.
54
10.0 REFERENCES CITED
Adamus P.R., L.T. Stockwell, E.J. Clairain Jr., M.E. Morrow, L.P. Rozas, R.D. Smith. 1991.
Wetland Evaluation Technique (WET), Volume 1: Literature Review and Evaluation
Rationale. Wetlands Research Program Technical Report WRP-DE-2. U.S. Army Corps
of Engineers Waterways Experiment Station. Vicksburg, MS.
Adamus, P.R., E.J. Clairain, Jr., R.D. Smith, and R.E. Young. 1987. "Wetland Evaluation
Technique (WET); Volume II: Methodology," Operation Draft Technical Report Y-87-_
U.S. Army Engineer Waterways Experiment Station, Vicksburg, Mississippi.
Adamus P.R., L.T. Stockwell. 1983. A Method for Wetland Functional Assessment, Volume
1. Critical Review and Evaluation Concepts. Federal Highway Administration Report
no. FHWA-IP-82-23. U.S. Department of Transportation, Washington, D.C.
Baumer, 0. and J. Rice. 1988. Methods to predict soil input data for DRAINMOD ASAE
Paper No. 88-2564. ASAE, St. Joseph, MI 49085.
Beals, E.W. 1984. Bray-Curtis Ordination: an Effective Strategy for Analysis of Multivariate
Ecological Data. Advances in Ecological Research, Volume 14. Academic Press, Inc.
Belcher, H. W. and G. E. Merva, 1987, Results of DRAINMOD verification study for
Zeigenfuss, soil and Michigan climate. ASAE Paper No. 87-2554. ASAE, St. Joseph,
MI 49085.
Brinson, M.M. 1993. A Hydrogeomorphic Classification for Wetlands. Wetlands Research
Program Technical Report WRP-DE-4. U.S. Army Corps of Engineers, Washington, DC.
Brinson, M.M., F.R. Hauer, L.C. Lee, R.P. Novitzki, W.L. Nutter, and D.F. Whingham. 1994.
Guidebook for Application of Hydrogeomorphic Assessments to Riverine Wetlands. The
National Wetlands Science Training Cooperative. Seattle, WA.
Brinson M., B. Swift, R. Plantico, J. Barclay. 1981. Riparian Ecosystems: Their ecology and
status. U.S. Fish and Wildlife Service FWS/OBS 81/17
Brower, J.E., J.H. Zar, and C. N. von Ende. 1990. Field and Laboratory Methods for General
Ecology. William C. Brown Publishers, Debuque, IA.
Brown, Philip M., et al, 1985, Geologic Map of North Carolina, North Carolina Department
of Natural Resources and Community Development, 1-.500,000 scale.
55
Castelle, A.J. et a/. 1992. Wetland Mitigation Ratios: defining equivalency. Shorelands and
Coastal Zone Management Program, Washington State Department of Ecology.
Olympia, WA.
U.S. Army Corps of Engineers (COE). 1993. Corps of Engineers (COE). WRP Technical Note
HY-IA-3.1 August 1993, Waterways Experiment Station, COE, Vicksburg, Mississippi.
Cooper, H. H., Jr., J. D. Bredehoft, and I. S. Papadopoulos. 1967. Response of a finite-
diameter well to an instantaneous charge of water. Water Resources Research, 3, pp
263-269.
Cowardin, L.M., V. Carter, F. C. Golet, and Edward T. Laroe. 1979. Classification of Wetland
and Deepwater Habitats of the United States. Fish and Wildlife Service, U.S.
Department of Interior.
Department of the Army (DOA). 1993 (unpublished). Corps of Engineers Wilmington District.
Compensatory Hardwood Mitigation Guidelines (12/8/93).
Department of the Army (DOA). 1987. Corps of Engineers Wetland Delineation Manual.
Tech. Rpt. Y-87-1, Waterways Experiment Station, COE, Vicksburg, Mississippi.
Department of Natural Resources and Community Development (DNR). 1985. Geologic Map
of North Carolina. NC Geological Survey.
Environmental Protection Agency (EPA). 1990. Mitigation Site Type Classification (MIST).
A methodology to classify pre-project mitigation sites and develop performance
standards for construction and restoration of forested wetlands. EPA Workshop,
August 13-15, 1989. EPA Region IV and Hardwood Research Cooperative, NCSU,
Raleigh, North Carolina.
Environmental Services, Inc. (ESI). 1994a; unpublished. Determination of applicable
mitigation credit For restoration of wetland buffers and wetland/upland ecotones: US
64 wetland restoration and conservation management plan, US 64 relocation, Martin
and Edgecombe Counties, North Carolina. Provided to the N.C. Department of
Transportation.
Environmental Services, Inc. (ESI). 1994b; unpublished. Mitigation Plan: Northeast Florida
Wetland Mitigation Bank. Technical Report for St. Johns River Water Management
District, Palatka Fla.
56
Federal Interagency Committee for Wetland Delineation (FICWD). 1989. Federal Manual for
Identifying and Delineating Jurisdictional Wetlands. U.S. Army Corps of Engineers,
U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, and U.S.D.A.
Soil Conservation Service, Washington, D.C. Cooperative Technical Publication. 76
pp. plus appendices.
Fouss, J. L., R. L. Bengtson and C. E. Carter, 1987, Simulating subsurface drainage in the
lower Mississippi Valley with DRAINMOD. Transactions of the ASAE 30 (6)-. 1679 -
1688.
Gantt, L.K. and D.A. Dell. 1992. Two Case Studies in Mitigation Banking: Can We Afford
It? Pp. 180-187 in T.A. Kusler and C. Lassonde (eds). Proceedings from a National
Wetland Symposium: Mitigation Banks and Joint Projects in the Context of Wetland
Management Plans. Palm Beach Gardens, FL. June 24-27, 1992.
Gayle, G., R. W. Skaggs and C. E. Carter, 1985, Evaluation of a water management model for
a Louisiana sugar cane field. J. of Am. Soc. of Sugar Cane Technologists, 4: 18 - 28.
Hvorslev, M. J. 1951. Time lag and soil permeability in groundwater observations. U.S. Army
Corps of Engineers Waterways Experimental Station Bulletin 36, Vicksburg, MS.
Jones, S.M. 1989. Application of Landscape Ecosystem Classification in Identifying
Productive Potential of Pine-Hardwood Stands. (in) Pine-Hardwood Mixtures: a
Symposium on Management and Ecology of the Type. Waldrop, T.E. (ed).
Southeastern Forest Experiment Station, Asheville, NC.
Karr, J.R., I.J. Schlosser. 1978. Water resources at the land-water interface. Science
201:229-234.
Keller, M.E., C.S. Chandler, and J.S. Hatfield. 1993. Avian communities in riparian forests
of different widths in Maryland and Delaware. Wetlands 13(2): 137-144, Special
Issue, June 1993. The Society of Wetland Scientists.
Laney, R.W., D.L. Stewart, G.R. McCrain, C. Mayer and V. Bruton. 1988. Final report on the
North Carolina Department of Transportation Company Swamp Mitigation Bank, Bertie
County, North Carolina. U.S. Department of the Interior, FWS, Raleigh, NC. 58 p.
McCrain, G.R. 1992. Habitat Evaluation Procedures (HEP) applied to mitigation banking in
North Carolina. Journal of Environmental Management. 35:153-162.
57
. 1994 Mitigation Ratios in the Southeast. Paper presented at the Annual
Symposium. Society of Wetland Scientists, May 31-June 3, 1994. Portland Oregon.
Neffsinger, R.E., R.W. Laney, A.M. Nichols, D.L. Stewart, D.W. Steffeck. 1984. Prulean
Farms,lnc., Dare County, North Carolina. A Fish and Wildlife Coordination Act Report.
U.S. Department of Interior, Fish and Wildlife Service, Raleigh, NC. 200 p.
Page, R.W. and L.S. Wilcher. 1990. Memorandum of Agreement Between the EPA and the
DOE Concerning the Determination of Mitigation Under the Clean Water Act, Section
404(b)(1) Guidelines. Washington, DC.
Peet, R.K., Christensen, N.L. 1980. Hardwood Forest Vegetation of the North carolina
Piedmont. Veroff. Geobot. Inst. ETH, Stiftung Rubel, Zurich 69. Heft (1980), 14-39.
Rogers, J. S., 1985, Water management model evaluation for shallow sandy soils.
Transactions of the ASAE 28 (3): 785-790.
Sacco, J.B. 1990. Infaunal Community Development of Artificially Established Salt Marshes
in North Carolina. Master's Thesis. N.C. State University, Raleigh, NC
Schafale, M.P. and A.S. Weakley. 1990. Classification of the Natural Communities of North
Carolina: Third Approximation. NC Natural Heritage Program, Division of Parks and
Recreation, NC Department of Environment, Health, and Natural Resources, Raleigh,
NC.
Skaggs, R. W., 1980, A water management model for artificially drained soils. Tech. Bull.
No. 267, North Carolina Agricultural Research Service, N.C. State University, Raleigh.
54 pp.
Skaggs, R. W., 1982, Field evaluation of a water management simulation model.
Transactions of the ASAE 25 (3): 666 - 674.
Skaggs, R. W., N. R. Fausey and B. H. Nolte, 1981, Water management evaluation for North
Central Ohio. Transactions of the ASAE 24 (4): 922 - 928.
Skaggs, R. W., J. W. Gilliam and R. 0. Evans, 1991, A computer simulation study of pocosin
hydrology. Wetlands (1 1): 399 - 416.
Skaggs, R.W., et a[, 1993, Methods for Evaluating Wetland Hydrology. ASAE meeting
presentation Paper No. 921590. 21 p.
58
Susanto, R. H., J. Feyen, W. Dierickx and G. Wyseure, 1987, The use of simulation models
to evaluate the performance of subsurface drainage systems. Proc. of Third
International Drainage Workshop, Ohio State Univ., pp. A67 - A76.
U.S. Department of Agriculture (USDA). 1986. Soil Survey of Chowan and Perquimans
Counties, North Carolina, USDA Natural Resource Conservation Service.
U.S. Department of Agriculture (USDA). 1994 (unpublished). Soil Survey of Gates County,
North Carolina, USDA Natural Resource Conservation Service.
U.S. Department of Agriculture (USDA). 1987. Hydric Soils of the United States. In
cooperation with the National Technical Committee for Hydric Soils, USDA Natural
Resource Conservation Service.
U.S. Department of Interior (USDI). 1980. Hbitat evaluation procedures. Fish and wildlife
Service, Division of Ecological Services, Washington, DC. 102 ESM.
U.S. Fish and Wildlife Service (USFWS). 1981. Habitat Evaluation Procedures Workbook.
National Ecology Research Center.
Van Lear D.H., Jones S.M. 1987. An example of site clasiification in the southern coastal
plain based on vegetation and land type. Southern Journal of Applied Forestry.
11(1):23-28.
Ward, L. W., Bailey, R. H., Carter, J. G., 1991, "Pliocene and Early Pleistocene Stratigraphy,
Depositional History, and Molluscan Paleobiology of the Coastal Plain." in The Geology
of the Carolinas, J. Wright Horton, Jr., and Victor A. Zullo, eds. The University of
Tennessee Press, Knoxville TN.
59
11.0 APPENDICES
HYDROGEOLOGICAL SITE ASSESSMENT
FOR
GREAT DISMAL SWAMP MITIGATION SITE
GATES - PERQUIMANS COUNTIES
ESI Job No.: ER94-018.2(8-2208A)
Prepared for:
N.C. Department of Transportation
1 South Wilmington St.
Raleigh, NC 27601
Prepared by:
ENVIRONMENTAL SERVICES, INC.
1318 Dale St., Suite 220
Raleigh, NC 27605
TEL [phone] FAX [phone]
March, 1995
HYDROGEOLOGICAL SITE ASSESSMENT
FOR
GREAT DISMAL SWAMP MITIGATION SITE
GATES - PERQUIMANS COUNTIES
ESI Job No.: ER94-018.2
Prepared for:
North Carolina Department of Transportation
1 South Wilmington St.
Raleigh, North Carolina 27601
Issue Date: 31 March 1995
Gerald R. McCrain, Ph.D., CEP
Vice President
Brian L. Hayes, P.G.
Senior Hydrogeologist
Signature
Signature
ENVIRONMENTAL SERVICES, INC.
13 18 Dale St., Suite 220
Raleigh, North Carolina 27605
TEL [phone] FAX [phone]
C:\ W PTEXT94\ESI\PROJECT\ER94.018.2\G WMOOL.REP

iy.
TABLE OF CONTENTS
LIST OF FIGURES
1. EXECUTIVE SUMMARY ........................................ iii
1.0 INTRODUCTION ..............................................1
1.1 Background ............................................... 1
2.0 SITE CHARACTERIZATION ACTIVITIES .............................. 4
2.1 Exploratory Soil Borings and Observation Well Installation ............. 4
2.2 Hydraulic Conductivity Testing ................................ 4
2.3 Water Level Measurements .................................. 5
2.4 Surveying .............................................. 5
3.0 GEOLOGY AND HYDROGEOLOGY ................................. 7
3.1 Regional Geology ...................................... 7
3.2 Local Geology ........................................... 7
3.3 Regional Hydrogeology ..................................... 8
3.4 Local Hydrogeology ....................................... 8
4.0 GROUNDWATER MODELING & RESULTS ............................ 18
4.1 Groundwater Model ...................................... 18
4.2 Model Description ....................................... 19
4.3 Model Calibration ........................................ 19
4.4 Model Results .......................................... 21
5.0 RECOMMENDED SITE ALTERATIONS TO PROMOTE WETLAND HYDROLOGY .. 23
5.1 Recommendations For Filling Drainage Ditches ................... 23
5.2 Recommendations for Site Grading ............................ 23
6:0 REFERENCES CITED ........................................... 25
LIST OF FIGURES
Figure 1 - Location map, Dismal Swamp
proposed mitigation tract ............................................. 2
Figure 2 - Well location map ..................................... Attached
Figure 3- Geologic cross sections fo selected transects .................. Attached
Figure 4 - Groundwater flow, December 8, 1994 ............................. 9
Figure 5 - Groundwater flow, December 13, 1994 ...................... ..... 10
Figure 6 - Groundwater flow, December 20, 1994 ...................... ..... 11
Figure 7 - Groundwater flow, December 28, 1994 ...................... ..... 12
Figure 8 - Groundwater flow, January 5, 1995 ........................ ..... 13
Figure 9 - Groundwater flow, January 10, 1995 ....................... ..... 14
Figure 10 - Groundwater flow, January 18, 1995 ...................... ..... 15
Figure 11 - Groundwater flow, January 25, 1995 ...................... ..... 16
Figure 12 - Conceptualized grading of site for restoration ................. Attached
Figure 13 - Estimated boundaries of wetland restoration
(5 cm surface storage) ......................................... Attached
Figure 14 - Estimated boundaries of wetland restoration
(10 cm surface storage) ........................................ Attached
Figure 15 - Estimated maximum extent of seasonal flooding ............... Attached
LIST OF TABLES
Table 1 - Groundwater measurement and water table
elevations - Dismal Swamp mitigation site ................................. 6
Table 2 - Soil input parameters ........................................ 20
Table 3 - Results of DRAINMOD simulations for saturation within 30 cm of surface
for selected percentages of the growing season (surface storage = 5 cm) ......... 22
Table 4 - Results of DRAINMOD simulations for saturation within 30 cm of surface
for selected percentages of the growing season (surface storage = 10 cm) ........ 22
HYDROGEOLOGICAL SITE ASSESSMENT
FOR
GREAT DISMAL SWAMP MITIGATION SITE
GATES - PERQUIMANS COUNTIES
1. EXECUTIVE SUMMARY
Environmental Services Inc.(ESI), was contracted by North Carolina Department of
Transportation (NCDOT) Planning and Environmental Branch to conduct a hydrogeological site
assessment of two tracts of land in Gates and Perquimans Counties, North Carolina which
NCDOT held an option to purchase and subsequently purchased . The two tracts are located
adjacent to one another and cross the boundaries between the counties . The total acreage
of the subject properties is 611 acres, of which approximately 115 acres consist of forested
jurisdictional wetlands . The remainder of the properties are comprised of prior converted
farmlands which have been drained by a series of ditches and canals.
ESI conducted the hydrogeological assessment as part of the development of a comprehensive
mitigation plan . In order to characterize existing conditions ESI performed a series of
exploratory soil borings and installed a series of 26 shallow observation wells to obtain data
on site stratigraphy and current depths to groundwater. Soil samples were collected from the
soil borings. Selected samples were submitted for analysis to a soils laboratory to confirm
field classification. Hydraulic conductivity tests were conducted on 20 of the wells to
determine aquifer characteristics. Water level measurements were collected over an eight
week period and were used to construct groundwater flow maps to determine current flow
direction and hydraulic gradients on the site.
The collected data was used to develop input parameters for DRAINMOD, a computer model
developed for simulating the effect of drainage systems on soils with a shallow water table.
The model can also be used to forecast the presence of wetland hydrology in these same soils.
The input parameters were calibrated against existing data and a series of simulations were
run to predict the occurrence and duration of saturation in the top 12 inches (30 cm) of soil
under various conditions. The model outputs indicate that saturation for at least 12.5 % of
the growing season would be achieved for all but approximately 80 acres of the prior
converted farmlands by effectively filling the central drainage canals and lateral feeder ditches
and scarifying the surface soils to increase surface storage on site. The data collected also
indicates that a significant portion of the property should be subject to overbank flooding
following the completion of restoration activities.
HYDROGEOLOGICAL SITE ASSESSMENT
FOR
GREAT DISMAL SWAMPMITIGATION SITE
GATES - PERQUIMANS COUNTIES
1.0 INTRODUCTION
The North Carolina Department of Transportation (NCDOT), Planning and Environmental
Branch obtained an option to purchase two tracts of land in Gates and Perquimans Counties
for the purpose of creating a mitigation bank for wetlands. Environmental Services, Inc (ESI)
was retained by NCDOT to conduct a preliminary site assessment (PSA) in October 1994. The
PSA was conducted to determine if the site could be restored to wetland conditions through
appropriate hydrological modification. The results of the PSA are presented in a letter report
dated 4 November 1994. Based upon the results of the PSA, NCDOT retained ESI to conduct
a detailed site assessment of the properties. This report documents ESI activities to
characterize the hydrogeological site conditions, including soil boring and well installation, slug
testing, water level measurements, and groundwater modeling. Based upon the data collected
and the results of analysis, this report presents conclusions and makes recommendations.
1.1 Backaround
The subject properties consist of two tracts of land comprised of 304 acres and 307 acres for
a total of 611 acres. The land is located in southern Gates and northern Perquimans County,
as shown in Figure 1. The northern tract (Tract 1) consists of 304 acres which has been
cleared, ditched, drained, and used primarily for tree plantations in the past, and various
agriculture activities through 1994. The southern tract (Tract 2) consists of 307 acres which
has been cleared, ditched and drained on the eastern two-thirds of the tract. The tracts are
divided by a road trending east-west with drainage canals on either side of the road. The
ditched portion of the tract has also been used for tree plantations in the past as well as
agriculture activities through 1994. The drainage system was originally installed by
Weyerhauser to facilitate the commercial growth and harvest of pine trees. The subject
property is bordered on the north by land owned by Weyerhauser, as a pine plantation. The
property is bordered on the east by formerly cultivated lands leased by a hunt club at the time
of the assessment. The property is bordered on the south by agricultural lands owned by D.
T. Hurdle. The property is bordered on the west by forested lands owned by Clyde Stallings
which are part of the Great Dismal Swamp. The cleared and cultivated portions of the tracts
are considered Prior Converted (PC) farmlands and currently are not under jurisdictional control
of the U.S. Army Corp of Engineers at this time.
The property was selected by NCDOT to serve as a mitigation bank for offsetting the impact
of road construction on other wetlands. The primary impetus was the need for mitigation for
project R-2208A, an improvement of US -17, with the expectation of excess credits to apply
to subsequent projects in the region.
1.2 Scone of Work
Based upon EST's proposal dated 18 November 1994, the scope of work for this project is as
follows:
158 3 -7-
_ E \ ?t _ 7C1
a 6- ! . it f? // -- __?? ,%? ?) ?? • a
``?? Mitigation Site
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eN+ I I 1 ...11.; f:
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? ?'? ? , V ??„ car • ?q ?•?? ' • ?\` ?`il ?
10
gg /
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10
W,?
I It i M
_T._.
kft
.r ?? „..
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N
Study Area ,.
0 I 2 3 MILES L ?
Source: DeLortne MappiM 1992 1 ?' F
40,
_ J4••.N /( RF`I ?,??
Figure:
Environmental Location Map
Services, Em Dismal Swamp y tiwf
1318 Dale Street Proposed Mitigation Tract Project: ER94018.2 C :: Mt
Suite 220 Gates and Perquimans Counties,
Raleigh, NC 27605 North Carolina
Date: 24 Jan 95
2
• Delineate the boundaries of jurisdictional wetlands. This determination will be
confirmed with the U.S. Army Corps of Engineers
• Install a series of soil borings and a network of observation wells to characterize
subsurface conditions, including aquifer tests at each well.
• Collect groundwater elevation data from the wells on a weekly basis for a two month
period in order to evaluate fluctuations in the water table at the site.
• Model current groundwater conditions on site, using DRAINMOD and project conditions
on the site for various interventions to restore the prior converted portions of the tract
to wetland conditions. Dr. George Chescheir of North Carolina State University in
Raleigh, NC, was consulted to assist with modelling and to verify results.
• Characterize existing vegetation on adjacent forested wetlands by means of field
analysis, botanical surveys, biological reports, or aerial/ground photography. Target
vegetation species and densities for the proposed mitigation shall be developed.
• Prepare a report documenting site conditions the results of the modeling effort, and
recommendations for the most cost effective methods for hydrological restoration. The
report will specify target conditions for the site for both hydrological and vegetative
restoration. The report will also contain a monitoring plan to evaluate achievement of
the target conditions.
NCDOT arranged for the soil mapping conducted, through the North Carolina Department of
Health, Environment, and Natural Resources (DEHNR) Division of Soil and Water to determine
the hydric/non-hydric soils boundaries. NCDOT was also responsible for all surveying aspects
related to the project, and obtaining access to adjoining properties, and scheduling the
mapping and surveying efforts within the time constraints of the project
2.0 SITE CHARACTERIZATION ACTIVITIES
To fully understand existing conditions at the subject property, ESI personnel conducted the
following activities. ESI installed a series of soil borings and converted the borings into
observation wells. Following completion of the wells, slug tests were performed to determine
hydrological properties. Water level measurements were collected over an eight week period
in order to evaluate fluctuations of the water table. The site was surveyed by another
consulting firm, as a subcontractor to NCDOT and a topographic map was prepared by NCDOT
Photogrammetry. These activities are more fully discussed in the following sections.
2.1 Exaloratory Soil Borings and Observation Well Installation
A series of 26 observation wells were installed on the subject property between 21 November
and 8 December 1994. The locations of which are shown on Figure 2 (attached). Wells PZ-1
through PZ-12 were installed by means of an all-terrain vehicle mounted Geoprobe rig. Wells
PZ-13 through PZ-21, and WP-1, EP-1 through EP-3, and HP-1 were installed using a hand
auger. The locations were chosen to provide full coverage of the site, and to install at least
one observation well in each soil type represented. PZ-1 through PZ-21 were installed on the
subject property. The remaining wells were installed to collect data from locations beyond the
boundaries of the tract subsequent to NCDOT obtaining access from the owners. The
Geoprobe borings were sampled continuously from the surface on two-foot centers to a depth
of 12 feet except for PZ-9 and PZ-12, which were sampled to a depth of 20 feet. The
remaining borings were installed to a depth where caving prevented advancing the boring
deeper The hand auger borings were sampled at each observed change in color, texture, and
consistency. The boring logs are presented in Appendix A. Nine soil samples were submitted
for particle-size analysis, and three were also tested for plasticity index to confirm the field
classification with the Unified Soil Classification (USC) System. The results are presented in
Appendix B. Following the completion of the soil boring, an observation well was installed in
each well. The well consisted of a five foot section of one-inch inner diameter (ID) flush
threaded machine-slotted schedule 40 PVC screen, and one-inch inner diameter (ID) flush
threaded schedule 40 PVC riser, except at PZ-1 where a 10 foot section of screen was
installed. Following the installation of the PVC screen and riser a filter pack consisting of
clean coarse sand(#2 DOT or equivalent) was emplaced in the annulus. A six-inch bentonite
seal was emplaced above the filter pack. The details of the well construction are presented
on the boring logs in Appendix A.
2.2 Hydraulic Conductivity Testing
Following the completion of well installation, the wells were tested to determine the hydraulic
conductivity of the soils at the site. The tests were conducted using a slug test method,
which measures the response of the saturated zone to a localized, induced stress. The tests
were conducted in the following manner: the static depth to water was measured in the well,
a quantity of distilled water was then added to the well to bring the water level in the PVC up
to the top of the riser, the resulting fall in water level with time were recorded . The time-
recovery data was then analyzed using methods given by Hvorslev0 951) and Cooper,
Bredehoeft, and Papadapoulos(1967). Slug tests were conducted on wells PZ-1 through PZ-
20. The data and calculations from the slug testing are presented in Appendix C.
4
2.3 Water Level Measurements
Water level measurements were taken in the observation wells during a period from 8
December 1994 to 25 January 1995, weekly. The ground water data is summarized in Table
1. The water level measurements were collected by use of an SINCO, Model 51453 Water
Level Indicator graduated to 0.01 feet.
2.4 Surveying
The North Carolina Department of Transportation (NCDOT) was responsible for having the site
surveyed and preparing a topographic base map. NCDOT was also responsible for having the
hydric/non-hydric soil boundaries delineated and located by means of the Global Positioning
Satellite (GPS) System. A boundary and topographic survey were conducted by another
consulting firm in December 1994. An aerial photography mission was flown by NCDOT
Photogrammetry on 8 December 1994. The hydric soils boundaries were flagged by North
Carolina Department of Environment, Health and Natural Resources (NCDEHNR) Division of
Soil and Water. Using the data from these sources, NCDOT Photogrammetry produced a
topographic base map and accompanying files on diskettes on 15 February 1995. These files
were used to generate the figures presented in this report.
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6
3.0 GEOLOGY AND HYDROGEOLOGY
3.1 Regional Geology
The subject property is located in the Atlantic Coastal Plain Physiographic Province of North
Carolina. The Coastal Plain extends from the Fall Zone located near Roanoke Rapids, North
Carolina, which forms the boundary with the Piedmont Plateau in the west, to the Outer Banks
in the east. The Coastal Plain is comprised of sediments deposited since the Cretaceous
Period, 138 million years before present(m.y.B.P.), to the present. The sediments were
deposited during a series of transgressions and regressions of the Atlantic Ocean. The subject
property is located within a portion of the Coastal Plain referred to as the Lower or Outer
Coastal Plain. The Outer Coastal Plain extends from Suffolk Scarp, a paleo-shoreline, to the
Atlantic Ocean. The North Carolina Geological Map (Brown et al., 1985) describes the primary
geologic unit as Quaternary Age (from 2 m.y.B.P. to the present) surficiai deposits. These
deposits consist of sand, clay, gravel, and peat deposited in marine, fluvial, eolian and
lacustrian environments. Generally these sediments are not present at elevations greater than
25 feet above mean sea level, which is the approximate elevation of the Suffolk Scarp. The
Surficial Deposits are rarely more than 25 feet deep and are most likely underlain by sediments
of Miocene Age (Stuckey, 1958). The Quaternary Deposits are underlain by the Yorktown
Formation of Miocene age ( 5 to 24 m.y.B.P.), which is described as a bluish gray fossiliferous
clay with varying amounts of fine grained sand, and shell material commonly concentrated in
lenses (Brown et al., 1985).
In North Carolina the sediments of the Atlantic Coastal Plain generally dip to the east or
southeast, and the thickness increases from west to east (Stuckey, 1958).
3.2 Local Geology
The subject property is located within the southern portion of the Great Dismal Swamp. The
surficial soils encountered were organic soils (Histosols) and organic mineral 'soils
(Umbraquults), with two small inclusions of nonhydric soils in the southern portion of the
tract. The classification was conducted by the Natural Resources Conservation Service
(NRCS), and a summary of their description is given below.
Soil phases mapped by the NRCS as occurring on the site include the Scuppernong/Belhaven
series (Terric Medisaprists), the Arapahoe series (Typic Humaquepts), the Icaria series (Typic
umbraquu/ts), the Leon/Lynn Haven series (Aeric to Typic Haplaquods), and the Echaw series
(Entic Hap/ohumods). Series represented by two names are typically similar soil map units that
occur on either side of the county line. Hydric soil series consist primarily of poorly drained
to very poorly drained mucks or loamy sands with high to very high organic content, strongly
to extremely acidic conditions, and moderate to low permeability.
The only non-hydric map unit observed on the site is the Echaw Series, situated primarily
within the southern portions of the site. This area consists of a minor, slightly elevated sand
rim with a seasonable high water table at approximately three feet below the surface.
Map units identified by the NRCS were evaluated during preliminary field surveys. NRCS
mapping of hydric/non-hydric soil boundaries appears to be fairly accurate. The organic
content, and subsurface texture of hydric soil areas varies considerably between sample points
7
3.0 GEOLOGY AND HYDROGEOLOGY
3.1 Regional Geology
The subject property is located in the Atlantic Coastal Plain Physiographic Province of North
Carolina. The Coastal Plain extends from the Fall Zone located near Roanoke Rapids, North
Carolina, which forms the boundary with the Piedmont Plateau in the west, to the Outer Banks
in the east. The Coastal Plain is comprised of sediments deposited since the Cretaceous
Period, 138 million years before present(m.y.B.P.), to the present. The sediments were
deposited during a series of transgressions and regressions of the Atlantic Ocean. The subject
property is located within a portion of the Coastal Plain referred to as the Lower or Outer
Coastal Plain. The Outer Coastal Plain extends from Suffolk Scarp, a paleo-shoreline, to the
Atlantic Ocean. The North Carolina Geological Map (Brown et at, 1985) describes the primary
geologic unit as Quaternary Age (from 2 m.y.B.P. to the present) surficial deposits. These
deposits consist of sand, clay, gravel, and peat deposited in marine, fluvial, eolian and
lacustrian environments. Generally these sediments are not present at elevations greater than
25 feet above mean sea level, which is the approximate elevation of the Suffolk Scarp. The
Surficial Deposits are rarely more than 25 feet deep and are most likely underlain by sediments
of Miocene Age (Stuckey, 1958). The Quaternary Deposits are underlain by the Yorktown
Formation of Miocene age ( 5 to 24 m.y.B.P.), which is described as a bluish gray fossiliferous
clay with varying amounts of fine grained sand, and shell material commonly concentrated in
lenses (Brown et at, 1985).
In North Carolina the sediments of the Atlantic Coastal Plain generally dip to the east or
southeast, and the thickness increases from west to east (Stuckey, 1958).
3.2 Local Geology
The subject property is located within the southern portion of the Great Dismal Swamp. The
surficial soils encountered were organic soils (Histosols) and organic mineral 'soils
(Umbraquults), with two small inclusions of nonhydric soils in the southern portion of the
tract. The classification was conducted by the Natural Resources Conservation Service
(NRCS), and a summary of their description is given below.
Soil phases mapped by the NRCS as occurring on the site include the Scuppernong/Belhaven
series (Terric Medisaprists), the Arapahoe series (Typic Humaquepts), the Icaria series (Typic
umbraquults), the Leon/Lynn Haven series (Aeric to Typic Haplaquods), and the Echaw series
(Entic Haplohumods). Series represented by two names are typically similar soil map units that
occur on either side of the county line. Hydric soil series consist primarily of poorly drained
to very poorly drained mucks or loamy sands with high to very high organic content, strongly
to extremely acidic conditions, and moderate to low permeability.
The only non-hydric map unit observed on the site is the Echaw Series, situated primarily
within the southern portions of the site. This area consists of a minor, slightly elevated sand
rim with a seasonable high water table at approximately three feet below the surface.
Map units identified by the NRCS were evaluated during preliminary field surveys. NRCS
mapping of hydric/non-hydric soil boundaries appears to be fairly accurate. The organic
content, and subsurface texture of hydric soil areas varies considerably between sample points
7
within hydric map units. Diversity may be partially due to the influences of artificial drainage
and agriculture on the site. The removal of semi-permanent anaerobic soil conditions has
accelerated the rate of decomposition and subsequently decreased the content of organic
matter in surface soil horizons.
The surficial soils were generally underlain by fine sands with layers of clayey fine sands. The
clayey sands ranged in thickness from just under one foot thick to at least seven feet thick at
PZ-10. In the two borings extended to 20 feet , a fine sand was encountered from a depth
of one foot to a depth of 19 feet where a clay seam was encountered extending to the bottom
of the hole at PZ-9, while at PZ-12, two seams of clayey sand were encountered at seven to
nine feet, and 12 to 14 feet. Saturated soils were encountered at depths ranging from one
to three feet below land surface. The soils encountered below the organic-rich surficial soils
appear to be of marine origin. Using the data from the boring logs and the survey a series of
cross-sections were prepared to illustrate the subsurface conditions, the cross-sections are
presented in Figure 3 (attached).
3.3 Regional HydroQeology
Regional groundwater flow in the Coastal Plain generally flows in a down dip direction, which
generally trends southeast in North Carolina. The rivers generally flow from northwest to
southeast in the Coastal Plain, roughly paralleling the dip direction. The southern portion of
the Great Dismal Swamp also drains south to southeast into the Perquimans and Pasquotank
Rivers, which drain into the Albemarle Sound. Shallow groundwater generally occurs under
unconfined (water table ) conditions within five feet of the surface in the region, as evidenced
by the large expanses of hydric soils, and the extensive use of drainage systems in agricultural
fields.
3.4 Local HydroQeology
The extensive ditching of the subject property and surrounding areas has altered the
hydrogeology of the site. The primary changes include the lowering of the water table in the
cleared portion of the field and the concentration of groundwater flow towards the channelized
headwaters of the Perquimans River on the western boundary of the subject property. The
results of the slug tests indicate that the soils on the site have a moderately low hydraulic
conductivity ranging from a low of 3.41 x1 G' Ft/day (1.04x1 (y2 meters/day (m/d), 4.33x1 G2
cm/hr) to a high of 2.0 Ft/day (6.2x1(?' m/d, 2.58 cm/hr). The water level measurements
presented in Table 1 were used to construct a series of water table maps presented as Figures
4 through 11. The maps all indicate that groundwater flow on the site is westward towards
the channelized headwaters of the Perquimans River.
The maps also show two localized high points in the water table, one is in the southeastern
portion of the site in the non-hydric Echaw soils which is represented as a topographic high,
the other is in the northern tract in the vicinity of PZ-3, PZ-7, and PZ-1 1 which appears to be
less related to topography. Surface drainage at the subject property is controlled by the
canals and drainage ditches. The drainage ditches in the northern tract are approximately 335
feet (102 m) apart and drain towards the southern edge of the field into a large canal which
drains into the canals running north-south on the eastern and western boundaries of the tract.
The drainage ditches in the southern tract are approximately 250 feet (76 m) apart, and flow
either north or south into canals that drain eastward into the north-south trending canal. The
knoll of non-hydric soils and the access road function as a drainage divide in the southern
tract.
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4.0 GROUNDWATER MODELING & RESULTS
4.1 Groundwater Model
The groundwater modeling software selected as most appropriate for simulating shallow
subsurface conditions and groundwater behavior at the site was DRAINMOD. This model was
developed by Dr. R.W. Skaggs of North Carolina State University (NCSU) to simulate the
performance of water table management systems. The model was originally developed to
simulate the performance of agricultural drainage and water table control systems on sites
with shallow water table conditions. DRAINMOD was subsequently modified for application
to wetland studies by adding a counter that accumulated the number of times that the water
table rose above a specified depth and remained there for a given duration during the growing
season. The model results can then be analyzed to determine if wetland criteria are satisfied
during the growing season, on average, more than half of the years modeled. Required model
inputs include the threshold water table depth, required duration of high water tables, and
beginning and ending dates of the growing season.
Dr. George (Chip) Chescheir of NCSU also participated in the current study by reviewing the
site characterization data and setting up the DRAINMOD model for the study area. Dr.
Chescheir provided input parameters required by DRAINMOD and supplied model results for
the study area. Output from the DRAINMOD model was then applied to the study area to
determine which areas would not achieve wetland hydrology criteria. Wetland hydrology
criteria was defined in the model as having groundwater within 12 inches (30 cm) of the
surface for both 12 consecutive days (5% of the growing season) and 31 consecutive days
(12.5% of the growing season). For the purposes of this study the growing season was
defined as the period between 21 March and 19 November( USDA-NRCS, 1986 & 1994).
Simulations were also conducted to forecast whether saturation within 30 cm of the surface
could be achieved for 49, and 61 consecutive days ( 20%, and 25% respectively) at the study
area under conservative, cost-effective site modifications. These additional simulations were
conducted to characterize the extent and duration of anaerobic soil environments and
forecasts the expected influence of flooding on various plant species populations.
4.2 Model Description
DRAINMOD performs water balances in the soil-water regime at the midpoint between two
drains of equal elevation. The model is capable of calculating hourly values for water table
depth, surface runoff, subsurface drainage, infiltration, and actual evapotranspiration over long
period of climatological data. The reliability of DRAINMOD has been tested for a wide range
of soil, crop, and climatological conditions. Results of tests in North Carolina (Skaggs, 1982),
Ohio (Skaggs et al., 1981), Louisiana (Gayle et a/., 1985; Fouss et aL, 1987), Florida (Rogers,
1985), Michigan (Belcher and Marva, 1987), and Belgium (Susanto et aL, 1987) indicate that
the model can be used to reliably predict water table elevations and drain flow rates.
DRAINMOD has been used to evaluate wetland hydrology by Skaggs et al (1993).
Water Balance
The water balance in DRAINMOD involve two basic equations. The first equation is a water
balance in the soil profile:
OVa=D+ET+DS-F
(1)
17
Where:
AV. = change in air volume
D = drainage from the profile
ET = actual evapotranspiration from the profile
DS = deep seepage from the profile
F = infiltration into the profile
The second equation is a water balance at the soil surface:
AS = P-F-RO
Where:
AS = change in volume of water stored at the soil surface
P = precipitation
F = infiltration volume
RO = surface runoff
(2)
Methods for evaluating equation variables are discussed in detail in Skaggs 0 980).
The hydrology of various soil water conditions applicable to the study area was simulated
using DRAINMOD. The simulations were conducted for the time periods from 1951 to 1980
using climatological data from Plymouth, North Carolina. Table 2 summarizes the soil
parameters used in the DRAINMOD simulations. Appendices B and C contain the results of
the slug testing, grain size analyses, and attaberg limit tests conducted on soils at the site.
4.3 Model Results
The hydrology of various soil water conditions applicable to the study site was simulated using
DRAINMOD. The simulation used the hydric organic-mineral Icaria soil, a fine sandy loam, and
the most prevalent soil onsite to conservatively represent the soil conditions for the portion
of the site consisting of prior converted wetlands. soil input parameters for DRAINMOD were
calculated by the NRCS model, DMSOIL (Baumer and Rice, 1988) using soil texture data from
soil samples collected on site. Soil hydraulic conductivity values used in DRAINMOD
simulations were determined from the on-site slug test data. Table 2 summarizes the soil
parameters used in the DRAINMOD simulations. The simulations were conducted for the time
periods from 1951 to 1980 using climatological record from Plymouth, North Carolina.
DRAINMOD simulations were conducted for the range of ditch depths and distances of a
midpoint to the ditch. Due to the very low relief of the site, of approximately six feetO.8 m)
over the approximately 5000 feetO 500 m) length of the tract east to west, it was assumed
that after filling and grading the ditches would be at the same grade as the adjacent existing
surface. Drain depth was taken as the depth from the ground surface to the surface of the
water in the remaining large perimeter canals. Simulations were then run to determine the
distance between ditches for the establishment of wetland hydrology at the midpoint for 5%,
12.5%, 20%, and 25% of the growing season for drain depths of one ft.(30 cm), two ft.(60
cm), three ft.(90 cm), four ft.0 20 cm), and five ft.0 50 cm). The simulation also assumed
that after 20 + years of forest growth the hydraulic conductivity of the top 60 cm of soil had
18
Table 2
Soil Input Parameters
Volume drained, Up flux, Green- mpt
Parameters, and Hydraulic Conductivity for
Icaria Soil
Water Table
Depth (cm) Volume
Drained (cm) Upflux (cm/hr)
0.0 0.00 0.1000
10.0 0.25 0.0800
20.0 0.40 0.0600
30.0 0.65 0.0500
40.0 0.92 0.0400
50.0 1.35 0.0200
60.0 1.85 0.0063
70.0 2.53 0.0025
80.0 3.40 0.0016
90.0 4.45 0.0014
100.0 5.50 0.0011
120.0 7.50 0.0005
140.0 10.45 0.0003
160.0 13.40 0.0000
200,0 19.30 0.0000
250.0 27.23 0.0000
300.0 35.40 0.0000
Green-Ampt Parameters

Water Table
Depth (cm) A B
0.0 0.0 0.00
60.0 4.0 0.25
120.0 12.0 1.00
500.0 12.0 1.00
100.0 12.0 1.0
Saturated Hyd raulic Conductivity

Depth to
Bottom of
Layer K (cm/hr)
60.0 25.0
240.0 2.0
19
ft.). The simulation also assumed that after 20 + years of forest growth the hydraulic
conductivity of the top 60 cm of soil had been increased to 25 cm/hr by the process of plant
growth. An impermeable layer was assumed to be present at a depth of 240 cm, since seven
to nine feet was the shallowest depth at which clayey sands were encountered.
The depth of depressional storage used in the in the initial DRAINMOD simulations was five
cm assuming that surface roughing would be used on the site to increase surface storage.
Based upon the input data saturation to within 30 cm of the surface for 25% of the growing
season (61 consecutive days) could not be achieved with a surface storage of five cm. The
simulations were repeated using a surface storage of 10 cm, and saturation for 25 % of the
growing season was achieved. The rooting depth function used in the simulation was a
constant depth of 45 cm, which is typically used for forested conditions.
4.4 Model Results
The DRAINMOD simulations predicted that a very high percentage of the cultivated land would
achieve wetland hydrology criteria. The model predicted that at a maximum of 100 meters
(330 ft) from the drainage canal, assuming a 150 cm (5 ft). depth to water in the canals,
saturation for 12.5 % of the growing season could be achieved by filling lateral ditches and
assuming surface storage of 10 cm. Tables 3 and 4 provide the results of the DRAINMOD
modeling study presenting different ditch depths and distances from the perimeter canals that
saturation would be present in the top 30 cm for*'5%, 12.5%, 20%, and 25% of the growing
season. Table 3 summarizes the results for five cm of surface storage, and Table 4
summarizes the results for 10 cm of surface storage. The relative depth of the canals was
determined from Figure 12, a conceptualized topography of the site following filling the lateral
ditches and central canals. Wetland hydrology was defined as the conditions that resulted in
the criteria being met in more than 15 out of 30 years. As was expected, wetland hydrology
was more likely to occur in the interior portion of the tract at a distance from the perimeter
canals. Based upon the DRAINMOD simulations, between 377 acres and 401 acres of the PC
farmlands would meet the criteria of saturation in the top 30 cm (1 ft) for at least 12.5 % of
the growing season for surface storages of 5 cm and 10 cm respectively.
The wetland hydrology results observed in Tables 3 and 4 were then used to determine
which portions of the tract would not meet wetland criteria, on average, more than half the
time. The issue of whether or not a specific portion of the site will have wetland hydrology
was determined using the ground elevation at the simulated midpoint relative to the elevation
of the water in the nearest perimeter canal. Areas that would not achieve the wetland criteria
were mapped on the site according to the ground elevation and the values in Tables 3 and 4.
Those areas which would not meet wet land criteria are illustrated in Figures 13 and 14. In
general the interior portion of the tract would meet wetland hydrology criteria with the
exception of the two small Knolls of upland soils, comprising approximately 12 acres, in the
southern portion of the site. Based upon the DRAINMOD simulations another 83 acres would
meet the criteria 5 % of the time or less and 24 acres would meet the criteria for between 5
to 12.5 % of the time for surface storage of 5 cm. For surface storage of 10 cm the acreage
for 5 % or less of the growing season is 56 acres, while 28 acres would be saturated between
5 to 12.5 % of the growing season. The distances from the ditches given in Tables 3 and 4
represent the minimum distance from a ditch of the given depth that saturation for the various
durations could be achieved.
20
been increased to 25 cm/hr by the process of plant growth. An impermeable layer was
assumed to be present at a depth of 240 cm, since seven to nine feet was the shallowest
depth at which clayey sands were encountered.
The depth of depressional storage used in the in the initial DRAINMOD simulations was five
cm assuming that surface roughing would be used on the site to increase surface storage.
Based upon the input data saturation to within 30 cm of the surface for 25% of the growing
season (61 consecutive days) could not be achieved with a surface storage of five cm. The
simulations were repeated using a surface storage of 10 cm, and saturation for 25 % of the
growing season was achieved. The rooting depth function used in the simulation was a
constant depth of 45 cm, which is typically used for forested conditions.
4.4 Model Results
The DRAINMOD simulations predicted that a very high percentage of the cultivated land would
achieve wetland hydrology criteria. The model predicted that at a maximum of 330 feet (100
meters) from the drainage canal, assuming a five ft.0 50 cm) depth to water in the canals,
saturation for 12.5% of the growing season could be achieved by filling lateral ditches and
assuming surface storage of four inches 0 0 cm). Tables 3 and 4 provide the results of the
DRAINMOD modeling study presenting different ditch depths and distances from the perimeter
canals that saturation would be present in the top 12 inches (30 cm) for 5%, 12.5%, 20%,
and 25% of the growing season. Table 3 summarizes the results for two inches (five cm) of
surface storage, and Table 4 summarizes the results for four inches (10 cm) of surface
storage. The relative depth of the canals was determined from Figure 12, a conceptualized
topography of the site following filling the lateral ditches and central canals. Wetland
hydrology was defined as the conditions that resulted in the criteria being met in more than
15 out of 30 years. As was expected, wetland hydrology was more likely to occur in the
interior portion of the tract at a distance from the perimeter canals. Based upon the
DRAINMOD simulations, between 377 acres and 401 acres of the PC farmlands would meet
the criteria of saturation in the top 12 inches (30 cm) for at least 12.5 % of the growing
season for surface storages of two and four inches (5 cm and 10 cm) respectively.
The wetland hydrology results forecast in Tables 3 and 4 were then used to determine which
portions of the tract would not meet wetland criteria, on average, more than half the time.
The issue of whether or not a specific portion of the site will have wetland hydrology was
determined using the ground elevation at the simulated midpoint relative to the elevation of
the water in the nearest perimeter canal. Areas that would not achieve the wetland criteria
were mapped on the site according to the ground elevation and the values in Tables 3 and 4.
Those areas which would not meet wet land criteria are illustrated in Figures 13 and 14. In
general the interior portion of the tract would meet wetland hydrology criteria with the
exception of the two small knolls of upland soils, comprising approximately 12 acres, in the
southern portion of the site. Based upon the DRAINMOD simulations another 83 acres would
meet the criteria 5 % of the time or less and 24 acres would meet the criteria for between 5
to 12.5 % of the time for surface storage of two inches (5 cm). For surface storage of four
inches 00 cm) the acreage for 5 % or less of the growing season is 56 acres, while 28 acres
would be saturated between 5 to 12.5 % of the growing season. The distances from the
ditches given in Tables 3 and 4 represent the minimum distance from a ditch of the given
depth that saturation for the various durations could be achieved.
21
TABLE 3
Results of DRAINMOD Simulations for Saturation within 30 cm of surface for Selected
Percentages of the Growing Season (Surface Storage = 5 cm)
Ditch Dept
Percentage
of Growing
Season Number
of Days 30 cm
(1 ft) 60 cm
(2 f) 90 cm
(3 ft) 120 cm
(4 ft) 150 cm
(5 f)
Ditch Spacing (meters)
5 12 25 37.5 50 75 75
12.5 31 50 75 75 100 100
20 49 150 200 300 300 300
25 61 Criteria could not be
met with surface storage
= 5 cm
TABLE 4
Results of DRAINMOD Simulations for Saturation within 30 cm of surface for Selected
Percentages of the Growing Season (Surface Storage = 10 cm)
Ditch Depth
Percentage
of Growing
Season Number
of Days 30 cm
(1 ft) 60 cm
(2 ft) 90 cm
(3 ft) 120 cm 1
(4 ft) 150 cm
(5 ft)
Ditch Spacing (meters)
5 12 25 37.5 50 50 50
12.5 31 37.5 50 75 75 75
20 49 50 75 75 75 100
25 61 75 75 100 100 150
22
5.0 RECOMMENDED SITE ALTERATIONS TO PROMOTE WETLAND HYDROLOGY
The results of the DRAINMOD modeling study indicate that wetland hydrology can be achieved
for an area between 377 acres and 401 acres at the study site, if the drainage ditches are
effectively removed and the surface depressional storage is made uniformly high across the
site. Removal of the drainage ditches can effectively be achieved by filling the lateral feeder
ditches and the two drainage canals between the northern and southern tracts of the site.
Increasing the depressional storage can be achieved by using both standard forestry practices
of rowing and bedding when planting specimens in the formerly cultivated fields and surface
roughing. Rows should be established roughly parallel to existing topographic contours with
one ft (30 cm) high beds spaced at intervals to allow access by a tractor to periodically mow
the area to control the growth of unwanted plant species and scarify the soils between the
beds during the first two years of restoration.
5.1 Recommendations For Filling Drainage Ditches
Restoring wetland hydrology on the site requires the effective filling the lateral feeder ditches
and the canals between the northern and southern portions of the site. The canals should be
backfilled in a manner to minimize the former canals serving as pathways of preferential
migration for ground water. An example of one means is to backfill in lifts of 30 cm (1 ft) with
each lift compacted to at least 90% of the maximum dry density determined by the standard
proctor test (ASTM D-698). Failure to minimize preferential migration will allow the former
canals to function as french drains and short circuit the groundwater flow at the site and
jeopardize the restoration efforts. The feeder ditches may be backfilled in one lift, but a series
of one or more clay dikes should be installed across each ditch to minimize preferential
migration and excess drainage to the former ditches. The clay dikes should be constructed
to extend to 30 cm (1 ft) below the existing bottom of the ditch and upon completion have
a hydraulic conductivity of 1 x10'' cm/s (3.6x104 cm/h), or less. Fill material is available on-
site from the spoils pile along the western boundary of the site , which currently functions as
a berm or dike to prevent overbank flooding. Fill material is also available by removing the
road between the two tracts and grading a smooth transition from the north to the south
across the former canals and road. Fill material for the ditches and canal should consist of low
permeability clays or silty clays, but due to the relative scarcity of clays in the near surface
soils, bentonite or montmorillonite clay should be mixed with fill material on site prior to
placement and compaction.
5.2 Recommendations for Site Grading
Along with backfilling the existing drainage system, portions of the site should be graded to
enhance the hydrologic function of the site. The spoils from dredging the canal on the
western boundary of the site were piled along the bank running the length of the property, and
has acted as a dike to prevent or minimize overbank flooding of the fields by the canal. The
spoils should be removed along the entire length of the boundary and used for fill material.
The western edge of the northern tract should then be graded down to an elevation of eight
feet at the bank of the canal. Following removal of the spoils pile and grading the field down
to the bank a berm approximately 1 foot tall should be constructed along the canal bank to
reproduce the functions of a natural levee by delaying the recession of flood waters during
flooding and extending the period when the western portion of the field is either inundated or
saturated. An opening in the levee should be constructed near the north end to facilitate the
23
diversion of flood waters onto the field. Based upon field observations elevations of flood
waters in the field are expected to range between 10 and 11 feet above msl. This grading and
berm construction would facilitate the restoration of riverine flood plain conditions adjacent
to the canal. Estimated acreage of flood plain achieved using 11 feet msl as the maximum
elevation is 57, actual acreage of flood plain resulting from grading could be determined in the
field during the next growing season. The estimated flood plain area is presented in Figure 15.
24
6.0 REFERENCES CITED
Baumer, 0. and J. Rice. 1988. Methods to predict soil input data for DRAINMOD ASAE
Paper No. 88-2564. ASAE, St. Joseph, MI 49085.
Belcher, H. W. and G. E. Merva, 1987, Results of DRAINMOD verification study for
Zeigenfuss, soil and Michigan climate. ASAE Paper No. 87-2554. ASAE, St. Joseph,
MI 49085.
Brown, Philip M., et al, 1985, Geologic Map of North Carolina, North Carolina Department
of Natural Resources and Community Development, 1-.500,000 scale.
Cooper, H. H., Jr., J. D. Bredehoft, and I. S. Papadopoulos. 1967. Response of a finite-
diameter well to an instantaneous charge of water. Water Resources Research, 3, pp
263-269.
Fouss, J. L., R. L. Bengtson and C. E. Carter, 1987, Simulating subsurface drainage in the
lower Mississippi Valley with DRAINMOD. Transactions of the ASAE 30 (6)-. 1679 -
1688.
Gayle, G., R. W. Skaggs and C. E. Carter, 1985, Evaluation of a water management model
for a Louisiana sugar cane field. J. of Am. Soc. of Sugar Cane Technologists, 4: 18 -
28.
Hvorslev, M. J. 1951. Time lag and soil permeability in groundwater observations. U.S.
Army Corps of Engineers Waterways Experimental Station Bulletin 36, Vicksburg, MS.
Rogers, J. S., 1985, Water management model evaluation for shallow sandy soils.
Transactions of the ASAE 28 (3): 785-790.
Skaggs, R. W., 1980, A water management model for artificially drained soils. Tech. Bull. No.
267, North Carolina Agricultural Research Service, N.C. State University, Raleigh. 54
pp-
Skaggs, R. W., 1982, Field evaluation of a water management simulation model.
Transactions of the ASAE 25 (3): 666 - 674.
Skaggs, R. W., N. R. Fausey and B. H. Nolte, 1981, Water management evaluation for
North Central Ohio. Transactions of the ASAE 24 (4): 922 - 928.
Skaggs, R. W., J. W. Gilliam and R. 0. Evans, 1991, A computer simulation study of
pocosin hydrology. Wetlands (1 1): 399 - 416.
Skaggs, R.W., et a[, 1993, Methods for Evaluating Wetland Hydrology. ASAE meeting
presentation Paper No. 921590. 21 p.
25
Susanto, R. H., J. Feyen, W. Dierickx and G. Wyseure, 1987, The use of simulation models
to evaluate the performance of subsurface drainage systems. Proc. of Third
International Drainage Workshop, Ohio State Univ., pp. A67 - A76.
USDA-NRCS. 1986. Soil Survey of Chowan and Perquimans Counties, North Carolina.
Publication of the National Cooperative Soil Survey.
USDA-NRCS. 1994. Soil Survey of Gates Counties, North Carolina. Publication of the
National Cooperative Soil Survey.
Ward, L. W., Bailey, R. H., Carter, J. G., 1991, "Pliocene and Early Pleistocene Stratigraphy,
Depositional History, and Molluscan Paleobiology of the Coastal Plain." in The Geology
of the Carolinas, J. Wright Horton, Jr., and Victor A. Zullo, eds. The University of
Tennessee Press, Knoxville TN.
26
COORDINATES: LOGGED BY: JLH
TOC ELEVATION: DRILLED BY- Geo-Environmental
G.S. ELEVATION: DRILL RIG: Scorpion Geoprobe
ELEVATION DATUM: DRILLING METHOD: Hydraulic Hammer
DATE DRILLED: 11-21-94
2" Stickup
SAMPLE C. SOIL DESCRIPTION PID
WELL DESCRIPTION TYPE REC RESIST U.S. (PPM)
Bentonite Seal

P 8/24
2:

V Sch 40
PVC Riser P 4/24
4
1" Sch 40 '
PVC Screen
J .
6 I. . L ...
is P 2/241
20-40 Sand
Filter Pack
•
I•
P
1 8/24
I

-a P 8/24

10 I i
Black, organic soil (MUCK)
Tan, very fine SAND; trace clay
Wet, tan, very fine SAND; trace clay
Very wet, tan, very fine SAND; trace
As above
medium-clayey
Very wet, dark gray, medium-clayey SAND
Boring terminated at 9 feet

12

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24-
25--
FILE NAME: ER94018.2-25PZ01
SOUTHEASTERN Dismal Swamp Mitigation Site
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY: PS
North Carolina Department of Transportation
AUDITS, INC. PZ-1 CHECKED BY. BH
COORDINATES: LOGGED BY: JLH
TOC ELEVATION: DRILLED BY: Geo-Environmental
G.S. ELEVATION: DRILL RIG: Scorpion Geoprobe
ELEVATION DATUM: DRILLING METHOD: Hydraulic Hammer
DATE DRILLED: 11-22-94
2.5" Stickup 10
PID
SAMPLE U.S.C. SOIL DESCRIPTION
TYPE ! REC RESISTI (PPM)
WELL DESCRIPTION
Bentonite Seal
Black or anic 'I k)
P 18/24
"
1
Sch 40
PVC Riser 2
:
..
F...... `. P 12/24:i
4 •'rr
i
1" Sch 40 I ..
PVC Screen
P 24/24

20-40 Sand
.

Filter Pack

... U-- -

P

24/24
8-
i
I
g soI (muc
1%0
Fine, brown SAND
As above
Brown, wet, very fine to fine SAND
As above
i
Wet, brown, very fine, sandy CLAY
Wet, blue/green, glauconitic, very fine, sandy
i
CLAY to clayey, very fine SAND
P 9/24
10 As above
Boring terminated at 10 feet
12
I
14
16
18-
20-

22-
24-
F
i
25
FILE NAME: ER94018.2-25PZ02
SOUTHEASTERN Dismal Swamp Mitigation Site
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY: PS
North Carolina Department of Transportation
AUDITS, INC. PZ-2 CHECKED BY: BH
COORDINATES: -
TOC ELEVATION: -
G.S. ELEVATION: -
ELEVATION DATUM:
4.31 " Stickup
Bentonite Seal
1 " Sch 40 -
PVC Riser
1" Sch 40 -
PVC Screen
20-40 Sand
Filter Pack
2?. .. .
4.:•::
i.
6 8-1
i
i
10
i
12-
14-
16-
18
20
22
24--
4 -
25
25-

LOGGED BY.
LOGGED
JLH
DRILLED BY: Geo-Environmental
DRILL RIG: Scorpion Geoprobe
DRILLING METHOD: Hydraulic Hammer
DATE DRILLED: 11-22-94
TYPESA EC RESIST! U.S.C. SOIL DESCRIPTION (P?
Black, organic (MUCK) and very fine, SAND
P 15/24
Rust, very fine SAND
As above, becoming moist
P 14/24

Moist, brown, very fine SAND

:. Rust, then tan, vety fine SAND
4
P 24
/2
Wet, light gray, very fine to fine SAND
I
P 6/24
Wet, dark gray, very fine to fine SAND
P 24/24
I ,
Wet, dark gray, sandy CLAY to clayey SAND
Borina terminated at 10 feet
FILE NAME: ER94018.2-25PZ03
SOUTHEASTERN Dismal Swamp Mitigation Site
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY. PS
North Carolina Department of Transportation
AUDITS, INC. PZ-3 CHECKED BY: BH
COORDINATES:
TOC ELEVATION:
G.S. ELEVATION:
ELEVATION DATUM:-
4.20' Stickup
Bentonlte Seal
1 " Sch 40 -
PVC Riser
V soh 40 -
PVC Screen
20-40 sand
Filter Pack
LOGGED BY: Jeri
DRILLED BY* Geo-Environmental
DRILL RIG: Scorpion Geoprobe
DRILLING METHOD: Hydraulic Hammer
DATE DRILLED: 11-23-94

SAMPLE U.S.C. SOIL DESCRIPTION PID
TYPE REC 'RESISTi (PPM)
?I
14
Black
MUCK) and
o
i
fi
,
rgan
very
ne,
c
d
k b
SAM
24/24. ar
rown
Brown, organic MUCK and very fine,
dark brown SAND
As above
P 24/24
Brown, very fine to fine SAND

Mottled rust-brown, fine SAND
..:. .. P 24/24
6 'Saturated, flight gray, fine SAND

P 13/24
' Saturated, dark gray, very fine to fine SAND
g with clay lens

P 0/24
.:.:

i
Saturated' dark gray, very fine to fine SAND
10
Boring terminated at 10 feet

12 I
j
I
FILE NAME: ER94018.2-25PZ04
SOUTHEASTERN Dismal Swamp Mitigation Site
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY. PS
North Carolina Department of Transportation
AUDITS, INC. PZ-4 CHECKED BY. BH
COORDINATES: LOGGED BY. JLH
TOC ELEVATION: DRILLED BY- Geo-Environmental
G.S. ELEVATION: DRILL RIG: Scorpion Geoprobe
ELEVATION DATUM: DRILLING METHOD: Hydraulic Hammer
DATE DRILLED: 11-21-94
2.5' Stickup
SAMPLE U.S.C. SOIL DESCRIPTION PID
WELL DESCRIPTION TYPE ' REC RESISTi (PPM)
Bentonite
Moist, black, organic soil (MUCK); trace clay

" P 18/24
Sch 40
1
PVC Riser
2 h. .. .V l?
As above
i
Wet, dark gray, sandy CLAY
P 20/24
"
Sch 40
1
PVC Screen
4
::
:
..: . i Wet, dark gray, fine SAND; trace clay
.
.
P 18/24
1
20-40 Sand
Filter Pack
6
: l .....
Wet, dark gray, fine SAND

:
p
1 i
4
6/2
8
Very wet, black, fine SAND

I:
:
1
l P 22/24
01 ? Moist, light gray, fine SAND

Boring terminated at 10 feet
12-
14-
j
16
18-
20-
22-
?
24
' I
25
FILE NAME:
SOUTHEASTERN Dismal Swamp Mitigation Site ER94018.2-25PZ05
ENVIRONMENTAL Gates and Peiquimans Counties, NC MADE BY. PS
North Carolina Department of Transportation
AUDITS, INC. PZ-5 CHECKED BY: BH
COORDINATES: LOGGED BY: Urn
TOC ELEVATION: DRILLED BY- Geo-Environmental
G.S. ELEVATION: DRILL, RIG: Scorpion Geoprobe
ELEVATION DATUM: DRILLING METHOD: Hydraulic Hammer
DATE DRILLED: 11-22-94

4.2" Stickup --
TELL DESCRIPTION
Bentonlte Seal -
1" Sch 40
PVC Riser
1 " Sch 40
PVC Screen
20-40 Sand
Filter Pack
SAMPLE
TYPE I REC

:
V P 14/24
.

P .21/24;
4

:. .. P 24/241

.. P
1 24/241
8 ?

:..:.:
P
24/241
10
12
14?
RERE T U.S.C. SOIL DESCRIPTION
Black, organic soil (MUCK)
Becoming moist, brown, very fine SAND
Becoming. dark
i
Wet, light gray, very fine SAND
Saturated, light gray, very fine SAND
Wet, slightly mottled, dark to light gray,
very fine SAND
PID
(PPM)
Saturated, light gray, very fine to fine SAND
Boring terminated at 10 feet
I
16 1
I
18 1
i 1
1 i
20
22
I
24
25
FILE NAME:
ER94018.2-25PZ06
SOUTHEASTERN Dismal Swamp Mitigation Site -.----
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY. PS
North Carolina Department of Transportation
AUDITS, INC. PZ-6 CHECKED BY: BFi
COORDINATES: LOGGED BY: JLH and BLH
TOC ELEVATION: DRILLED BY Geo-Environmental
G.S. ELEVATION: DRILL RIG:- Scorpion Geoprobe
ELEVATION DATUM: DRILLING mETNOD: Hydraulic Hammer
DATE DRILLED: 11-23-94

3.09" Stickup
SAMPLE SOIL DESCRIPTION PID
U
S
C
JELL DESCRIPTION .
.
.
TYPE REC RESISTI (PPM)
BentonRe Seal
:•.
' Black, organic soil (MUCK)

" lh P 24/24 j
I
S
se
R Becoming brown
fine SAND w
i
r
PVC
2 ,
? -
Moist, brown, fine SAND; some cla
y
P j 22/24!
V sci, 40 As above
PVC Screen 4
20-40 Sand
Filter Pack 6 P 8/24
! I Moist, dark gray, fine SAND; trace clay

P
?
8/24
8 j Wet, dark gray, clayey, SAND to sandy CLAY

10 p 12/24Wet, blue-gray, very fine to fine SAND
with clay seam

Boring terminated at 10 feet
12
14
16
18
20
22
24
25
SOUTHEASTERN
ENVIRONMENTAL
AUDITS, INC.
Dismal Swamp Mitigation Site
Gates and Perquimans Counties, NC
North Carolina Department of Transportation
PZ-7
FILE NAME:
ER94018.2-25PZ07
MADE BY: PS
CHECKED BY. BH
COORDINATES: LOGGED BY: J%Xi
TOC ELEVATION: DRILLED BY- Ge0-Environmental
O.S. ELEVATION: DRILLRKi: Scorpion Geoprobe
ELEVATION DATUM: DRILLING METHOD: Hydraulic Hammer
DATE DRILLED: 11"23"94
3.3T Stickup
SAMPLE U.S.C. SOIL DESCRIPTION PID
WELL DESCRIPTION TYPE REC RESIST', (PPM)
Bentonite Seal
Dark brown, to black, fine, sandy, organic soil
4/24
t° Sch 40
PVC Riser 2 :. •::? 2
(MUCK)

-
; As above

1" Sch 40
4
PVC S
!
:
:
:
.: p 18124;.
Dark brown, fine, organic, rich SAND
creen :
:
.
..
.
. • . •?.......
Wet, dark brown, fine, organic, rich SAND

20-40 Sand
Filter Pack g
: P i 12/24

Becoming gray at 5.5 feet

8 i..:...: P 3/24
Saturated, blue-gray, clayey to slightly clayey,
fine SAND

10 P 1
I 24/24
Saturated, gray-green, very fine, sandy CLAY
Boring terminated at 10 feet
12
-
14
-
161

18
i
i
20-

22-

24
25
FILE NAME: ER94018.2-25PZ08
SOUTHEASTERN Dismal Swamp Mitigation Site
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY. PS
North Carolina Department of Transportation
AUDITS, INC. PZ-8 CHECKED BY: BFi
COORDINATES: LOGGED BY: Jun
TOC ELEVATION: DRILLED BY• Geo-Environmental
G.S. ELEVATION: DRILL RIG: Scorpion Geoprobe
ELEVATION DATUM: DRILLING METHOD: Hydraulic Hammer
DATE DRILLED: 11-22-94
4.25" Stickup
SAMPLE
WELL DESCRIPTION TYPE REC R
Bentonite Seal ti
p 18/24
1" Soh 40
PVC Riser 2

P 22/24
I" Sch
r
een
PVC Sc

.:::. 24/24
20-40 Sand
Filter Pack 6

P 24/24
8

P 6/24
10
-
P
12/24
I
12
i
P 24/24
I
14
-
p j 16/24 1
16
::..
i
p 16/24
18
-
P 120/24
20
-
22
I
24
25
U.S.C. SOIL DESCRIPTION IPPIID11
Black, organic, soil (MUCK)
Moist, very brown, fine SAND
Moist, very brown, fine SAND
As above, wet j
As above
i
Wet, very fine to fine SAND
As above
Wet, light gray, fine SAND
As above
Light gray, saturated, very fine to fine SAND
As above
As above, clay seam at 19 feet
Boring terminated at 20 feet
!
r
FILE NAME: ER94018.2-25PZ09
SOUTHEASTERN Dismal Swamp Mitigation Site
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY: PS
North Carolina Department of Transportation
AUDITS, INC. PZ-9 CHECKED BY. BH
COORDINATES: LOGGED BY. JI-H
TOC ELEVATION: DRILLED BY Geo-Environmental
G.S. ELEVATION: DRILL RIG: Scorpion Geoprobe
ELEVATION DATUM: DRILLING METHOD: Hydraulic Hammer
DATE DRILLED: 11-22-94
2.5' Stickup
WELL DESCRIPTION
Bentonlte Seal
1" Sch 40
PVC Riser
1 " Sch 40
PVC Screen
20-40 Sand
Filter Pack
SAMPLE
TYPE REC

?.
2

:r.. i
P
22/24

?:...:. , .
P 15/24!

1

6
'

: 24/24
-
P 124/24
8
P 24/24
10
12-
14
i
16
1
18 j
20
22
24
25
U.S.C. SOIL DESCRIPTION (PPM)
RESISTI M
M)
Black, organic, soil (MUCK)
Orange CLAY seam at 1 foot, brown
i ve fine SAND
i
Brown, slightly mottled dark, fine
j
clayey SAND to sandy CLAY
As above
! Becoming wet, blue-green, glauconitic, fine
san CLAY
Becoming sandier
Saturated blue-green, clayey, fine SAND
Becoming more clayey
Saturated blue-green, fine, sandy CLAY
Boring terminated at 10 feet
FILE NAME:
SOUTHEASTERN Dismal Swamp Mitigation Site ER94018.2-25PZ10
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY. PS
North Carolina Department of Transportation
AUDITS, INC. PZ-10 CHECKED BY: BH
COORDINATES: LOGGED BY: JLH
TOC ELEVATION: DRILLED BY- Goo-Environmental
G.S. ELEVATION: DRILL RIG: Scorpion Geoprobe
ELEVATION DATUM: DRILLING METHOD: Hydraulic Hammer
DATE DRILLED: 11-23-94
2.95' Stickup
REC RESIST U.S.C. SOIL DESCRIPTION IPA
WELL DESCRIPTION SAMPLE
Bentonite Seal
? .. • : • a,, P :19/24

W
1 " Sch 40
PVC Riser P 18/24
•
4 . i
11" Sch 40 : .::...
PVC Screen :.: {. `.

P

24/24
11
20-40 Sand !
Filter Pack 6 .... i
, I
: I .
P
24/24
8
Black, organic MUCK; some clay
Wet, dark brown MUCK and fine SAND
Wet, brown, fine SAND
As above
Wet, dark gray, fine SAND
Wet, dark gray, very fine SAND with clay
Gray-green, fine to very fine SAND with clay
Boring terminated at 10 feet
P i 24/24
Saturated
10-
i
12-
it
14-
i
r
16-
L
18
I
i
20
22
l
24
25
FILE NAME:
SOUTHEASTERN Dismal Swamp Mitigation Site ER94018.2-25PZ11
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY: PS
North Carolina Department of Transportation
AUDITS, INC. PZ-11 CHECKED BY: BH
COORDINATES: LOGGED BY: JLH
TOC ELEVATION: DRILLED BY- Geo-Environmental
G.S. ELEVATION: DRILL RIO: Scorpion Geoprobe
ELEVATION DATUM: DRILLING METHOD: Hydraulic Hammer
DATE DRILLED: 11-23-94
4.18' Stickup
SAMPLE SOIL DESCRIPTION PID
U
S
C
WELL DESCRIPTION TYPE RFC 'RESIST .
.
.
(PM
Bentonite Seal
' Dark brown
organic
SAND j
:
'j
' 24/24 ,
,
.
.
. p
Brown
very fine to fine SAND
2
,

1 " Sch 40
PVC Riser
P
4/24

1" Sch 40
PVC Screen
4

: j
Wet, brown, fine SAND
.. a :: I light brown
Saturated
fine SAND
... p 24/24 j ,
,

20-40 Sand
Filter Pack
g : :.. .
r ..
Becoming gray at 5.5 feet

P 24/24
8 r Saturated, gray-green, sandy CLAY to clayey SA

- i

1

10 p 4/24 Saturated blue-gray, slightly clayey, fossiliferous
fine SAND
P 24/24 As above

12 Becoming more clayey
i
12/24'

14 P i
Becoming less fossiliferous and less clayey
24/24
16 Saturated gray-green, slightly clayey, fine SAND
i
22/24
18 p As above
,
6/24 i
20 P
Saturated, gray, very fine SAND
Borina terminated at 20 feet
22-
24-
25-
FILE NAME:
SOUTHEASTERN Dismal Swamp Mitigation Site ER94018.2-25PZ12
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY. PS
North Carolina Department of Transportation
AUDITS, INC. PZ-12 CHECKED BY: BH
COORDINATES:
TOC ELEVATION:
G.S. ELEVATION:
ELEVATION DATUM:-
2.6' Stickup
Bentonite Seal j
.vans
2
V Sch 40
PVC Riser
V Sch 40
PVC Screen 4

20-40 Sand
Filter Pack 6
8-
10-
12-
141
16
18
20
22
4
24-
25
25-

LOGGED BY:
LOGGED
JLH
DRILLED BY- TJK
DRILLRG: TJK
DRILLING METHOD: Hand Auger
DATE DRILLED: 11-30-94

SAMPLE U.S.C. SOIL DESCRIPTION I PID
TYPE REC RESIST! IPPMI
i
Black, organic, slightly sandy LOAM
Becoming brown, organic, slightly clayey SAND,
wet at 1.5 feet; As above, saturated
Gray-brown, sandy CLAY, saturated
Blue-green, clayey SAND, saturated
Brown-green, very fine to fine SAND
Becoming bluer
Boring terminated at 5.5 feet
i
i
i
FILE NAME:
ER94018.2-25PZ13
?-
SOUTHEASTERN Dismal Swamp Mitigation Site
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY: PS
North Carolina Department of Transportation
AUDITS, INC. PZ-13 CHECKED BY: BH
COORDINATES: LOGGED BY: TJK
TOC ELEVATION: DRILLED BY: JLH
G.S. ELEVATION: DRILL RIG: JLH
ELEVATION DATUM: DRILLING METHOD: Hand Auger
DATE DRILLED: 11-30-94
2.7" Stickup ---??
Bentonite Seal
1 " Sch 40 -
PVC Riser
1" Sch 40 -
PVC Screen
20.40 Sand
Filter Pack
SAMPLE '
TYPE REC RESIST U.S.C. SOIL DESCRIPTION
'
Black, organic, slightly sandy LOAM
2 ; Black, organic loam to very fine SAND
Dark brown, very fine SAND; some clay
4 As above, saturated
Brown, very fine SAND, saturated
Becoming blue-green, very fine SAND
6 ..:.I
very fine SAND; trace clay
Blue-gray,
8 As above
Boring terminated at 7 feet
10-12

14
16
18
20
22
24
25
I
F
PID
(PPM)
FILE NAME:
ER94018.2-25PZ14
SOUTHEASTERN Dismal Swamp Mitigation Site
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY: PS
North Carolina Department of Transportation
AUDITS, INC. PZ-14 CHECKED BY: BH
COORDINATES: LOGGED BY- TJK
TOC ELEVATION: DRILLED BY- JLH
G.S. ELEVATION: DRILL RIG: JLH
ELEVATION DATUM: DRILLING METHOD: Hand Aucer
DATE DRILLED: 11-29-94
2.48" Stickup
TYPE SAMPLE
ECRESIST! U.S.C. SOIL DESCRIPTION IPID
PPM)
WELL DESCRIPTION
Bentonite Seal
Slightly sandy, black, organic LOAM
" '
'
'
'
Sch40
1
PVC Riser 2 ?

i •
•
•
•
=
s
Becoming black, organic CLAY

" Black, organic, sandy CLAY, wet at 1.5 feet
Sch 40
1
PVC Screen 4

.. ,.,
I
Brown, very fine to fine SAND, some clay

20-40 sans
Finer Pack
6 Saturated at 3.5 feet, slightly clayey
Becoming more sandy
j Brown, fine SAND, saturated at 4.5 feet

g Blue-gray, sandy CLAY, clayey SAND,
saturated at 5.5 feet

i Boring terminated at 8.5 feet, no recovery
10
i
12-
14-
? i
i
16-
I
18
I
20-
22-
i
24
25
FILE NAME:
SOUTHEASTERN Dismal Swamp Mitigation Site ER94018.2-25PZ15
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY: PS
North Carolina Department of Transportation
AUDITS, INC. PZ-15 CHECKED BY: BH
COORDINATES: LOGGED BY- JLH
TOC ELEVATION: DRILLED BY- TJK
G.S. ELEVATION: DRILL RIG: TJK
ELEVATION DATUM: DRILLING METHOD: Hand Auger
DATE DRILLED: 11-30-94
2.48' Stickup
SAMPLE U.S.C. SOIL DESCRIPTION PID
wF? rscRlaTleN TYPE •. REC iRESIST (PPM)
Bentonite Sea[ ?j\ M
"
Sch 40
1 ?
PVC Riser 2 ; • .,
"
Sch 40
I
4
PVC Screen
20.40 Sand :.:
Filter Pack 6 ; •'.1...... .
8
10
12
Black, organic, slightly sandy loam,
becoming clayey
Dark brown, o manic, very fine SAND,
very moist at 2)I feet
Mottled rust, organic, brown, sandy CLAY,
wet at 3 feet
Becoming sandier, brown, sandy CLAY to
gyey SAND, saturated at 3 feet
i
Becoming blue-gray, sandier
Blue-gray, very fine to fine SAND,
saturated at 5.5 feet
i
As above
j Boring terminated at 7 feet
14
i
16-
18
j
20-
22-
24-
25-
FILE NAME:
SOUTHEASTERN Dismal Swamp Mitigation Site ER94018.2-25PZ16
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY: PS
North Carolina Department of Transportation
AUDITS, INC. PZ-16 CHECKED BY: BH
COORDINATES: LOGGED BY. JLH
TOC ELEVATION: DRILLED BY. TJK
G.S. ELEVATION: DRILLNG: TJK
ELEVATION DATUM: DRILLING METHOD: Hand Auger
DATE DRILLED: 11-29-94
2.5' Stickup
SAMPLE U.S.C. SOIL DESCRIPTION PID
WELL DESCRIPTION TYPE REC RESIST! (PPM)
Bentonite Seal
Black organic, very fine, sandy LOAM
t ° Sch 40
PVC Riser 2 ! Becoming brown very fine SAND at 1.5 feet
Very moist tan fine SAND at 2.0 feet
Becoming more clayey
Becomin less cla a wet at 3.5 feet
I„ sch

40
en 4
PVC scre Brown, very fine to fine SAND,

saturated at 4 feet
As above
20-40 Sand
Fitter Pack 6 : .
Becoming blue--ggra very fine to fine,
slightly ciga a SAN
8
As above
10 I Boring terminated at 9 feet

12
I
I
14
I
16
I
i
18

20 i
-
22
-
24
-
25

ation Site
Miti
l S
i FILE NAME:
ER94018.2-25PZ17
SOUTHEASTERN
ENVIRONMENTAL wamp
sma
D
g
Gates and Perquimans Counties, NC
North Carolina Department of Transportation MADE BY: PS
AUDITS, INC. PZ-17 CHECKED BY., BH
COORDINATES:
TOC ELEVATION:
G.S. ELEVATION:
ELEVATION DATUM:-
3.8' Stickup
VELL DESCRIPTION
Bentonite Seal 33-8'?

1" Sch 40
PVC Rlser 2
1 " Sch 40
4
PVC Screen
20-40 Sand
Filter Pack 6
8-
10
12-
14-
16
18
20
22
24
25

FILE NAME: ER94018.2-25PZ18
SOUTHEASTERN Dismal Swamp Mitigation Site
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY: PS
North Carolina Department of Transportation
AUDITS, INC. PZ-18 CHECKED BY: BH
LOGGED BY: 4Lr1
DRILLED BY• TJK
DRILL RIG: TJK
DRILLING METHOD: Hand Auger
DATE DRILLED: 11-30-94

SAMPLE U.S.C. SOIL DESCRIPTION PID
TYPE REC RESISTI. (PPM)
Black, organic, slightly sandy LOAM
Black, organic, clayey SAND, moist at 1 foot
Brown, very fine to fine SAND, wet at 3 feet
Tan, very fine SAND, saturated at 4 feet
Becoming blue-brown, very sandy
CLAY to clayey SAND
Tan, very fine to fine SAND, saturated at 5 feet
Blue-green, slightly sandy CLAY
Becoming blue-green, clayey SAND
i
Boring terminated at 7 feet
r
I
I? ?I
'r
COORDINATES:
TOC ELEVATION:
G.S. ELEVATION:
ELEVATION DATUM:-
2.4' Stickup
/ELL DESCRIPTION
Bentonite Seal
V Sch 40
PVC Riser
1" Sch 40 -
PVC Screen
20-40 Sand
Filter Pack

4 /.

8
10
12
14
16
18
20
22
24
25
LOGGED BY: omen
DRILLED BY- JLH
DRILL RIG: JLH
DRILLING METHOD: Hand Auger
DATE DRILLED: 11-29-94
SAMPLE U.S.C. SOIL DESCRIPTION P1D
TYPE . REC RESIST (PPM)
Black, fine, sandy LOAM
Becoming brown and sandy, fine sand
at 2 feet
Becoming wet, brown, clayey SAND,
saturated at 3.8 feet
11
Blue rayy,, clayey, fine SAND to sandy,
fine CLA Y, saturated at 6 feet
Loose blue-gray, slightly clayey, fine SAND
Boring terminated at 6.5 feet
FILE NAME:
SOUTHEASTERN Dismal Swamp Mitigation Site ER94018.2-25PZ19
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY: PS
North Carolina Department of Transportation
AUDITS, INC. PZ-19 CHECKED BY. BH
COORDINATES: LOGGED BY- JLn
TOC ELEVATION: DRILLED BY BLH
G.S. ELEVATION: DRILL RIG: BLH
ELEVATION DATUM: DRILLING METHOD: Hand Auaer
n DATE DRILLED: 11-29-94
1.96
Bentonite Seal
UJOi
1" Sch 40 W U
PVC Riser 2 ^
..7,77
1 Sch 40 4
PVC Screen ... .

20-40 Sand - -:::
Fliter Pack 6 i.

12-1
14
16?
18
20
i
22
24
25
SAMPLE
TYPE ; REC RESIST;
i
U.S.C. SOIL DESCRIPTION
Black, organic, sandy LOAM
Becoming brown, less organic, very fine SAND
Becoming tan
Becoming moist, wet at 3.5 feet
Dark gray, sandy CLAY to clayey SAND
PID
(PPM)
Blue-gray clay seam at 4.25 feet, j
saturated at 5 feet
Sand, clay mixture becoming more sandy,
blue ra at 5.5 feet
i More sandy, blue-gray at 5.5 feet
Saturated blue-gray, slightly clayey SAND
Boring terminated at 8.5 feet
FILE NAME:
SOUTHEASTERN Dismal Swamp Mitigation Site ER94018.2-25PZ20
----
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY. PS .
North Carolina Department of Transportation
AUDITS, INC. PZ-20 CHECKED BY: BH
10-?
I i
COORDINATES: LOGGED BY: BLH
TOC ELEVATION: DRILLED BY- BLH
G.S. ELEVATION: DRILL RIG: BLH
ELEVATION DATUM: DRILLING METHOD: Hand Auger
DATE DRILLED: 12-8-94
2.4' Stickup
SAMPLE U.S.C. SOIL DESCRIPTION PID
WELL DESCRIPTION TYPE REC (RESIST; (PPM)
Bentonite Seal
Orange, slightly silty, fine to very fine SAND
"
Sch 40
1
PVC Riser 2
I" Sch 40
PVC Screen
20-40 Sand
Filter Pack 4

Boring terminated at 4.62 feet
;
6 i
-
8
-
10
-
i
12
-
i
14

? I

16 I
-
18
i I

20 i
-
22
-
24
-
25
-

ation Site
Miti
m
l S
Di FILE NAME:
ER94018.2-25PZ21
SOUTHEASTERN
ENVIRONMENTAL g
p
wa
sma
Gates and Perquimans Counties, NC
North Carolina Department of Transportation MADE BY. PS
AUDITS, INC. PZ-21 CHECKED BY. BH
COORDINATES: _
TOC ELEVATION:.
G.S. ELEVATION:.
ELEVATION DATU
1.96
Bentonlte Seal
"
Sch 40
1
PVC Riser 2
"
1
Sch 40
PVC Screen
20-40 Sand :
Fitter Pack 6 ::: •i
8

10 i
12
14
16
18
20
22
24
25
LOGGED BY. JLH
DRILLED BY: TJK
DRILL RIG: TJK
DRILLING METHOD: Hand AWr _
DATE DRILLED: 12-1-94
SAMPLE U.S.C. SOIL DESCRIPTION PID
TYPE REC 'RESIST! (PPM)
i
Black, organic, rich, fine, sandy LOAM
Tan, very fine to fine SAND
White, well-sorted, very fine SAND
Becoming moist and mottled
Wet at 4 feet j
Becoming slightly clayey to clayey
j Slightly mottled orange, dark-gray clayey SAND
j to sanCLAY
Blue-gray, very fine to fine SAND; trace
clay, saturated at 5.5 feet
Blue-gray, marine CLAY with sand lenses
i
Blue-gray, very fine to fine SAND, saturated
j Boring terminated at 8 feet
FILE NAME:
SOUTHEASTERN Dismal Swamp Mitigation Site ER94018.2-WPPZ01
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY: PS
North Carolina Department of Transportation
AUDITS, INC. WP-1 CHECKED BY: BH
COORDINATES:.
TOC ELEVATION:
G.S. ELEVATION:
ELEVATION DATUM:-
2.1' Stickup
Bentonite Seal
1 ° Sch 40 -
SAMPLE
TYPE I REC F
LOGGED BY: BLH
DRILLED BY BLH
DRILL RIG: BLH
DRILLING METHOD: Hand AuOer
DATE DRILLED: 12-5-94
U.S.C. SOIL DESCRIPTION APP
Black, fine, sandy, loamy, organics
Dark brown, organic, rich, fine SAND
Becoming light brown i
Dark brown, fine, sandy, high plastic CLAY
Becoming mottled, orange-gray and wet
Blue-gray, medium to fine SAND, saturated
I'
i
i
i
As above
terminated at 8 feet
I
FILE NAME:
SOUTHEASTERN Dismal Swamp Mitigation Site ER94018.2-EPPZ03
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY: PS
North Carolina Department of Transportation
AUDITS, INC. EP-3 CHECKED BY: BH
COORDINATES: LOGGED BY: ULM
TOC ELEVATION: DRILLED BY. BLH
G.S. ELEVATION: DRILL RIG: BLH
ELEVATION DATUM: DRILLING METHOD: Hand Auger
I-l DATE DRILLED: 12-8-94
2.1 " Stickup
SAMPLE U.S.C. SOIL DESCRIPTION PID
WELL DESCRIPTION TYPE REC RESISTI (PPM)
Bentonite Seal
Dark-brown, slightly fine sandy, organics
1 " Sch 40
Ri
ser 2
PVC
i,
Becoming dark-brown, loamy fine SAND
1" Sch 40
Becoming light brown at 3 feet
PVC Screen 4 -
interbedded, fine SAND and
i Clay
20-40 sand -?::::
Filter Pack :.:: j ,
brown ray, high mastic, CLAY lenses

Blue-gray, slightly to clayey, fine SAND, wet
Blue-gray, high plastic CLAY
Blue-gray. sli htl to cla a fine SAND
Saturated

! I
Boring terminated at 8 feet
10 ', i I
I ?
12

14;

16?
18
j

I

I

20

i I

i
22
I

24- i
25

FILE NAME: ER94018.2-EPPZ02
Site
ti
Miti
SOUTHEASTERN on
ga
Dismal Swamp
Gates and Perquimans Counties, NC MADE BY: PS
ENVIRONMENTAL North Carolina Department of Transportation
AUDITS, INC. EP-2 CHECKED BY, BH
COORDINATES: LOGGED BY: T,1K
TOC ELEVATION: DRILLED BY: BLH
G.S. ELEVATION: DRILL RIG: BLH
ELEVATION DATUM: DRILLING METHOD: Hand AUDer
DATE DRILLED: 12-8-84
4.51' Stlcku
SAMPLE U
SOIL DESCRIPTION PID
S
C
WELL DESCRIPTION .
.
.
TYPE REC RESIST: (PPM)
Bentonite Seal
.....k Black, fine, sandy LOAM

1° sch 40
PVC Riser
2 Organic Soil
Brown, fine, organic, rich SAND

V Sch 40

4
Wet at 3.5 feet
PVC Screen
20-40 Sand
Filter Pack
- Boring terminated at 5.5 feet
6

8
10
12
14
16
18
20
22
24
25
FILE NAME:
ER94018.2-HPPZ01
SOUTHEASTERN Dismal Swamp Mitigation Site
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY. PS
North Carolina Department of Transportation
AUDITS, INC. HP-1 CHECKED BY' BH
COORDINATES: LOGGED BY: BLH
TOC ELEVATION: DRILLED BY: BLH
G.S. ELEVATION: DRILL RIG: BLH
ELEVATION DATIAI: DRILLING mmoD: Hand Auger
DATE DRILLED: 12-8-94
2.1" Stickup
PID
SAMPLE U.S.C. SOIL DESCRIPTION
WELL DESCRIPTION TYPE REC 'RESIST. i (PPAA)
Bentonlte Seal
Dark-brown, fine sandy, organic LOAM (topsoil)
1 " Sch 40 l? l l
PVC Riser 2 White seam at 2 feet
lM
Becoming light-brown, fine SAND
!
I" h
PVC screen 4 1 Becoming very light buff at 2.5 feet
20-40 Sand
Finer Pack
6 j Becoming light-gray and wet at 5.5 feet
I
Becoming clayey at 7.5 feet
!
Boring terminated at 8 feet
10
12
14
16
18
20
22
24
25
FILE NAME:
SOUTHEASTERN Dismal Swamp Mitigation Site ER94018.2-EPPZ01
ENVIRONMENTAL Gates and Perquimans Counties, NC MADE BY: PS
North Carolina Department of Transportation
AUDITS, INC. EP-1 CHECKED BY: BH
7*S&ME
January 31, 1995
Environmental Services, Inc.
1318 Dale Street
Suite 220
Raleigh, North Carolina 27605
Attention: Mr. Brian Hayes
Reference: Laboratory Test Results of Soil Samples
Job Reference ER94-018.2
S&ME Job No. 1053-95-120
Dear Mr. Hayes:
At your request, S&ME, Inc. has performed laboratory Grain Size Analysis with
Hydrometer on nine (9) soil samples delivered to our office. Plasticity index was
determined on three (3) samples as requested. Testing was performed in general
accordance with ASTM D-422, "Particle Size Analysis of Soil", and ASTM D-4318,
"Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils".
Plasticity Index was determined for samples P2-2 (6'-8'), P2-2 (8'-10'), and P2-16.
Plasticity Indices are 14, 3, and 19 respectively, as shown in Table I. Attached are Grain
Size Distribution Sheets for each sample.
S&ME, Inc. appreciates the opportunity to perform laboratory testing for Environmental
Services, Inc. If you have any questions or comments concerning these results, please
do not hesitate to contact our office.
Sincerely,
S&ME, Inc.
,?gL C ,k?
Brian C. Glidewell, E.I.T.
Staff Professional
Wes Lowder, P.E. U
Construction Services Manager
S&ME, Inc. 3100 Spring Forest Rood, Raleigh, North Carolina 27604, [phone], Fox [phone]
Mailing address: P.O. Box 58069, Raleigh, North Carolino 27658-8069
TABLE I
ATTERBURG LIMITS
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APPENDIX C
HYDRAULIC CONDUCTIVITY TEST RESULTS
Slug Test PZ -1
1.00
9
8
7
6
5
4
O

0.10
0.00
200.00 400.00 600.00 800.00 1000.00 1200.00 1400.00 1600.00
Time
Well Number: PZ' Date: Q2,' j 4
Computed By:
Casing diameter d = " 5' -r (cm)
Borehole diameter D = S, OR (em)
Length of screen L = 2, /, j (cm)
Time lag at 0.37 H-/Ho T = 1333- (seconds)
k = d2 in r 2mL 1 m= 1
h L D J
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn & Fang, pp. 29-35. 7
z,?. (z?vl ?? jJ
S, v
(2z1. 3)?/33S)
Note: m = khorizontal Assume kh = kv = 1
/kvertical .

/, L Z X/d cam, sP?
kh=-
DRAWDOWN TEST
'ELL NO. f"- -/
_40P OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER I
BOREHOLE DIAMETER .Z
SCREEN DEPTH-(,, 0 - ?. L9
c
REFERENCE POINT 761
AMOUNT OF WATER REMOVED
LOCATION (rY rPf ?o?h T
DATE
TIME
COMPUTED BY
ASSISTED BY
PERSONS OBSERVING
EVACUATION METHOD
STATIC WATER LEVEL ?r 4 7
RECOVERY DATA
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
0 2,yq 2,aj /.C) s
2,55? /, 7 0,77o

1147
Z; dl z. K3
L.
77
3?3r? .2, -70 1,74 K 7
. ° Z, 73 1,72 c?.,Y 47

s. 2.1 5? , Sy 0, 778
l(S° 0,7.E /
7:10 : d? / ?o c1 6°1
?? 130 0
2- ?v6
(d 3, f ° /f ?S 4
0,

?? s 11 0 , 71,
0, 3 6,5
--?- I

0,?,,
D• OS
NOTES ! -, -4.,,i I, Ll 4
Slug Test PZ - 2
1.00 -,-
9 -
8 -
7
6
5
4
3
2
O
= 0.10
= 8
7
6
5
4
Time
Well Number: PZ - a
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 H-/Ho
Date: 1a' - ?4 - 9 y
Computed By: S"
d = z- S 4 (cm) I
.,
D = S .eR (c m) -Z
L = 153. oo (cm) to
T (seconds)
kh = d2 In -in L 1
8 LT
m=1
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn & Fang, pp. 29-35.
Z (z-) (IX-1 5' 1) ?-
K ? CZ.S? ( y -1) ZS.lI -
5 , 0 8 a. O4 d( 9cl -
_ a5-40 4U ZS?°`IO
C$1? ?s3? C Z wl .
Note: m = khorizontal
?kvertical
Assume kh = kv =1
kh = 9.9'4- x 1 b _T C?M I Sew
DRAWDOWN TEST
SELL NO.
TOP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER t ,
BOREHOLE DIAMETER 2
SCREEN DEPTH 2, 3 S - 'S
REFERENCE POINT 7.r/ C
AMOUNT OF WATER REMOVED
LOCATION -G r 7?,f ('e
DATE 30 '41" 94
TIME
COMPUTED BY Fj . ?G>
ASSISTED BY
PERSONS OBSERVING is . /fir o
EVACUATION METHOD
STATIC WATER LEVEL ?f • q,?
SQL - T wL = /4
RECOVERY DATA Sk L lJ vL,T = l
'a
ELAPSED
TIME GROUNDWATER
DEPTH (pw? ) H H/Ho
d o 4,?8 7d0
jo 450 0.6
Z,7Y
1. r? z. 7 z, 1 2-y
2" a C , 2, Z, Z q ©. 6"0
2, Z.?d zoo
3.??
3 7J
0'0 ZS
?, 3, d 3 S v 1, `(? , Z9 7
4
? f.?6 ?zZ ?,Zys
7 ?.?4 ?,?? o,2v9
g 4,o?
9 /
`f. Or? l o-16-3
Id 4?L? U 7 d 4, /5Z
r r yr 3d v, < d O, 11 0

' L
14.
;

MOTES sue; c G, < S
Slug Test PZ -4
O
1.00
9
8
7
6
5
4
3
2
0.10
0.00
50.00
100.00
150.00
Time
I
250.00
200.00 300.00
Well Number: />Z- .?f
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 H-/Ho
Computed By:
Date: 2c57-1--l- 74
d = Z, S? (cm)
D = S a'? (c m)
L (cm)
T = ?y (seconds)
k = d2 in r 2mL m = 1
h L D
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn & Fang, pp. 29-35.
Note: m = khorizontal
/kvertical
Assume kh = kv =1
kh = z.29Xlo_y ?I sic
DRAWDOWN TEST
? ELL NO. Do:? - ?I
OP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER
BOREHOLE DIAMETER a',
SCREEN DEPTH . (? S - -, . ?,
REFERENCE POINT i y C
AMOUNT OF WATER REMOVED
LOCATION G,-?es C,,.
DATE It 30-2-+
TIME 13 4 =rl
COMPUTED BY
ASSISTED BY -%7
PERSONS OBSERVING_
EVACUATION METHOD
STATIC WATER LEVEL q 3
RECOVERY DATA
iS
30
bo
'? S
qo
IGS
IZ?
14b
z
Z4
0
;? 40
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
0
.? I
S!, go -- k
a,13=1!
•?0 ?? 9'.

r
1 L1 5 4

i
I
a a 3
L

- 33

v
0
-NOTES Se ?k SecS e to psed Ln,,<2
Slug Test PZ - 5
1.00 -
9
8
7
6
5
4
0
2
2
TIME

Well Number: F2 -S Date:
Computed By: --SA
Casing diameter d = (cm) 1 `
Borehole diameter D = S.oq (cm)
Length of screen L = (cm) +o' - 3.Cn = (".09
Time lag at 0.37 H-/Ho T = (seconds)
k = d2 In r 2ml, m = 1
h L D J
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn be Fang, pp. 29-35.
--' • \ p ? ??56896 b• 0 000 \1
-• S (o (e
Cad C?b?•?1 C(?avl
Note: m = khorizontal/kvertical Assume kh =k v =1
kh = 1, x (?"s c,?, l?
DRAWDOWN TEST
'ELL NO. 1"22 - 5
TOP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER
BOREHOLE DIAMETER
SCREEN DEPTH
REFERENCE POINT
AMOUNT OF WATER REMOVED
+?,
LOCATION GG s Co
DATE ?l/?/tea v
TIME
COMPUTED BY
ASSISTED BY
PERSONS OBSERVING __d
/ice, p
EVACUATION METHOD
STATIC WATER LEVEL 3
RECOVERY DATA
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
a 3. 9J /, o

S 3 3 0 1 oc,52--
3 3<4 0413

2,76 0, 6 /
Z/ z,` ? o. 6bS
5: /? i 4 Z z? ?, 6 3 7
5-6 2, 4-f
d j.
7d

z/
2-,
?? r?6 L,o D5'
4
21 1,71 0.4 7
?= 2, i, o, 391

NOTES ??. a - Z - ty
Slug Test PZ - 6
1.00
9
8 --
7
6
5
4
0
3
2
0.10
200.00
0.00
:
0
600.00 1000.00 1400.00
400.00 800.00 1200.00 1600.00
TIME
Well Number: RZ- 6
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 H-/Ho
Date: Z.0-12-
Computed By: /f 4 f' I
d = Z• `< (cm)
D = Sad (cm)
L = /!1 Z (cm)
T = y i (seconds)
k = d2 In [ 2mL 1 m = 1
h L D J
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn be Fang, pp. 29-35.
Note: m = khorizontal/kvertical
Assume kh = kv =1

k = Z?' S k/? fsP?
h
DRAWDOWN TEST
.YELL NO. / Z-
TOP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER P '
BOREHOLE DIAMETER
SCREEN DEPTH 0, 71
- S. T 9
REFERENCE POINT To('
AMOUNT OF WATER REMOVED
LOCATION G1 7,,-; re&* r"
DATE 3 0 /4-y'/
9 y
TIME
COMPUTED BYE,. o
ASSISTED BY
PERSONS OBSERVING
EVACUATION METHOD
STATIC WATER LEVEL
RECOVERY DATA
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
0 6"6 e, c l 0 G
3 0.7 7
,z7 3.y1 0,727
3, 4 o,
Z;atl 1,-73 2,7S p.G D
z? ; ° /. `%v z 7 585
3 . / s 5-2 7
?-3j ?. z 3
Z?S
S
4.00 Z,37 g
p

2
2, OP
?, yv9
8(e Gy0 2-
7 z 9s 73 70

3. `+ 2 7 ©, 27/

o, 2 3J5'
/ q
p 7,P J
II

0, 6 3 o, ij5
'OTES i 7 , 4 - 4 zr
Slug Test PZ - 8
1.00 -?-
9
8
7
6
5
4
3
2
O
= 0.10
= s
7
6
5
4
3
2
0.01
0.00
Well Number:
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 H-/Ho
Date: la- ?v - 9 y
Computed By: ?3Z K
d = a.yi (cm)
D = S.oB (c m) ?.
L = II h _ t^ (cm) ?o' - h• 3? = 3.?3
T = 3? , S (seconds)
k = d2 In r 2mL1 m=1
h L D J
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn be Fang, pp. 29-35.
---- ------ - -- - 3'S N 8 O 3 B O
K>
Note: m = khorizontal Assume kh = kv =1
?kvertical .
kh = 10 ?Te?
DRAWDOWN TEST
4 'ELL NO.-
OP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER 10
BOREHOLE DIAMETER a"
SCREEN DEPTH 1. o -- L. C a
REFERENCE POINT
AMOUNT OF WATER REMOVED
LOCATION C? ?lP S C1 ?, .
DATE 11- 3 0 - 9 a
TIME
COMPUTED BY
ASSISTED BY -r r S-tA
PERSONS OBSERVING
EVACUATION METHOD
STATIC WATER LEVEL
RECOVERY DATA
1S
3,1
4S
6o
31?
40
I OS
12J
I?
I?
Ibt
16o
;)\o
Zoo
300
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho

U.8S =
.30
S °l
u S.(,-+
.8 335
.I ?
I r ?' 't?
eV

ci 0,1

5.3o
a ?.
?3 1 0. 0
Z
0.1? 0. b-49
57 ?e 1

NOTES ?? ?k ?? Sccs e la psec\ i , e
Slug Test PZ - 9
1.00
9
8
7
6
5
4
0
2
3
2
0.10
0.00 20.00 40.00 60.00
80.00 100.00 120.00 140.00 160.00
TIME
Well Number: 14?12 -J
Computed By:
Date: zd' -12
Casing diameter d = (c m)
Borehole diameter D = Sa.? (cm)
Length of screen L = 135, 4 (cm)
Time lag at 0.37 H/Ho T = 32 (seconds)
kh = d2 1n ( 2mL 1 m = 1
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn be Fang, pp. 29-35.
Note: m = khorizontal
?kvertical
Assume kh = kv =1

DRAWDOWN TEST
/-ELL NO. "Z - D-
TOP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER A
BOREHOLE DIAMETER Z "
SCREEN DEPTH o 79 - S, 7y
REFERENCE POINT 7o r
AMOUNT OF WATER REMOVED
LOCATION (2 r?
DATE 30' .4'a ? `?
TIME
COMPUTED BY If
ASSISTED BY
PERSONS OBSERVING fl o
EVACUATION METHOD
STATIC WATER LEVEL S- 41 -
2-RECOVERY DATA

ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
D o S, ?f z
(?-3 Zi 9 d Z /. d
/-
7
-7
a. z8S
?•3? 2-
l%Z
z S,
37 d
z
o al
2., 6,o7
o,l3S

NOTES
Slug Test of PZ -10
0
1.00
9
8
7
6
5
4
I
0.10
50.00 150.00 250.00 350.00
0.00 100.00 200.00 300.00
TIME
400.00
Well Number: PZyd
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 Hi/Ho
Date: - 12 -4?
Computed By:
d = 2. S4 (cm)
D = 5" 6)21' (cm)
L (cm)
T = ?S (seconds)
k = d2 in r 2mL 1 m= 1
h L D J
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn & Fang, pp. 29-35.
Note: m = khorizontal
/kvertical
Assume kh = kv =1
kh
DRAWDOWN TEST
/ELL NO.? z - l
?40P OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER /11
BOREHOLE DIAMETER 2-
SCREEN DEPTH 2, 4-7 - -7 7
REFERENCE POINT TO "
AMOUNT OF WATER REMOVED
LOCATION 6-?w >is Cal?g y
DATE 3
TIME
COMPUTED BY ? /?a ?.r
ASSISTED BY
PERSONS OBSERVING
EVACUATION METHOD
STATIC WATER LEVEL s 4 ,
RECOVERY DATA
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho

O?s? 3.jt ?,a6 0, ?
(.s 3.S5 6 o,z f?

Or 76 . 4 0

2?° ?r.?PZ 0 d,/D

6, 0
S. i? S,d? 0 7 v.o6?
0,057

/, v

J
(<
NOTES S;,T ,,- - 2
Slug Test of PZ -11
O
2
1.00
9
8
7
6
5
4
3
2
0.10
F
E
L
b
0.01
25.00
0.00 50.00
75.00 100.00 12500 150.00 17500 200.00 22500 250.00
Time
Well Number:
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 H-/Ho
Date: -94
Computed By: SLA
d = a.Sy (cm)
D = S.u? (cm) z
L = ?90.C) (cm) IC - 3.?? = ?.a3
T = 13 -4 - ICT (seconds)
k = d21n r 2mL? m=1
h L D
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn be Fang, pp. 29-35.
_ .?- , 33 oao
Note: m = khorizontal?kvertical
Assume kh =k v =1
kh = `;?. 0 x \ 0-1-i cm1 S,- C, ?
DRAWDOWN TEST
YELL NO.
-rOP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER
BOREHOLE DIAMETER Z
SCREEN DEPTH Z o P 7 c j
REFERENCE POINT ! ?- c
AMOUNT OF WATER REMOVED
LOCATION ?a s Ca
DATE 1 ?? - 94
TIME
COMPUTED BY
ASSISTED BY
PERSONS OBSERVING
EVACUATION METHOD
STATIC WATER LEVEL 3. 7
RECOVERY DATA
30
(?o
GU
,7o
b? b
?C
3ok
3bt
`q

osk
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
c)

l Z
j v a. S
? .a3 O

9 ?Ss
3 51
?-
?-
- 3 of oa.

NOTES

Slug Test PZ -13
1.00
9
8
7
6
5
4
3
2
O
= 0.10
7
6
4

n
a i
0.01 -
50.00
0.00 100.00
i
I
li
j
150.00 200.00 25000 300.00
Time
Well Number: P-2 - ?3 Date:
Computed By:
Casing diameter d = :;k.(cm)
Borehole diameter D = io. (cm)
Length of screen L = S , (cm) a, - ? C'o _ 4
Time lag at 0.37 H/Ho T = ? y (seconds)
k = d21n r 2mL? m=1
h L D
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn & Fang, pp. 29-35.
K" ? C L Io.a - ??- = o.oao4??(
- -- - - S 30 . Z S 30(0 4 . Z
= 1
Note: m = khorizontal?kvertical Assume kh =k v
kh= H,,a xlh?Li
cm.i??c

DRAWDOWN TEST
J 'ELL NO. 'P:?- - 13
OP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER BOREHOLE DIAMETER "
SCREEN DEPTH Q. 5-1- 4. S ,
REFERENCE POINT To C
AMOUNT OF WATER REMOVED
LOCATION C--,,-? PS C~? .
DATE 11- 3a -7y
TIME i y?, b
COMPUTED BY
ASSISTED BY , K
PERSONS OBSERVING
EVACUATION METHOD
STATIC WATER LEVEL 3.
- 3?
RECOVERY DATA .
IS
30
yG
(oJ
qo
1ef;
?zo
?eS
1R0
Zoo
2H sac

5w
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho

g9 0. o 3

.? 10, 3\FS
3 O . ?l 3 Z
.30 .? a
1 t

2. 3. 3 3 t
2.30 I t ?-
0 1
3 3,,44 n. 0190
3
4
3. /A 0,
4,3o - t 56
6-,
5 3 S-? O? 04S

NOTES_
Slug Test PZ -14
O
2
5
4
3
2
Time
Well Number:
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 H-/Ho
Date: Z.P -/z - y "r,
Computed By: /jz N
d = ?. s4 (cm)
D z (cm)
L = /6? 6 (cm)
T (seconds)
k = d21n r 2mL? m=1
h L D
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn cat Fang, pp. 29-35.

Note: m = khorizontal/kvertical
Assume kh =k v =1
k h = //X/a-v ?f . ?.?
DRAWDOWN TEST
'ELL NO.
TOP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER 1"
BOREHOLE DIAMETER 3
SCREEN DEPTH 2.45
REFERENCE POINT -c)(_-
AMOUNT OF WATER REMOVED
LOCATION
DATE M - 3,0 - gv
TIME
COMPUTED BY
ASSISTED BY M 4 : -T K
PERSONS OBSERVING
EVACUATION METHOD
STATIC WATER LEVEL q.
3
RECOVERY DATA
z
3
a
S
i
4
10
MOTES
0
z?
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho

Q, 6
3c? u
4- 1
I 3.?

. I?
3 Q
i Q, 45?;L
l , 3? 1 &
,4 3, 8 0.8 0
a 3.9 s o
z is-

y. 30 b
a
20

3

??
t s.h 0.53 .a

? y? as
set- ct? IS S,•c. Q?ar
b- HE o .:j
Slug Test PZ -15
1.00
9
8
7
6
5
4
O
2
Z `

Time
Well Number: 'Pa -0S Date: !a - I'S _ q(4
Computed By: a? ?A
Casing diameter d (cm)
Borehole diameter D (cm)
Length of screen L = , q (cm) gyp' - 3. i8 = (". 'S -I
Time lag at 0.37 H-/Ho T = q L( O (seconds)
k = d2 in r 2mL1 m=1
h L D J
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn be Fang, pp. 29-35.
(a.5 z Ir Cad<.?? (do?.? >? 1
?B???O?.y )? q,v01 IS?o3VOa
Note: m = khorizontal?k Assume kh = kv = 1
vertical
kh = 1.S x 1o-s CO) j?,C-c
DRAWDOWN TEST
ELL NO. I?z - IS
TOP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER 0
BOREHOLE DIAMETER 3"
SCREEN DEPTH 7 . L? 1
REFERENCE POINT ;-p
AMOUNT OF WATER REMOVED
LOCATION
DATE _ 3 0 - 9 y _
TIME 14'Tb
COMPUTED BY
ASSISTED BY 5H T t?C
PERSONS OBSERVING
EVACUATION METHOD
STATIC WATER LEVEL ? . i R
RECOVERY DATA
I?,
3o
4rj
ba
90
zr
301
4 2.c
45?
?c
900
12«
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
eel

30
?-
8 t, L4
Y

9
a 4 --
3 -t .-4 w

17

D
Root
"? • S 3 D ?
:x .
1519 r)
D,?1
to
2.
6-A
.S
4?
1S ?, B3 3' o. LI Ib
Q- a

NOTES ?? S a ?Ci Q?nnS 2A 4',n,,z -
O
2
1.00
9
8
7
6
5
4
3
2
0.10
8
7
6
5
4
2

0.01
Slug Test PZ -16
s,
0.00 200.00 400.00 600.00
Time
800.00 1000.00 1200.00
Well Number: PZ- /6
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 H-/Ho
Computed By:
Date:
d =•S? (cm)
D = /c.1 (cm)
L = /67, (cm)
T = 7 4- S (seconds)
k = d2 In l L- 1 m= 1
h L D J
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn & Fang, pp. 29-35.

Note: m = khorizontal/kvertical
Assume kh =k v =1

DRAWDOWN TEST
'ELL NO. P ? - Ih
?OP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER 1
BOREHOLE DIAMETER
SCREEN DEPTH X0% a. s a- . 5 3
REFERENCE POINT TO
AMOUNT OF WATER REMOVED
LOCATION f-z.1 p (? o ,
DATE ?I - ?n - 9 y
TIME
COMPUTED BY
ASSISTED BY 1-4A t Z
PERSONS OBSERVING
EVACUATION METHOD
STATIC WATER LEVEL y NA
RECOVERY DATA

ELAPSED
TIME GROUNDWATER
DEPTH H I/Ho
P'

Z ?? o
. ?S ?. Ll 14
a off 'A li

1 ?0 9b : O ? ?

r)- 49N
2 '' S
0. ?t4 0, Lk 3,T

'F
i 73, (o ;L
n
?>9

?.. -5 9 LA
?u 3 b.
a
a.
314
31

o . ?S
NOTES o '

?t, 48
6
gI o0 c n, 0. ZILZ?x
y 0% c). 4o e7 1KS
1 ?nc) 4 IS O 33 n ISa
Slug Test PZ -17
O
-17
1.00
9
8
7
6

0.10
0.00
20.00 40.00 60.00
i I
100.00 140.00 180.00
80.00 120.00 160.00 200.00
Time
Well Number: Date:
Computed By: SAN
Casing diameter d = a_Sy (cm)
Borehole diameter D = (c m) LO
Length of screen L = C) (cm)
Time lag at 0.37 H-/Ho T = (seconds)
--a?
k = d2 in r 2mL1 m=1
h L D J
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn & Fang, pp. 29-35.
;L99a 13;2990 o, o00?-4q
Kr- (z.5?,? CaIC?? Cao?.s? (`.x>(3.8> Z"
p, 000
<51 (zo?.S`? (iaa.?
Note: m = khorizontal?kvertical Assume kh = kV =1
?---
-- ki
??+?.=
S. a -A ?b 4 m Se,-
6.000 1\ }
DRAWDOWN TEST
'ELL NO. f - I-4-
"TOP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER I"
BOREHOLE DIAMETER 3!t
SCREEN DEPTH Z- S I- 5 1
REFERENCE POINT
AMOUNT OF WATER REMOVED
LOCATION lTa? es c en
.
DATE -1 I- 3p-q
TIME r5- ; 2, o
COMPUTED BY
ASSISTED BY 74j
PERSONS OBSERVING
EVACUATION METHOD
STATIC WATER LEVEL 3. -3
RECOVERY DATA
0.
30
4S
7V
lob
120
kv
ISO
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
D

O
4? a __ -+

IS Y ?/

of O ,

9S 0. H (4 'Zlxq

?- 3 as
0.
1 3.1 Z

NOTES Se ` ?k i? SPC s e i 4 '
Slug Test PZ -18
1.00 -
9
8
7
6
5
4
0
3
2
0.10
50.00 150.00 250.00
0.00 100.00 200.00 300.00
TIME
Well Number: P-a - k$
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 H-/Ho
Date: ta-- is -94
Computed By: SLEA
d = a.sti (Cm) I''
D = io, a (cm) 4
L = L4 Q, y (cm) 44 .'7o
T = 9 a. (seconds)
k = d21n r 2mL1 m=1
h L D J
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn be Fang, pp. 29-35.
N1 14)
Note: m = khorizontal?kvertical Assume kh =k v =1

DRAWDOWN TEST
/ELL NO. 1':?z - 1$
?fOP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER
BOREHOLE DIAMETER
SCREEN DEPTH
REFERENCE POINT
AMOUNT OF WATER REMOVED
RECOVERY DATA
LOCATION '.3
DATE t Z - ? q %f
TIME III%:
COMPUTED BY
ASSISTED BY -\
PERSONS OBSERVING_
EVACUATION METHOD
STATIC WATER LEVEL.

ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
1 0

0
34
0 3 3
n. 'a tcl
r{ j .Z3
1• 'z'Z
n.49 f)-
44
% o, 3 b
kx Ilk
n. IL. kk 0
•? ?+ 114

NOTES
Slug Test PZ -19
O
-17
?-
1. 00
9
8 -
7
6
5
4
3
2
0.10
0.00
0
100.00 200.00 300.00 400.00 500.00 600.00 700.00 800.00
Time
Well Number:
Date: z,P-1 z -2y
Computed By: /f Gib
Casing diameter d = Z, S`' (cm)
Borehole diameter D = /V. -2 (cm)
Length of screen L = / S7, (cm)
Time lag at 0.37 H/H0 T = Zoo (seconds)
k = d2 in r 2mL 1 m= 1
h D
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn & Fang, pp. 29-35.
Note: m = khorizontal/kvertical
Assume kh = kv =1

-s
kh = P. 7q x"la ,? ?S
DRAWDOWN TEST
'ELL NO. ^ t
TOP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER
BOREHOLE DIAMETER
SCREEN DEPTH t ,
REFERENCE POINT
AMOUNT OF WATER REMOVED
LOCATION
DATE
TIME r 2
COMPUTED BY
ASSISTED BY t ti _. T
PERSONS OBSERVING
EVACUATION METHOD
STATIC WATER LEVEL 8
RECOVERY DATA - - n
IS
3G
?C?
IZO
l?
($O
ZIU
2140
2-:W
2)G- v
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho

µ

00

1. 3

x ?
s
11
'?
0. q
'?-

S
. o -?g o a
s 0. o a
37D ro Nr p ,
42d
t.!
4d° ? ?I.II 3 3
Su u 9 ?f .! 9 D6
,.?
0 t ?.
:-sue COG ?° `I • a1 O, 8fo
NOTES J,64a 7 ?? I 44. 3 q 6. ISO
X -' !J 4' U - 1 '49 -- 3. 0" = Z, -
1.00
9
8
7
6
5
4
O
r
Slug Test PZ - 20
Time
Well Number: P? - in Date: ?a IiS 1 ev
Computed By: :,y
Casing diameter d = a.54 (cm)
Borehole diameter D = is (cm) 14
Length of screen L = i S y , Z (c m) 11 3'- 4 . CN = 5, a b
Time lag at 0.37 H/H0 T = «3. S (seconds)
k = d2 In [ 2mL 1 m = 1
h L D J
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn be Fang, pp. 29-35.
IS?
x? = L io.D.
60 > 6 - o,6b0139
_S) ISa 3y9,
Note: m = khorizontal? Assume kh = kv =1
kvertical
kh = I. y x 10-y Can I Se C-
DRAWDOWN TEST
/ELL NO. 'fq - zib
TOP OF CASING ELEVATION'
GROUND SURFACE ELEVATION
CASING DIAMETER Yl
BOREHOLE DIAMETER 3 "
SCREEN DEPTH ta-
REFERENCE POINT
AMOUNT OF WATER REMOVED
LOCATION ?SU?Ps ?`o
DATE
TIME
COMPUTED BY
ASSISTED BY -Z-?A a, rt -
PERSONS OBSERVING
EVACUATION METHOD
STATIC WATER LEVEL L4, 14
RECOVERY DATA

4S
6c?
90
lob
1Zc,
I roy
t?
22?
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
O
.30 1
ncn

.v5
.? 19 ISLA
?. 1 3 3

a
4 ?
.
01 3 11
1
z u G: 3 k
a.t z T;)-

Z .30 3,q4
2.4 . 8 S
3 q Zti
3. t 5-
y e5 _;;toli
.
3. 1! y! s3 1
4 U, u ? o . 14S

'MOTES ? - S ? ? ? 7,0 5? ? ?\? n5 e ? ?; Me

Community Restoration Types
Nonriverine Swamp Forest - Organic Soil Subtype
Nonriverine Swamp Forest - Mineral Soil Subtype
Mesk: Lonnleaf Pine-Oak Forest
?:
7z
y
-?Forns ed red&-- -w
7 Avail-
??-
• ylr-
%I- A
?- _.,n.?• = ....,,,,.. ter, ?.
Also-
DRAFT
i
U

.i
;t
;? 11
? %t I

-?? -?- - --°- Ili`
000-
r.r.{ +r- .. ter.- .,''1 i
From USGS 7.5' Quadrangles: Hobbaville (19M. Sunbury
(1881), Chapanoke (109?), LYn(:f9 Canter OW)
1\
Community Piantlrtg Plan Map 7-16": E1194018.2 Ftgu-No.. 3
gym ?%Inr- Proposed Clsmaf Swamp
1318 044 Sant Mitigation Tract Drawn Hr: PS Scale-. 10 = 1000'
Suits 220 Gates and Perquimans Counties ----
RnWgk. NC 21605 North Carolina
c?pckrd By; JWp 18 Jan 95
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Proposed Dismal Swamp
iai` g n stc Mitigation Tract nrnW„ BY: PS s?s?: 1000'
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ROADSIDE DITCH IMPACT STUDY
US 17 WIDENING
HERTFORD TO EDENTON
CHOWAN AND PERQUIMANS COUNTIES, NORTH CAROLINA
ESI Job No.: ER94-018.2 (R-2208A)
Prepared for,
N.C. Department of Transportation
1 South Wilmington St.
Raleigh, NC 27601
Prepared by:
ENVIRONMENTAL SERVICES, INC.
1318 Dale St., Suite 220
Raleigh, NC 27605
TEL [phone] FAX [phone] •
April, 1995
?° .w-ten
M ?o-
STATE OF NORTH CAROLINA
DEPARTMENT OF TP ANSPORTATION
JAMES B. HUNT, JR. DIVISION OF HIGHWAYS
GOVERNOR P.O. BOX 25201. RALEIGH. N.C. 27611-5201
May 15, 1995
Dr. G. Wayne Wright
Chief, Regulatory Branch
Department of the Army
Wilmington District, Corps of Engineers
Post Office Box 1890
Wilmington, North Carolina 28402-1890
Dear Dr. Wright:
R. SAMUEL HUNT III
SECRETARY
SUBJECT: Roadside Ditch Impact Study, Supplemental Report to Dismal Swamp Mitigation Site
Report; TIP No. R-2208A, State Project No. 6.03900T, Widening of US 17 from
Hertford to Edenton, Perquimans and Chowan Counties
Please find enclosed three copies of the Roadside Ditch Impact Study for TIP Project
R-2208A. This study, issued as a supplement to the Dismal Swamp Mitigation Plan, was identified
in my letter to you dated April 24, 1995. The study was conducted by our consultant, Environmental
Services, Inc. (ESI). It quantifies the additional impacts to wetlands caused by the excavation of
ditches parallel to sections of the proposed widening of US 17. We propose that the additional
10. 11 acres of wetland impacts identified in this study be added to those already set forth in the
Dismal Swamp Mitigation Plan.
We propose that all impacts from TIP Project No. R-2208A be debited from the Dismal
Swamp Mitigation Site. Please note that the 10.11 acres of ditch impacts do not affect riverine
wetlands (page 10 of ESI's Roadside Ditch Impact Study).
If you should need additional information, please feel free to contact me or Dr. David
Robinson at [phone]. Thank you for your cooperation in reviewing this document.
HFV/dhs
Enclosures (3)
cc: (with one copy of enclosure)
Mr. Mike Bell, COE
Mr. Lee Pelej, USEPA
Mr. David Cox, NCWRC
Mr. David Dell, USFWS
L,-Mr. Ron Ferrell, NCDEHNR
Sincere
Franklin Vick, P. E., Manager
Planning and Environmental Branch
Mr. Eric Galamb, NCDEHNR
Mr. Ron Sechler, NMFS
Mr. N. L. Graf, P.E., FHWA; Attn: Roy Shelton
Mr. D. R. Morton., P.E., State Highway Engineer-Design
Mr. W. D. Johnson, P.E., State Roadside Environmental Eng.
Mr. A. L. Hankins, P.E., State Hydraulics Engineer
ROADSIDE DITCH IMPACT STUDY
US 17 WIDENING
HERTFORD TO EDENTON
CHOWAN AND PERQUIMANS COUNTIES, NORTH CAROLINA
ESI Job No.: ER94-018.2 (R-2208A)
Prepared for:
N.C. Department of Transportation
1 South Wilmington St.
Raleigh, NC 27601
Prepared by:
ENVIRONMENTAL SERVICES, INC.
1318 Dale St., Suite 220
Raleigh, NC 27605
TEL [phone] FAX [phone]
April, 1995
ROADSIDE DITCH IMPACT STUDY
US 17 WIDENING
HERTFORD TO EDENTON
CHOWAN AND PERQUIMANS COUNTIES, NORTH CAROLINA
ESI Job No.: ER94-018.2
Prepared for:
North Carolina Department of Transportation
1 South Wilmington St.
Raleigh, North Carolina 27601
Issue Date: 26 April 1995
Gerald R. McCrain, Ph.D., CEP
Vice President Signature
Brian L. Hayes, P.G.
Senior Hydrogeologist Signature
ENVIRONMENTAL SERVICES, INC.
13 18 Dale St., Suite 220
Raleigh, North Carolina 27605
TEL [phone] FAX [phone]
D:\W PTEXT94\ESI\PROJECT\ER94-018.2\DTCHMPT.RPT
.r C R, (.,
ee ?
8 SE At
_ 1018 ,

Seal
TABLE OF CONTENTS
LIST OF FIGURES ................................................... i
LIST OF TABLES ...................................................ii
INTRODUCTION ....................................................1
SITE DESCRIPTION .................................................1
SOIL BORINGS AND SITE HYDROLOGY ................................... 1
ASSESSMENT METHODOLOGIES ....................................... 4
GROUNDWATER MODEL .............................................4
MODEL DESCRIPTION ...............................................5
WATER BALANCE ..................................................5
MODEL CALIBRATION ............................................... 6
MODEL RESULTS ...................................................9
ADDITIONAL RESEARCH .............................................9
CONCLUSIONS ...................................................11
REFERENCES CITED ................................................13
APPENDICES
Appendix A - Boring Logs
Appendix B - Slug Test Data
LIST OF FIGURES
Figure 1 - Site Location ............................................... 2
Figure 2 - Location Map Showing Sites of Wetlands and/or Surface
Waters of the United States .................................... 3
LIST OF TABLES
Table 1 - Soil Input Parameters for Roanoke Soil ............................. 7
Table 2 - Soil Input Parameters for Portsmouth Soil ........................... 8
Table 3 - Projected Additional Wetland Impacts from R-2208A .................. 10
ROADSIDE DITCH IMPACT STUDY
US 17 WIDENING
HERTFORD TO EDENTON
CHOWAN AND PERQUIMANS COUNTIES, NORTH CAROLINA
INTRODUCTION
North Carolina Department of Transportation (NCDOT) retained Environmental Services Inc.
(ESI) to prepare a Compensatory Mitigation Plan for the widening of US 17 from Hertford to
Edenton, TIP No. R-2208A. ESI was commissioned, as part of this plan, to conduct a study
to assess the additional impact of the proposed roadside ditches on adjacent wetlands along
the alignment. The scope of the study involved analyzing the effect of excavated ditches
along approximately 6000 linear ft 0 829 m) of the proposed alignment. The proposed
roadside improvements are expected to directly impact approximately 5.7 acres (2.3 ha) of
wetlands as described in NCDOT's permit application dated February 7, 1994. ESI was
requested to determine the probable additional acreage affected by the ditches and provide
supporting data for this determination.
SITE DESCRIPTION
The site of interest for this investigation consists of the proposed right of way alignment for
widening of US 17 between Edenton and Hertford, North Carolina (Figure 1). The existing
highway consists of a two-lane roadway, primarily paved with an asphaltic concrete surface.
The proposed widening would convert this section of US 17 to a four-lane divided highway.
The proposed widening would include excavation and fill of wetlands along the highway. The
wetland boundaries were mapped by NCDOT personnel. The approximate locations of the four
sites accounting for the majority of the 6000 linear ft (1829 m) of ditching are shown in Figure
2. The majority of the land along the proposed alignment is forested with some cleared land
for agriculture and residential property. All wetland sites impacted by ditching are typed as
nonriverine/interstream forest habitats.
SOIL BORINGS AND SITE HYDROLOGY
ESI personnel visited the site on 5-6 April 1995 to evaluate three proposed wetland crossings
for R-2208A for hydrologic characteristics. A review of soil survey maps for the area (NRCS,
1986) indicated the presence of two hydric soils, Portsmouth sandy loam (thermic Typic
Umbraquu/ts) and Roanoke clayey loam (thermic Typic Ochraquu/ts). The sites were chosen
to provide representative data for each soil type. Nine hand auger borings (three per site)
were advanced to determine the current depth to groundwater at various locations. The
borings were advanced to a maximum depth of 9 ft (2.7 m) below land surface and logged to
record changes with depth. The boring logs are attached as Appendix A to this report. After
1
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.? raw - ?? -T - ? I I ? I ? R•? r _/' '0?6
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US 17 Edenton to Hertford Fr.
R-2208A
I
/4 T
® De(.ortn
.i li ?1'i _ -__- °`'?a, ... ?, ..va .a - ' ?• a "w".. _ "?'..° .'I.
?,? ? I I ?• ? O 1 Z J MM1ES
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1 rrtav..mna '•. r^ ? i ? ? • ? arr ? ,»+ ?a'...rr k ?i .
Figure: 1
` Environmental Site Location h ` y3( k
Services, Inc. US 17 Edenton to Hertford,
1318 Dale Street (R-2208A) Project: ER94018.2
Suite 220 Perquimans, and
Raleigh, NC 27605 Chowan Counties, NC
Date: 5 April 1995 •'??'?
2
Legend
4 Location of primary
wetland crossings
NCDOT Project R-2208A
Map Source: Project Location Map
NCDOT Permit Application,
Feb. 7, 1994
Environmental Location Map Showing
Services, Inc. Sites of Wetlands
1318 Dale Street US 17 Edenton to Hertford,
Suite 220 (R-2208A)
Raleigh, NC 27605 Perquimans, and Chowan
Counties, NC
3
Project No.: ER94018.2 I Figure: 2
Drawn By: PS Scale: NTS
Checked By: BH I Dam: April 1995
a boring was completed, a 5 ft (1.5 m) section of PVC screen and a 5 ft 0.5 m) section of
PVC riser was installed in the boring to prevent caving while slug tests were conducted to
determine hydraulic conductivity of the soils. The results of the hydraulic conductivity tests
are also attached to this report as Appendix B. The depths to groundwater varied from 0.19
ft (5.8 cm) below-land-surface(bis.) to 5.48 ft (167 cm) bls. The measured hydraulic
conductivities ranged from 5.3 x 10r3 ft/hr 0.6 x10C3m/hr)to 6.4 x 10-2 ft/hr (2.0 x10"2m/hr)
in the Portsmouth soil, and from 2.3 x 10"3 ft/hr (7.0 x 10"4m/hr) to 9.5 x 10"2 ft/hr (2.9 x 10r
2m/hr in the Roanoke soil. The data collected was used to facilitate the assessment of the
impact of the proposed ditching on the soils.
ASSESSMENT METHODOLOGIES
Assessing the probable impacts of the proposed ditches on adjacent wetlands can be
conducted by at least three methods: Empirical observation, mathematical calculations, and
analytical modeling. The first method (empirical observation) requires identifying one or more
sites with analogous conditions to the areas to be impacted and collecting data on the
behavior of groundwater at the site over a period of time. The duration of the observation
must be sufficiently long to accommodate annual fluctuations in weather (rainfall and
temperature). The requirements of this study preclude a long term study of impacts at
analogous sites. The second method (mathematical calculations) are based upon the
assumption that the water table follows an elliptical curve from the level in the ditch to a point
where the influence of the ditch is non-existent, or balanced by another ditch some distance
away. Mathematical calculations, such as those outlined in "Agricultural Water Table
Management 'A Guide For Eastern North Carolina"' (USDA-NRCS, 1986b) are static
representations of a dynamic system, requiring new calculations for each change of
conditions. This method is also intensively time consuming if every possible variable is
accounted for in the calculations. Repeated iterations of the calculations using all possible
variables in essence comprises the beginning of analytical modeling of the site as a dynamic,
system. The third method (analytical modeling) allows the evaluation of the system rapidly
and with the capability to assess the sensitivity of the system to variability of soil properties
used to create the simulation. DRAINMOD is one such model with a history of wide spread
application to the effects of drainage structures on soils with a shallow water table. The wide
spread use of DRAINMOD and the relative simplicity of the model were factors considered in
selecting this model for the study.
GROUNDWATER MODEL
The groundwater modeling software selected as most appropriate for simulating shallow
subsurface conditions and groundwater behavior at the site was DRAINMOD. This model was
developed by Dr. R.W. Skaggs of North Carolina State University (NCSU) to simulate the
performance of water table management systems. The model was originally developed to
simulate the performance of agricultural drainage and water table control systems on sites
4
with shallow water table conditions. DRAINMOD was subsequently modified for application
to wetland studies by adding a counter that accumulated the number of times that the water
table rose above a specified depth and remained there for a given duration during the growing
season. The model results can then be analyzed to determine if wetland criteria are satisfied
during the growing season, on average, more than half of the years modeled. Required model
inputs include the threshold water table depth, required duration of high water tables, and
beginning and ending dates of the growing season.
Dr. George Chescheir of NCSU also participated in the current study by reviewing the site
characterization data and setting up the DRAINMOD model for the study area. Dr. Chescheir
provided input parameters required by DRAINMOD and supplied model results for the study
area. Output from the DRAINMOD model was applied to the study area to determine the
probable distance from the centerline of the ditch achieving wetland hydrology criteria.
Wetland hydrology criteria were defined in the model as having groundwater within 12 in (30
cm) of the surface for 12 consecutive days (5% of the growing season). For the purposes
of this study the growing season was defined as the period between 21 March and 19
November( USDA-NRCS, 1986).
MODEL DESCRIPTION
DRAINMOD performs water balances in the soil-water regime at the midpoint between two
drains of equal elevation. The model is capable of calculating hourly values for water table
depth, surface runoff, subsurface drainage, infiltration, and actual evapotranspiration over long
periods of climatological data. The reliability of DRAINMOD has been tested for a wide range
of soil, crop, and climatological conditions. Results of tests in North Carolina (Skaggs, 1982),
Ohio (Skaggs et a/., 1981), Louisiana (Gayle et aL, 1985; Fouss eta/., 1987), Florida (Rogers,
1985), Michigan (Belcher and Merva, 1987), and Belgium (Susanto et aL, 1987) indicate that
the model can be used to reliably predict water table elevations and drain flow rates.
DRAINMOD has been used to evaluate wetland hydrology (Skaggs et a/., 1993). The model
has also been used to evaluate wetland hydrology criteria and threshold drain spacing for
various soils and criteria (Skaggs et a/., 1994)
WATER BALANCE
The water balances in DRAINMOD involve two basic equations. The first equation is a water
balance in the soil profile:
AV.=D+ET+DS-F (1)
Where:
AV. = change in air volume
D = drainage from the profile
5
ET = actual evapotranspiration from the profile
DS = deep seepage from the profile
F = infiltration into the profile
The second equation is a water balance at the soil surface:
AS = P - F - RO
Where:
AS = change in volume of water stored at the soil surface
P = precipitation
F = infiltration volume
RO = surface runoff
Methods for evaluating equation variables are discussed in detail in Skaggs (1980).
(2)
The hydrology of various soil water conditions applicable to the study area was simulated
using DRAINMOD. The simulations were conducted from 1951 to 1990 using climatological
data from Plymouth, North Carolina. Tables 1 and 2 summarize the soil parameters used in
the DRAINMOD simulations. Appendix B contains the results of the slug testing conducted
on soils at the site.
MODEL CALIBRATION
The hydrology of various soil water conditions applicable to the study site was simulated using
DRAINMOD. The simulation used the soil water characteristics of the Portsmouth and
Roanoke soils. Soil input parameters for DRAINMOD were calculated by the NRCS model,
DMSOIL (Baumer and Rice, 1988) using soil texture data from soil samples collected on site,
and existing data from prior research. Soil hydraulic conductivity values used in DRAINMOD
simulations were determined from the on-site slug test data. The simulations were conducted
for the years from 1951 to 1990 using climatological record from Plymouth, North Carolina.
The model simulates the fluctuations in the water table depth at the mid point between ditches
spaced a given distance apart. DRAINMOD simulations were conducted for a ditch depth of
2 ft (60 cm) (the maximum ditching depth shown on plan drawings) and various distances.
An impermeable layer was assumed to be present at a depth of 9.8 ft(300 cm) based upon
data collected from the soil borings. For this study the simulations modeled the effects of a
two-ditch system with spacing at distances ranging from 50 ft (15 m) to 197 ft (60 m). The
ditch spacings are approximately twice the distances that a single ditch is expected to
influence.
6
Table 1
Soil Input Parameters
for Roanoke Soil
Volume rained, pf ux, Green-Ampt
Parameters, and Hydraulic Conductivity for
Roanoke Soil
Water Table
Depth (cm) Volume
Drained (cm) Upflux (cm/hr)
0.0 0.00 0.1000
10.0 0.25 0.0800
20.0 0.40 0.0600
30.0 0.65 0.0500
40.0 0.92 0.0400
50.0 1.35 0.0200
60.0 1.85 0.0063
70.0 2.53 0.0025
80.0 3.40 0.0016
90.0 4.45 0.0014
100.0 5.50 0.0011
120.0 7.50 0.0005
140.0 10.45 0.0003
160.0 13.40 0.0000.
200.0 19.30 0.0000
240.0 25.60 0.0000
280.0 32.10 0.0000
320.0 38.70 0.0000
1000.0 100.00 0.0000

Green-Ampt Parameters
Water Table
Depth (cm) A B
0.0 0.0 0.00
60.0 4.0 0.25
120.0 12.0 1.00
500.0 12.0 1.00

Saturated Hydraulic Conductivity
Depth to
Bottom of
Layer K (cm/hr)
45 3.0
90 0.60
135 0.30
170 1.50
300.0 0.16
Table 2
Soil Input Parameters
for Portsmouth Soil
Volume drained, pf ux, Green-Ampt
Parameters, and Hydraulic Conductivity for
Portsmouth Soil
Water Table
Depth (cm) Volume
Drained (cm) Upflux (cm/hr)
0.0 0.00 0.1000
10.0 0.1858 0.5000
20.0 0.488 0.2000
30.0 0.8328 0.0625
40.0 1.23 0.0306
50.0 1.6895 0.0142
60.0 2.20 0.0112
80.0 3.6244 0.0035
100.0 5.3624 0.0012
120.0 7.2505 0.0001
140.0 9.234 0.0000
160.0 11.3131 0.0000
180.0 13.5069 0.0000
200.0 15.82 0.0000
220.0 18.15 0.0000
240.0 20.49 0.0000
250.0 21.65 0.0000
1000.0 100.00 0.0000

Green-Ampt Parameters
Water Table
Depth (cm) A B
0.0 0.0 0.00
50.0 1.2 0.75
100.0 6.5 1.2
150.0 10.0 1.5
200.0 12.0 1.5
500.0 15.0 1.5

Saturated Hydraulic Conductivity
Depth to
Bottom of
Layer . K (cm/hr)
60 2.00
300.0 0.375
The depth of depressional storage, used in the initial DRAINMOD simulations, was 1.6 in (4
cm) assuming that surface roughness would increase due to biological processes as vegetation
recovers following construction. The simulations were repeated using a surface storage of 0.8
in (2 cm) to simulate a site that was graded and maintained by human intervention. ESI
expects that the actual surface storage will vary between these values dependent on factors
such as distance from the ditch, vegetation types, and other influences.
The rooting depth function used in the simulation was a constant depth of 12 in (30 cm),
which is an average value used for mixed forest and grass covered lands.
MODEL RESULTS
The DRAINMOD simulations predicted wetland hydrology criteria would be met at a distance
from the ditch of 50 ft (15 m) in the Portsmouth soil and 57 ft (17.5 m) in the Roanoke soil
for a surface storage of 1.6 in (4 cm). Modeling a surface storage of 0.8 (2 cm) in resulted
in distances from the mid point of the ditch of 74 ft (22.5 m) and 98 ft (30 m) for the
Portsmouth and Roanoke soils respectively. The average zone of influence for the respective
soils is 62.5 ft (19.1 m) for the Portsmouth and 77.5 ft (23.6 m)for the Roanoke. Using these
averages approximately 10 acres (4.1 ha) of additional impacts. will occur (calculated impacts
range from 7.6 acres (3.1 ha) to 12.6 acres (5.1)). Based upon the data in NCDOT's permit
application to the U.S. Army Corps of Engineers (COE) dated 7 February 1994 the proposed
ditches would increase the impacted wetlands as presented in Table 3.
ADDITIONAL RESEARCH
Published literature regarding ditch impacts in situations similar to those of this study has been
found to be rare and somewhat inconsistent. Several studies have been based on
observations without empirical data. For example, Sharitz and Gibbons (1982) found that
ditch impacts on adjacent plant communities are generally localized and limited in extent.
However the authors provided no data in their report supporting their claims.
Site specific studies were performed by Skaggs et al (1994) in New Hanover County, North
Carolina using DRAINMOD to predict ditch impacts on wetlands. This study forecast a zone
of influence of 107 ft (32.5 m) to 157 ft (48 m) in Portsmouth soils with 1-2 in (2.5 -5 cm)
of surface storage. However the Skaggs study involved ditch depths of 4 ft (1.2 m) -
approximately twice the depth of the US 17 study, and hydraulic conductivities substantially
greater than those measured at the US 17 sites. Both of these factors greatly affect the zone
of influence extending out from the ditches. When the Skaggs data was re-analyzed for 2-ft
(60 cm) ditches, the zone of influence was reduced to a range of 82 ft (25 m) to 131 ft (40
m). It is reasonable to assume that if the soil hydraulic conductivities in the Skaggs study had
been lower, the forecasted zone of influence would have been smaller and closer to the
forecasted distances found in the US 17 study.
9
Table 3
Projected Additional Wetland Impacts
From R-2208A
Site Project Station Soil Type Length of Average Distance Additional
* Ditching (ft/m) of Influence Area
(ft/m) Impacted
by Ditching
(Acres/ha)
4 52 + 60 to 69+15 Portsmouth 1655/504.4 62.5 / 19 2.4/.9
9 213+95 to 225 + 00 Roanoke 1105/336.8 77.5/23. 6 2.0/.8
10 247 + 20 to 259 + 80 Roanoke 1260/384 77.5/23.6 2.2/.9
13 270+40 to 284+15 Roanoke 1375/419.1 77.5/23.6 2.5/1.0
Misc. 14 minor wetland Roanoke 605/184.4 77.5/23.6 1.1 /.4
excavation sites
Totals 10.11 /4.1
*See Figure 2 for locations of sites 4, 9, 10, and 13.
All sites consist of r1onriverine/interstream forest.
10
The Agricultural Water Table Management guidelines (NRCS 1986b) have often been employed
as standard protocol for designing drainage systems in eastern North Carolina by farmers and
agricultural engineers. These guidelines contain sets of standard equations which utilize
certain parameters measured in the field which allow the user to predict spacing and depth of
ditches (or drains) in an effort to maximize crop yields. However, it is important to note that
values for zones of influence vary greatly depending on baseline information used in
calculations. For example, zones of influence were found to vary from 18 ft ( 5.5 m) to 117
ft (35.7 m) in Portsmouth soils assuming a 2-ft (60 cm) ditch depth and targeted water table
depths ranging between 0 to 12 in (0 -30 cm) below the surface. The widely variable range
demonstrates the importance and need for site specific information, such as in situ hydraulic
conductivities, on calculating the zone of influence in varying soil types under certain, well
defined conditions.
Based upon available information, the work performed on the US 17 project is a demonstrable,
marked improvement over existing, subjective assessments of zonal ditch influence. Site
specific data using tested analytical models afford a more realistic picture of probable ditch
impacts, as compared to the sole use of empirical observation, or NRCS guidelines where site
specific data is not utilized. Therefore, the average zone of influence of 62 ft (19 m) to 77
ft (23.6 m) for ditching in Portsmouth and Roanoke soils assuming a ditch depth of 2 ft (.6 m)
as in this project, is believed to constitute a reasonable representation of average field
conditions in the project area. Due to the variability of site specific parameters such as
hydraulic conductivity, infiltration capacity, or surface storage from site to site, it is very
important to collect and interpret in situ field data on a case by case basis for future studies.
CONCLUSIONS
Based upon field observations, and available data, ESI has developed the following conclusions
for this site:
• The soils encountered on site and hydrological conditions observed, are consistent with
the mapping performed by the NRCS.
• DRAINMOD simulations indicate that the zone of influence of ditching varies from a
minimum of 50 ft (15 m) to a maximum of 98 ft (30 m)based on varied surface storage
characteristics. The average zones of influence are 62 ft (19 m), for the Portsmouth
soil and 77 ft (23.6 m)for the Roanoke soil.
• A review of existing literature indicates that observed impacts from road side ditching
are inferred to be localized to the immediate area of the ditches. Previous studies using
DRAINMOD infer that the US 17 findings are within reasonable expectations given
existing field characteristics and in situ soil properties. Other methodologies, such as
NRCS guidelines provide widely variable results and were discounted for use in
11
evaluating ditch impacts associated with this project.
Based on model results, the proposed ditches along the alignment would increase the
impacted amount of wetland by an average of 10 acres (4 ha) (ranging from 7.6 acres
(3.1 ha) to 12.6 acres (5.1 ha)).
12
REFERENCES CITED
Baumer, 0. and J. Rice, 1988. Methods to predict soil input data for DRAINMOD ASAE
Paper No. 88-2564. ASAE, St. Joseph, MI 49085.
Belcher, H.W. and G.E. Merva, 1987. Results of DRAINMOD verification study for Zeigenfuss,
soil and Michigan climate. ASAE Paper No. 87-2554. ASAE, St. Joseph, MI 49085.
Bower H. and R.C. Rice, 1976. A slug test for determining conductivity of unconfined aquifers
with completely or partially penetrating wells. Water Resources Research. 12: 423-428.
Bouwer, H., 1989. The Bouwer and Rice slug test -- an update. Ground Water. 27 (3):
304-309.
Fouss, J. L., R. L. Bengtson and C.E. Carter, 1987. Simulating subsurface drainage in the
lower Mississippi Valley with DRAINMOD. Transactions of the ASAE 30 (6): 1679 -
1688.
Gayle, G., R.W. Skaggs and C.E. Carter, 1985. Evaluation of a water management model for
a Louisiana sugar cane field. J. of Am. Soc. of Sugar Cane Technologists, 4: 18 - 28.
Hvorslev, M.J. 1951. Time lag and soil permeability in groundwater observations. U.S. Army
Corps of Engineers Waterways Experimental Station Bulletin 36, Vicksburg, MS.
Rogers, J.S., 1985. Water management model evaluation for shallow sandy soils. .
Transactions of the ASAE 28 (3): 785-790.
Sharitz, R.R. and J.W. Gibbons, 1982. The ecology of southeastern shrub bogs (pocosins)
and Carolina bays: a community profile. U.S. Fish and Wildlife Service, Div. of
Ecological Services, Washington DC. FWS/OBS-82/04.
Skaggs, R.W., 1980. A water management model for artificially drained soils. Tech. Bull. No.
267, North Carolina Agricultural Research Service, N.C. State University, Raleigh. 54
pp-
Skaggs, R.W., 1982. Field evaluation of a water management simulation model.
Transactions of the ASAE 25 (3): 666 - 674.
Skaggs, R.W., D. Amataya, R.O. Evans, and J.E. Parsons, 1994. Characterization and
evaluation of proposed hydrologic, criteria for wetlands. Journal of Soil and Water
Conservation 49 (5): 501-510.
13
Skaggs, R.W., N.R. Fausey and B.H. Nolte, 1981. Water management evaluation for North
Central Ohio. Transactions of the ASAE 24 (4): 922 - 928.
Skaggs, R.W., J.W. Gilliam and R.O. Evans, 1991. A computer simulation study of pocosin
hydrology. Wetlands (1 1): 399 416.
Skaggs, R.W., et a[, 1993. Methods for Evaluating Wetland Hydrology. ASAE meeting
presentation Paper No. 921590. 21 p.
Susanto, R.H., J. Feyen, W. Dierickx and G. Wyseure, 1987. The use of simulation models
to evaluate the performance of subsurface drainage systems. Proc. of Third
International Drainage Workshop, Ohio State Univ., pp. A67 - A76.
USDA-NRCS. 1986. Soil Survey of Chowan and Perquimans Counties, North Carolina.
Publication of the National Cooperative Soil Survey.
USDA-NRCS. 1986. Agricultural Water Table Management "A guide for eastern North
Carolina."
14
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*
r
JOB: ER94018.2
LOGGED By._B.L. Hayes
DRILLED By. B.L. Hayes
DRILL RIG:
DRILLING METHOD: Hand Auger
DATE DRILLED. 4 April 1995
SAMPLE PID
U.S.C. SOIL DESCRIPTION
TYPE REC RESIST (PPM)
Black, organic, rich, sandy LOAM; abundant roots
A A A A A 1.0'- Gray, very fine SAND; trace clay and sift
1
?1.5'- Becoming orange, mottled, clayey, fine SAND
2
3 3.0'- Becoming sandier, moist
3.5- Becoming gray, very fine SAND; wet
41? 4.0'- Becoming slightly clayey, mottled orange
5-r///? 5.0' -Becoming sandier, saturated
H
W 5.5' - Becoming slightly clayey; saturated
LL
= 6
F-
W As above
O 7 V11Z
8
8.5'- Termination of drilling - no recovery; saturated
9
10
11
12
SOUTHEASTERN DP-1
Dit
h I
d
S FILE NAME: DP01 DSML

ENVIRONMENTAL c
mpact
tu
y
US-17 Widening MADE BY:
PS
AUDITS INC R-2208A
. CHECKE
NCDOT D BY: BH
A-1
JOB: ER94018.2
LOGGED BY: J.L. Hardy
DRILLED BY• B.L. Hayes
DRILL RIG: B.L. Hayes
DRILLING METHOD: Hand Auger
DATE DRILLED.. 4 April 1995
SAMPLE U.S.C. SOIL DESCRIPTION PID
TYPE REC RESIST (PPM)
Gray, slightly, clayey, fine SAND
Becoming clayey at 8.0
1 Gray, mottled orange, clayey, very fine SAND
2 -?

3 Gray, mottled, orange, clayey, very fine SAND
Becoming sandier
q 4.0'- Gray, slightly mottled, orange, fine SAND; wet
Becoming wetter
5 Gray, mottled, orange, fine SAND; saturated
W
LL
= 6 •'
Blue-gray, fine SAND; saturated
H
W
7
As above

8 As above
8.6 - Termination of drilling
9
10
11
12
SOUTHEASTERN DP-2
d
S FILE NAME: DP02DSML

ENVIRONMENTAL y
Ditch Impact
tu
US-17 widening MADE BY.
PS
AUDITS
INC R-2208A
,
. E
NCDOT CH
CKED BY: BH
A-2
JOB: ER94018.2
LOGGED BY: J.L. Hardy
DRILLED BY- B•L HayeS
1
2
3
4
5
1-
W
W
U.
= 6
f-
a
W
D
7
DRILL RIG: B.L. Hayes
DRILLING METHOD: Hand Auger
DATE DRILLED. 4 April 1995
SAMPLE U.S.C. SOIL DESCRIPTION PID
TYPE REC RESIST (PPM)
0.5'- Black, organic, muck; wet
1.0'- Gray, very clayey, very fine SAND; with roots, saturated
1.5'- Gray, silty CLAY, trace sand
8-
9-
10-
11
12
2.5'- Becoming sandier
3.0'- Gray, slightly mottled, orange, clayey SAND
As above
5.0'- Termination of drilling
As above
SOUTHEASTERN DP-3
h I
d
Di
t St FILE NAME: DP03DSML

ENVIRONMENTAL mpac
y
tc
u
US-17 Widening MADE BY:
PS
AUDITS INC R-2208A
. CHECK
NCDOT ED BY: BH
A-.3
JOB: ER94018.2
LOGGED BY: J.L. Hardy
DRILLED By.. B.L. Hayes
DRILL RIG: B.L. Hayes
DRILLING METHOD: Hand Auger
DATE DRILLED. 5 April 1995
SAMPLE U.S.C. SOIL DESCRIPTION PID
TYPE REC RESIST (PPM)
Dark brown, slightly mottled, silty CLAY
1 1.0'- Becoming gray, slightly mottled orange
2 1 1 1 As above
3 As above
3.5- Becoming sandy, moist
4 Gray, clayey, fine SAND; moist
4.5' - Brown-gray, slightly silty, fine SAND; wet
5 5.0'- Brown-gray, mottled, slightly clayey, fine SAND; wet
W
W
U.
= 6
6.0'- Gray, slightly clayey, fine SAND; saturated
a
W
7 7
0' - Becoming mottled orange; more clayey
- Termination of drilling
r75
8-

9-

10-

12

SOUTHEASTERN DP-4 FILE NAME: DP04DSML

ENVIRONMENTAL Ditch Impact Study
US-17 widening
R-2208A MADE BY:
PS
AUDITS INC. NCDOT CHECKED BY: BH
A-4
JOB: ER94018.2
LOGGED BY: J.L. Hardy
DRILLED By. B.L. Hayes
DRILL RIG: B.L. Hayes
DRILLING METHOD: Hand Auger
DATE DRILLED- 5 April 1995
SAMPLE U.S.C. SOIL DESCRIPTION PID
TYPE REC RESIST (PPM)
0 - 6.0" - Dark brown, organic, rich LOAM
j Mottled gray-orange, slightly sandy CLAY
1
1.5" - Mottled gray-orange, silty CLAY; very stiff
2 / 2.0'- Slightly mottled gray, highly plastic CLAY
2.5- Soft, gray CLAY; moist
3 3.0'- Becoming sandy
3.5- Gray, very silty, fine SAND
4 4.0'- Gray, slightly silty, fine SAND; wet
4.5- As above; saturated
5 As above
W
W 5.5- mottled orange; saturated
U.
3 6 60 - Becoming slightly clayey; saturated
1-
a
W
0 7 As above
8 8.0' -Termination of drilling
9
10
11
12

SOUTHEASTERN
DP-5 FILE NAME: DP05DSML

ENVIRONMENTAL Ditch Impact Study
US-17 Widening MADE BY:
PS
R-2208A
AUDITS, INC. CHECKED BY

NCDOT .
BH
A-5
JOB: ER94018.2
LOGGED BY: J.L. Hardy
DRILLED By. B.L. Hayes
DRILL RIG: B.L. Hayes
DRIWNGMETHOO: Hand Auger
DATE DRILLED. 5 April 1995
SAMPLE U.S.C. SOIL DESCRIPTION PiD
TYPE REC RESIST (PPNQ
0- 3" - Dark brown omar
,/ 6" - Dark gray, mottled or
1 1.0" - As above
1.5" - Becoming very stiff
2 As above
3 i% 3.0'- Becoming sandy
3.5'- Gray, slightly mottled orange, sandy CLAY
4 4.0'- As above
4.5'- Light gray, fine SAND; wet
5 As above; saturated
W Becoming clayey, blue-gray
LL
3 6
Blue-gray, clayey, fine SAND; saturated
a
W
D
Blue-gray, very clayey, SAND

$ Becoming greenish-blue

9.0'- Greenish-blue, sandy CLAY
9 9.0'- Termination of drilling
10
11
12
SOUTHEASTERN DP-6 FILE NAME: DP06DSML
1
D
ENVIRONMENTAL US
7 Widening
MADE BY.
PS
AUDITS
INC R-2208A
,
. CHECKED
NCDOT BY: BH
A-6
1
2
3
4
5
1-
W
W
LL
= 6
1
a
0

D
7
8
9
10
11
12
JOB: ER94018.2
LOGGED BY: J. L- Hardy
DRILLED By. B.L. Hayes
DRILL RIG: B.L. Hayes
DRILLING METHOD: Hand Auger
DATE DRILLED: 4 April 1995
SAMPLE U.S.C. SOIL DESCRIPTION PiD
TYPE REC RESIST (PPM)
Black, organic, rich, sandy, clayey LOAM
Becoming sandier; gray
1.5' - Very moist, gray, sandy CLAY
Firm, gray, slightly mottled orange, silty CLAY
2.5'- Becoming sandier
Soft, gray, slightly mottled orange, sandy CLAY
3.5'- As above; very moist
Gray, slightly mottled, slightly clayey, fine SAND; very moist
4.5' - As above
As above; wet
5.5'- Tan, mottled orange, slightly clayey, fine SAND; wet
Becoming mottled with gray
6.5'- Blue-green, slightly clayey, fine SAND
As above; saturated
As above
As above
As above
9.0' - Termination of drilling - no recovery
SOUTHEASTERN DP-7 FILE NAME: DP07DSML

ENVIRONMENTAL Ditch Impact Study
US-17 Widening MADE BY.
PS
AUDITS INC R-2208A
. CHECKE
NCDOT D BY: BH
A-7
JOB: ER94018.2
LOGGED BY: J. L. Hardy
DRILLED BY• B.L. Hayes
DRILL RIG: B.L. Hayes
DRILLING METHOD: Hand Auger
DATE DRILLED. 4 April 1995
S AMPLE P(D
U.S.C. SOIL DESCRIPTION
TYPE REC RESIST (PPM
0-6" - Black, organic, rich, silty, clayey LOAM
Firm gray, slightly mottled orange CLAY
1

As above
2 As above; trace fine sand
2.5'- Very moist, light gray, slightly clayey, fine SAND
3 Light gray, slightly silty, fine SAND; wet
3.5' - Gray, mottled orange, sandy CLAY; saturated
4 As above
4.5' - Gray, mottled, orange, slightly clayey, fine SAND; wet
5 As above; saturated
F-
LU As above
UJI
No recovery
= 6

a
W
7 Becoming browner; more clayey
As above
8 As above

As above
9 90-Termination of drilling
10
11
12
SOUTHEASTERN DP-8 FILE NAME: DP08DSML

ENVIRONMENTAL Ditch Impact Study
US-17 Widening MADE BY:
PS
R-2208A
AUDITS INC. CHECKED BY
NCDOT : BH
A-8
SAMPLE
TYPE REC I
1
2
3
4
?i
W
W
LL
= 6
rr-
a
W
D
7
8-
9-
10-
11
12
SOUTHEASTERN
ENVIRONMENTAL
AUDITS, INC.
JOB: ER94018.2
LOGGED BY: J. L. Hardy
DRILLED BY- B.L. Hayes
DRILL RIG: B.L. Hayes
DRILLING METHOD: Hand Auger
DATE DRILLED- 4 April 1995
U.S.C. SOIL DESCRIPTION P)D
(PPM)
0-6" - Dark gray, silty CLAY; saturated at 2"
Gray, slightly mottled orange, silty CLAY; saturated
As above
2.5' - Becoming sandy
Gray, mottled orange, clayey, fine SAND
3.5'- As above
Orange, mottled gray, clayey, fine SAND
4.5' - Becoming grayer
4.5' - Termination of drilling
DP-9
Ditch Impact Study
US-17 Widening
R-2208A
NCDOT
FILE NAME: DP09DSML
MADE BY: PS
CHECKED BY. BH
A-9
H
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7
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L L L
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~ Y Y Y Y Y Y
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- ?. ? Lv m w cc m m
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N Q Q
#
DRAWDOWN TEST
LL NO. Q / `
OP OF CASING ELEVATION
=ROUND SURFACE ELEVATION
CASING DIAMETER 2
BOREHOLE DIAMETER Z, 7
SCREEN DEPTH
REFERENCE POINT T 0 r.
AMOUNT OF WATER REMOVED
LOCATION S -17
..,? , DATE_ L f -V-`7 5
TIME?[
COMPUT D BY y u-??
ASSISTED BY
PERSONS OBSERVING ff 4r ?J d lea/f r
EVACUATION METHOD_ 3, , j e.
STATIC WATER LEVEL _ 6. i L
S-r('c.e 7.1!
RECOVERY DATA
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
a o q 3? ?,a6 d
?o ?v z S? ?Y4- 3
o, zz
3G 10
Z 12d .d 1.?9 ?.sgz
'?.? ?? 15-0 7; Z 1. Sv 0.490
.

Lr d
-33a
-?
1?i7
o3?z
L4U 7, 3 !,(1 z a, 333
300 7 U . 2 d. 2?
6'ld 310 7.02 O. 7o z2?
C, ?Lf 0, 6,7- 0, 26
kid (. 6 0. s y o. 179-
go, 6d 77 0. ? 0,/4,7
fZ.S 7 SO so G • 2 /

3o

NOTES
B-1
DP-1
time dtw H WHO
0 9.38 3.06 1
30 8.90 2.58 0.843137
60 8.53 2.21 0.722222
90 8.25 1.93 0.630719
120 8.01 1.69 0.552288
150 7.82 1.50 0.490196
180 7.64 1.32 0.431373
210 7.49 1.17 0.382353
240 7.34 1.02 0.333333
300 7.14 0.82 0.267974
370 7.02 0.70 0.228758
420 6.94 0.62 0.202614
480 6.86 0.54 0.176471
600 6.77 0.45 0.147059
750 6.69 0.37 0.120915
B-2
DP-1
recovery vs. time
- - - best fit
U
1.00-
9
8
7
6
5
4
0.10

i ?
1 ?

i
i
?

0.00 200.00 400.00
TIME (sec)
600.00 800.00
B-3
Well Number: n P-t
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 H-/Ho
Date:
Computed By: 9,1-, d = .S (cm)

D = (cm)
L = /32 (cm)
T = 2g- d (seconds)
k d2 in r 2mL 1 m= 1
h D
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn & Fang, pp. 29-35.
Note: m = khorizontal/kvertical
Assume kh = kv = 1

2, U 11X(v 13??
,, z
B-4
DRAWDOWN TEST
fA LL NO. Q ? - Z-
P OF CASING ELEVATION
OUND SURFACE ELEVATION
SING DIAMETER Z
BOREHOLE DIAMETER s, 7
SCREEN DEPTH
REFERENCE POINT % 0 L
AMOUNT OF WATER REMOVED
LOCATION
DATE 4 - 5
TIME
COMPUTED BY // 4 ,., , / .-
ASSISTED BY
PERSONS OBSERVING
EVACUATION METHOD
STATIC WATER LEVEL
RECOVERY DATA

ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
0 . a
o ?.S
1 o
t.-3 °

b.
3

s s s

6 S, a
to ' a
iz s S, oS

l ?
rya

1-1
NOTES
d•s1
3$
.r t °I
B-5
DP-2
time dtw H WHO
0 8.20 3.69 1
30 7.58 3.07 0.831978
60 7.04 2.53 0.685637
90 6.80 2.29 0.620596
120 6.65 2.14 0.579946
150 6.49 1.98 0.536585
180 6.33 1.82 0.493225
240 6.07 1.56 0.422764
300 5.88 1.37 0.371274
360 5.71 1.20 0.325203
420 5.55 1.04 0.281843
480 , 5.42 0.91 0.246612
600 5.23 0.72 0.195122
750 5.05 0.54 0.146341
900 4.93 0.42 0.113821
B-6
DP-2
recovery vs. time
1.00 -
9
8
7
6
5
4
= 3
2
0.10
- - - best fit

I ?

I ?

I

I
170
0.00 200.00 400.00 600.00
TIME (sec)
800.00 1000.00
B-7
Well Number: D?, 2 Date:
Computed By: yla 1'1S

Casing diameter d = 5 (cm)
Borehole diameter D = 7 (cm)
Length of screen L = 187 (cm)
Time lag at 0.37 H-/Ho T = 330 (seconds)

k= d2 in r 2mL 1 m= 1
h L D J
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn & Fang, pp. 29-35.
Note: m = khorizontal
?kvertical
Assume kh = kv =1

B-8
DRAWDOWN TEST
WELL NO.--UP 3
OP OF CASING-
AS G ELEVATION
ROUND SURFACE ELEVATION
4ASING DIAMETER V
BOREHOLE DIAMETER_ 2, 7
SCREEN DEPTH
REFERENCE POINT To
AMOUNT OF WATER REMOVED
LOCATION
DATE_ u - Lk- 9<?-
TIME
COMPUTED BY -St-t
ASSISTED BY
PERSONS OBSERVING
EVACUATION METHOD_
STATIC WATER LEVEL _ _ a \
RECOVERY DATA y
ELAPSED
TIME GROUNDWATER
DEPTH H H/Hq
0
V-zc 14. -4 Li
` G y
3 g
/L U 4
3-ao 150 3.51
3-3n??6 3. A
t L(0
S 270
6 . 330 ?.
?9d
g 4S?
A.
STo }a
t 7za ?•. t3
I
20
311.

NOTES
B-9
DP-3
time dtw H WHO
0 5.08 4.27 1
30 4.74 3.93 0.920375
60 4.41 3.60 0.843091
90 3.86 3.05 0.714286
120 3.64 2.83 0.662763
150 3.51 2.70 0.632319
180 3.42 2.61 0.611241
210 3.32 2.51 0.587822
270 3.02 2.21 0.517564
330 2.76 1.95 0.456674
390 2.50 1.69 0.395785
450 2.22 1.41 0.330211
570 1.72 0.91 0.213115
B-10
DP-3
recovery vs. time
best fit
2
1.00
0.10

i
i

J
i

0.00 200.00 400.00 600.00
Time (sec)
B-1 1
Well Number: DP- 3
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 HJH0
Date:
Computed By: /3.4 AoyP1
-- I
d = S (cm)
D 7 (cm)
L = Y4t41 (cm)
T = 3SIL (seconds)
k d2 In r 2mL m = 1
h L D
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn be Fang, pp. 29-35.
Note: m = khorizontal/kvertieal
Assume kh = kv = 1

kh = 2. 0 ? WO If c?/s
/ A1ti1
B-12
DRAWDOWN TEST
WELLNO. ()P- U
SOP OF CASING ELEVATION
ROUND SURFACE ELEVATION
--CASING DIAMETER 2 `'
BOREHOLE DIAMETER 2 , 75
SCREEN DEPTH
REFERENCE POINT To
AMOUNT OF WATER REMOVED
LOCATION ?,- 7, / j
DATE a ,¢nn - / 'i S
TIME (? d
COMPUTED BY /4
„ /ASSISTED BY
PERSONS OBSERVING
EVACUATION METHOD ?/3 , •%,
STATIC WATER LEVEL
?.Z`1 s9ory
RECOVERY DATA t.
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
Q 9.2-4 1,01
3 ?. ?? s
.a
. TO
2 ? SS

3 (? ?2 ° 0, /1 L
Y o zc• 4 off t,ocy 0.36
4 a. a

7 .5
(
d
(G .Ks
1 ?• 3
S 4.33
?U
30
14u
NOTES Z 3 X (? ' CL
20
T= e - l 1
B-13
DP-4
time dtw H WHO
0 9.87 2.87 1
30 9.48 2.48 0.864111
60 9.12 2.12 0.738676
90 8.90 1.90 0.662021
120 8.58 1.58 0.550523
150 8.38 1.38 0.480836
180 8.20 1.20 0.418118
210 8.04 1.04 0.362369
240 7.92 0.92 0.320557
300 7.75 0.75 0.261324
360 7.65 0.65 0.226481
420 7.58 0.58 0.202091
480 7.54 0.54 0.188153
600 7.45 0.45 0.156794
750 7.38 0.38 0.132404
900 7.33 0.33 0.114983
B-14
DP-4
recovery vs. time
- - - best fit
z
1.00
E
L
2
0.10

\

I
I
\

\
I
I
I \
\

\
I \
I
I
\

Zyo
0.00 200.00 400.00 600.00
Time (sec)
800.00 1000.00
B-15
Well Number: 0,P- y
Casing diameter
Borehole diameter
Length of screen
71me lag at 0.37 H-/Ho
Date:
Computed By: 13. /{?yPr
d = '9 S (cm)
D = 7 (cm)
L (cm)
T = 2 it d (seconds)
kh = d2 In C 2mL 1 m = 1
D
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn & Fang, pp. 29-35.
Note: m = khorizontal/kvertical
kh= ?.US
l ?6
Assume kh =k v =1
B-16
DRAWDOWN TEST
WELL NO. D F- -S
TOP OF CASING ELEVATION
GROUND SURFACE ELEVATION
CASING DIAMETER 'a
BOREHOLE DIAMETER a,-45
SCREEN DEPTH
REFERENCE POINT -TO r:
AMOUNT OF WATER REMOVED
LOCATION- ,?; Ae
DATE y-? _q ?-
TIME
COMPUTED BY: t-1
ASSISTED BY r-3LK
PERSONS OBSERVING
EVACUATION METHOD , ; 1 e. a
STATIC WATER LEVEL '4, q g
tu,73 x.98
RECOVERY DATA -Z 5
ELAPSED
TIME GROUNDWATER
DEPTH H WHO
O I 3 Zr 3S
?. o O
30
? zS

Z
3 10 4
1 . F
S 1 6
off
1 oA
.9
15
z (5d'

leo
i-I -2
(1 1., Ta 15•5\
v. 53
0, 23

XTi -Tn
z?
B-1/
DP-5
time dtw H WHO
0 10.33 2.35 1
60 10.25 2.27 0.965957
90 10.18 2.20 0.93617
120 10.18 2.20 0.93617
180 10.14 2.16 0.919149
240 10.10 2.12 0.902128
300 10.06 2.08 0.885106
360 10.04 2.06 0.876596
420 10.02 2.04 0.868085
600 9.91 1.93 0.821277
900 9.76 1.78 0.757447
1500 9.51 1.53 0.651064
2100 9.16 1.18 0.502128
3780 8.50 0.52 0.221277
B-18
DP -5
recovery vs. time
1.00
9
8
7
6
5
4
3
I
0.10
- - - best fit

i
i
I

0.00 1000.00 2000.00
Time (sec)
3000.00 4000.00
B-19
Well Number: OP-5
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 H-/H0
Date:
Computed By: 13. L. / P-r
d = S (cm)
D = 7 (cm)
L = $/ (cm)
T = Z6?_3 (seconds)
kh = d2 In 12 m L 1
8 LT
m=1
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn be Fang, pp. 29-35.
Note: m = khorizontal
/kvertical
Assu me kh = kv = 1

kh = ?. S 2 X (o
K(°- ) /n4
B-20
DRAWDOWN TEST
WELL NO. 9p-S.
P OF CASING ELEVATION
ROUND SURFACE ELEVATION
-ASING DIAMETER Z
BOREHOLE DIAMETER_ 2 .?S
SCREEN DEPTH
REFERENCE POINT -m c
AMOUNT OF WATER REMOVED
LOCATION
DATE_ ti _ _ q•s
TIME
COMPUTED BY t1
ASSISTED BY g k
PERSONS OBSERVING
EVACUATION METHOD_ k,,
A
STATIC WATER LEVEL _ S. 3 3
RECOVERY DATA
`d . 3 j S ?3
3 5 5 . ?,
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
U 83 5. ?0 da
:3a $ 3B
1 a
1'•'i I ?- ?(9

?' 30
3 '? . 4 4

b she Io. ? (.Y j b. ?f J
a if7

ID a
Iz. s
IS s a
/0 c
1-4•
7Z
5.x+3
"I

NOTES
B-21
DP-6
time dtw H WHO
0 8.83 3.50 1.000
30 8.38 3.05 0.871
60 8.22 2.89 0.826
90 7.99 2.66 0.760
120 7.83 2.50 0.714
150 7.66 2.33 0.666
180 7.44 2.11 0.603
210 7.31 1.98 0.566
240 7.18 1.85 0.529
300 6.97 1.64 0.469
360 6.76 1.43 0.409
420 6.59 1.26 0.360
480 6.50 1.17 0.334
600 6.22 0.89 0.254
750 6.00 0.67 0.191
900 5.82 0.49 0.140
1069 5.68 0.35 0.100
B-22
DP-6
recovery vs. time
1.00 -
9
8
7
6
5
4
A
r 3
2
0.10
- - - best fit

- i
I
i ?
I

i
i

i
I

b
f i b
0.00 400.00 800.00 1200.00
Time (sec)
B-23
Well Number: (),P- L
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 H-/Ho
Date:
Computed By: 13 , Gt '/4,, rf
d = 5 (cm)
D = 7 (cm)
L = g L' (cm)
T = 436 (seconds)
k d2 In r -2m--L 1 m= 1
h D
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn & Fang, pp. 29-35.
Note: m = khorizontal/k
vertical
Assume kh = kv = 1

kh = /. 7 2ly - y c'./S.
B-24
DRAWDOWN TEST
LL NO. IJP- --:?
P OF CASING ELEVATION
OUND SURFACE ELEVATION
SING DIAMETER a
BOREHOLE DIAMETER a . ?
SCREEN DEPTH
REFERENCE POINT TOL "
AMOUNT OF WATER REMOVP
LOCATION
DATE 4 - C - 9
TIME
COMPUTED BY _
ASSISTED BY t3-K
PERSONS OBSERVING
EVACUATION METHOD 6, kc d
STATIC WATER LEVEL 3. z 3
':?,'3'z ZS
3• q3 `' ?
RECOVERY DATA --4-,-601 3
ELAPSED
TRAE GROUNDWATER
DEPTH H H/H,
o . 3a L d . d d
. o b . S(o

Z? S 9
75
S. S
3' 3o S • a
4 zti? 4 9 (? 7 s o Y
S ??o y. s ?, 31 3 Z

3.94
& 3.-4
6.St?
IZ.S
IS
Zo
3a

,z 1

G ?.
B-25
DP-7
time dtw H WHO
0 7.32 4.09 1.000
36 6.56 3.33 0.814
60 6.17 2.94 0.719
90 6.18 2.95 0.721
120 6.27 3.04 0.743
150 5.95 2.72 0.665
180 5.58 2.35 0.575
210 5.23 2.00 0.489
240 4.98 1.75 0.428
300 4.54 1.31 0.320
360 4.20 0.97 0.237
420 3.97 0.74 0.181
480 3.79 0.56 0.137
536 3.64 0.41 0.100
B-26
DP-7
recovery vs. time
- - - best fit
-6
2
1.00
0.10

i
i
I ,

s?
0.00 200.00 400.00 600.00
Time (sec)
B-27
Well Number: np-7
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 HIH0
Date:
Computed By:
d = S (cm)
D = 7 (cm)
L = 2L,C (cm)
T = 2- 5", (seconds)
kh = d2 In C 2 m L 1 m= 1
D
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn be Fang, pp. 29-35.
Note: m = khorizontal/kvertical
Assume kh = kv = 1

kh = Z ZS k(a-y eAZ?
8, l Y/0- 3 log
B-28
DRAWDOWN TEST
X LL NO. DP- 8
P OF CASING ELEVATION
_OUND SURFACE ELEVATION
CASING DIAMETER a
BOREHOLE DIAMETER a , a<
SCREEN DEPTH
REFERENCE POINT -rvc-
AMOUNT OF WATER REMOVED
LOCATION S;Aa 9
DATE - 5 - q S
TIME
COMPUTED BY -<"
ASSISTED BY '8+k
PERSONS OBSERVING
EVACUATION METHOD tea: \ c? rN
STATIC WATER LEVEL 'C , 0 0
RECOVERY DATA yy 3
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
+

L'•1V B .8S

3 $. 4 4

.s

Lft0

6a"
?o .
0, A
iz.5
S S

30 (1 9

NOT9S
B-29
DP-8
time dtw H WHO
0 9.57 4.57 1
30 9.42 4.42 0.967177
60 9.22 4.22 0.923414
90 8.66 3.66 0.800875
130 8.85 3.85 0.842451
150 8.66 3.66 0.800875
180 8.44 3.44 0.752735
210 8.22 3.22 0.704595
240 8.04 3.04 0.665208
300 7.87 2.87 0.628009
360 7.54 2.54 0.555799
420 7.19 2.19 0.479212
480 6.88 1.88 0.411379
600 6.65 1.65 0.36105
750 6.59 1.59 0.347921
900 6.55 1.55 0.339168
1200 6.41 1.41 0.308534
1800 5.85 0.85 0.185996
2880 5.12 0.12 0.026258
B-30
DP-8
recovery vs. time
1.00
= 0.10
2 s
E
2
0.01
- - - best fit

G

r `
i
I
I
\

\

I \
I
i
i
f
i
Bon
0.00 1000.00 2000.00
. Time (sec0
3000.00
B-31
PP, ?
14
12
A
AND
C
10
e
E
1 (i
4M
Le=
w
H -
XrK,3 6, 3
r
z.7f
-rd
c -
(I h
e
3
2
O
I 5 t0 5o 100 500 1000 5000
Le It
Fig. 2. Dimensionless parameters A, B, and C as a function
of I Jr... fnr r,4 I., 10 11 1
B-47
.IMPERMEABLE
.,FIGURE 1
Well Number: nP4
Casing diameter
Borehole diameter
Length of screen
Time lag at 0.37 H,/Ho
Date:
Computed By: 13. L.,
d = S (cm)
D = 7 (cm)
L = I7Z (cm)
T = 8o() (seconds)
kh = d2 In C 2mL 1 m= 1
D
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn & Fang, pp. 29-35.
Note: m = khorizontal?
kvertical
kh C A?
Assume kh = kv = 1
B-32

14
12
A
AND
C
10
e
E

SS 31

H ' (Ih)
to = ?D, z3
4rk/
1
C = 2,
8
3
Z
O
I 5 t0 50 100 500 1000 5000
Lc /r
Fig. 2. Dimensionless parameters A, B, and C as a function
of I - /r... fnr „f I., ID 1. 1
B-43
IMPERMEABLE
.-F?GuRE ?
c
DRAWDOWN TEST
==WELL NO. DP- g
SOP OF CASING ELEVATION
,ROUND SURFACE ELEVATION
CASING DIAMETER ( 5
BOREHOLE DIAME PER. SCREEN DEPTH
REFERENCE POINT -Mc
AMOUNT OF WATER REMOVED
ELAPSED
TIME GROUNDWATER
DEPTH H H/Ho
O Z. ZZ ?. O
z.14
30 1.9z

1. -tZ 0, Ite
x:30 1. 0•3y ?3S
( 3?lo a
• 4 . 4?
3 43

Mk 1. '31
14 S4 1 . is
1
S
1

?a

LOCATION q
DATE V-5-9r
TIME
COMPUTED BY
ASSISTED BY gN
PERSONS OBSERVING
EVACUATION METHOD b?; IQ a
STATIC WATER LEVEL
2.2z ?•2b
\,Z(o
"N
RECOVERY DATA k 0
,. d1 7
a 1(
B-33
L, 3-1 r 11.
DP-9
time dtw H WHO
0 2.22 0.96 1.000
15 2.14 0.88 0.917
30 1.92 0.66 0.688
45
60 1.80
1.72 0.54
0.46 0.563
0.479
90 1.60 0.34 0.354
120 1.53 0.27 0.281
150 1.47 0.21 O.2
180 1.43 0.17
210
240
294 1
.42
1.39
136
0.16
0.13
0.10 A
B-34

DP-9
recovery vs. time
best fit
A
2
2
1.00
2
0.10

.d s
0.00 100.00 200.00 300.00
Time (sec) B-35
Well Number: /gyp-5
Casing diameter
Borehole diameter
Length of screen
71me lag at 0.37 H/H
0
Date:
Computed By: lj L,
d = S (cm)
D = 7 (cm)
L = /3/s (cm)
T = - ios (seconds)
k = d2 In r 2mL 1
h D J m=1
8 LT
Note: This equation is valid only for a typical monitoring well situation. If the
situation differs significantly consult Foundation Engineering Handbook,
Winterkorn & Fang, pp. 29-35.
Note: m = J-k---
horizontal/kvertical
Assume kh = kv = 1

kh = ?lU X?? - k/:?c
B-36
? ?S4
Environmental Services, Inc. JOB NO. ER
SHEET NO.
DATE
JOB NAME Z2,'4- A, a/ S.'? 4 .., e 1-2,, Tj 4 5 COMPUTED BY 13'
SUBJECT - _r g /r ii/ f T r -r o jz' /r '4 y ?v,.ryr? d- JQ t Mrfb? CHECKED BY
'!?<re /f
pP
k= (? ?Zx (,?Cy
2-5 4r C #1
2-V; e
Y Z, ?1 , - c17 96<h,

2.s4er k-

-r _ Yya sPc
J1 4(, 11
y?

r?= 2. Sy
L /4 v . S c.4-
610sec
y r31?o6
Y6 16'. "t ?
K= 4(2,6 1) 7. q " ?,
21 o4xio "`?c"?f?L
/ XIliB to•ir
Z?3
Z C?6s
CZ?/qo_S) ?zC) 3 _
B-37
c:\coreldrw\pam\network\ jrid1-i . cdr
DP-1
drawdown vs. time
10.00
s
s
7
6
5
4
3
2
C
1.00
U 9
cu 8
Q.
N 7
6 6
5
4
3
2
0.10
0.00 400.00 800.00 1200.00
Time (sec) B-38
DP-2
drawdown vs.time
10.00
s
8
7
6
5
4
3
2
1.00
co s
a 8
U) 7
6
5
4
3
2
0.10
0.00 400.00 800.00 1200.00
Time (sec) B-39
DP-3
drawdown vs. time
10.00
s
E 1.00
cc
N \
O
0.10
0.00 400.00 800.00 1200.00 1600.00
B-40
pP,?/' r
r

e= 4,;f (raj
4

14
12
A
ANO
C
to
A- z. ?s
i a o, Z(
1 = ZI4J
8 4
B
E 3
s Z
O
i
to -- too --- 1000 5000
Le /r.
Fig. 2. Dimensionless parameters A, B, and C as a function
! f I /r f-, .._t .mot I_ rrn r. %
B-41
'IMPERMEABLE
F-I6 UR E 1
2
OP
r
14
12
A
AND
C
10
l;
E

_ 6 s. 0 4

q7, 3
w
v v.s
4
H
3
2
O
1 5 10 50 100 500 1000 5000
Le /r
Fig. 2. Dimensionless parameters A, B, and C as a function
B-42
IMPERMEABLE
.:F?GuRE !
c
? "I ? U !0 • Z
NO.
Environmental Services, Inc. JOB SHEET NO. ER
NO. 3
DATE -/ TAO/ 9f
JOB NAME 20 '.CA c? Ski C i Li
COMPUTED BY
SUBJECT t o i ?v?vvn? d IQ 'c + Mr>1ft CHECKED BY
137-111
of- 7 30,
zC/Cs.2J 3co
2.fy
IGS. Z
-? - 360
y? = 137, 1,4
yam' 3v_4?
2- el&) PC
pp-? L. skit
r? 2-SY
l1 SO
Y4-
2-W7-
2 L Z66
Y z
Y = 3, 0 N,V cM
F.
B-44
cAcore1drw\pam\network\arid1-1.cdr

14
12
A
AND
C
10
e
E
e
l
LIP
H - \Ih
q 7, 3
`w
13 u??g
1 C- z . 7s
B
3
2
O
I 5 10 50 100 500 1000 5000
Le /r
Fig. 2. Dimensionless parameters A, B, and C as a function
B-45
.IMPERMEABLE
F-IGURF !
c,-

14
12
A
AND
C
10
s
6
4
C

S `?L (i?,j
L e=
ty -: L, 7. 3
"
W
C
13
8
3
2
10
5 10 50 100 500 1000 5000
Ce /r
Fig. 2. Dimensionless parameters A, B, and C as a function
t, , . . . .
B-46

IMPERMEABLE
Fa6U.RE 1
C / i
/
DP-7
drawdown vs. time
10.00
s
8
7
s
5
4
3
2
1.00
? s
CO) a. 8
7
s
5 \
4 \
3 \
2 \
0.10
0.00 200.00 400.00 600.00 800.00
Time (ft) B-48

DP-8
drawdown vs. time
10.00
8
7
6
5
4
3
2
1.00
U 9
t? 8
Q
CO) 7
5 6
5
4
3
2
0.10
0.00 1000.00 2000.00 3000.00
Time (sec) 6-49
DP-9
drawdown vs. time

E
N
U
cu
0-
ca
0
1.00
0.10
9
8
7
6.
5
4
3
2
0.00 100.00 200.00 300.00 400.00
Time (sec) B-50
O P- q

IY
12
A
ANO
c
10
8
6
4
2
C

77 6 11
7 'O
3. G (in j
L e=
Lw=
h - (1 h)
C 31, ?w
A 2.sd
L _ Z d
t
B
3
2
O
1 5 10 50 100 500 1000 5000
Lc /r
Fig. 2. Dimensionless parameters A, B, and C as a function
B-55
.IMPERMEABLE
c /
Environmental Services, Inc. JOB NO. ?
SHEET NO.
DATE
JOB NAME i f /? c? SiL/ w+ f Tj ?I S 7-/?.
COMPUTED BY
SUBJECT _+?r ?./, 7.'.h t o 7C j,
CHECKED BY
SrP ?3
o? y 6
?z, stiff (/l 1 ?2 ? _ /,
s
\ - Z (ire, 2S? Z
C = ZZ Ss Pc
yo = a 7 9?.
'y' 3 0. 4 aq
f. o l xr -S?l?yse?
2C-- S -C Al
t`, i Su u `1 1 Sd 2 L ?? q SD ? 3d .4?
y 7 /. 9 ? yo Z . I?a<?
C'OK
LZ.sg)Z?
Yv
y? 3G. 4?
B-51
C*\cnraltirw\nnm\natwnrk\nrirH _1 -4,
DP-4
drawdown vs. time
10.00

a) 1.00
a
U
_N
Q
N
0.10
0.00 400.00 800.00 1200.00 s-52
Time (sec)
DP-5
drawdown vs. time
1?
N
U
_cu
Q.
N_
0
10.00
1.00
E
4
2
2
0.10
3
3

0.00
2000.00
4000.00
6000.00
Time (sec)
B-53
DP-6
drawdown vs. time
10.00

E 1.00
U
_co
Q.
N

0.10
0.00 400.00 800.00 1200.00 1600.00
Time (sec)
B-54

I
12
A
AND
C
10
e
6
4
2
C
32,04
L e= 2-K7 Lw= 2.67 (;.,)

f-i =
23, ?
2. z?
= v. 3 3
(t h?
e
3
J2
0
5 to 50 100 500 1000 5000
Lt /r
Fig. 2. Dimensionless parameters A, B, and C as a function
B-56
IMPERMEABLE
..FIGURE 1
C

14
12
A
AND
C
10
8
l e= -? L (r n j
rw
?? 3 da
U • 4S?
13
C Z, 7S
t
6 B
3
a
2
O
I 5 10 SO IDO 500 1000
5000
? 0
LC /r
Fig. 2. Dimensionless Parameters A, B, and C as a function
*-If I - /r, fnc 1_I,+;_ - -f I- I r:) /. I
B-57

IMPERMEABLE I
FJGURF / f
C??