Loading...
HomeMy WebLinkAbout20040325 Ver 1_Mitigation Plans_199704011 1 1 1 1 1 1 1 1 1 1 1 1 1 CONCEPTUAL WETLAND MITIGATION PLAN BARRA FARMS/HARRISON CREEK WETLANDS CAPE FEAR REGIONAL MITIGATION SITE CUMBERLAND COUNTY, NORTH CAROLINA Prepared for: ECOBANK 1555 Howell Branch Road Winter Park, Florida 32789 Prepared by: Environmental Services, Inc. 1100 Wake Forest Road, Suite 200 Raleigh, North Carolina 27604 Telephone (919) 833-0034 FAX (919) 833-0078 April 1997 i CONCEPTUAL WETLAND MITIGATION PLAN BARRA FARMS / HARRISON CREEK WETLANDS CAPE FEAR REGIONAL MITIGATION SITE CUMBERLAND COUNTY, NORTH CAROLINA Prepared for: ECOBANK 1555 Howell Branch Rd. Winter Park, Florida 32789 Prepared by: Environmental Services, Inc. 1 100 Wake Forest Road, Suite 200 Raleigh, North Carolina 27604 APRIL 1997 i i TABLE OF CONTENTS LIST OF FIGURES .................................................. iii LIST OF TABLES .................................................. iii 1.0 INTRODUCTION ...............................................1 2.0 METHODS ..................................................4 3.0 POTENTIAL WETLAND IMPACTS .................................. 6 4.0 MITIGATION SITE EXISTING CONDITIONS ............................ 9 4.1 Physiography, Topography, and Land Use ....................... . 9 4.2 Soils ................................................. 10 4.3 Plant Communities ....................................... 12 4.4 Hydrology ............................................. 15 4.4.1 Stream Hydrology .................................. 17 4.4.2 Groundwater Hydrology .............................. 17 4.4.3 Influent Surface Waters .............................. 21 4.5 Water Quality .......................................... 21 4.6 Hazardous Materials ...................................... 22 4.7 Cultural Resources ....................................... 24 4.8 Protected Species ....................................... 24 5.0 PRELIMINARY WETLAND FUNCTIONAL EVALUATIONS .................. 25 5.1 Wetland Functions under Existing Conditions .................... 25 5.2 Projected Wetland Functions Under Post-Restoration Conditions ....... 27 5.3 Implementation Schedule .................................. 28 6.0 PHASE 1 CONCEPTUAL WETLAND RESTORATION PLAN ................ 29 6.1 Wetland Hydrology Restoration .............................. 29 6.2 Wetland Community Restoration ............................. 32 6.2.1 Planting Plan ...................................... 34 6.3 Wetland Soil Restoration ................................... 34 7.0 MONITORING PLAN ........................................... 36 7.1 Hydrology Monitoring ..................................... 36 7.2 Hydrology Success Criteria ................................. 36 7.3 Vegetation ............................................36 7.4 Vegetation Success Criteria ................................ 37 7.5 Report Submittal ........................................ 37 7.6 Contingency ...........................................38 ' 8.0 DISPENSATION OF PROPERTY ................................... 39 ' 9.0 PRELIMINARY MITIGATION CREDIT POTENTIAL ....................... 40 10.0 CONCEPTUAL REGIONAL MITIGATION PLAN SUMMARY ................ 42 11.0 REFERENCES ................................................ 43 ii i LIST OF FIGURES Figure 1: Site Location ............................................ 2 Figure 2: 1997 Aerial Photograph .................................... 5 Figure 3: Soil Survey and Hydric/Nonhydric Soil Boundaries ................. 11 Figure 4: Existing Plant Communities ................................. 13 Figure 5: Hydrology and Drainage Area ............................... 16 Figure 6: Preliminary DRAINMOD Wetland Hydrology Simulations ............. 19 Figure 7: Preliminary Mitigation Design Units and Implementation Phases ....... 26 Figure 8: Phase 1 Conceptual Wetland Hydrology and Soil Restoration Plan ...... 30 Figure 9: Conceptual Model of Target Community Patterns ................. 33 LIST OF TABLES Table 1: Potential Nonriverine Wetland Impacts by Project .................. 6 Table 2: Ditch Radii of Influence on Wetland Hydroperiods ................. 20 Table 3: Preliminary Assessment of Phase 1 Mitigation Credit Potential ........ 42 0 CONCEPTUAL WETLAND MITIGATION PLAN ' BARRA FARMS / HARRISON CREEK WETLANDS CAPE FEAR REGIONAL MITIGATION SITE CUMBERLAND COUNTY, NORTH CAROLINA 1.0 INTRODUCTION I I ECOBANK, a private sector mitigation banking company, has investigated available wetland mitigation sites within the Coastal Plain region of the Cape Fear River Basin of North Carolina. This region is expected to sustain unavoidable wetland impacts associated with projected population growth, infrastructural development, and construction of highway projects planned in the Cape Fear River Basin. Specific highway related wetland mitigation needs associated with pending North Carolina Department of Transportation (NCDOT) projects as defined in the Transportation Improvement Program (TIP) have been a major impetus for investigating mitigation sites in this region. The Department has identified NC 24 improvements in Cumberland, Sampson, and Duplin Counties (R-2303); NC 87 widening and bypasses in Cumberland and Bladen Counties (R-2562 and R-522); and NC 24 improvements around Fayetteville (X-2) as immediate and in potential need of compensatory wetland mitigation (NCDOT letter; Appendix A). ' This search resulted in the identification of the Barra Farms property along upper reaches of Harrison Creek in Cumberland County (Figure 1). This site is strategically located in the same drainage basin as the proposed highway projects previously mentioned. In addition, the site ' is positioned within the Interstate 95 (1-95) development corridor and in an area subject to continual residential, commercial, and industrial outgrowth around Fayetteville. 1 I,II' The Barra Farms/Harrison Creek site is composed of 2247 acres (ac) of interstream flats, former Carolina Bays, and historic stream origins which have been ditched and drained to support agricultural and silvicultural activities. This site offers opportunities for nonriverine and riverine (stream) wetland restoration and enhancement which can be phased in over a period of time. This conceptual regional mitigation plan outlines restoration and enhancement procedures for the entire wetland ecosystem located within Barra Farms. However, the initial phase of up- front wetland restoration is anticipated to compensate for specific highway related projects. Decision for use of this mitigation will be made by NCDOT. However, the NC 24 improvement project in Cumberland, Sampson, and Duplin Counties (R-2303) is the most likely mitigation candidate for Barra Farms Phase I mitigation credits. Additional up-front restoration phases at Barra Farms will be implemented as unavoidable wetland impacts are quantified within the region. A mitigation banking instrument will be formulated during later phases of site restoration for non-project specific usage. 1 ' The benefits of such a regional mitigation plan are numerous. Mitigation will be performed up- front prior to permit submittal and construction of a specific highway project. This will allow ' resource and regulatory agencies to evaluate the success of proposed mitigation efforts early in the planning process for a particular project. Mitigation will be in-kind and within basin, thereby replacing lost wetland functions and acreage for impacted wetland losses. Private t sector mitigation relieves NCDOT of the responsibility for site selection, acquisition, implementation, monitoring, and long term management. In addition, scheduling delays for highway construction can be eliminated by having mitigation in place and approved early in the ' planning process. The long term success of this private sector mitigation project will be ensured through financial assurances (trust funds) in accordance with State and Federal guidelines established for monitoring, long term management, contingency, and remedial ' actions. The primary goal for this conceptual mitigation plan is to demonstrate the suitability of Barra Farms as a potential mitigation site. The secondary goal is to receive consensus from various resource and regulatory agencies regarding the acceptability of this site as mitigation for ' specific highway projects currently being proposed by NCDOT. Therefore, this document will: 1) briefly evaluate potentially impacted wetlands associated ' with highway improvement projects in the area; 2) describe existing conditions at the entire 2247-ac mitigation site; 3) present a conceptual mitigation plan for restoring wetlands in a phased approach; and 4) describe methods for monitoring and management of restoration ' efforts. If this site is considered acceptable for mitigation use, detailed mitigation plans will be implemented at Barra Farms in an expedited manner to ensure project completion in advance of targeted wetland impacts. 3 0 n F C 0 2.0 METHODS Natural resource information for the Barra Farms / Harrison Creek site was obtained from available sources. U. S. Geological Survey (USGS) topographic mapping and Natural Resource Conservation Service (NRCS) soil surveys (USDA 1984) were utilized for base mapping and to evaluate existing landscape and soil information prior to on-site inspection. Current (1994) aerial photography (Figure 2) was obtained and evaluated to determine primary hydrologic features and to map relevant environmental features on USGS base mapping. North Carolina Natural Heritage Program (NCNHP) data bases were evaluated for the presence of protected species and designated natural areas which may serve as reference (relatively undisturbed) wetlands for restoration design. Regional management areas administered by The Nature Conservancy were also evaluated for reference use. Identified sites were evaluated to provide baseline information on target (post-restoration) wetland condition. Characteristic and target natural community patterns were classified according to constructs outlined in Schafale and Weakley's, Classification of the Natural Communities of North Carolina (1990). Field investigations were performed in March 1997, including preliminary hazardous materials review, hydrological evaluations, natural community assessments, and classification of soil and landscape features. Existing plant communities, surface water flow, and soil disturbances were delineated, mapped, and described by structure and composition. To characterize existing hydrologic conditions, conceptual mitigation planning included the following activities: 1) installation of a series of soil borings strategically placed throughout the site and conversion of these borings into piezometers (6); 2) performance of in situ hydraulic conductivity tests (slug tests); and 3) a general evaluation of potential groundwater flow gradients on the site. General groundwater conditions were conceptually modeled using DRAINMOD, a computer model for simulating relatively shallow soils with high water tables. Field survey information was platted and compiled within Geographic Information System (GIS) base mapping and analyzed to develop conceptual wetland restoration plans. Based on wetland component analyses, the site was divided into appropriate mitigation phases. Mitigation phases are designed to maximize wetland functional replacement benefits and to facilitate success in restoration of a contiguous wetland ecosystem. Phase 1 of proposed mitigation at Barra Farms was designed to provide suitable nonriverine wetland replacement for potential roadway projects in the region, such as NC 24 improvements (R-2303). 4 u I I lisp t arr 1s`??rr-.. kZ " a rK d? rk` T , 71 1-4, 1 ^ 7,` t IF ? lv dF B t ! F ` w i ?, t a! ''? fi??rn ar{ ,Y ?yw? Farm Outbuildings 3 1 % sr > ? 1 41- 7}5 !"?t >r :;?yj,?{.' x^ : 6d'4•. fir,-`""S,.f`w v ,:: ? t ? ? ,% .wv. r - E ^ U ;F'. 9 ?'' r L 1f Y. tK R? ?+..+?J r? r / n? n1 i .4 i;t w 4;,;?r. +: ,7?i!?, r -,?, ..F_ ":•rr: ' i.• 4 °r^'-, .^'`.,:,?x r air vr? a iJ I W 1 t ' ?-?€,: - ? sl `irk ?A. .?..:.- ?+f,` lr -' \ h•::, ???? .? ?1`ta ? tr ?• ;?t., M1 J ,rt ?,, } a s,: -1 ? t V?. i. ?^ ? '? ?' "fir Ii1 [+', ?` ?}}p,.. ?rw r ^ Y r? y 4 ` 4l,.r S': '' rn i ht W' 1 it f 4t, F ?t 4 R w7 1 4 ; rr ,ti l 1 { ?F ' t t r dry ti _ A J.e ae. e' w V try{ ^ ':i ?",? ^ }:. s.? A!1 ?.x?! I 0 1000 2000 feet 0 500 meters Source: Weyerhaeuser Photography, 1994 Environmental Services, Inc. 1994 Aerial Photograph Barra Farms/Harrison Creek Wetlands Cumberland County, North Carolina Figure: 2 Project: ER97010 Date: April 1997 t 3.0 POTENTIAL WETLAND IMPACTS The initial phase of this up-front mitigation project will serve to mitigate for highway related projects in the region. Project specific mitigation needs include NC 24 improvements in Cumberland, Sampson, and Duplin Counties (R-2303); NC 87 improvements in Cumberland, ' Bladen, and Columbus Counties (R-2561 and R-2562); and NC 24 improvements around Fayetteville (X-2). Therefore, a general description of unavoidable wetland impacts potentially resulting from these projects is provided to orient restoration planning, to compare up-front restoration plans to potential impacts, and to facilitate successful initiation of Phase 1 of this mitigation plan. ' For the purposes of this assessment, wetland types associated with the above referenced highway projects are grouped into riverine/bottomland wetlands and nonriverine/interstream ' wetlands for descriptive purposes. Riverine wetlands are defined as wetland corridors which surround a stream channel and support, or historically supported, overbank flooding, fluvial sediment deposition, and floodplain wetland communities. Nonriverine wetlands are defined ' as precipitation and groundwater driven systems occurring along interstream divides. Nonriverine wetlands do not contain streams and associated floodplains, although streams may originate within headwater storage areas (groundwater discharge zones) associated with the ' nonriverine wetland. This wetland impact assessment and up-front compensatory mitigation plan has been designed ' to compensate primarily for nonriverine wetland impacts. However, the plan is expected to provide additional opportunities for riverine (stream) wetland mitigation as well. Table 1 depicts a conservative estimate of nonriverine wetlands potentially impacted by targeted ' highway improvement projects. TABLE 1: Potential Nonriverine Wetland Impacts by Proiect NCDOT TIP: X-2 TIP: R-2561 and 2562 TIP: R-2303 Traffic NC 24 Improvements NC 87 Improvements NC 24 Improvements Improvement Cumberland County Cumberland, Bladen, Cumberland, TOTAL Project (TIP) and Columbus Sampson, and Duplin Counties Counties Area (acres) 25 40 210 275 ' More than 250 ac of nonriverine wetlands are expected to be impacted by roadway improvements projects, dependent upon final project alignments. Nonriverine pine/hardwood forested wetlands represent a large majority of wetland impacts potentially associated with ' improvements of NC 24/87. These wetlands are positioned along the center of interstream tracts which are temporarily saturated or inundated during early portions of the growing season. Interstream wetlands in proximity to alternative road alignments are typically ' fragmented within farmed landscapes or road networks and exhibit negligible forest connectivity with riverine/bottomland corridors. Interstream wetlands exhibit indications of 6 ' long-term disturbance such as antecedent farming, affected hydrology, or systematic logging. Included within this wetland class is nonriverine shrub-scrub wetlands which dominate the ' region. This community represents interstream woodland or pine plantation which has been clear cut in the last 10-20 years. ' Soil types within potentially impacted interstream wetlands include series such as Rains (Typic Paleaquults), Pantego (Umbric Paleaquults), Cape Fear (Typic Umbraquults), Portsmouth (Typic ' Umbraquults), Torhunta (Typic Humaquepts), and Croatan (Terric Medisaprists) (USDA 1984, USDA 1990, USDA 1985, USDA 1954). These soils are nearly level, poorly drained, with the seasonal high water table at or near the surface. Silty clays or organic matter of limited ' permeability lie a few inches to a few feet below the ground surface is some potential impact areas. Relatively low permeability of subsoils may contribute to the presence of wetland hydrology in these areas. When drained, these soils are generally well suited for agriculture. ' Interstream communities traditionally support trees such as water oak (Quercus nigra), pond pine (Pious serotina), willow oak (Quercus phellos), swamp chestnut oak (Quercus michauxiil, ' laurel oak (Quercus laurifolia), sweet gum (Liquidambar styraciflua), black gum (Nyssa biflora), and loblolly pine (Pious taeda). Swamp red bay (Persea palustris), sweet bay (Magnolia virginiana), red maple (Acer rubrum), and sweet pepperbush (Clethra alnifolia) are common ' understory/shrub components. Characteristic ground cover species may include partridge berry (Mitchella repens), switch cane (Arundinaria gigantea), netted chain fern (Woodwardia areolata), false nettle (Boehmeria cylindrica), and dog hobble (Leucothoe axillaris). ' Nonriverine forested wetland functions may include long-term water storage during periods of ' groundwater drawdown, moderation of groundwater flow/movement within the watershed, and attenuation of surface runoff into streams and agricultural (slope) 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. The ability of potentially 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, small pockets which fill with water during winter and early spring. ' 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. However, field evaluations suggest that the potentially impacted, nonriverine wetlands in the general area of NC 24 and NC 87 proposed corridors exhibit relatively low value for wildlife. These areas exhibit negligible connectivity with riverine corridors and have sustained long-term degradation from 7 ' human activity. In addition, the early successional stage generated by systematic clear-cutting in these systems is considered common habitat throughout eastern North Carolina. Compensatory mitigation strategies which consolidate fragmented nonriverine wetland impacts into contiguous watershed reserves are expected to replace wetland functions potentially lost as a result of NC 24/87 improvements. The mitigation should provide for functional replacement of impacted nonriverine wetlands within the same river basin (Cape Fear) and the same physiographic province (Coastal Plain) (DWQ 1996). In addition, the mitigation proposal ' should provide for the spatial replacement of wetland acres lost due to proposed highway improvements at a minimum of a 1:1 ratio up to a 2:1 ratio, through restoration, prior to ' utilizing enhancement or preservation to satisfy the mitigation requirements. The mitigation site should also exhibit direct connectivity to riparian (bottomland) ecosystems after reforestation is completed. These primary objectives for mitigating impacts from highway ' projects in the region are achievable through up-front wetland restoration at the Barra Farms / Harrison Creek regional mitigation site. n u P 8 R 4.0 MITIGATION SITE EXISTING CONDITIONS ' The Barra Farms / Harrison Creek site comprises approximately 2247 ac situated 4 miles south of NC 24, 7 mi east of NC 87, and 10 mi southeast of Fayetteville (Figure 1). The site, situated 3 mi east of the Cape Fear River, represents a broad coastal plain interstream divide ' which supports the NC 210 highway corridor immediately north of the mitigation site. The site contains several relict Carolina Bays and stream origins with a majority of these hydrogeomorphic features converted for agricultural land use. The site receives drainage from ' elevated sand (Carolina Bay) terraces which support the NC 210 corridor, several state roads, and discharges these influent waters into Harrison Creek, a tributary of the Cape Fear River. ' 4.1 PHYSIOGRAPHY, TOPOGRAPHY, AND LAND USE The mitigation site is located in the Atlantic Coastal Plain Physiographic Province of North ' Carolina within the Inner Coastal Plain region of the Cape Fear River Basin. The Cape Fear Basin extends from the Piedmont/Coastal Plain boundary (Fall Line) near Fayetteville southeast to the City of Wilmington (Hydrologic Unit #03030005 and #03030006 [USGS 1974]). The ' mitigation site is located approximately 15 mi southeast of the Fall Line and approximately 95 mi northwest of the coast. ' The site is situated along a Coastal Plain interstream divide which contains the historic stream origin of Harrison Creek. Adjacent, elevated sandy terraces cover approximately 300 ac of land with groundwater and surface water discharging from these terraces towards the ' mitigation site. Elevations within upper reaches of the watershed extend to approximately 140 ft above mean sea level (MSL) along these sandy terraces. Conversely, elevations within the mitigation site range from approximately 125 ft above MSL at the upper mitigation site boundary, to approximately 120 ft above MSL at the mitigation site out-fall. Therefore, historic wetlands along the interstream divide were most likely complex, influenced by radial ' groundwater and surface water (stream) flow in lower reaches of the site as well as precipitation and vertical groundwater fluctuations in interior wetland areas. A majority of the site has been cleared, ditched, drained, and removed from jurisdictional wetland status. The original drainage system was installed to facilitate agricultural production and to convey drainage from upslope areas through the site. Subsequently, additional drainage ' systems and a dirt road network were constructed periodically over the last several decades. These expanded canals, ditches, and culverts appear to have been installed in response to changing agricultural land uses and additional drainage requirements. The patchwork of antecedent ditch networks and current drainage structures includes approximately 250,000 linear feet of ditches/canals distributed systematically throughout the mitigation site. A number of farm outbuildings and structures reside within the historic wetland area. Structures include maintenance sheds and grain storage bins located along the eastern site ' periphery (Figure 2). In addition, electric power lines and irrigation wells are distributed systematically throughout the agricultural land use area. 9 r As a result of extensive ditching and canalization, spoil ridges and piles occur systematically throughout the site. Much of the excavated spoil material was used to build and elevate dirt roads adjacent to canals. However, substantial spoil ridges persist along isolated ditch segments and range from 1 ft to 6 ft in height above the adjacent soil surface. If wetland hydrology is restored to the site, these spoil ridges and elevated dirt roads would require removal and/or grading to re-expose wetland soil surfaces. The site is located approximately 2 mi north of the Bushy Lake State Natural Area. This natural area currently encompasses approximately 2570 ac with an estimated additional 800 ac to be added in 1997 through acquisition by The Nature Conservancy. The Bushy Lake State Natural Area is managed by the North Carolina Park and Recreation Service out of the Jones Lake State Park Office. Adjacent to the State Natural Area, several NCNHP designated Priority Areas occur, including Horseshoe Lake, Marshy Bay, Suggs Mill Pond, Big Gallberry Bay and Little Singletary Lake. These sites have been listed by NCNHP as Priority Areas because they exhibit a unique array of ecosystems in the State and Nation which may warrant future protection from disturbance. In addition, these systems contain a significant assemblage of threatened and endangered plant and animal species. The Barra Farms mitigation site may serve to enlarge the area of management associated with the Bushy Lake State Natural Area and adjacent NCNHP Priority Areas. Restored wetlands at Barra Farms will diversify opportunities for management of wildlife and unique natural communities in the region. 4.2 SOILS The mitigation area occurs along a landscape-soil gradient characterized as the Lakeland- Torhunta-Croatan-Johnston catena (Figure 3). Carolina Bay sand rims along a majority of the site periphery consist of excessively drained, sandy sediments (Lakeland, Autryville map units) while interior portions of the site are dominated by very poorly drained, organic soils associated with the Torhunta and Croatan series. However, southern portions of the historic ' wetland comprise a complex of organic material, coarse marine deposits, and fine alluvial surficial sediments that have been mixed and reworked by fluvial actions. Soil patterns suggest that southern portions of the site, including the Johnston soil map unit (Figure 3) historically consisted of a complex supporting groundwater recharge areas and groundwater (headwater) discharge areas serving as sources for intermittent, ephemeral, and permanent streams. ' 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 ' soils comprise 97 percent (approximately 2180 ac) of the 2247-ac mitigation area. Hydric series present include the Cape Fear, Torhunta, Johnston, Woodington, and Rains soil map units. Organic matter within these series potentially ranges from a minimum of 1 percent in I the Rains series to 60 percent in the Croatan series. However, reductions in organic matter at the site are anticipated as a result of long term drainage, tillage, and harvest. 10 i NC SR2 023 C, U ?O VSO _. / CT on p 0) r• m L_ W •? QQ to 'm 0 if o n g b LO N 3 m II S. a m v u v v o U UI Q Z J -? I O W01 3Q U >- W2 W I- ?UO V)zZ JOB OXZ ?QO U?U Z?Z J Q rK ?W Qm QU m Mitigation site boundary AuA Bn , ,:. I Le ® NONHYDRIC SOILS (67 acres) pR Le Leon BuA Butters t AuA Autryville LaB Lakeland St Pa Pactolus KuB Kureb Le u St Stallings CaB Candor HYDRIC SOILS (2180 acres) Tr d S? CT Croatan 10 ?, TR Torhunto St w Ra Rains SR20 2 Wo Woodington 4 JT Johnston <q X I ' Construction of large canals and feeder ditches has drained most of the mitigation site to the extent that hydric conditions in the 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. To effectively re-establish wetland hydrology within hydric soil areas, drainage canals require modification to recreate surface and ' subsurface drainage patterns. Organic matter relations in the soil profile are expected to return to relict condition over time after restoration of wetland hydrology. ' Non-hydric series present include the Autryville, Pactolus, Leon, and Stallings map units. These series comprise approximately 67 ac of the mitigation site. These soils are primarily ' non-hydric but may contain hydric inclusions of the Torhunta or Woodington series. The non- hydric series generally occupy elevated sandy terraces and exhibit drainage classes ranging from somewhat poorly drained to excessively drained. These soils lack wetland hydrology but ' are included in the mitigation landscape to provide the potential for restoration of upland/wetland ecotones. These ecotones are among the most diverse and productive environments for wildlife (Brinson et al. 1981). L Soil surfaces have been levelled, graded, and compacted as a result of agricultural practices. Surface microtopography represents an important component of nonriverine wetlands as water storage functions and micro-habitat complexity are provided by hummocks and swales across the wetland landscape. Reintroduction of microtopographic complexity across soil surfaces represents an important component of wetland restoration in converted cropland. 4.3 PLANT COMMUNITIES Plant communities at Barra Farms are influenced primarily by hydrogeomorphic conditions and past/current land use practices. The site is located primarily within intermittent rims of several Carolina Bays. Site preparation, drainage, and continued maintenance over the years have substantially altered the natural plant communities. Seven plant communities have been identified for descriptive purposes, including: 1) Active Cropland; 2) Fallow Cropland; 3) Early Successional Scrub; 4) Pond Pine Woodland/Bay Forest; 5) Nonriverine Swamp Forest; 6) Riverine Bottomland Hardwood/Swamp Forest; and 7) Commercial/Disturbed Land (Figure 4). Active and Fallow Cropland Approximately 48% (1082 ac) of the 2247-ac area consists of active or fallow cropland. These areas include farm-fields which have been planted during the current season (active cropland) and farm-fields which have been planted within the last 3 years (fallow cropland). Agricultural production for wheat and corn are concurrent on farmed portions of the site. In fallow fields, disturbance adapted species indicative of moderately well drained conditions are currently recolonizing the area. Species composition and vegetation height differ at several locations depending on time since last cultivation, site fertility, and hydrology. Characteristic pioneer species include broomsedge (Andropogon virginicus), asters (Aster spp.), geranium (Geranium caroiinianum), goldenrod (Sofidago spp.), horseweed (Erigeron canadensis), young red maple (Acer rubrum), loblolly pine (Pious taeda), and groundsel-tree (Baccharis haiimifoiia). 12 ?c SR2023 D i.- 0C21 IV ..,, ..,. SR2033 ....................................... . s ++ tit` ? - + + _____- __ ± ++++' + + _ ----------_ + + + + - - - - - - - - - - - - + + + + ------ --- ----- ----------------- - ----------- + + + + + - -___ + + + + + Ile) + + + + + + + + + + + + + + --- + _-_-- _- Mitigation site boundary ::':•':;:;':;;;'.,'.''``',.'`.'•?: "_ , Area (acres) ® RIVERINE BOTTOMLAND HARDWOOD/ 18 SWAMP FOREST ::::•::::::::::::.:,:::.,::::::::::: EARLY SUCCESSIONAL SCRUB 417 POND PINE WOODLAND/BAY FOREST 683 ® NONRIVERINE SWAMP FOREST 19 (STEADY STATE REFERENCE) s? O 0 ACTIVE CROPLAND 667 BOO Q FALLOW CROPLAND 415 2 ® COMMERCIAL/DISTURBED LAND 28 SR2442 TOTAL 2247 o ? o rn ? rn rn U_ ?Wa U U N d o N ? O O J 3 N 9 S', II m m Q) 3 U v N o` U W oQ Z z Q ?O V3 Li Of W?Q 1- U ZW2 QUO Z O Z U Or ?V? Q ? -IQO a- Z?Z <J Q XLL.X WQM LLJ <U Q /y W a 00 r? ' A number of inclusions support dense, young sweetgum (Liquidambar styraciflua). Scattered loblolly bay (Gordonia lasianthus), winged sumac (Rhus copallinum), and laurel-leaf greenbrier ' (Smilax laurifolia) are also present. Numerous inter-field ditches support hydrophytic plants such as soft rush (Juncus effusus), ' woolgrass (Scirpus cyperinus), cattail (Typha latifolia), seedbox (Ludwigia alternifolia), yellow- eyed grass (Xyris sp.), and beak rush (Rhynchospora sp.). Inter-field dirt road berms are invaded by various upland and invasive species such as blackberry (Rubus spp.), broomsedge, ' asters (Aster spp.), and numerous annual and perennial grasses and herbs. Characteristic wetland forest vegetation is absent from fallow and active cropland portions the site. 0 I I Early Successional Scrub Early successional scrub communities are currently recolonizing portions of the site that have been heavily logged or not farmed within 3-5 years or more. These sites, comprising approximately 417 ac, contain decreasing populations of broomsedge but increasing greenbrier, winged sumac, loblolly pine, red maple, and evergreen shrubs such as bitter gallberry (flex glabra), sweet gallberry (/Hex coriacea), and fetter-bush (Lyonia lucida). Pond Pine Woodland/Bay Forest Northwestern and southeastern reaches of the site maintain pond pine woodland/bay forest communities (683 ac) which have sustained degradation from past logging and construction of intermittent road and ditch networks. The disturbed forest canopy consists of character species such as red maple, loblolly bay, pond pine (Pious serotina), and occasional swamp tupelo gum or black gum (Nyssa biflora, Nyssa sylvatica). Red maple dominates most of the area with scattered pond pine and loblolly bay present. The shrub layer is tall and dense with characteristic species including bitter gallberry, sweet gallberry, fetter-bush, sweet pepperbush (Clethra alnifolia), highbush blueberry (Vaccinium corymbosum), sheepkill (Kalmia angustifolia), laurel-leaf greenbrier (Smilax laurifolia), and occasional swamp bay (Persea palustris). More recently disturbed areas contain sweet bay (Magnolia virginiana), titi (Cyrilla racemiflora), and yellow jessamine. Some of this forest has been logged, removing much of the pine so that red maple and loblolly bay typically dominate the canopy. Along the eastern boundary, the trees are intermittent and the shrub layer is more dense, possibly as the result of intense fire or logging. Nonriverine Swamp Forest Within the northwestern periphery of the site, an inclusion of relatively undisturbed, steady state nonriverine swamp forest persists within the complex. This community, comprising approximately 19 ac, is a remnant of what was probably a more extensive system before logging in the present bay took place. The canopy is dominated by bald cypress (Taxodium distichum), Atlantic white cedar (Chamaecyparis thyoides), red maple, swamp tupelo gum (Nyssa biflora) and intermittent pond pine. Scattered red bay and sweet bay are found in the understory, and sweet pepperbush, titi, and fetterbush are found in the shrub layer. This community represents a steady state, reference forest ecosystem utilized to orient wetland 14 restoration planning. After restoration activities are implemented, this site will be used to establish monitoring plan parameters and to evaluate achievement of wetland mitigation ' success criteria. Riverine Bottomland Hardwood/Swamp Forest Within south-central portions of the site, a bottomland hardwood/swamp forest community persists along a potentially degraded floodplain and relict stream channel. This mid- successional community, covering approximately 18 ac, appears to have been affected by reductions in surface hydrodynamics, reductions in hydroperiod, and periodic timber harvest. The canopy is dominated by disturbance adapted tree species such as red maple, sweet gum, loblolly bay, and pond pine. However, relict stems of swamp tupelo, overcup oak (Quercus /yrata), and laurel oak (Quercus /aurifo/ia) were noted within subcanopy and shrub layers. Organic soil subsidence has exposed root collars on many of the remaining tree stems. Commercial/Disturbed Land This classification, comprising approximately 28 ac, designates man-dominated areas such as buildings, developed areas, maintenance yards, and machinery parking areas. These map areas are concentrated in northeastern portions of the mitigation site and include what appears to represent an old runway on compacted fill material. Characteristic plant species within these disturbed lands include lawn grasses, wild grasses, and opportunistic herbs. 4.4 HYDROLOGY Hydrology at Barra Farms is driven by precipitation inputs and primarily vertical to semi-radial fluctuations in the groundwater table (Figure 5). However, lateral groundwater flow and surface flow may have represented a significant component of wetland hydrodynamics under historic conditions. Topographically, the site is generally expressed as a complex of broad flats and depressions (Carolina Bays) with lands at higher elevations occurring on sand terraces to the north, east, and west. Under historic conditions, a majority of the interior wetlands most likely served as an above headwater storage area for Harrison Creek. Precipitation inputs and episodic radial groundwater flow most likely migrated from interior wetland areas towards south-central portions of the site. Conversely, lateral groundwater and surface flow is expected to have dominated wetland hydrodynamics in south-central portions of the site as above-ground discharge assisted in development of a historic floodplain. The floodplain appears to have surrounded a number of intermittent stream channels which coalesced into a primary channel denoting the origin of Harrison Creek. The Harrison Creek segment evident immediately below farm-field ditches appears to represent a first or second order stream (Outlet #1, Figure 5) (Strahler 1964). Currently, semi-radial and lateral groundwater migration has been intercepted by a network of interior canals and interfield ditches which effectively drains farmed portions of the mitigation area. Approximately 250,000 linear feet of ditches and canals have been constructed and range from approximately 1 ft deep in interfield ditches to 10 ft deep at the site out-fall. 15 r R20 0 ?3ET Mitigation site boundary PROJECTED GROUNDWATER AND STREAM FLOW UNDER HISTORIC CONDITIONS 3 O J a a a a m 0 0 m a w DITCHES AND CANALS > DIRECTION OF FLOW UNDER EXISTING CONDITIONS INLET OUTLET #2 ?P ?O ?O e fayFR 04 14 CR?Ek INLET #l o r o rn ? rn rn a N w r a 00 o i- a o a ? b 0 04 N II 3 in m v C Y Qj U ? U U7 0 oQ zz Ld w0 Q?U LLI (D LLJ QWI=- QUO z oo} QQo }2U O V) 0x< J 0U"W Ca ?D QU a] ,; da ov WA Groundwater migration has been redirected away from the historic floodplain and diverted into the Central, East-West Canal (Figure 5). The discharge is directed to the west in this canal and ' discharged from the mitigation site in a, constructed canal denoted as Outlet #2 in Figure 5. Drainage redirection and lowering of the water table has effectively eliminated wetland hydrodynamics in farmed areas and potentially degraded the Harrison Creek bottomland ' ecosystem. This unprotected drainage network connects site discharge within the interstream divide to tributaries of the Cape Fear River. 4.4.1 Stream Hydrology The potentially degraded segment of riverine wetlands along Harrison Creek includes ' approximately 1800 linear ft or more of lost primary stream channel on the mitigation site and approximately 4600 linear ft of degraded or lost stream channel below the mitigation site. Based on NRCS soil mapping (Johnston map unit, USDA 1984), The floodplain associated with ' this degraded or lost stream system ranges from approximately 300 ft in width near stream origin to approximately 800 ft in width at confluence with the constructed drainage canal and Harrison Creek. Relict riverine wetland floodplains within the mitigation site encompasses up to 18 ac of land area. Field surveys of the floodplain indicate that the primary channel consists of relict stream segments and stream segments effectively obliterated by organic debris accumulation, past logging activity, and ditch construction. Subsidence of organic material due to drainage is also apparent within the riverine system. Under historic conditions, the stream channel may have ' supported riverine aquatic habitat and the floodplains may have sustained periodic overbank flooding, groundwater discharge, and riverine wetland function. 4.4.2 Groundwater Hydrolo Based upon soil borings and piezometer samples collected on-site, groundwater was ' encountered as part of a shallow, unconfined surficial aquifer within 0 ft to 6 ft of the ground surface. The highest groundwater elevations were measured in northwestern portions of the site where isolated forest wetlands persist within the agricultural landscape. Water table elevations decrease (i.e. depth to groundwater increases) along drainage gradients extending up to approximately 6 ft below ground surface adjacent to the major drainage canals. ' Under existing conditions, groundwater generally flows towards the central canal and westward to a constructed canal which extends south below the mitigation site. Historically, groundwater flows within central portions of the site are expected to have flowed south into the origin of Harrison Creek. Drainage networks have effectively re-routed groundwater flows away from the Harrison Creek floodplain and into a confined drainage canal. Restoration of wetland hydrology may redirect groundwater and downstream flows towards potentially more ' stable, historic conditions. In addition, riverine wetland functions along the approximately 6,400-ft downstream segment of Harrison Creek may be restored as a result of mitigation. 17 i Groundwater modeling was performed to characterize the water table under current drainage conditions. The model was applied to evaluate wetland restoration alternatives and to predict wetland mitigation potential (hydrological restoration, enhancement, or protection). The groundwater modeling software selected as most appropriate for simulating shallow subsurface conditions and groundwater behavior at the site is DRAINMOD. This model was developed by R.W. Skaggs, Ph.D., P.E., 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 accumulates the number of events wherein the water table rises above a specified depth (12 in) and remains above that threshold depth for a given duration during the growing season. Model results are analyzed to determine if wetland criteria are satisfied during the growing season for more than half of the years modeled. Required model inputs include: 1) precipitation data; 2) soils data; 3) drain data; 4) the threshold water table depth (12 in); 5) the required duration of high water tables (ex: 28 days); and 6) beginning and ending dates of the growing season. Output from the DRAINMOD model was applied to determine which areas would not achieve wetland hydrology criteria under existing conditions. Wetland hydrology is defined in the model as groundwater within 12 inches of the surface for 31 consecutive days during the growing season (12.5 percent of the growing season). For the purpose of this study, the growing season was defined as the period between 21 March and 19 November (USDA 1984). For the development phase of this conceptual mitigation plan, additional modeling was performed to predict the maximum radius of influence on wetland hydrology caused by the ditches and canals. The maximum radius of influence was utilized to provide an indication of preliminary potential for wetland hydrological enhancement resulting from mitigation. DRAINMOD simulations were conducted for the range of ditch/canal depths and distances of a midpoint to the ditch or canal. The simulation evaluated the Croatan soil; the primary wetland soil type at Barra Farms. Based on the model, wetland hydrology has been eliminated at distances ranging from 66 ft to 174 ft from on-site ditches (Table 2). The pre-restoration DRAINMOD simulations indicate that wetland hydrology has been removed from approximately 1018 ac of PC cropland as a result of ditching and soil surface modifications (levelling, compaction, removal of microtopography) (Figure 6). Wetland hydrology has been significantly degraded within early successional and forested ' areas as a result of ditching. The model indicates that the annual occurrence of wetland hydrology has been reduced to 24 out of 31 years at distances ranging from 131 ft to 231 ft from drainage ditches (Table 2). Based on the model, enhancement of wetland hydrology may ' be realized within approximately 626 ac of degraded wetland forest in northwestern and southeastern portions of the site. 0 18 I 1 fl I? WETLAND HYDROLOGY DEGRADED 626 WETLAND HYDROLOGY UNAFFECTED 535 WETLAND HYDROLOGY REMOVED 1018 NONHYDRIC (UPLAND) SOILS 68 TOTAL 2247 SR2042 o n 0 rn rn w Q i d W a` o° N a o J L0 3 a ?+ II 5 m x m ? M-e 0 z O Z O? UZQ ?QJ 3a WYU W? IOC cnUO OZZ 1=0} ? J _ rY Z ?QO N\U Z Q J 0 L'W m =Q? om O 2 z Q 0 g? C? C H n N W J m Q F-- N N 10 O O O 'O i E ? = N C E r c O O N N V ,i t+ = IC N (n C? C E (D ?- 0 U- N _ cv •R °a i E m c Q c)-- 4) C_ N M U > N C H ? w d O O • - L + ' N m y - U - ? N U r m>_ L p p _ 'O U m N ° >' M M M M M O U T O = p j N O O O O O C C > a) E c C 7= O U L O a It N It N V N it N N N X j m 7 p U Q m Z> = d c m E m a7 ' N 0 C _ U o > O p y > N cm 0 O o Q ) 0 , ` p o >- O w-a E w w j N L A n co N E m O y a) U O) U C M C D r O N M N m m N y CD > 0 3 > a c o N C O I y ? a = c + _ a) : aa) m 3 3 6 0 U °> °? Cl) Cl) M M M M M 0 M 0 m ) 03 ° • c v Q7 0 (D 0 0 0 0 co co o m . 0 O E m L2 ?2 t2 a° c z E??a p c O N W > N > cm m c m m a) m 0 o > ° ? > - 0 0 0 7 U O a _ -p L n a) '- N u 'O U -- vim- - w- •- V? w L w CO C 2 L m c C 7 (O N w a) U C M r n d c c O m ? •, - m L M a) O N N C a m ° m > m y p d L O l0 . m U ' c ' O > t 3 U O O C C D , C U O M M M M M M M M U m O U > N "L w O w O w O w O - O - O w O - O C p a) in N a C U (D LO M M O p? a E m O It m m c 0 ° z?= E - o () c ? m m 0= p p °+ Im m O) m > 7 O m .C V O O U) O) a U •- N U -O w - - w w w 'O =>.C: >• C y 3 c U LU N (D N 1l O LO N 00 Cl) N r O M C Im c (D co 3 m C7 a) (DY a C L N C L .- a y m Q) m m n ai w C m y?j w w vY-. .= ? d 0 c -O N M a' m (p UL M It (O a?N c UO a « CD = C L m N >• N O O O 3 ?' 8 C C L O aC7? 'ca O N as O L a) _ L V, O V7 ? > O CT) r O O 00 N O U > O (0 . L ?, 7 O U C y 00 U (0 L N O 7- L N o oO 0 N \ N ` LO M cc N L j Q O >• (n M U CA ,? .? O O O L CA O ? ? O N O L L +Z Cf' N O C -0 O 4N f6 O +cvo v m 0 CL 'a y U O E . U C: Cc '= O m •N O O O O L >'00 U - CA a) CY) O p .? O E ` N m O +? a) > CL O x -0 L O O O d7 O O U 00 + C N E ? -O N CD E 2 a 3 ? co c O } CO `? E O co U O •y 7 E (B C N U N -O U O t' ca CA -0 (n - U O E o c +J O 'Cu O O E E N C L . C O co U o °? - CD E 0) (L° c 2 a? v ~ o RS E > (n L U N U M E U =o U N O = C O -C c t- I- S E ° .-- N n G Remaining forested systems situated away from major drainage structures (535 ac) may maintain wetland hydroperiods approaching historic condition. However, hydrological fragmentation within these isolated wetland pockets is expected to induce wetland degradation throughout the mitigation site, with the possible exception of a relatively contiguous forested system in the northwestern site periphery. Post-restoration drainage impacts on wetland hydrology will be modeled for various project phases during preparation of detailed restoration plans. Target wetland hydroperiods after restoration will be redirected towards historic condition based on the reference (relatively undisturbed) wetland hydroperiods expected in northwestern portions of the site. 4.4.3 Influent Surface Waters As depicted in Figure 5, five surface flow inlets have been identified extending from adjacent uplands into the mitigation site. These inlets consist of ditches which have been constructed and connected to the on-site drainage network. Due to the size of the mitigation site and expected slope gradients below in-fall, these influent surface flows appear to maintain base level elevations that are conducive to on-site storage after interior drainage networks are removed during wetland restoration activities. Discharge from surface flow inlets along the site periphery may be potentially accommodated within the wetland restoration area, as needed, through routing into the origin of Harrison Creek or through routing into constructed ephemeral pools (stormwater catchments) on the site. These stormwater catchments are anticipated to represent cypress-gum ponds which will provide additional wetland habitat diversity. Stormwater drainage and runoff within these cypress-gum ponds will be discharged as radial to lateral groundwater infiltration. Restoration of water quality functions associated with this mitigation project may be significantly enhanced by incorporating flows from the upper watershed before entry into Harrison Creek and the Cape Fear River. 4.5 WATER QUALITY Harrison Creek and tributaries extending into the site have a best usage classification of C. Class C uses include aquatic life propagation and survival, fishing, wildlife, and secondary recreation. Secondary recreation refers to activities involving human body contact with water on an infrequent or incidental basis (DEM 1993). The mitigation site consists of cropland located adjacent to a network of drainage ditches and canals. Fertilizers, pesticides, and nutrients associated with farming practices are expected to have influenced water quality in flows leaving the mitigation site. Vegetated buffers adjacent to drainage ditches, which may serve as nutrient and chemical filtration strips, do not exist within the farm-fields. As such, runoff is expected to have entered the drainage network and transported off-site into Harrison Creek with associated deleterious effects on water quality. These unprotected drainage networks extend into tributaries of the Cape Fear River. Drainage structures within the mitigation site service a watershed covering approximately 300 ac of land area. The land area is composed primarily of roads and residential areas intermixed among cropland and pine plantation. Runoff from this land area effectively bypasses wetland 21 L ' surfaces as drainage canals transport flow directly through the site. Restoration of wetland hydrology and diversion of influent surface flows onto the site may increase water quality I functions associated with nutrient removal, particulate retention, and chemical transformation performed by the mitigation area. ' 4.6 HAZARDOUS MATERIALS A limited regulated/hazardous materials review was performed for the Barra Farms / Harrison Creek mitigation site. This review was conducted for the purpose of identifying potential ' environmental concerns which may affect site utility for wetland restoration. Methods utilized to complete this review included: 1) limited vehicular reconnaissance and ground truthing; 2) ' an interview with the site manager; and, 3) cursory regulatory database review. Issues of environmental concern may include: electric transmission lines and pole-mounted ' transformers, abandoned above-ground storage tanks (ASTs), fuel powered irrigation pumps, and farm outbuildings associated with a maintenance facility. ' An electric transmission line with pole-mounted transformers runs east to west along the central, east-west canal (Figure 5) and north to south in central portions of the site. In addition, a pad-mounted transformer was observed in association with an irrigation pump in ' the southwestern corner of the mitigation area. No staining was noted on ground surfaces beneath the transformers. These power lines and transformers could be removed as part of wetland restoration activities. The potential for containment of polychlorinated biphenyls ' within these transformers will be evaluated as part of detailed restoration planning in this area. An abandoned AST was observed near the western terminus of the central, east-west canal. The AST does not appear to contain petroleum or other hazardous materials at the present time. No evidence of soil staining was noted in connection with this tank. The site manager indicated that the AST will be used as a culvert, as needed, under new or improved road/canal crossings. ' A fuel-powered irrigation pump was observed along central sections of the central, east-west canal. Limited stained soil and dead vegetation was observed at this location, indicating that potentially minor spills/leaks have occurred at the pump site. Remediation measures such as spreading, excavation, and contaminant studies may be required to facilitate wetland restoration activities in this area. ' Farm outbuildings associated with a maintenance facility are located along the northeastern site periphery (Figure 2). This approximately 15-ac tract includes a Vehicular Maintenance Area, a Pesticide Storage Building, a Dump Site, and a Greenhouse Area. In addition, an Air ' Strip Area is located approximately 2000 ft west of the maintenance facility. 22 r 0 Vehicular Maintenance Area Potential environmental concerns associated with this area include: 1) an above-ground storage tank (AST) containing approximately 3 inches (in) of petroleum product is laying on its side outside the building; 2) lubricants and other chemicals are improperly stored inside and outside the building; 3) stained concrete, soil, and/or dead vegetation was observed in association with the improperly stored lubricants and chemicals, and several discarded batteries were observed inside and outside the building; 4) a pile of an unknown chemical was observed inside the building; 5) an AST which contains a petroleum product is located inside the building and it appears to have leaked; and, 6) linoleum floor covering inside the building may include asbestos-containing material. Two water supply wells were also observed at this location. Pesticide Storaae Buildina ' Potential concerns observed in association with this building include improper storage of chemicals. However, access was unavailable to the locked building during preliminary site surveys. The site manager indicated by phone contact that only spare disc parts are stored ' in the pesticide storage shed. The manager is unaware of any improper storage or releases of regulated and/or hazardous waste associated with the storage building. ' Air Strip Area Potential concerns associated with this area include a vent pipe connected to a fuel dispenser, several ASTs, and areas of stained soils with a petroleum odor near the fuel dispenser. Based ' upon a telephone interview with the site manager, the ASTs were brought in and used as culverts, and the fuel dispenser located at the air strip was previously connected to an AST which functioned as a self-contained unit. Remediation measures such as spreading, oxidation, excavation, and additional contaminant studies may be required within the spill area to facilitate wetland restoration activities in this area. I C? Dump Site and Greenhouse Area Potential concerns associated with a dump site and greenhouse area within the maintenance facility include tires, plastic/vinyl sheeting, piping, pallets, and an abandoned AST. Additional studies will be required to evaluate the potential for improper storage or releases of regulated and/or hazardous waste in these dump areas. Cursory Regulatory Database Review A cursory regulatory review of standard databases was conducted as part of this project. Databases reviewed included the National Priorities List, Superfund List, Hazardous Waste Generators List, Leaking UST List, and UST registrations. The only listing associated with this site is a current UST registration for an 8,500 gallon diesel fuel UST. The site occupant stated that a Level I Environmental Assessment was conducted at this site in September 1993. Reportedly, all USTs had been removed by a previous owner, and, as no evidence of leaking was documented, the tank removals were therefore exempt from formal NCDEHNR closure procedures. 23 n 1 r Conceptually, these sites of potential environmental concern are not expected to affect the viability of Barra Farms for mitigation use, with the possible exception of the farm maintenance facility located along the northeastern site periphery. This site, encompassing approximately 15 ac, is depicted in Figure 4 as Commercial/Disturbed land and is identified on aerial photography in Figure 2. The farm maintenance facility would require detailed analyses as part of mitigation plan development for the area to evaluate removal of structures, clean-up, or disturbance-avoidance measures. All or part of the approximately 15-ac maintenance facility may reside on upland soils or compacted earthen fill material. 4.7 CULTURAL RESOURCES Archeological records were researched at the State Historic Preservation Office (SHPO) for the Barra Farms Mitigation Site and surrounding areas. Although several archeological studies have been conducted around the mitigation site, no significant information was discovered in the SHPO records. Installation/maintenance of electrical utilities lines by the South River Electrical Membership Cooperative required archeological reviews around the Barra Farms in 1993. In addition, development of hog farms one mile east of the mitigation site required historic surveys to be conducted and submitted to SHPO. These surveys did not reveal potential for significant archaeological sites in the immediate proximity of Barra Farms. ' 4.8 PROTECTED SPECIES Federal listed species with Endangered (E) or Threatened (T) status receive protection under the Endangered Species Act of 1973 (16 U.S.C. 1531 et seq.). The U.S. Fish and Wildlife ' Service (FWS) lists the following animal or plant species as federal-Threatened or Endangered within Cumberland County. 0 G Endangered or Threatened (E or T) Red-cockaded woodpecker (Picoides borealis) (E) Rough-leaved loosestrife (Lysimachia asperulaefolia) (E) Pondberry (Lindera melissifolia) (E) American chaffseed (Schwalbea americana) (E) American Alligator (Alligator mississippiensis) (TS/A [similarity of appearance]) Small-whorled pogonia (lsotria medeoloides) (T *) *: Historic record - the species was last observed in the county more than 50 years ago. The N.C. Natural Heritage Program (NCNHP) has no documented recordings of threatened or endangered species at the Barra Farms mitigation site as of 26 March 1997. However, red- cockaded woodpecker (RCW) and rough-leaved loosestrife populations occur approximately 2 miles south of the mitigation site, within the Bushy Lake State Natural Area. Habitat for these federal endangered species at Bushy Lake consists primarily of Carolina Bay sand rims and pine forest interiors which have been lost at Barra Farms due to farming activity. Wetland mitigation activities would potentially restore and expand habitat for RCW and rough-leaved loose-strife populations documented in the region. In addition, field surveys for rough-leaved loosestrife will be performed on relict sand rims at Barra Farms during detailed mitigation planning activities. 24 H r: 0 n 5.0 PRELIMINARY WETLAND FUNCTIONAL EVALUATIONS Mitigation activities at the Barra Farms / Harrison Creek site should be determined based on wetland functions generated by restoration and enhancement and comparison of restored functions to potentially impacted wetland resources. Therefore, a preliminary evaluation of mitigation wetlands at Barra Farms is provided to evaluate site utility for mitigation in the region. In addition, the evaluation will provide information on the appropriate mitigation area designated for initial restoration use at Barra Farms. 5.1 WETLAND FUNCTIONS UNDER EXISTING CONDITIONS PC Cropland Based upon preliminary analyses, the approximately 2247-ac, Barra Farms/Harrison Creek mitigation site consists of approximately 1058 ac of PC cropland or drained forest fringes on historic wetlands (Figure 7; nonriverine wetland restoration units). An additional 52 ac of cropland resides in upland/wetland ecotones (Figure 7; upland/wetland ecotone restoration). Under agricultural land uses, the entire area exhibits negligible wetland functions. Hydrodynamic functions have been effectively eliminated due to construction of drainage networks, soil levelling/compaction, and removal of forest vegetation. Features which depict performance of hydrodynamic wetland functions, such as surface microtopography, ephemeral ponding, intermittent stream channels, forest vegetation, and characteristic wetland soil properties have been eliminated by alternative land uses. Up to 18 ac of riverine wetland restoration may also be available in forested, south-central portions of the site (Figure 7; riverine restoration unit). Reduction or elimination of wetland hydrology and removal of forest vegetation throughout the site has also negated biogeochemical cycling and biological functions within the complex. PC croplands typically do not support natural communities adapted to wetlands or the wetland dependent wildlife characteristic in the region. Wetland restoration potential is available in these areas. Significantly Degraded Wetlands Wetlands which have sustained significant degradation or elimination to vegetation, hydrology, and/or soil components comprise approximately 734 ac within the mitigation site (Figure 7; nonriverine wetland enhancement units). Drainage impacts on wetland hydroperiod are evident based on plant community characteristics, field evaluations, and preliminary groundwater models. Soil leveling/compaction, organic matter subsidence, and removal of characteristic vegetation in these areas has significantly reduced or eliminated the capacity of these wetlands to perform characteristic functions within the watershed (as described above). Wetland restoration and/or enhancement potential is available in these areas. 25 0 i i ?e Mitigation site boundary \ Area (acres) ? NONRIVERINE WETLAND RESTORATION 1058 ? RIVERINE WETLAND RESTORATION/ENHANCEMENT 18 UPLAND/WETLAND ECOTONE RESTORATION 67 NONRIVERINE WETLAND PROTECTION AND MANAGEMENT 370 ? NONRIVERINE WETLAND ENHANCEMENT 734 TOTAL 2247 FUTURE PHASES S n?? ?JOO ??V SR2042 ?O ?O o ? o rn W a 5 a o o a O N 3 m II m a N ? y N U N O U (? (n W Q I d Z O? 1- O Q QZZ ZJJ W I- O W?U ?Y LLJ I -W Cl Q Z Z cf) 0 } ?cn FZE z ?QO Z\U ?cn 0 W:2 ?QQ Z L- W O Q m < QU ?m J W tl abi q i v M ? u, e 0 ' Moderately Degraded Wetlands The northwestern tract and southeastern fringe of the mitigation site contains relict wetland ' forests which have sustained impacts from area-wide drainage, systematic clear-cutting, and road construction (Figure 7; nonriverine wetland protection and management unit). However, this approximately 370-ac area may continue to serve as a biological reservoir for expansion ' into adjacent restored and enhanced wetlands at Barra Farms. In addition, protection from disturbance and long-term (fire, composition) management may enhance wetland functions ' within these forested sites. Wetland enhancement potential is considered available in these areas. ' 5.2 POTENTIAL WETLAND FUNCTIONS UNDER POST-RESTORATION CONDITIONS Wetland restoration activities will be designed to restore wetland features and functions associated with reference wetlands in the region.' Projected performance of wetland functions ' on the mitigation site is inferred from conditions expected after mitigation activities are completed. This assessment assumes that restoration plans are appropriately implemented (Section 6.0) and that the wetland is protected from man-induced disturbances in perpetuity. ' Assumptions are most likely achieved if a trust fund is established and the site is dispensed to a wetland conservation organization that will continue to monitor and manage the site after wetland restoration success is achieved. u u I i Site alterations would be designed to restore near-surface and above-surface hydrodynamics throughout a large majority of the site. Ephemeral and intermittent streams characteristic of reference wetlands would be expected to re-establish within south-central portions. Moderation of groundwater flow and discharge towards downstream areas would be redirected towards historic wetland conditions. The transformation of cropland adjacent to groundwater discharge zones into seasonally to semi-permanently saturated 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 ephemeral, intermittent, and permanent stream channels. Due to the ecological significance of this potential bottomland ecosystem in the mitigation landscape, the first phase of mitigation activities at Barra Farms should target farm lands surrounding this stream system (Figure 7: Phase 1 area). These farmlands historically served as recharge zones for the riverine wetland and potentially provide the greatest benefit to wetland functional resources in the region. Wetland functions typically associated with water quality will be potentially replaced within the Cape Fear River basin. Riverine wetland restoration may also be achievable within up to 18 ac of land area (Johnston soil map unit (USDA 1984). Detailed mitigation planning would address drainage redirection and stream reconstruction needs within upper reaches of Harrison Creek. Upland/wetland ecotones should also be restored within the wetland complex. Integration of wetland and upland interfaces represents an important component of wetland restoration 27 n u u plans. Restored wetland buffers would provide an ecological gradient from uplands to wetlands and would establish streamside management zones (SMZs). Without upland restoration/enhancement and wetland buffer establishment, intrinsic functions in adjacent, restored wetlands may be diminished or lost in the future. In addition, a number of biological and physical wetland parameters are also enhanced by the presence of wetland/upland ecotones on the mitigation site (ESI 1994a, Brinson et al. 1981). Biotic functions potentially restored in the complex include re-introduction 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 riparian and non-riparian wetland interactions are considered degraded throughout a majority of the project region as agricultural lands dominate intermediate landscape positions (between interstream and riverine wetland habitat). Habitat value and community maintenance functions will also be improved by creation and interconnection of five plant community types along the restored environmental gradient. Cover will be expanded and species diversity may be promoted in proximity to the Bushy Lake State Natural Area and NCNHP Priority Areas. 5.3 IMPLEMENTATION SCHEDULE ' Mitigation activities at Barra Farms will be implemented during several project phases (Figure 7). Phases consist of detailed mitigation plan development, expedited implementation, and initiation of the monitoring plan in advance of permitted wetland impacts. Based on conceptual mitigation design, each phase is expected to generate restoration and enhancement mitigation credit based on modifications to wetland hydrology, soil, and vegetation parameters. n 1 r Phase 1 mitigation activities have been specifically designed to replace nonriverine and possibly riverine wetland functions and acreages potentially lost by roadway development projects in the region. Phase 1 will entail detailed mitigation planning and implementation of restoration activities within approximately 623 ac depicted in Figure 7. Phase 1 mitigation activities, including stream reconstruction and restoration of ephemeral drainageways, will be concentrated within the groundwater discharge areas surrounding the origin of Harrison Creek. Future mitigation phases will encompass approximately 1624 ac of land within northwestern, north-central, and eastern portions of the site (Figure 7). Detailed mitigation planning and up- front restoration will be completed and mitigation credit allotted in future phases as potential wetland impacts are quantified in the region. 28 0 C I I L L? 6.0 PHASE 1 CONCEPTUAL WETLAND RESTORATION PLAN The proposed Phase 1 wetland restoration area encompasses approximately 623 ac encompassing the historic origin of Harrison Creek (Figure 7). This conceptual restoration plan for the Phase 1 area has been developed according to specifications outlined in the COE/EPA mitigation banking guidelines (60 FR 12286-12293, 1995) and N.C. Division of Water Quality's wetland mitigation policy (Administrative Code for 401 Water Quality Certification; Section: 15A NCAC 2H.0500). Specifically, this mitigation proposal will provide for the replacement of wetland acres lost due to a proposed activity at a minimum of a 1:1 ratio up to a maximum 2:1 ratio, through restoration, prior to utilizing enhancement or preservation to satisfy the mitigation requirements. In addition, mitigation shall replace impacts to nonriverine wetland types occurring within the same river basin (Cape Fear) and physiographic province (Coastal Plain) when practical (DWQ 1996). 6.1 WETLAND HYDROLOGY RESTORATION Site alterations to restore groundwater, surface flow dynamics, and wetland hydrology include: 1) placement of impermeable plugs at systematic intervals along drainage structures; 2) backfilling of ditches and canals; 3) construction of ephemeral pools along open ditch segments; 4) diversion of surface inlets onto wetland surfaces; 5) wetland surface modifications; and 6) stream reconstruction (Figure 8). Ditch Plugs Impermeable plugs will be installed along drainage ditches and canals on-site. The plugs will consist of low permeability materials, impermeable liners, or hardened structures designed to be of sufficient strength to withstand the erosive energy of surface flow events across the site. Each plug should consist of a core of impervious material and be sufficiently wide and deep to form an imbedded overlap in the existing banks and ditch bed. Ditches will receive impervious plugs at bends, junctions, and intervals determined by total slope over the ditch lengths. The plugs will serve to prevent the former ditches and canals from acting as french drains. Continued drainage in back-filled ditches would be expected to effectively short-circuit or delay hydrology restoration success in the absence of imbedded, impervious plugs. Ditch Back-fill ' After impermeable plugs are installed, ditches will be back-filled with available on-site earthen material from spoil piles, dirt road fill, and spoil ridges adjacent to canals. Where vegetation has colonized the spoil ridges, trees and rooting debris will be removed, to the maximum ' extent feasible, before re-insertion of earthen fill into the canal. The ditches/canals will be filled, compacted, and graded to the approximate elevation of the adjacent wetland surface. ' Ephemeral Pool Construction A deficit of fill material for ditch back-fill purposes is expected on the site. Therefore, a series ' of ephemeral pools (closed depressions) may be constructed along certain confined ditch segments. Open ditch segments may also serve as stormwater catchment areas for surface 29 i i 3 0 J a a D i a m 0 0 rn a w \ \ PHASE 1 BOUNDARY ,mom am 'm r> Phase 1 boundary Mitigation site boundary AREA (acres) STREAM RECONSTRUCTION 18 ? UPLAND REFORESTATION 29 ? PRESCRIBED FIRE MANAGEMENT AND 237 SUPPLEMENTAL WETLAND PLANTINGS SOIL SURFACE SCARIFICATION 325 AND WETLAND REFORESTATION DITCHES AND CANALS PROJECTED 14 TO REMAIN AFTER RESTORATION TOTAL 623 -- PLUGGING AND BACKFILLING OF DITCHES AND CANALS RESTORATION OF INTERMITTENT STREAM CHANNELS i, F ii i o r, 0 07 m W w 'C a rn 0 o li d o a J O C7 00 3 ? II m c u a o L u O U n Z Q J Z O Q? ?C) Q Z ?JZ w LLJ _?U O l)wl ova' ZUO Q Z Z w O y. cf) (-,c? =0rrz ?OfQo p=U ?Z oa Q J QLL'w J m ? wCh 3 of J Qm a_ w U Z O U U v? d o, d # WV) L I r fl flow inlets onto the mitigation site. Initially, earthen fill material for ditch back-fill use will be excavated from planned open ditch segments. These shallow excavation areas will be graded into the former ditch to create closed elliptical or oval depressions. In essence, the ditch will be converted to a sequence of shallow ephemeral pools adjacent to effectively plugged and back-filled ditch sections. These pools will be planted with characteristic tree species in an effort to establish cypress-gum ponds in the landscape. Stormwater Catchment Basins Discharge from surface flow inlets along the northern site periphery will be accommodated within the wetland restoration area, as needed, through drainage routing into the stream origin or through constructed ephemeral pools on the site. If ephemeral pools are utilized, ditches along surface flow inlets will be plugged below the in-fall at distances dependent upon channel invert elevations and ground slope. Below the plug location, the constructed cypress-gum pond (as described above) will be contoured to a maximum depth of 3 ft and graded to store a 10-year storm event. Topsoil will be stockpiled and replaced onto the wetland surface after pool construction. Subsequently, the depression will be planted with wetland species specifically adapted to vernal ponding. Stormwater drainage and runoff within these ephemeral cypress-gum ponds will be discharged as radial to lateral groundwater infiltration across the mitigation site. Restoration of water quality functions associated with this mitigation project will be significantly enhanced by incorporating flows from the upper watershed before entry into Harrison Creek and the Cape Fear River. Wetland Surface Scarification Before wetland community restoration is implemented, agricultural fields and graded back-fill material should be scarified (disked or harrowed) in a randomized cross-hatch pattern. After scarification, the soil surface should exhibit complex microtopography ranging to 2 ft in vertical asymmetry across local reaches of the landscape. Restored microtopographic relief is considered critical to hydrology restoration efforts. Therefore, a harrow plow or deep disking plow is recommended, including multiple passes, to ensure adequate surface roughing and surface water storage potential across the site. Subsequently, community restoration will be initiated on scarified wetland surfaces. Stream Reconstruction Stream reconstruction may be considered within south-central portions of the mitigation site. The reconstructed stream will be designed to restore riverine wetland function and to accommodate re-directed groundwater flow into the riverine system. Stream reconstruction would entail removal of accumulated organic debris from blocked channel segments, removal of fill material from the relict channel (deposited during logging activities and ditch construction), and construction of several ephemeral channels which induce flow from restored wetlands into upper reaches of the stream and floodplain. Detailed stream reconstruction 31 I I I I design within the Johnston soil map unit will be considered as part of the detailed mitigation plan. 6.2 WETLAND 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, on-site observations, and ecosystem classification will be used to develop the species associations promoted during community restoration activities. Preliminary community associations include: 1) nonriverine swamp forest: Atlantic white cedar dominated; 2) nonriverine swamp forest: hardwood dominated; 3) riverine swamp forest; 4) nonriverine wet hardwood forest; and 5) upland longleaf pine-scrub oak forest. Figure 9 provides a conceptual depiction of potential forest communities to be restored across wetland mitigation landscape. The subdivision of swamp forest restoration areas into two planting regimes (Atlantic white cedar dominated and hardwood dominated) may be implemented primarily to provide additional habitat diversity in the wetland. Stems of Atlantic white cedar would be targeted to landscape areas which contain soils of relatively high organic content and exhibit the potential for relatively long term soil saturation (Schafale and Weakley 1990; pers. comm. Brownlie, USFWS Dismal Swamp National Refuge Office). Mineral soil and shallow organic soil areas of the swamp forest complex may also include intermittent stems of Atlantic white cedar, if planting sources are available. However, species such as bald cypress, laurel oak, swamp tupelo, willow oak, and yellow poplar may exhibit higher affinity for these areas. The restoration of upland forest communities within the wetland complex has also been proposed. Upland forest restoration plans would be 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. For upland restoration areas, the forest restoration can be modified to allow for maintenance of food plots or other wildlife management features. Upland restoration efforts would be coordinated with the N.C. Wildlife Resources Commission, the U.S. Fish and Wildlife Service, or other management contingencies. Opportunistic species, which typically dominate disturbed swamp forests, will be excluded from initial community restoration efforts. Opportunistic species include loblolly pine, sweet gum, and red maple. 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. 32 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 COMMUNITY ASSEMBLAGE SELECT VEGETATION LAND FORM SOILS RIVERINE BOTTOMLAND NONRIVERINE HARDWOOD/ ATLANTIC WHITE SWAMP FOREST CEDAR FOREST i Environmental Services, Inc. Bald Cypress Water Tupelo Overcup Oak Yellow Poplar Laurel Oak American Elm American Sycamore Drainage Swales (Concave) Johnston Very Poorly Drained Atlantic White Cedar Pond Pine Bald Cypress Water Tupelo Sweet Bay Red Bay NONRIVERINE NONRIVERINE WET HARDWOOD SWAMP FOREST FOREST Bald Cypress Swamp Chestnut Oak Water Tupelo Laurel Oak Swamp Tupelo Willow Oak Cherrybark Oak Water Oak Overcup Oak Swamp Tupelo Laurel Oak Yellow Poplar Willow Oak Cherrybark Oak Green Ash LONGLEAF PINE/ SAND RIM FOREST Longleaf Pine Bluejack Oak Dwarf Post Oak White Oak Blackjack Oak Southern Red Oak Black Gum Low Flats Low Flats Broad Ridges Intermediate Flats and Depressions and Depressions (Convex) Torhunta Rains Croatan Croatan Very Poorly Drained Poorly to Very Poorly Drained Poorly Drained Conceptual Model of Target Landscape Ecosystems Barra Farms/Harrison Creek Wetlands Cumberland County, North Carolina Centenary Autryville Leon Well Drained to Excessively Drained Figure: 9 Project: ER97010 Date: April 1997 ' 6.2.1 Planting Plan A planting plan is proposed for the Phase 1 mitigation areas to reestablish wetland community ' patterns across the landscape. The plan will 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) will be utilized in developing this plan. ' Bare-root seedlings of tree species will be planted within specified map areas at a density of 435 stems per ac (10-ft centers). 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. ' 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, will be considered. The t 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 will be considered to encourage higher survival rates and more rapid growth. ' 6.3 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. 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 in Phase 1 may include removal of spoil ridges and roadway fill and reestablishment of surface microtopography. During wetland hydrology restoration efforts, fill for ditches will be obtained, wherever ' feasible, from elevated roadbeds and spoil ridges adjacent to canals. Any spoil which remains after wetland hydrology restoration is complete will be removed from the mitigation site. Spoil areas will be graded to the elevation of the historic surface and landscaped to produce a ' smooth transition across the former spoil ridge and adjacent canal. ' Reference wetlands in the region 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. As discussed in the hydrology restoration section, efforts to advance the development of characteristic surface roughness will be implemented on the mitigation site. Disking and harrowing 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 34 11 1 1 amphibians. Scarification of surface soils between planted trees will further promote surface microtopography on the mitigation site. Woody debris generated during site preparation will ' be distributed across the wetland mitigation surface before planting. I r n 0 0 35 0 C 7.0 MONITORING PLAN The Monitoring Plan for the Barra Farms / Harrison Creek mitigation site will consist of a direct comparison between relatively undisturbed (reference wetlands) in the northwestern site periphery and wetland restoration/enhancement areas within the mitigation site interior. The wetland restoration and enhancement success criteria will be based upon a comparative analysis between designated reference wetlands and the wetland mitigation site. Monitoring of wetland restoration and enhancement efforts will be performed until success criteria are fulfilled. ' 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. ' Initially, surficial monitoring wells will be placed within reference wetlands along the northwestern site periphery. These reference wells will be embedded within vegetation sampling plots to provide representative coverage within each wetland ecosystem type to be restored. Ecosystem types are depicted as community restoration map units (Figure 9) which support similar soils, landform, and target community structure. Subsequently, monitoring ' wells will be placed within wetland mitigation areas at a density providing adequate coverage for comparison to reference. ' Hydrological sampling will be performed throughout the growing season (21 March to 19 November) at intervals necessary to satisfy the hydrology success criteria within each community restoration area (EPA 1990). n r 1 7.2 HYDROLOGY SUCCESS CRITERIA Target hydrological characteristics include saturation or inundation for at least 12.5 percent of the growing season during average climatic conditions. Additional hydrology success components include hydroperiods redirected towards, and approaching those of reference wetland ecosystems. Specific target hydroperiods relative to reference will be established during development of the detailed mitigation plan. 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). 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. 36 0 u I I u H 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, plots will be placed within each restored ecosystem type. Sample plot distributions will be correlated with hydrological monitoring locations to provide point-related data on hydrological and vegetation parameters. In each 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 a species composition sufficient 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/ac must be surviving for at least 3 years after initial planting. Characteristic tree species are those within the reference ecosystems, elements enumerated in the 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 percent 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 percent of the 320 stem/acre total, with the exception of Atlantic white cedar. Atlantic white cedar may comprise up to 100 percent of the 320 stem/ac total in swamp forest restoration areas. Supplemental plantings will be performed as needed to achieve the vegetation success criteria. 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/composition 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. 37 ' 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 in reference and mitigation wetlands. 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 and reference ecosystem (Figure 9). ' 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. u 38 0 8.0 DISPENSATION OF PROPERTY ECOBANK will remain responsible for the mitigation site. The site will be bonded and a trust fund established for future management and monitoring. After success criteria are fulfilled, ECOBANK will continue to manage the mitigation area in perpetuity, or entrust the properties to an appropriate management entity. The N.C. Wildlife Resources Commission (WRC), The Nature Conservancy, the North Carolina Park and Recreation Service (Jones Lake State Park Office), and other conservation groups will be contacted concerning potential management capabilities or land transfer into State or private conservation programs. Perpetual management programs supported by trust funds appropriated to the mitigation site may include (but not limited to) the following activities: 1) Wildlife harvesting activities in mitigation areas will be allowed to continue under local tradition, dependent upon site constraints, and based on recommendations from the WRC. 2) A long-term fire management program will be implemented, as necessary, to facilitate steady state community development, promote hunting opportunities, and promote endangered species habitat. Local residents should become involved in long term management. Several residents have indicated an interest in following the development of protected wetlands at the site and serving to act as land stewards. Stewardship opportunities with nearby landowners and adjacent designated gamelands will be pursued, in consultation with WRC, during detailed mitigation planning for Phase 1 of this project. 4) Garbage dumping, forest clearing, or other disturbances in mitigation areas will be regulated, monitored, and alleviated. Road access to the mitigation area, if maintained after restoration for management use, should be appropriately gated to prevent dumping activity. 5) Protective covenants on the mitigation land will specify that the land be allowed to succeed to specified tree densities, composition, and sizes before timber harvest is considered. After the successional phase, covenants will stipulate that there is to be no forest clear-cutting and no selective timbering that lowers per-acre stem counts below a target density of 6 mast producing or Atlantic white cedar (AWC) trees per ac greater than 20 in. in diameter (within each acre of mitigation area). Managing for the presence of large hardwood trees or AWC this size is required to provide potential habitat for species typical of mature growth wetland forests. In addition, densities of mast producing trees or AWC greater than 10 inches in diameter will be maintained at or greater than 30 ftz of basal area per ac (for each ac of land) to provide adequate foraging potential for mast-consuming wildlife (Yoakum et a/. 1980). 6) Dead and dying trees, snags, and logs will be left on-site to provide foraging habitat as well as to provide cavity formation potential for species such as wood duck, pileated woodpecker, and barred owl (Yoakum et a/. 1980). 39 9.0 PRELIMINARY MITIGATION CREDIT POTENTIAL Based on conceptual plans (Figure 7 and Figure 8), Phase 1 at Barra Farms will encompass approximately 623 ac of land. Restoration may be achieved within up to 325 ac of nonriverine wetlands, 18 ac of riverine wetlands, and 29 ac of upland buffers. In addition, up to 237 ac of nonriverine wetlands may be enhanced within the area. Table 3 depicts preliminary mitigation credit potential exhibited by the mitigation proposal. Preliminary credit potential is estimated based upon Environmental Protection Agency (EPA) guidelines (Page and Wilcher 1990). In summary, a minimum of 232-ac replacement credits are expected to become available for compensatory mitigation use after Phase 1 restoration. ' Actual mitigation credit generated by restoration activities should be determined based on the achievement of Success Criteria, completed provisions for site protection in perpetuity, and ' the type and condition of wetlands impacted by a particular project. Restoration and enhancement strategies are designed to create primarily steady-state nonriverine wetland ecosystems which support an array of native plant and wildlife communities. Restored steady- state wetland ecosystems would be expected to generate higher mitigation credit when compared to the degraded condition of potentially impacted wetlands typical of the project region. Therefore, above-estimated credit for this mitigation plan should be considered a base- line for determining appropriate credit on a project-by-project basis. P u 40 C O ° V N U ? c O y O ? Y L U M J C N O co Q !d .i a o O ' ? N d E N LL h y y Q m ' E a` u °a (D ++ c G) r O V OA Ch co N M Y i to N CL ? V m La .. O O ++ C d '++ G1 U ? U 7 ? N a CO N N ? ? ? N d 0 . a ' CD UJ 4 :?+ t0 ? a M N i 00 LO OA r? Q - N co N co N r- N CO c O +-+ ?- c6 C C c N E C c O_ O cn E N O F , ' O O OC U c Q. c . . m +? cn a) m r- cn 'y y O + O 0= C O C LU O .`f J N "0 O "O m H c W 0 c 0 m O C1 f6 cco c6 C N c0 C 0 > c N c c0 c + z S z N m c0 'O O O N } CO 'O 7 N C + C L N +1 CD 4- O X E E j E C c 0 a N .` U- f0 c O 0 0 U c 0 p N ? cn L p O +, N m o a? c CU CD m L y N fA >' a) c 4? N U 0 +1 E +0 -0 N y ui C C > p c c C` -0 E L 0 a) 0 u C } 0 fD C O N . ?p U . f0 c ? U . ` 4- y c E U +O CL> C 0 N •0 3 ' 000 ++ ca ?n Q E L N Q cn c p c p C ca cm cm N to . CL U c +1 (D E CEO w rn 0 +1- ?. fn c c 0 ? O O c C CO (D N O O• >• "fl a)p c O U 7 L ` C - 'a p *' c a) v- N 0 O O y O =p T c > . O L N +, f0 N L O +? 0) c c , CD r- > x 0 m N C C a) 0 O E O a..' CO y N N O U Q i O ° 0 O a 3 0) c c- c 0 w >, L +J ? v C cn O t0 U 0 (D > E co E a) N U, Cc x 3? m 0 0)-++ y N 0 0 L L N c + C O U p p W U 'p a• N O 0 N c6 O C C (p v- c6 d 0 0 O 0 O c to L 0 'a F- c y O N N C E W C 0 f IV 3 p U > '0 E • rn o a U E cn U y }., E .. C O cn ?M y a) c)U N 0) C 0 0)>0 wa? cn - M?-0 m N N N C y co U N L > C f0 . O C c f0 O ? C N N O cc o (0 E . N U D N 0 y C ++ O c N c a) p V) O N "O L +- E U O j-0 co O L 0 c0 t0 N O N >• m Q m~ •? Co ` N N EM j 7 m O p cm p N ++ .c ?- U c0 m O O 'C . C 'S i U O Q) Y E m C c O O (D c (0 •c C c o 0r oa Q 0 0 0 ;7, m w fn -0 c m c 0 0) a) 3 O O E 0 c: c: 0 f6 N ++ (6 E O c y d CU cn D N O CC U E cn O a. 3 .? -0 > > O E N lh d t 10.0 CONCEPTUAL REGIONAL MITIGATION PLAN SUMMARY Restoration activities have been subdivided into proposed implementation phases with mitigation credit generated by each phase. Phase 1 of this mitigation proposal, encompassing the origin of Harrison Creek and farmed, headwater storage areas surrounding the floodplain, ' is expected to generate over 200 acre credits for wetland replacement in the region (Table 3). Restoration activities will be completed and mitigation credits will be generated in advance of wetland impacts. Phase 1 mitigation planning is intended to provide up-front compensation for potential highway related impacts to wetlands in proximity to the mitigation site. This document is intended to facilitate an indication from resource agencies as to the potential use of Phase 1 mitigation at Barra Farms for potential highway related impacts, such as NC 24 and NC 87 roadway improvements. If acceptable, detailed mitigation planning and implementation of Phase 1 will occur at a efficient pace to ensure up-front riverine and nonriverine wetland t restoration success. Subsequent mitigation phases at Barra Farms will be implemented as potential nonriverine ' wetland impacts are quantified in the region. If acceptable, wetland restoration activities will be completed and mitigation credit generated in advance of wetland functional losses in the Cape Fear River basin. Because up-front mitigation is a focal point of this project, no net loss ' of the wetland base can be realized within this region by restoration of the Barra Farms/ Harrison Creek wetland complex. fl 42 11.0 REFERENCES ' 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 I: Literature Review and Evaluation ' Rationale. Wetlands Research Program Technical Report WRP-DE-2. US 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 Operational Draft Technical Report Y-87- US Army Engineer Waterways Experiment Station, Vicksburg, MS. ' 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. US Department of Transportation, Washington, DC. Brinson M.M., F.R. Hauer, L.C. Lee, W.L. Nutter, R.D. Smith, D. Whigham. 1995. Guidebook for Application of Hydrogeomorphic Assessments to Riverine Wetlands. U.S. Army Corps of Engineers Waterways Experiment Station. Vicksburg, MS. Brinson, M.M. 1993. Changes in the functioning of wetlands along environmental gradients. Wetlands 13(2): 65-74, Special Issue, June 1993. The Society of Wetland Scientists. ' Brinson M.M. 1993. A Hydrogeomorphic Classification for Wetlands. Wetlands Research Program Technical Report WRP-DE-4. U.S. Army Corps of Engineers Waterways ' Experiment Station. Vicksburg, MS. 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 Department of the Army (DOA). 1993 (unpublished). Corps of Engineers Wilmington District. Compensatory Hardwood Mitigation Guidelines (12/8/93). Division of Environmental Management (DEM). 1993. Classifications and Water Quality Standards Assigned to the Waters of the Cape Fear River Basin, N.C. Department of Environment, Health, and Natural Resources, Raleigh, N.C. II Division of Water Quality (DWQ). 1996. Water Quality Certification Administrative Code Section: 15A NCAC 2H.0500 as amended October 1, 1996. State of North Carolina Department of Environment, Health, and Natural Resources. 43 Environmental Protection Agency (EPA). 1990. Mitigation Site Classification (MiST) A Methodology to Classify Pre-Project Mitigation Sites and Develop Performance Standards for Construction and Restoration of Forested Wetlands. USEPA Workshop, August 13-15, 1989. USEPA Region IV and Hardwood Research Cooperative, North Carolina State University, Raleigh, NC. 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. Raleigh, N.C. Environmental Services, Inc. (ESI). 1994b; unpublished. Mitigation Plan: Northeast Florida ' Wetland Mitigation Bank. Technical Report for St. Johns River Water Management District, Palatka Fla. ' Environmental Services, Inc. (ESI). 1997; unpublished. Detailed Mitigation Plan: North Carolina Global TransPark. Provided to the N.C. Global TransPark Authority. Raleigh, N. C. ' 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. ' Reinhart, R.D., M.M Brinson, P.M Farley, J.J Russell. 1996 (unpublished). Development of an Initial Reference Data Set for Functional Assessment of Forested Wetland Flats in North Carolina. Biology Department: East Carolina University, Greenville, NC. ' Schafale, M. P., A.S. Weakley. 1990. Classification of the Natural Communities of North Carolina: Third Approximation, NC Natural Heritage Program, Division of Parks and Recreation, NC DEM, Raleigh NC. Skaggs, R.W., et al., 1993. Methods for Evaluating Wetland Hydrology. ASAE meeting presentation Paper No. 921590. 21 p. Smith, R.D., A. Ammann, C. Bartoldus, M.M. Brinson. 1995 (unpublished). An Approach for ' Assessing Wetland Functions Using Hydrogeomorphic Classification, Reference Wetlands, and Functional Indices. Wetlands Research Program Technical Report WRP DE-_. US Army Engineer Waterways Experiment Station, Vicksburg, MS Strahler, A.N. 1964. Geology. Part II. Quantitative geomorphology of drainage basins and channel networks. (in) Handbook of Applied Hydrology. (ed. V.T. Chow), pp. 4-39 to 4-76, McGraw Hill, New York. 44 u f 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 Agriculture (USDA). 1990. Soil Survey of Bladen County, North Carolina. Natural Resource Conservation Service. U.S. Department of Agriculture (USDA). 1984. Soil Survey of Cumberland and Hoke Counties, North Carolina. Natural Resource Conservation Service. U.S. Department of Agriculture (USDA). 1985. Soil Survey of Sampson County, North Carolina. Natural Resource Conservation Service. U.S. Department of Agriculture (USDA). 1954. Soil Survey of Duplin County, North Carolina. Natural Resource Conservation Service. U.S. Fish and Wildlife Service (USFWS). 1985. Habitat Suitability Index Models: Wild Turkey. FWS/OBS-82/10.106, August 1985. U.S. Fish and Wildlife Service (USFWS). 1981. Habitat Evaluation Procedures Workbook. National Ecology Research Center. U.S. Geological Survey. 1974. Hydrologic Cataloging Unit Map for the State of North Carolina. Workshop. 1995. (unpublished). Workshop on Depressional Wetlands on Floodplain Alluvium in the Puget Sound Area Near Seattle Washington: A Hydrogeomorphic Approach to Assess Functions Inherant to Depressional Wetlands. July 1995. Yoakum, J., W.P. Dasmann, H.R. Sanderson, C.M. Nixon, and H.S. Crawford. 1980. Habitat Improvement Techniques. Pp 329-403 in S.D. Schemnitz (Editor). Wildlife Management Techniques Manual, 4th ed., rev. The Wildlife Society, Washington, DC 686 pp. 45 n C C n 0 0 0 Appendix A r JAI 14 '97 12: 46PM ECOBAK e+ STATE Of NORTH CAROLINA DEPARTMENT OF TRANSPORTATION JAMES B. HUNT JR. GOVEMOR Mr. Alan G. Fickett, Ph.D. ECOBANK 1555 Howell Branch Road Winter Park, Florida 32789 Dear Mr. Fickett: DIVISION OF HIGHWAYS P.O. BOX 2520;. RALEIGH. N.C. 27611.5201 December 30, 1996 P.4 GARLAND B. GAMUTT JR. SECRETARY Thank you for your letter dated December 18, 1996, summarizing the meeting on mitigation issues in general, and the Barra Farm property in Cumberland County. The future highway improvement projects in the coastal region of the Cape Fear River Basin that could possibly be mitigated from agency approved mitigation bank the Barra Farms property include: • X-2 (NC 24 between existing NC 24 and I-95 in Cumberland County) • R-2561 and R-2562 (NC 87 in Cumberland, Bladen and Columbus Counties) R-2303 (INC 24 in Cumberland, Sampson and Duplin Counties) Although the precise wetland impacts of these three projects have not been determined in both magnitude and habitat type, at this time, combined wetland impacts are currently estimated to exceed 500 acres. Construction let dates for sections of these projects vary from May 1998 through October 2003. Based upon current guidance from the permit review agencies, on-site mitigation opportunities will have to be explored before we wculd be allowed to consider offering credits purchased from an off-site mitigation bank, such as Barra Farms. Based upon past ' experience, however, the amount of on-site mitigation is unlikely to provide a significant portion of the total mitigation needs, so the need for about 500 mitigation credits from the Barra Farms property over a five-year period is not an unreasonable projection. PHONE (919) 733-738 4 FAX (919)733.9428 +w JAN 14 '97 12:47PM ECOBAW P.5 Mr. Alan G. Fickett, Ph.D. December 30, 1996 Page 2 Of course, all this is contingent upon the Barra Farms being approved as a mitigation bank by the permit review agencies and the bank service area being defined to include all of the wetland impact areas of these projects. Until that happens, we must continue to explore other mitigation opportunities, both on- and off-site, for these and other projects in the same river basin. Sincerely, V t l?-• Larry R. ode, Ph.D., P.E, State Highway Administrator LRG/hfv cc: Garland B. Garrett, Secretary, Department of Transportation Calvin W, Leggett, P.E., Director of Planning and Programming H. Franklin Vick, P.E., Manager of Planning and Environmental \, ^' b R _ /'', b ? ? q 1& !: ? ELON R ? ' \ J e??1 "1 ••__ N G E f ? f _... ea+ ,? '+ •, - \ ctr'm laRxr.Jt\. J " •lf°? +? rt RdDDaDA _ 1 ?l 'Y4WlaM+ R ? \ I S ... ?? ?.1 _ ? C) ,tZ,^ ? ui s4'p?` MJlportx! t 4MEA >? `wsa - It ?Z :' i .8 % __ eus i 1 w? ° _ 1 0\ ?' : o r ! _ 4AN Rdi a _._ . o • . ,. ? ? Du Q"ft roues ? - - ` A'? O rf •reENxr,. ;? ?".• G N'^Dm ?'_ _ s'+< '? I S ti 90' ? •tib ! . _^? . Aa'•rR 'raw s ?p ? : a t • \ .. _ f l d e ? -x? £i? d',•. t Po •. 24 {oowwna 40 ?;, F 3h \ $ \? ° qo xNx avove w g __:0qq No CNURCN Rex =` F 6 ?4 1 Irv•WL 4 C LrR A IIff ° _ ' • ' ?+ ' 4 ? uo N? a ?o ?,'8 ° ? Mf ? ? fJ $u6ele.w _! q° '_.`` ,t !4 ` ? .,\.?r- ?('? Q . Cp P h• '?? ? o yR \ „ .. •.'g Jai J > p0 \ ?' ? `? ^, 5 ??1 ?4?? T Y , •• - _.l'I? a1pD o 9 , 'OP ? diWA /7 ? \ iNUn- (($T' `,b?Pa ??1 1 •, t q MRCS ?• ,?\ 1 \24+' Alr ?; ?' ,` ?4' ° 1 j NC 24 ? 1 l ? ?I?.`. V ADC U ? ! tryvl9 W .. 1 \- _?-\ - 1 1 a,. p?V p°pyW 210 % it; r ^• r"eQr ^/k 1 ` \ eqy .r; `J V'pvr.P 8 io gr dtlr'?ogA '"A ,/?4k , 53 +? 1 +R aru RD % EPA m? _ P -No NC 87 Da 0 ? RO l°°acE ?? .. r ?P _,•, ,ix?.sot' p A _J\ , `? w -\? to °4 .? I s I eE??"•-•o -?`? 210 ,p?,y' o ,? °. 1 R? •?uj 1, C•?'... ??. +vrrso e o° at Q La ,? fq qp / i se .?a1p b i ! • - . . f ( o ,'',..S i,' i -- ,. \ '?? .±- ; 5„rYIR. ee1n •. .p _ '- - a. / #Rl ,.LE ft. - u? I /? 3 \ \ ? Iuslrrt((xxc 41 ATE,NATUNM. Aq i` • - 1 AF 1 ! f `??_ sw LL Al ' ? owEU? 7+Aingamr+- - rPAA ,•, ` '``?*.:? .? •t ` i 1. .El4see -6 .9p i/ w :es 1 r? ^_ _ _ 0 4gfq k a t z- . ' >b wH - .... _ Jaomn+ - r _ - Study Area -ap - LA DA r 0 1 2 3 Miles 0 1 2 3 4 Kilometers Reproduced with permission from the North Caroline - 1 ' •c F ?'(Y?, .? - - _ Atlas and Gazetteer, Delnrma Mapping, 1993 f ? /'.?._. `\X ?`.-. __ l Ra ,?? 1-. ? ? \t. ?\ \±..t SON.. r ??, _ ,-.•.^',i 1.+?.u Site Location Figure: 1 Environmental Barra Farms/Harrison Creek Wetlands Services, Inc. Cumberland County, North Carolina Project: ER97010 Date: April 1997