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HomeMy WebLinkAbout20071107 Ver 1_Monitoring Plan_20071101--=- M U 1_ K E Y ~: N is I N E E F' ~ ~ C f~ N S Ll E_-F'A tv T S 701 Gervais St. Suite 120 Columbia, SC Phone: 803-376-8440 Fax: 803-933-9811 www.mulkeyinc.com LETTER OF TRANSMITTAL To: John Dorne Date: October 31, 2007 NCDWQ 2321 Crabtree Boulevard; Suite 250 Ralei h, NC 27604 From: Quinton E s Mulke En ineers & Consultants Re: Wetland Monitoring Plan Down Gradient of Level Spreaders, Hawes Tract Development, Pamlico Cnty, North Carolina Job No.: I am sending you the following item(s): COPIES DATE NO. DESCRIPTION 2 31 Oct. 07 Wetland Monitoring Plan Down Gradient of Level Spreaders, Hawes Tract Development, Pamlico Cnty, North Carolina These are transmitted as checked below: ^ As re uested ^ For our use ® Fora royal ^ For Si natures ® For review and comment ~~uU 1 2007 ~~ ~~~~~~ - warW~ cau.~~ir~~ W~TIA!'3R3 ?,~D STORiJPtv~,TER ~RA(~CN WETLAND MONITORING PLAN DOWN GRADIENT OF LEVEL SPREADERS HAWES TRACT DEVELOPMENT PAMLICO COUNTY, NORTH CAROLINA October 30, 2007 Prepared for: RR Development North II, LLC 110 Matthews St. Street Suite 2D, Matthews, NC 28387 Prepared By: Mulkey Engineers and Consultants, Inc.. 701 Gervais Street Suite 120 Columbia, SC 29201 Introduction RR Development North II, LLC (RR Development) has submitted a development plan for the Hawes Tract (see vicinity map). As a part of the stormwater plan, the North Carolina Division of Water Quality (NCDWQ) has requested a monitoring plan for wetlands down gradient of the 4 outfalls from the main stormwater facility. See attached maps for stormwater facility and outfall locations. Site Description The proposed Hawes Tract Development is a 560.69 acre parcel is located off of NC Highway 55 (NC 55) in Pamlico County, North Carolina approximately 1.6 miles southeast of the intersection of NC 304 and NC 55. The parcel is located within the Neuse River Basin and the nearest receiving streams are Bay River, Trent Creek, Alligator Creek and Swindell Bay. There are approximately 163 acres of wetlands and coastal marsh on the parcel. The wetlands and coastal marsh on the site will not be developed and will be left in their natural state. Project Description This project consists of subdividing the parcel into 891 single family residential lots. Stormwater from the high density portion of the project drains to the inland excavated basin that will serve as a wet detention infiltration basin. This basin has been designed to treat and attenuate stormwater runoff from approximately 127 acres of the site. Level spreaders will be located at 4 outfall locations around the basin and will discharge into the riparian buffer and adjacent wetlands. Monitoring will be done quarterly for a period of five years in the wetlands down gradient to the four level spreaders. The monitoring effort will collect data on baseline and post construction conditions as well as selected reference areas. Baseline data will be compared with post construction data, as well as reference sites to document potential changes in the wetlands below the level spreader outfalls. Monitoring Methods Ve eta Pre-construction baseline vegetation monitoring will be conducted for one year. Baseline samples will be collected to determine surface water quality, groundwater level, vegetative dominance, relative cover, frequency, and importance values. Vegetative baseline samples will include sampling of the canopy, shrub and herbaceous layers in quadrats located down gradient of each level spreader. Ancillary data will also be collected including the presence of surface water flows and photographic documentation at each quadrat. Post construction, five-years of monitoring will be conducted using the same methods as the baseline monitoring. Should the monitoring determine that the stormwater outfalls are having no effect RR Development may elect to seek an end to monitoring at the concurrence of DWQ. 2 Line transects and quadrats will be established at two reference locations and below 4 level spreaders (see attached maps for locations). Reference transect and quadrats will be established for the freshwater wetlands areas (Outfall #2, 3, 4) and the estuarine marsh area (Outfall #1) as described below and depicted on the attached maps. A pre and post disturbance species list will be prepared and reported for each quadrat and transect. Canopy / Subcanopy Quadrats (freshwater wetland areas, Outfalls #2, 3, and 4) Permanent quadrats will be established 5 m wide by 5 m long (25 m2) in size and all corners will be marked by PVC post with flagging and GPS data. To facilitate the calculation of species frequency occurrence, each quadrat will be divided into four subquadrats 2.5 x 2.5 m wide (5 m2). Quadrats will be located directly down gradient of level spreaders. Numbers of quadrats will be based on site specific considerations related to length of level spreader and the form, function and size of the down gradient wetlands. Trees with a diameter at breast height (DBH) greater than or equal to 2.5 cm in each quadrat will be flagged and permanently identified with numbered tree tags during the initial baseline monitoring. Additional trees meeting this minimum size requirement will be tagged and reported when found during subsequent monitoring events. Values for dominance and density will be calculated for each tree species in each quadrat combined, and will be summed to estimate the total canopy dominance and density in each quadrat. Importance values for the canopy and subcanopy species will be calculated from dominance, density, and frequency data as follows: Dominance for Spp. A (m3/ha) =Total basal area of Spp. A (m2) Area sampled (ha) Relative Dominance for Spp. A =Total basal area of Spp. A (m2) x 100 Total basal area of all species (m2) Density for Spp. A (#/ha) =Number of Individuals of Spp. A Total area sampled (ha) Relative Density of Spp. A =Density of Spp. A (#/ha) x 100 Total density of all species (#/ha) Frequency of Spp. A = Number of subquadrats in which Spp. A occurs Total number of quadrats Relative Frequency of Spp. A = Frequenc~pp. A x 100 Frequency of all species Importance Value of Spp. A = (Rel dominance + Rel Density + Rel Frequency 3 Values for dominance and density will be calculated for each tree species in each quadrat, and summed to estimate the total canopy or subcanopy dominance and density in each quadrat and in the area below the level spreaders. Shrub/Herbaceous Transects (freshwater wetland areas, Outfalls #2, 3, and 4) The shrub/herbaceous stratum is defined as all vascular plant species exclusive of the canopy and subcanopy. A tape measure will be stretched along the 20m sides of each vegetation quadrat and all shrubs and groundcover vegetation intercepting the vertical plane of this line will be recorded for the total linear distance covered. Line-intercept data will be used to generate estimates of percent cover and frequency (frequency will be based on dividing the 20 m transect into 5 m subtransects), which will be converted to relative vegetative cover and relative frequency. The values for each plant species will be summed and averaged to yield an importance value as follows: Linear Cover Distance for Spp. A = the sum of line intercept distances fro Species A (m) Percent Cover =Linear cover distance of Spp_A~m) x 100 Total transect distance (m) Relative Percent Cover =Linear cover distance of Spp. A (m) x 100 Total linear cover distance of all species (m) Absolute Frequency = Number of subtransects in which Spp. A occurred Total number of all subtransects Relative Frequency = Absolute frequency of Spp. A x 100 the sum of the absolute frequencies of all species Importance Value = (Relative Vegetative Cover + Relative Frequency 2 Marsh Transect (estuarine wetland area, Outfall #1) Outfall # 1 level spreader will discharge into an estuarine marsh. A single line transect with 13 one meter square quadrats (1 every 10 feet) will be placed down gradient of this level spreader. Line-intercept data will be used to generate estimates of percent cover and frequency which will be converted to relative vegetative cover and frequency. The values for each plant species will be summed and averaged to yield an importance value as described in the above shrub/herbaceous layer section. ~/ Groundwater Level Groundwater monitoring will be done using wells with continuous recorders set to record at least once every two weeks. One well will be placed to collect data pre-construction 4 and post construction at each outfall location within one of the vegetation plots or near the vegetation transect at each outfall location. Surface Water Sampling Surface water sampling will include quarterly measurements of water depth, temperature, pH, DO, conductivity and salinity in the field and laboratory analysis of total nitrogen and phosphorus and their fractions, Copper, Zinc, Lead and Mercury as well as fecal and total coliform. Surface water samples will be collected in properly prepared sample bottles. Sample bottles will be clearly labeled with a permanent marker for station location and date. Samples will be collected just below the water surface, at or down stream of the outfalls. All samples for laboratory analyses will be iced or refrigerated as soon after sampling as practical. If the water depth is less than approximately 0.2 feet, this condition will be noted and no sample shall be collected for any analyses. Field analyses for temperature and dissolved oxygen will be made with an approved dissolved oxygen meter with saturated air calibration. Field pH will be measured with an approved meter, calibrated by use of buffer solutions at pH 4 and pH7. Specific conductance will be analyzed with an approved meter calibrated with a standard solution. All laboratory analyses will follow appropriate standard methods and sample holding times specified by EPA Region IV and the NCDENR. ~ Soils The existing soil profile will be described using texture, color, and thickness of the each °'~ layer down to 18 inches using a hand auger or other accepted methods. Soils will be ~- further described using hydrology indicators for wetlands. One soil profile will be completed in each vegetative plot or transect during each quarterly sampling period to include photographic documentation. Soil profile data will be compared to the baseline and each successive profile to assess soil accretion. Soil accretion will also be assessed using measuring stakes at permanently established points within or near the vegetation plots or transect. ~/ Amphibians Most terrestrial amphibian species are identified through direct observation methods; however, where appropriate dip nets will be used to search for aquatic species. Visual and auditory monitoring for amphibians will be conducted bi-annually during spring and winter seasons using the vegetation sample quadrants and outfall locations. Monitoring will be accomplished using protocols similar to those endorsed by the USGS North American Amphibian Monitoring Program and Southeast Amphibian Research and Monitoring Initiative. Surveys will include searches for egg masses in appropriate locations. The checklist of North Carolina amphibians (NC Museum of Natural 5 Sciences), The Frogs and Toads of North Carolina, Amphibians and Reptiles of the Carolinas and Virginia (Martof et al.), and similar field guides will be utilized in species and habitat identification. Benthic Macroinvertebrates Aquatic macroinvertebrate surveys will be conducted annually during a spring sampling event using sampling methods from the NCDWQ Standard Operating Procedures Manual. Several Mulkey staff are certified in NC Macrobenthic Collection Protocols. Species collected will be identified at a DWQ-certified lab. Sampling locations will be located near vegetation plots and storm outfalls. Ancillar. The presence or absence of surface water including inflows and outflows, water marks, stained leaves, and sediment deposits will be documented during the baseline and continued during the post-construction monitoring. This will include photographic documentation from permanently established points within the transects and below the level spreaders. Reporting Data will be collected on a quarterly basis, analyzed and reported to NCDWQ on an annual basis. The reports will include all collected data, photographs, analysis and conclusions. 6 s _ .~~ `•• ~ n •/ 4-__ i / i _ y. ~ ~a-~ _ j ) n'i ~ ~ ~ ~ b I ~ ~ - ~ • ~ LI s ~ . 4 ~' _ o e ~0 ~ ~ '~rbno` ""' RI VER "Racc ~n o 1i ~ oon err - d ' ~ !, M(q- _~~ ~~ / _ ~.. Hall.. „~ , ''~ A Trmt (Ly 1 , ~ , S ~(,r ~ `, ~ 4~ - j swl = ' c ' a..-t . ->u~ ~~ - ~ /~ ~' ~~ 7 / !/ ,f ~ -' Z ~_. r ~ `~ ~ ~ F y ~ ~ _ _ r ~ , ~~ ~ , \ ,~ _ ~ a ~ ,{{ J ~'~ ,~._ _ is F x r.r -. s` ~,t.~ -.~ . ~ l ``1 1 ~'-' -~ ~ ~ ee ~ ~~ ~ t .-„ ;~ ~ ~, ~,,~- ~- ` am , }a _ ~ ~ (l ' / .3f `y ~ ~ .~ , j ~~, J - : ~ .,r b - ~ T~ ,rl ,~ _ ~ : ,, ~- ~~ _w• - PROJECTVICINITY MAP .;uMULKEY Hawes Tract F. ure 9 No. r r~ ~ ~ . ~~ ~~ •. ~ ., . ~. ~ .'= ;~~ ~ -~~ Pamlico County, North Carolina 1:30 000 , Feet 0 5001,000 2,000 3,000 4,000 5,000 USGS 7.5-Minute Topographic Quadrangles:Arapaoe, Bayboro, Oriental, & Vandemere Contour Interval 5 Feet LOi ,~~ LaT 162 Loi ~, :~ ~, ~ ~ ~ \~ ~~ ~• '~' . ~ ~1 -- _: -,4, GNP S ,_~ J,, ;_ T ~ ~-r~ ~T ~= , __ r ~ ,I~ ~. I __ ~, :~ ICI ~ I I~' _ x-_ ~ I i i r~ ~ ' F -- Loi 1.9 ;~ ~ ~ i L; , ~•~`~ rii~ - I :\- ~ 40A `. 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