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HomeMy WebLinkAboutACSA201100095 Other 1992-10-06 139z see SITE, RISK, AND REMEDIATION ASSESSMENT OF GROUNDWATER CONTAMINATION AT THE SHADWELL "76" STATION SHADWELL, VIRGINIA June 12, 1990 1�4 PREPARED FOR: d MN 22 VS° MR. SHERWOOD EXUM, PRESIDENT vp�t EY REGIONS GOCO OIL COMPANY OFFICE 924 HARRIS STREET CHARLOTTESVILLE, VA 22901 PREPARED BY: HYDROSYSTEMS, INC. 2340 COMMONWEALTH DRIVE SUITE 202 CHARLOTTESVILLE, VA 22901 RErq: CONTACT: JEFFREY A. SITLER O C T U 6 1992 EXECUTIVE VICE PRESIDENT PLANNiNG LIEF' '. 804-973-9740 HYDROSYSTEMS WC • TABLE OF CONTENTS 1.0 INTRODUCTION 1 2.0 SITE ASSESSMENT 2 2.1 Site Location. Description, and Land Use 2 2.2 Nature and Quantity of Release 7 2.3 Hydrogeology 8 2.4 Contamination Investigation 12 2.4.1 Methods 12 2.4.1.1 Soil Gas Survey 12 2.4.1.2 Boring Installations and Soil Sampling 13 2.4.1.3 Monitoring Well Installation 14 2.4.1.4 Well Development And Ground Water Sampling 16 2.4.1.5 Laboratory Analyses of Soils and Groundwater 16 2.4.2 Vapor Phase - Contamination in the Unsaturated Zone 16 2.4.3 Free Product Phase - Contamination on the Water Table 17 2.4.4 Dissolved Phase - Contamination in the Ground Water 18 3.0 RISK ASSESSMENT 20 3.1 Man-Made Pathways 20 3.2 Groundwater Pathway 21 3.3 Surface Water Pathway 22 3.4 Air Pathway 22 4.0 REMEDIATION ASSESSMENT 23 5.0 CORRECTIVE ACTION PLAN 24 APPENDIX 1 - BORING LOG AND WELL CONSTRUCTION DETAILS APPENDIX 2 - SOIL GAS SURVEY DATA APPENDIX 3 - LABORATORY ANALYTICAL RESULTS APPENDIX 4 - TANK AND LINE INTEGRITY TEST REPORT HYDROSYSTEMS wc LIST OF FIGURES Figure 1. Topographic Map 4 Figure 2. Location of commercial and residential wells 5 Figure 3. Site layout 6 Figure 4. Site plan showing the topography and boring/monitoring well locations 10 Figure 5. Groundwater flow direction 11 Figure 6. Soil gas survey sampling locations 15 LIST OF TABLES Table 1 - Headspace Analyses of Split Spoon Samples 14 Table 2 - Laboratory Analyses of Groundwater Samples 19 HYDROSYSTEMS INC 1.0 INTRODUCTION This report presents the results of an investigation of groundwater contamination from petroleum hydrocarbons at the Shadwell "76" Service Station and distribution center on Route 250 in Shadwell, Virginia. HYDROSYSTEMS was engaged to conduct this investigation by Mr. Sherwood Exum of GOCO Oil Company of Charlottesville, Virginia, owner of the facility. This investigation was requested by the State Water Control Board (SWCB) in their letter of August 14, 1989 to Mr. Exum. The SWCB action was initiated in response to a report of petroleum taste and odor in the domestic well water supply at the site. This report was filed by the Albemarle Fire Inspector, Mr. John Paul Jones on April 28, 1989. On June 29, 1989 the SWCB collected water samples from the well which serves the site. Analytical results of these samples, provided in Section 2.4.4, indicate that petroleum contamination is affecting ground water quality at the site. Based on these results, the SWCB requested GOCO Oil Company to prepare and submit a Site, Risk, and Remediation Assessment to address the apparent contamination at the site. The purpose of this assessment is to identify the source, nature, and extent of contamination at this site, assess the risks which such contamination poses, and determine the need for remediation or corrective action. This study is intended to satisfy draft SWCB regulations governing release response and corrective actions for underground storage tank (UST) systems containing petroleum products [VR ' 680-13-02, Parts V and VI]. 1 HYDROSYSTEMS we 2.0 SITE ASSESSMENT 2.1 Site Location. Description, and Land Use The Shadwell "76" service station and distribution center is located along the northern side of State Route 250 in Shadwell, Albemarle County, Virginia, as shown in Figure 1. The property is bounded by Route 250 to the southwest, a C&O railroad right-of-way downslope and to the northwest, and private property (Michie residence) upslope to the east. The property is located at the head of a relatively shallow, narrow ravine which trends west- southwest toward the Rivanna River. The C&O railroad tracks lie within this ravine along the northeast boundary of the property. An unnamed, intermittent stream also flows in this ravine along the railroad tracks. This stream discharges to the Rivanna River, approximately 2000 feet west-southwest from the facility boundary. The area surrounding the site is rural, with mixed agricultural, residential, and commercial land uses. Land use to the east and upgradient of the site is primarily agricultural, with the Michie residence and commercial construction company office located approximately 500 feet from the site on the hill to the east. Additional agricultural land occurs to the north across the railroad tracks, with a convenience store (the Shadwell Food Store) and private residence located approximately 500 feet to the northwest of the site. Finally, largely undeveloped land occurs southwest of the site across Route 250. The Stone-Robinson elementary school and private residence (Lang residence) are located across Route 250 to the southwest, approximately 1000 feet downgradient of the site. A railroad spur and gravel storage area from the Luckstone Quarry is also located west of the site along the C&O railroad tracks across Route 250. All of the surrounding residences and commercial properties are served by private wells, as shown in Figure 2. The Shadwell "76" station is both a commercial gas station and a bulk distribution center for gasoline and fuel oil for GOCO Oil Company. The original facility, built in approximately 1940, consisted of the station building and four 15,000 gallon above-ground • tanks located behind the building as shown on Figure 3. The original piping from these tanks ran underground from the tanks directly underneath the building, to truck loading racks on the front porch of the building. Piping also ran to the far southwest corner of the property to a railroad unloading pad near the former railroad station. The two gas pumps in the front of the building were served by two small (<550 gallon, now removed) USTs located in the grassy area immediately adjacent to the pumps. 2 HYDROSYSTEMS we GOCO Oil Company bought the property in 1963, and soon thereafter moved the unloading rack from near the old railroad station to beside the front porch of the building, next to the loading racks. In approximately 1974-75, major changes were made to all piping at the facility. The loading/unloading racks were moved from the porch to its present location in the lot adjacent to the tanks. The small USTs near the gas pumps were retired and new piping from the above-ground tanks to these pumps was installed as shown in Figure 3. The 12,000 gallon kerosene UST, piping, and pump, and the diesel piping and pump were also installed at this time. The rear of the property was filled and graded, to build a truck staging and turn-around area. Presently, the four aboveground tanks are used to store super unleaded, regular leaded, regular unleaded, and diesel fuel. The adjacent UST currently stores kerosene. A complete UST notification form has been submitted to the SWCB for this kerosene tank installation. • HYDROSYSTEMS w� • l \ �I � f,M.,./v, • `. . ,• j' '. ,ems /:•• (--4( �{ N /i)1 iI ` y `;41 ((l.� -/\ . I 1. rJ. - 1 ! .- ;' ' i )� •�' . .. \ 1\ ./, a..• 6. � .1 , ,,...._\-\__ , : \\ \ `\.' •all ki . .•2 I`J• ' ` / i7,,, .....„�((``.. Pn CAI\ ,- ,-„ , „,, ,,,, ,x, . °" N.-• zA-2)_,--N. 2._ _1,_u. c.,,,,,,,,.._.___,_,....t„...,. 11. ^\N 1 ._ _., % r•L1•,. /`� N -"-a,), (`\. \J)1. i 1-.1-+t` I. , /l ,,,d l• .;. . i : 1.- 11 id /,,,(v-... , Iralin 11 .5\\. " ��\'�i I \' ''0„1 xli �<�� _.�� I_\460 N�x� � ` 440'�r•1�1,�'� N lay \• \rt ll.. ��C,/ 1�1 � ) 1)? ,'/`/(�:`i�4dss �,��x�11 . ye>0�PN/a • .. '` • ter. � • , \: ' vaN.f, ' ///'.i3)."(c'F l ( ) t is j ., •M3 2 u 4p. *� • 22 ,` • -i 1 1 ` J \Ir/ 3' Wiz-, 11 / ( '`_f I -'N 1 x '<= gM `1`i=fit .. Ti: 1 • .�� ' ` } 1` V' �: l:r;'•� '' '1' 1*; 1�kyb 2 I1LOCAT I ,t -\-a,l (�\;`. I a� � ION. /._ °cty • ' BK.'��'r}'' �%'�.N^ �'�i�j � /I : 1 ,^1 a 424� `' ` OHIO ' '(I Jlladwell• AIS `�" nw���Cli s rl` •1 ice-- _= � GN —' .--�_ •\ Wne.Itolyn_wn 1 II4 rNR - II ',; A47X �'r jp0'_ki•V sue,\\Z-SelleN \Ir �LC\l-"..))' �•4f f�Q 1 .�'l'...,,, •Thir: \ ' 11 1 u \_ 1 � � .1 l l( i I .' I 11 L�"•t, \l C au1,'^ �� '/� • a . N aim r�� \ " 1 ( ' J a 4. ar _,..,..).,i, - - .4 1\*:.`'‘.. \ ) 1,-i --4. * ' e 29 t . .� �' 1 ' •CaA4N)/""''\ ' -1.) Ir":211y.,,'-‘ --.••• --4". <,.-:!)\ ..''' \ - " ) i , '..; -- . k 1,,_/ ....-1),.)-- i -/-7-1,‘ --- >...i), SCALE: 1 INCH APPROXIMATELY 2000 FEET Figure 1. Topographic Map (U.S.G.S. Charlottesville East, VA 7.5-Minute Quadrangle) showing the location of the Shadwell "76" Station Virginia. 4 HYDROSYSTEMS INC___ po 1 / „,,,r ,„ ,._„Ns..___,J 4 60-11Ji I ` 4 40' d 'L _______--2_n,!„... .-z___,- -- \ *,__,_-_--);___, , ...... .- ,,, ., ..,\ \,_____ ) ( ,( i 0 —/, . \\ ..7 b. ,v* --......„.._,, \\„._ (Q.\\\ ' -7--_-_,,.- ________ ‘\ ‘- ., ( ) 7.7._:>----------- 0\ , cv.,\ ,.........;;;\ \\,..., ( ._7--c c -I „ - ,4., ` 49/ x .. I/ di 1 lL - - ,-l/�� J 1 (...--N \ \ ii !..."''''..u.-- ----7 . .i)--t, •‘.• • ..1 \ -.; -•:.--...----• :. .-. __ ( \-1,11 400 • �� :fir..,.'�C„J� -/ _ rQ } '). "►t.:% '„,. '�- I i\ 4 - .` 6`-- __--i ;: jam/ /�_� C i, q , Yam_ . �S • (: p ==ic=�x// ' �' . SITE, i t;;` ofeh,,,,. -qt.,_,-- - tii '�� -�� (; Shadwel`l : . 's /ju iorLiRur� c �.----_ . _ ___. _------300 -- -----r -___.7-- • •• ------:-2.-------' , . .7:L— ' , ( 8 —k••, ram_ tone;Ro _ ,\... , I ,i,I\ rl�...1.-.0."-5-- r<---1. . 1 - - _ SC,h� 'Q� Ala'.' , _ ) V.k.,- . a : / I 11.-/-:4 8 ji ,_ . �� BY INDIVIDUALAWATERIS)UPP y VVELERTIES SERVED -- �! LS � ��- /. ( • I ° . 7.I\ \� I ,\ t : J/ �1� f 11 ;r,-- -•'', ) 1 • j?/ p -1 � 11 .348•' ♦\ \ '�, ;•29.. 1 / // ni . . Milton \'\ '•', ' ' \ ,,i 1 ' r40° -- \� \ \. `' SCALE: ��� /' ^,�; \` ; \ 1 INCH APPROXIMATELY i� � ^^ " 1000 FEET Figure 2. Location of commercial and residential wells in the vicinity of the Shadwell "76" Station, Shadwell, VA. 5 HYDROSYSTEMS INC_ � � ' LEGEND. SCALE- | | | � 40 Feet , ~ Edge of Gravel ~'' '.'''''~.'~..''''..'_''. .'' — ~~ Diesel Pump WELL Pumps ABOVEGROUND TANKS STATION UNDERGROUND KERO TAW I EMBANKMENT Dike Pump FORMER RR STATION� ~~^`-----~---............—~~~^'-~~~-~--^'~-~—~`-----~-----------^^--------'------...... -----------'-----~-----'------------------- --`--------`-----~ ---^------------- ---------------------` -----------`------------------------------------------- -° RAILROAD TRACKS Fi*oDo 3' Site layout showing tank, piping, ' ' and fuel dispensing equipment locations at the Sh8dvve\l »76^ StatiUD, Shadwe}l rh VA. C� � � � � 6 2.2 Nature and Ouantity of Release To date, no release from the kerosene UST or piping serving the aboveground tanks have been confirmed. Although of questionable value for leak detection, GOCO has also indicated that inventory control records from these systems show no significant product losses. Additionally, soil borings, monitoring wells, and soil gas survey data show no evidence of free product occurring anywhere on the site. As described in Section 2.4.4, the highest levels of ground water quality degradation occur near the loading/unloading rack. Therefore, it is likely that this structure or its operation are responsible for at least part of the contamination at the site, with the most likely sources being either overfill or spillage. Significant leakage from the lines serving the rack appears unlikely, since no significant soil contamination or free product was found in the boring or well installed adjacent to this rack or on the surface where the lines are exposed. Pressure testing of these lines has confirmed that they currently are not leaking, thus, not a current source of contamination (Appendix 4). Therefore, since the lines test tight, the most likely source is overfill and spillage at rack, and past operations. Soil gas data collected immediately adjacent to the rack showed high levels of organic vapors, a situation commonly found at loading racks resulting from surface spillage. The kerosene UST does not appear to be a source of contamination. Soil samples collected from MW-3, placed adjacent to the tank show insignificant levels of hydrocarbons, and groundwater samples collected from this boring show no dissolved hydrocarbons. The soil gas data in this area also show background values. Finally, tightness testing results on the tank confirm that it is not leaking. Another potential contaminant source investigated was the abandoned USTs stockpiled on the rear of the property. However, soil gas survey data collected immediately beneath these tanks show very low levels of organic vapors. If a release had occurred from these tanks at any time, residual soil organic vapors would be detected in the underlying soils. Additionally screening of vapors in the tanks themselves show low levels of organic vapors, suggesting that the tanks had been emptied and cleaned or present on-site for an extended period of time. Finally, the past practices, unrelated to the current operation at the facility may be responsible for at least part of the contamination. This facility has been in operation since the 1940s. It is likely that isolated spillage and leakage has occurred in the past. 7 HYDROSYSTEMS�� 2.3 Hydrogeology The site is located just south of the contact between the Catoctin Formation and the Loudoun Formation. This contact appears to run along the C&O railroad which borders the site to the north. The Loudoun Formation in this area consists of shaley sandstones, sandy shales, and yellow/pink paper-bedded shales, while the Catoctin Formation consists of greenstone, or metamorphosed basalt. Based on geologic maps, the site appears to be underlain by the Loudoun Formation, although borings which terminated at rock surface (refusal) showed some greenstone chips. It is likely that the contact between the two formations is not distinct in this area. Figure 4 provides a site plan showing topography and boring/monitoring well locations. Boring data (Appendix 1) show that silty saprolitic soils ranging in thickness from 20-50+ feet overly bedrock on the site. Competent rock (refusal) was encountered a approximately 20 feet in depth in the rear portion of the site near the unloading rack and kerosene UST (MW-2, MW-3). However, soils thicken to greater than 40 - 50 feet upgradient of the site near MW-1 and along the downgradient boundary of the site near MW-4 and MW-5. Competent rock (refusal) was not encountered in these borings. These saprolitic soils show significant structure and clearly defined bedding planes at approximately 45-60°, and are interspersed with seams of clay and more-intact rock fragments. Groundwater appears to occur under unconfined conditions across the site. Depth to groundwater ranges from 17-22 feet in topographically higher portions of the site (MW-1 and MW-4) to 9-12 feet across the rear of the property (MW-2 and MW-3) and in the topographically lower front portion of the property. Groundwater therefore occurs within the saprolitic soils, although the most appreciable water-bearing zones appear to occur at the top of bedrock. The significant structure and bedding planes observed in these soils clearly influences groundwater flow both above and below the groundwater table. Water level data collected from the monitoring wells show groundwater to be flowing west- northwest across the site, from the highland located beyond the rear of the property to the topographically lower western corner of the site near the C&O railroad cut and Route 250, as shown in Figure 5. Water levels in MW-1, MW-2, and MW-3 differ by less than 0.5 feet, revealing a very flat gradient in this area. After rainfall events, water levels in MW-2 and MW-3 are often a few tenths of a foot higher than the intended upgradient well, MW-1. These water levels are obviously affected by rainfall/recharge, the highly-structured saprolitic soils, and the location of competent rock. In MW-1, MW-2, and MW-3 either 8 HYDROSYSTEMS .e refusal or a hard saprolitic/rock layer was encountered at approximately 347 feet MSL, while borings placed along the front of the property (MW-4, MW-5) did not encounter rock, even to well below this depth. This competent rock surface/layer may serve to locally redirect or control flow in this area, especially during recharge events. As shown on Figure 5, water levels in MW-2 and MW-3 are at or slightly higher than the elevation of the intermittent stream along the northern boundary of the property, indicating that groundwater discharges to the stream in this area. Groundwater discharge to this stream is also indicated by wet conditions and seepage occurring at the northwest corner of the station building at approximately the same elevation. However, along Route 250 (MW-5) groundwater levels drop to approximately 7 feet below the stream elevation, suggesting that the stream is perched above the water table in this area. The overall groundwater gradient across the site is approximately 0.05. Typical hydraulic conductivity values for saprolitic soils derived from the Loudoun Formation average approximately lx10-4 cm/s. Effective porosities for such soils could be assumed to be on the order of 0.2-0.5, while effective porosities for the underlying rock may be as low as 0.01. Assuming these values, ground water flow velocities on site would be expected to range from 20-550 ft/yr. This somewhat large range is possibly due to the heterogeneous conditions observed on site. 9 HYDROSYSTEMS INC . . - . • • -C.O. RAILROAD . .. ..... . . S t I . / tr ....-..-4- • : .. -•-•!•.....:----:* •f••• f ; i• -! I , 4 ..1 -... :... :.. t-. -,... ..s.-...,................. ... ; . : - -7 17 1 : . . , i • ...-•....... • : ••••• • • I 1 • -...._ ' : : : • : • I ! : • • ' ! • •___. .......l.....:-- - ''... ` ` ` I ; 1 -'''i-..--- ;..... :, ' ; s 4 i :.. . i 4 1-•... .••------ • • • -.-_ ___ •31..1 ---...•-.... ......... •••- •-..... P •132.• • ..•••.- .........- . ..... • ........... *LULL .-.-..•- --••••.•... ..----....•-•...... • .......*- 316.......*-- .....3 • ...311.'. ( ..."--............7.........• ..-- --..-----•.--11 1.-I.8 ...-•••.-'-.-----..--.'.‘---'.-- -•-....==.-- .=1;•••'..:.. t---- — —_-.1 -i• .• •i• t, t ? .... ,..•.......1 ........%6...4.1...., / / ...-__.,, — .. ,e-- Ai-.7._-_-_ -------------------------,........,..--,_-- : 11.6•6116 i / /.. //C 1... *-*-7..:.:--“*-—•-•----=.....-.--..-—zathAracmEgr:____----,------------ ...,•• • ., _ ..- --,--.:-,- . .. • , / • //i . • w.,......,... • 11.16 161.. •*---- •••••••...-*-- 161 I.,.t .. \\ . ...",. ../ ./-,.• .: - - , ///,',.7‘.-.4"" —.,____,..-- A \ •• -------. ----- ,.;,..,./ i/ .„... , ,, „. „e„,,,,, — ......,i I- ..; .. , •/// e :.4 ..-----———---,,,, r-—1 •. --- .. -----. / /// (( fi7:1•_-----——---- I ICEROSENE UST z/ •• • .• • . ' • , , . * MW-S \ .•• . _/.. // • , . 1 : .• % . • • ‘ ) . KEROSENE PUMPf..7./ I\ - "/1 le .. . I I I 1 -} . . / •, -.Y ., .. • "r0 '.. i " - ,,•zli 1 / t 1\ I I i / o . e vi i / • -.. . STORE WELL . .„. . .o. '•.. • ABOVEGROUND GROUND T * MW-3 .qt•• • I/ I _L'. , . -• € Is,..s • • *W. •/ / J1 c •. i/ i - /,‘1 11 II II lilt I . .r.• / ...., • : . I / •; STATION 1 .r/e—-j / i . . • , I • n 0 -...; I I . / .xc i: .0.......... , • • i LI, ; , , i• ,-.\---------- _.--,.... 44, \ . , .• .........a....'''. .... A ! •,,,:.•) i -*NI\v*--: • - • • y I I ,. \--...--- _,.--“:7":7' . %.1V'. ' .......,••••-• .'•• GAS PUMPS V. I-------**".------------- \..• // I . ---)".7....-.-- l , --•-0 /.; -- • .--- %•••••,---- ,.... - --1.i 0/ ...---"' •: 1: i1 „:,,•%')•,., \ \..:. % 4/ ..-,•;"--- ••••••,••-;-,1.( , „... ....-.....-, : „.., !,!„,a• 1111.0•LL %,,..... \\\A‘‘0 \ ••••••*r .1 • ••••. /ii/ ...• . . • ............/.../›.....•_•:„.1•'''....• it3 MO 31-..60/ _,..,.. •••••::::. 1,\\\V‘\\\1,\\\‘‘...*°-'... .. C:)1` sL \ . ........t.MW.-,2;. ' \ .. ' •-• ,.-.- ---, .. % •••••2• -'• -'",, .- ..- •,!,r•-•-•--- •,•-.••%A.v \s* ' 2;1 /....:,....-, .,..:...-- 51......:/..,:-/- .... rti z • • , ... s,„.• ---i ! / •-ri..-...... .„... .... . .---- ....--..---, ..........- UNLOADING RACK ••.',.- _.-- ........ ...... . .... ..-- -k / ‘,.... . ,fe . .-- .....- ..„.- ..11- . ''...t. 'C* " - -% --- ..-, i / .../- ...., . - , .•1". • .....,.s.. ,..................- . .... ••"‘N\•\ • -- 1 /,, /e:. ,:6•-• . / .1.:---- ...-- .--' ...." •/- .:1*.• VI \\ \'t % . . %\ A .‘A, .. i -_____,J /// ./...•:.•::-•- - ..• . ...---,-..... !:/,/,•,,/,'" ,.,- . PUMPS ,..,--.- -• -/"•.- .- '....% <.--" / ,13."-_,,.-------- C) ...; ,..... ".... ,............. . ••••••7 ....-...-------.....- --:"..- .."3.. ..•1%. \\%4N-- . .• . . ...i•-•//// / ..•-- .•••••'•%;---,5- -------:--:.----_-----. ..-.•:f.:-. •-•' ---...--:--- .-•,.4.e. ....- ... ...--- .......- or.' :,„,-., t •O 'WV V\ 3 r • • II ........." .. - '-.-.....-..•:.1•63. ..1/// •••• / • • ••.... ./ .... ..... ... _..... •••......, ................/ / .. / •• ..•••••••-_, •••••• .... ...... .."... .6. \:••• •'-' ''. ... ( :•f''ra -• ..,...-• - -.-------- -------•5-•-•--- -ee" . .4.1.-.`:‘ %% \ ...,.-- ,- 0. A\V\ . __....4 .. / .'...--,..-- ..--;----...-"" 4..11, ..../- ....•'s 6......li't .. t. %As • /..---- 4, '• / P.I. ( .. ,-..,... ..-----../ „,..--rs s- ..., . .., ......... ...VS.,...-----/...." ...... • ..-"" / ......... .../....• .1.% ••%...... ..........'. .•••.... / ....%• 3......k'. q k\\ • / % ..... .1.,.., •;<,.. 3•1 .:. .1‘ / 1-- G ..1::,. ‘‘‘,‘,,,-..._ / /1 ...••• i \ .... \,',\6\ -...../ / : -- ,--r----•:,_ ..-:.:;:-...-..----;;;EMBANKMENT ,...„-F.:-.----- •-:.::-"---------_- ---- .•-• *(11 ; •:..r. t,,\A _- 2... - ••:. t1\\v.___------- •;., . i • -5) • ' / ,.--- ,..:•• -----' ,-,-- .. SCALE:------".V ' • .4*-,,•‘' " (----... --" • •• 1 INCH APPROXIMATELY 45 FEET ., •:. \ 6 ., ...... \\•••••-___ . .. „/ .3.„...-... ..;:.:„,-../ •.....--- ---.... *MONITORING WELL .‘ -•:.---'". •'.-. .- .. -*MW-4' .... "-.,.--.-, .),' /. - , .. ,,ed \ • •:'' ..." • 6/61 1. „.„ / .. /i • 121. C6 1 .••• • . ...... / ./. i...Al-- .• ••••• S., •• •••• * .... ....... .• / .. !1 1 if ...... .6. ...... /.. / ..; ..%. ..‘ •., •,• /*. / . •..*•' ....• • / / 0 • I.. ...• • 1 / { DZ) ...S. ... ....• V / • / • . 6 •,• ... .. ...) , . 0 • L. 0) --i Figure 4. Site plan showing the topography and boring/monitoring well locations at the Shadwell "76" Station, Shadwell, rn VA. . o • 1 •C.O: RAILROAD .. ' ,..._, r :.-••- • .r 1 . ..... .. _ ...4 f....I . .,... . ...4-_. -- t �....... ._ •• _ .1. .. • .. ...:: ;....I ' t.... . t - -_ • 1...-.i .- `.1.`: .. . . l.. . , , �.�--'�..- • i :-- 'f....- •__--__------- as. ____.... afe.. —-- 7 C� •aaa sa �� �� ..i. . .. .. ' at— ..t. -......� ^^ ^� / �_,_ax-� il'i ---- —__ __ __:.".••e ... ...� r �' • '7� r - -- i -�`''a- --- •- =_t, ..�. _ _._ - .i— -;,-rat .. - i o M a,•ao ), — ....♦ - - - / /• �. '' ter-- �••, / • �\ / KERS ' • �' // 10✓RSENE USTM5 \\ \ I( 1I t /• : \ i / \1 y` I I I I I I I f // A_STORE WELL ° • / .I G OUND G ND TAl MW-3 • br..a cam. :/ � � ABOVE R • • I // STATION I .I I I VJ I !ii-. / 1; t • _ �.Y III /. '` _ 1 .=� , •• .� GAS PUMPS ' • APPROXIMATE DIRECTION OF GROUNDWATER FLOW /.. •" '''— l sir ` / // I \ �' ::' a...ar ••a;.� \\\\\�• • • +-- -�--; *`_emu 1 ,ll a i/,j/• :... MW_ \ /• / // i' , .., •�•, \\\\\�\\\1\_..••l' ��/ ram •��i/.•'' ;..-Q';. f•� , •/ // j/ ,!._�+ ::'\\\\\\,��@Q\\\ �`-`---'-- 1// ;:Y--i.. e UNLOADING RACK. is ,/• i�//-2 2 - ''&• +' \cO�\1� YY‘ i�• -' •:• ", =--- i// ODIESEL PUMPS /' ;`.• i i�i i� /:' / ,a.e „.-• , b' ,,--� �: 1\;\\ --.. // /i �� ����E_MBAI\ MENT .• r••r. \1 \\\�_�_ // j��•'..- •: '-.' SCALE • 90 ': 11\\\\—--_J r � ---' �// --•r 1 INCH APPROXIMATELY 45 FEET ''; \A ._ Y- J � � •" MONITORING WELI. G� \\ -'vim i• i�;• - '-' im• GROUNDWATER CONTOUR ' \ ..,. / \\ `'` MW-4'• / i// ., coded OCCO -‹ '.% ..-:• „/.i . i ODZ) ',an-- ,/ '_—'' •• 0) 0 Figure 5. Groundwater flow direction at the Shadwell "76" Station, Shadwell, VA. Z 2.4 Contamination Investigation 2.4.1 Methods Several techniques were employed to delineate the source, nature, and extent of contamination at this site. These included: • Conducting a soil gas survey to identify the potential contaminant sources and areal extent of contamination; • Drilling 5 borings to collect split spoon samples for lithologic descriptions and headspace/laboratory analysis; • Analysis of headspace on split spoon samples obtained during drilling to screen samples for the areal and vertical extent of contamination; • Laboratory analysis of selected split spoon samples for total petroleum hydrocarbon (TPH) analysis to confirm and quantify areal and vertical extent of contamination; • Installation of 5 monitoring wells to determine the presence of free product and to collect ground water samples; • Laboratory analysis of groundwater samples to determine presence of dissolved phase hydrocarbons; and • Tightness testing of product lines and underground tanks. Each of these investigative techniques are described in detail below. 2.4.1.1 Soil Gas Survey HYDROSYSTEMS conducted a two-phased soil gas survey to attempt to identify potential contaminant sources and the areal extent of contamination in the unsaturated zone. The presence of significant organic vapors in the shallow soils are often good indicator of contaminant sources and extent. An initial survey consisting of a rough 50-foot grid across 12 I-IYDROSYSTEMS we the entire site was conducted on August 28, 1989. A follow-up survey which included more closely-spaced points along piping runs and other potential contaminant sources was performed on September 19, 1989. The soil gas surveys consisted of the installation of 51, 1.5-inch diameter, 4-foot deep auger holes at the locations shown in Figure 6. After installation, the opening of each hole was sealed at the surface to retain any volatilized gases for sampling. Soil gas data were collected using a Foxboro Century 128 Organic Vapor Analyzer (OVA) and Gas Chromatograph (GC). A 0.25-inch diameter teflon probe was inserted into each hole to measure the concentration of organic vapors within the boring. The OVA can detect volatile organics to 0.2 parts-per-million (PPM) total organic vapors. 2.4.1.2 Boring Installations and Soil Sampling On September 1, 1989, three borings MW-1, MW-2, and MW-3 were installed at the locations shown in Figure 5. MW-1 was sited to provide data on upgradient conditions, while MW-2 and MW-3 were sited to provide information in the areas of likely contaminant sources, the fuel unloading rack and piping and the kerosene UST. These borings were drilled using a 7 5/8-inch hollow stem auger to refusal at the bedrock surface (for MW-2 and MW-3) or until an appreciable water bearing zone was encountered. Split spoon samples were collected at 5-foot intervals to refusal. These split spoon samples were screened with the OVA to assist in identifying the areal and vertical extent of contamination. Soil samples were placed in a 1-quart glass jar and warmed for 20 minutes prior to analysis. The OVA was then used to measure organic vapor concentrations in the headspace above the soil samples (Table 1). Selected split spoon samples which showed the highest concentrations of organic vapors were then retained for laboratory analysis. Two supplemental borings, MW-4 and MW-5, were installed at the site on October 3, using the same methods described above. These borings were sited to better delineate ground water flow directions and to identify the extent of the water quality degradation shown in MW-2. 13 1-IYDROSYSTEMS iNC Table 1 - Headspace Analyses of Split Spoon Samples, GOCO "76", Shadwell, VA. Soil Sample Total Organic Vapor Boring Depth (ft.) Concentration (ppm) TB-1 4 0.6 9 0.5 14 1.0 19 1.6 24 1.5 TB-2 4 0.7 9 >1000 14 200 19 180 TB-3 4 14 9 58 14 12 TB-4 4 0.0 9 0.7 14 0.2 TB-5 4 6.8 9 0.8 14 0.2 * Sample retained for laboratory TPH analysis 2.4.1.3 Monitoring Well Installation Upon completion of all borings, 2-inch PVC monitoring wells were installed. Although completion details differed for each well, typically 10-20 feet of 0.01-inch slotted screen with an appropriate length of riser pipe were installed in each boring. The well screen was packed with clean gravel extending to at least one foot above the well screen. Each well was completed with a bentonite seal, grout backfill, locking cap, and protective casing or manhole covering. Well construction details for all wells are provided in Appendix 1. 14 HYDROSYSTEMS INC LEGEND: • SCALE 1 40 Feet A Edge of Gravel *h+ .. ......- .. .....•• ..........— .. .....-- . . ...........-- ............ ,. ...........— ........-......• ..... ........--- .........--- •••••••• .. — •............... .....................................................................................................................................................................................................................................................................................................................................................................................................................................................................s..........................9.................5..-.....•.....-*...........,,..1 ......—....---r- ..........+.............o.....................-... •. . . 30.0..•••••• .•'.. Pump i ,•:::%.. . •• 0.0 j ! 44) i 10.0 i ' .• ••+ ! .•• 3-3 0,0 . C.1.13. ., 2 0 '-' ..' AP4x. Piping Loc.022 1 + / 3+.0 •0.0 ii 7...4 4. . : -0- , 1.°6as 1.. .- • •o.o • • t • .. ---- Wf.d...L \ . 2°4 °...° ABOVEGRO ND .NKS ! : Pumps .• STATION 1 [to • • RL . RU D I) 1 IS , • •, . +.. • + + + 1 .e.0 ••• 5.. 0.0 '''•• 0 0 / t...1i.0. .15 -It + ............4......•••••••- + Approx.Pl Location 1000 .:0. .-1.5 0 1000.0 150.0 l :•-..•pIga UNDERGROUND KERO TANK Kero + • + + + • Tank Dike Pump FORMER RR STAT101 50.0 EMBANKMENT 15.0 ••• • •••~1••••.11•1•••••••.M••M••••••MM••• ••••••••••••••••••••••=1.••••••M••• •••• •••••MM••••••••• •••••M••••••=•• •• •••••••••• •••••••••••••••••.M••• •••• ••••••••••• ••••••••••• •••• ••••••••••••••••••.•••••• ••• ••••• •••.••••••• •• ••• • ,1111.•• •••• •••• ••••IM.•••=••••••• ••••=1••••••M,••••••••••• ••• ••••• •••=••••••••.•••• ••••••••••=••••• •••.•••••••.1••••• •••••M.••M••••...1.••••••1.,••••• •••• ••• ••••••••••••• •• ••••• •••••••••••••• ••••••••M••• ••• ••••• ••••• •••• •••••••••••••• xi RAILROAD TRACKS 0 u) --< 0 Figure 6. Soil gas survey sampling locations and measured organic vapor concentrations at the Shadwell "76" Station, --i rn Shadwell, VA. cn *. . 0 1 2.4.1.4 Well Development And Ground Water Sampling On September 8, 1989 MW-1, MW-2, and MW-3 were developed and purged by bailing a minimum of 5 well volumes of water, or until dry, from each well using a teflon bailers dedicated to each well. After purging, groundwater samples were collected using the teflon bailers. Additionally, each well was checked for the presence of free product both before and after purging with a clear acrylic bailer. A groundwater sample was also collected at this time from the well supplying the store located to the rear of the property, as shown on Figure 4. This well is a 55-foot deep drilled well with an unknown length of steel casing in the overburden. The well was purged from a faucet in the well pit for approximately 20 minutes at 7.5 gpm prior to sampling. Monitoring wells MW-4 and MW-5 were developed and sampled following these same procedures on October 9, 1989. A second round of samples was also collected from MW-1, MW-2, and MW-3 at this time. Samples were placed in clean glass jars, sealed, and preserved with ice during shipping. Chain-of-custody procedures were also followed during sample collection and transport. 2.4.1.5 Laboratory Analyses of Soils and Groundwater All laboratory analyses were performed by Central Virginia Laboratories of Lynchburg, Virginia (CVLC). The groundwater samples were analyzed for total petroleum hydrocarbons (TPH) and benzene, toluene, ethylbenzene, xylene, (BTEX). Since most soil samples showed low levels of organic vapors based on headspace screening with the OVA, only one sample which showed the highest organic vapor readings was retained for confirmatory laboratory analysis. The sample from MW-2 collected at the 10-foot depth was forwarded to CVLC for TPH analysis. 2.4.2 Vapor Phase - Contamination in the Unsaturated Zone Contamination in the unsaturated zone appears to be limited based on the results of the soil gas survey, headspace analysis of split spoon samples collected during drilling, and laboratory analysis of selected split spoon samples for TPH. 16 HYDROSYSTEMS iNC a Results of the soil gas survey is provided in Figure 6 and Appendix 2. Although this survey reveals several areas of appreciable (>100 ppm) organic vapor concentrations, most appear to be related to minor surface spillage from dispensing equipment or site runoff. Elevated soil gas readings near the diesel pumps and gas pumps appear to be due to minor spillage associated with dispensing equipment. Elevated readings along the edge of the gravel area south of the unloading rack and in the low lying area near the former railroad station and Route 250 appear to be due to runoff from the gravel parking lot area. The elevated readings to the west of the building and near the kerosene pump appear related to the wet conditions in this area, which result from the surface seepage of contaminated groundwater. The elevated soil gas readings near the loading/unloading rack appear to be the most notable contamination in the unsaturated zone. Since the lines tested tight, it is likely that these elevated readings are due to surface spillage in this area. Results of the organic vapor headspace analyses performed on the split spoon soil samples collected during drilling are provided in Table 1 and indicate that contamination in the unsaturated zone is minimal. No appreciable organic vapors were detected in samples from MW-1, MW-4, or MW-5. Based on the low levels found at depth in MW-5, it appears that the high soil gas survey readings near the railroad tracks and route 250 are surficial and very localized. Near the kerosene tank in MW-3, headspace concentrations were slightly above background, but well below levels indicative of releases from this UST. The only appreciable organic vapor headspace concentrations occurred in MW-2 near the loading/unloading rack, where concentrations in excess of 1000 ppm were recorded in the soil sample collected at 8.5-10 feet in depth. This soil sample at 10 foot depth in MW-2, which showed the highest headspace readings of any sample collected on site, was retained for laboratory analysis of TPH. Laboratory analysis of this sample revealed TPH level of only 35 ppm, well below the SWCB's action level of 100 ppm for soils. Thus, other than some surface spillage in the immediate vicinity of the unloading rack, contamination in the unsaturated zone appears minimal. 2.4.3 Free Product Phase - Contamination on the Water Table No evidence of free product was observed during any phase of this investigation, which suggests a diffuse or slow source is responsible for the groundwater quality degradation. No free product was observed in soils during drilling or monitoring well installation. All monitoring wells were also checked for free product using an acrylic bailer prior to well development and each sampling event. No free product was observed on any monitoring 17 HYDROSYSTEMS wC wells. Additionally, visual observation of water level tapes indicate that no free product is present in the store well either. 2.4.4 Dissolved Phase - Contamination in the Ground Water Results of laboratory analyses of TPH and BTEX performed on ground water samples collected from the monitoring wells, the well supplying the store, and from the intermittent stream at the downstream border of the property boundary are provided in Table 2. Also provided for comparison are analytical results for a sample the store well collected on June 29, 1989 by the SWCB. All samples showed nondetectable levels of TPH (< 1 ppm), with the exception of MW-4, which reported a value of 1.4 ppm. This TPH value is believed to be an outlier, since all BTEX components in this well were below detection, and no other indication of contamination (sheen, odor) was observed in this well. Significant levels of contamination were observed in the store well and MW-2, located near the loading/unloading rack. Contaminant levels MW-2 exceeded drinking water limits by 100's of times for benzene, toluene, ethylbenzene, and approached the limit for xylene. Contaminant levels in the store well were not quite as severe, but still exceeded drinking water limits for benzene by a factor of 100. These high contaminant levels in MW-2 indicate a source at the loading/unloading rack. The lower, but still elevated, levels observed in the store well appear to be due to contaminants spreading in the unsaturated zone or in the groundwater during times of recharge to the site. The flat water table gradient and soil structure observed in the saprolitic soils may account for this spreading in an apparently "upgradient" direction. Low levels of contamination were also observed in the upgradient well, MW-1. Although much lower than that observed in MW-2 or the store well, drinking water standards for benzene were still exceeded by 10's of times. As with the store well, these levels are attributed to spreading in the unsaturated zone, or due to the flat water table gradient in this area. MW-4, MW-5 and a sample collected at the property boundary from the intermittent stream along the C&O railroad tracks show nondetectable levels of all BTEX constituents. This indicates that the contamination is confined to the local area of the loading/unloading rack, and is not moving off-site via ground water or surface water pathways. 18 HYDROSYSTEMS we Table 2 - Laboratory Analyses of Groundwater Samples, GOCO "76" Station, Shadwell, VA (1). STORE PARAMETER (ppm) MW-1 MW-2 MW-3 MW-4 MW-5 WELL STREAM [Regulatory Limit (2)] (Upgr) (Rack) (Kero) (Entrance) (250 & RR) Total Petroleum Hydrocarbons [1.0] <1.0 <1.0 <1.0 1.4 <1.0 <1.0 <1.0 Benzene [0.005] 0.149 2.40 <0.001 0.723 0.047 2.67 0.001 <0.001 <0.001 0.350 (3) <0.001 Toluene [2.00] 0.002 4.07 0.002 0.198 <0.001 1.81 0.001 <0.001 <0.001 0.220 (3) <0.001 Ethylbenzene [0.700] 0.002 1.53 <0.001 0.007 <0.001 1.09 <0.001 <0.001 <0.001 0.070 (3) <0.001 Xylenes [10.0] 0.002 5.68 0.001 0.609 0.007 7.06 <0.001 <0.001 <0.001 0.680 (3) <0.001 0 a) 0 (1) Upper value indicates samples collected 9/8/89; lower values collected 10/9/89 -.< (2) EPA Maximum Contaminant Levels (MCL) for Drinking Water ry (3) SWCB sample collected 6/29/89 t) 19 1 • 3.0 RISK ASSESSMENT This section of this report defines the risk the contamination observed on-site poses to the environment and human health. In conducting this risk assessment, HYDROSYSTEMS defines: • What pathways exist along which the contaminants may migrate • Who/what are the potential receptors along each pathway • At what levels could these receptors be exposed and, given these levels, what is the risk to the receptor, ■ Do these risks warrant corrective actions to reduce or eliminate the risks The following discussion evaluates the above items based on each likely pathway for contaminant migration. Since no significant levels of soil contamination or free product have been found on-site, migration via the ground water pathway appears to be the most significant cause for concern. 3.1 Man-Made Pathways Two man-made pathway exist on site which may be contributing to the spreading of contaminants. As shown in Figure 3, a 12-inch conduit carries surface water runoff from the rack area past the store well and discharges to the intermittent stream near the railroad . tracks. Contaminated runoff carried by this line could be spreading to the well area, if a breach exists in this line. Additionally, although a drain line exits from the store well pit, no outfall could be found. This drain line may join the surface water runoff line. If so, blockage present now or previously in the surface drain line may result in a direct conduit for contaminants to travel from the rack area to the well pit. Further investigation of this pathway is warranted. A second man-made pathway which may be contributing to the spreading of the contamination is the septic system. Contaminated groundwater derived from the store well is used for sanitary purposes and discharged to a leachfield on the north-northwest side of the station. The resultant discharge has the potential to further spread the hydrocarbon contamination to the groundwater and possibly to surface waters via the seeps. 20 HYDROSYSTEMS�� The potential for contaminant migration or impacts via other man-made pathways at the site are nonexistent. All utilities serving the site are overhead, thus no underground conduits exist for contaminant migration. 3.2 Groundwater Pathway Given the significant levels of BTEX components in the groundwater near MW-2 and the store well, the potential migration of contaminated groundwater poses the greatest risks to receptors near this site. The primary receptor of concern is the store well which has already shown to be impacted. Described in Section 2.1 (and shown on Figure 2), other nearby residential wells include the Michie residence upslope and approximately 400 feet to the east of the property, the Stone-Robinson Elementary School Well located approximately 800 feet to the southwest of the property, the Lang residence located approximately 1200 feet to the east-southeast of the site near the Stone-Robinson school, and wells located at the Shadwell Food Store, located approximately 800 feet northeast of the site at the intersection of Routes 250 and 22. Given the ground water flow directions determined in Section 2.3, only one of these wells should potentially be affected from contamination at the site. The Michie residence located upslope and to the east of the site is upgradient of the site, and therefore should not be impacted by conditions at the site. The wells located at the Shadwell Food Store are located across the apparent ground water divide formed by the discharge area along the topographically low area along the railroad tracks. Therefore, these wells would not be impacted by flow from the site either. The Stone-Robinson school, southwest of the site, is laterally downgradient from the site. However, a the west-northwest gradient toward the intermittent stream makes impacts to this well unlikely. Additionally, MW-4, located along the property boundary directly between the contaminated area and the school well shows no impacts. The one residential well which potentilally could be impacted by contaminated ground water on the site is the Lang residence located west of the site in the topographically low area along the railroad tracks. Although groundwater on the site flows west-northwest, and appears to discharge to the intermittent stream, groundwater which does not discharge (during dry periods, for example) would be expected to flow west parallelling the intermittent stream. Although this is a possible pathway, exposure via this pathway is unlikely for two reasons. First, MW-5 which is sited to monitor this flowpath, reveals no contamination. This indicates that contamination has not yet even traveled to the site boundary. Based on the suspected groundwater discharge to the seepage area at the 21 HYDROSYSTEMS W� t northwestern corner of the station building and intermittent stream, contamination may never travel to the site boundary. Second, based on groundwater flow velocities provided in Section 2.3, and assuming no attenuation, it would take on the order of 2.2 - 60 years to travel the 1200 feet to this well. Continued monitoring of MW-5 could serve as an indicator of such migration. 3.3 Surface Water Pathway The potential for contaminant migration and impacts to receptors via a surface water pathway exists, but appears limited for a number of reasons. The only receptor of surface water discharges is the intermittent stream itself and eventually the Rivanna River. No human receptors exist since this intermittent stream is not used for human consumption. Although human receptors are not of concern, pathways do exist for potentially contaminated surface water exiting the site. Pathways include: (1) runoff of surface water from the site (2) groundwater seepage which surfaces at the front of the building entering the intermittent stream, and (3) discharge of contaminated groundwater from the rack area directly to the stream. Although these pathways exist, sampling of the intermittent stream shows no impacts to the stream. All TPH and BTEX components were nondetectable in one grab sample collected at the downstream property boundary. Either no contaminated groundwater is reaching this stream, or if it is, the BTEX components are volatilizing in this surface flow. Continued monitoring of this stream may be warranted to determine if any contaminants are exiting the site via the surface water pathway. 3.4 Air Pathway Since no free product or significantly contaminated soils occur on site, the accumulation or migration of significant concentrations of organic vapors is unlikely. The existing station structure has no basement, and there are no nearby residences in which vapor accumulation would be of concern. OVA readings taken in the ambient atmosphere in the spill area also show no detectible levels of organic vapors. Therefore there is no risk to any potential receptors via any air pathway. 22 HYDROSYSTEMS INC 4.0 REMEDIATION ASSESSMENT Based on investigations performed to date, remedial measures do not appear to be warranted for this site. No significant hydrocarbons in soils, vapor phase contamination, or free product occurs on the site. Thus, corresponding remedial measures such as soil excavation and removal, soil venting, biodegradation, or free product recovery are not applicable or necessary. With some improvements in product handling on site, recommended in section 5.0, natural biodegradation should be sufficient to remove the low levels of soil contamination observed. Although remediation of the contaminated groundwater is feasible, such work does not appear to be warranted for several reasons. First, the quality problems at the station well have been in existence for at least 10 years. Although ground water contamination apparently has existed throughout this time period, HYDROSYSTEMS' work to date shows contamination to be localized in the vicinity of the unloading rack and store well. Thus, it appears that contamination has not moved significantly, and is therefore not likely to migrate and negatively impact nearby residential wells. Further monitoring and the recommendations outlined in Section 5.0 would confirm this assumption. Second, other than the store well, no other receptors exist which would likely be impacted by the contamination on the site. As described in Sections 2.1 and 3.2, although the Lang residential well is located downgradient of the site, impacts to this well are unlikely due to a combination of the distance to the well and that the contaminated groundwater appears to be discharging to the intermittent stream on the rear portion of the property. Likewise, although the Stone-Robinson School is laterally downgradient, impacts to this well are unlikely since groundwater flows more due west, along or discharging to the intermittent stream along the railroad. In either case, monitoring wells MW-4 and MW-5 located along the downgradient boundary of the property, and one additional well placed near the station building could be used to monitor for and detect any such migration toward these users. If water quality degradation were to be observed in these wells, appropriate remedial actions could be pursued as needed at that time. If required, a remediation scheme using ground water pumping/collection followed by treatment and discharge to surface water would most likely be used at this site. Since ground water is shallow (< 11') in the most highly contaminated portion of the site, a groundwater collection system composed of horizontal drains may be applicable. In shallow water table situations, such systems are often more cost-effective to install and operate than pumping well systems. If use of horizontal drains is not possible, a pumping well system could be installed. This system would most likely be a 2-well system, using the existing well 23 HYDROSYSTEMS�c supplying the store as one pumping well. An additional pumping well would be installed near the unloading rack in the most highly contaminated area. Pumping rates of these wells would be determined based on an analysis of pumping test data. Contaminated groundwater collected by a drain or pumping well system would then require treatment. Air stripping is clearly the technology of choice for treatment and removal of volatile organic compounds at these levels from water. Sizing of an air stripping unit would be based on expected pumping rates from the recovery wells. Depending upon the influent water quality, an oil/water separator may be installed in-line ahead of the air stripping unit. After treatment, water would be discharged to the intermittent stream bounding the site, since no sewerage facilities serve the area. This discharge would most likely be conducted under an Virginia Pollution Abatement permit (VPA). Depending upon the removals achieved with air stripping and the effluent limitations imposed on this discharge, a carbon adsorption finishing unit may be required for final treatment prior to discharge. 5.0 CORRECTIVE ACTION PLAN • As described in Section, 4.0, ground water remediation at this site does not appear to be necessary at this time, based on the relatively immobile nature of the contamination and the lack of receptors likely to be impacted. However, further work should be performed to define and eliminate potential sources of contamination and to ensure that contamination which is present does not migrate off-site and impact potential receptors. Work recommended to adequately characterize the source of contamination and limit such sources includes: ■ Investigate the line carrying runoff from the gravel area near the unloading rack to ensure this is not connected to or otherwise a source of contamination in the well pit. • Discontinue use of the store well. Drill a replacement well in the vicinity of MW-4 to provide water supply for the station. • Excavate and remove surficial petroleum-contaminated soils near the fuel loading/unloading rack. Pave this area with concrete to eliminate continued contamination due to product spillage. Berm or slope this area to contain runoff, which should be directed through an oil/water separator prior to discharge. 24 HYDROSYSTEMS INC • •,s Work recommended to ensure that the contamination present does not migrate off-site and impact potential receptors includes: • Monitor water quality in all monitoring wells, the store well, and the intermittent stream semiannually for a minimum of two years. Samples should be analyzed for BTEX components, and results provided to the SWCB. At the end of this two year period, provide the SWCB with a summary of all data collected to date and recommendations for further monitoring and disposition of the site. • If significant water quality degradation is observed in any monitoring well, which indicates that the contamination is migrating, implement ground water remediation as discussed in Section 4.0. Provide the SWCB a corrective action plan prior to implementing this work. Other housekeeping recommendations which are largely unrelated to the ground water contamination on-site include: • Remove and properly dispose of the abandoned USTs currently stockpiled at the rear of the site. • Excavate and properly dispose surficial petroleum-contaminated soils in the vicinity of the gas, diesel, and kerosene pumps, and along the northeast corner of the gravel parking lot. • 25 HYDROSYSTEMS W� 268 Soil Survey I i TABLE 11.--SANITARY FACILITIES--Continued I '. Soil name and Septic tank Sewage lagoon Trench Area Daily cover map symbol absorption areas sanitary sanitary for landfill fields landfill landfill 8C3 Moderate: Severe: Severe: Moderate: Poor: Braddock percs slowly, seepage, seepage, slope. too clayey, slope. slope. too clayey. hard to pack. 9B Moderate: Severe: Severe: Slight Poor: Braddock percs slowly, seepage. seepage, too clayey, large stones. too clayey. hard to pack, small stones. 9C Moderate: Severe: Severe: Moderate: Poor: Braddock percs slowly, seepage, seepage, slope. too clayey, slope, slope. too clayey. hard to pack, Ilarge stones. small stones. 9D Severe: Severe: Severe: Severe: Poor: Braddock slope. seepage, seepage, slope. too clayey, I slope. slope, hard to pack, too clayey. small stones. 10 Severe: Severe: Severe: Severe: Poor: Buncombe flooding, seepage, flooding, flooding, seepage, poor filter. flooding. seepage, seepage. too sandy. too sandy. 11D*, 11E*: Cataska Severe: Severe: Severe: Severe: Poor: depth to rock, seepage, depth to rock, depth to rock, area reclaim, slope. depth to rock, seepage, seepage, small stones, slope. slope. slope. slope. Hartleton Severe: Severe: Severe: Severe: Poor: slope, seepage, depth to rock, seepage, large stones, large stones. slope, seepage, slope. slope. Coco large stones. slope. 12C Severe: Severe: Severe: Severe: Poor: Catoctin depth to rock. slope, depth to rock, seepage, area reclaim, depth to rock, seepage. depth to rock. small stones. seepage. 12D, 12E Severe: Severe: Severe: Severe: Poor: Catoctin slope, slope, slope, slope, area reclaim, depth to rock. depth to rock, depth to rock, depth to rock, small stones, seepage. seepage. seepage. slope. I 13C Severe: Severe: Severe: Severe: Poor: Catoctin depth to rock. seepage, depth to rock, depth to rock, area reclaim, depth to rock, seepage. seepage. small stones. slope. 13D, 13E Severe: Severe: Severe: Severe: Poor: Catoctin depth to rock, seepage, depth to rock, depth to rock, area reclaim, slope. depth to rock, seepage, seepage, small stones, slope. slope. slope. slope. 14B Moderate: Moderate: Slight Slight Fair: Chester percs slowly. seepage, small stones. slope. 14C Moderate: Severe: Moderate: Moderate: Fair: Chester percs slowly, slope. slope. slope. small stones, slope. slope. 14D, 14E Severe: Severe: Severe: Severe: Poor: Chester slope. slope. slope. slope. slope. See footnote at end of table. I I i I 274 Soil Survey TABLE 11.--SANITARY FACILITIES--Continued Soil name and Septic tank Sewage lagoon Trench Area Daily cover map symbol absorption areas sanitary sanitary for landfill fields landfill landfill 53B Moderate: Moderate: Severe: Slight Poor: Masada percs slowly. seepage, too clayey. too clayey, slope. hard to pack. 53C Moderate: Severe: Severe: Moderate: Poor: Masada slope, slope. too clayey. slope. too clayey, percs slowly. hard to pack, 54B Moderate: Moderate: Moderate: Severe: Fair: Mayodan percs slowly. seepage, too clayey. seepage. too clayey, slope. hard to pack. 54C Moderate: Severe: Moderate: Severe: Fair: Mayodan percs slowly, slope. slope, seepage. too clayey, slope. too clayey. hard to pack, slope. 55B Severe: Slight- Severe: Moderate: Poor: McQueen percs slowly. too clayey. y y. flooding. too clayey. 56B Severe: Severe: Severe: Severe: Fair: Meadowville wetness. seepage, depth to rock, seepage, area reclaim, wetness. seepage, wetness. too clayey. wetness. 56C Severe: Severe: Severe: Severe: Fair: Meadowville wetness. slope, depth to rock, seepage, area reclaim, seepage, seepage, wetness. too clayey, wetness. wetness. slope. 57B Severe: Severe: Severe: Severe: Poor: Mount Lucas wetness, seepage, depth to rock, seepage, small stones, percs slowly. wetness. seepage, wetness. wetness. 8604 wetness. 111111W111111111MModerate: Moderate: Slight Fair: sville seepage, too clayey. too clayey, slope. small stones. 58C Moderate: Severe: Moderate: Moderate: Fair: Myersville percs slowly, slope, slope, slope. too slope. too clayey. small stones, slope. 58D, 58E Severe: Severe: Severe: Severe: Poor: Myersville slope. slope. slope. slope. slope. 59C - Moderate: Severe: Moderate: Moderate: Fair: Myersville percs slowly, slope. slope, a slope. too clayey, P clayey, small stones. large stones. i 59E, 59E Severe: Severe: Severe: Severe: Poor: Myersville slope. slope. slope. slope. slope. 6 0C*: Myersville Moderate: Severe: Moderate: Moderate: Fair: f peres slowly, slope. slope, slope. too clayey, slope. too clayey, small stones. large stones. Catoctin Severe: Severe: Severe: Severe: Poor: depth to rock. seepage, depth to rock, depth to rock, area reclaim, depth to rock, seepage. seepage. small stones. slope. See footnote at end of table. N CD N TABLE 13.--WATER MANAGEMENT--Continued Limitations for-- Features affecting-- Soil name and Pond Embankments, Aquifer—fed Terraces map symbol reservoir dikes, and excavated Drainage Irrigation and Grassed areas levees ponds diversions waterways 11D*, 11E*: Cataska Severe: Severe: Severe: Deep to water Large stones, Slope, Large stones, depth to rock, seepage. no water. depth to rock, large stones, slope, slope. slope. depth to rock. droughty. Hartleton Severe: Severe: Severe: Deep to water Large stones, Slope, Large stones, seepage, piping, no water. droughty, large stones. slope, 6.660 slope. large stones. slope. droughty. 12Cy. 12D, 12E Severe: Severe: Severe: Deep to water Droughty, Slope, Large stones, Catoctin seepage, thin layer. no water. depth to rock, large stones, slope, slope. slope. depth to rock. droughty. 13C, 13D, 13E Severe: Moderate: Severe: Deep to water Large stones, Slope, Large stones, Catoctin seepage, seepage, no water. droughty, large stones, slope, slope. piping, depth to rock. depth to rock. droughty. large stones. 14B Moderate: Severe: Severe: Deep to water Slope Erodes easily Erodes easily. Chester seepage, piping. no water. slope. 14C, 14D, 14E, 15C, 15D, 15E---- Severe: Severe: Severe: Deep to water Slope Slope, Slope, Chester slope. piping. no water. erodes easily. erodes easily. 16 Moderate: Severe: Moderate: Flooding Wetness, Wetness Wetness. Chewacla seepage. piping, slow refill. flooding. wetness. 17 Severe: Severe: Severe: Deep to water Large stones, Large stones, Large stones, Craigsville seepage. seepage, no water. droughty. too sandy. droughty. large stones. 18B Slight Severe: Severe: Peres slowly, Wetness, Wetness, Peres slowly. Creedmoor hard to pack. no water. slope. percs slowly. peres slowly. 19B Moderate: Moderate: Severe: Deep to water Slope, Erodes easily Erodes easily. Cullen seepage, hard to pack. no water. erodes easily. slope. 19C, 19D Severe: Moderate: Severe: Deep to water Slope, Slope, Slope, Cullen slope. hard to pack. no water. erodes easily. erodes easily. erodes easily. 20B3 Moderate: Moderate: Severe: Deep to water Slope, Erodes easily Erodes easily. Cullen seepage, hard to pack. no water. erodes easily. slope. 20C3, 20D3 Severe: Moderate: Severe: Deep to water Slope, Slope, Slope, Cullen slope. hard to pack. no water. erodes easily. erodes easily. erodes easily. cn O. See footnote at end of table. Cn m • cD TABLE 13.--WATER MANAGEMENT--Continued Limitations for-- Features affecting-- Soil name and Pond Embankments, Aquifer-fed Terraces map symbol reservoir dikes, and excavated Drainage Irrigation and Grassed areas levees ponds diversions waterways 51B Severe: Severe: Severe: Deep to water Large stones, Large stones, Large stones, Manteo depth to rock. piping. no water. depth to rock, depth to rock. depth to rock. slope. 51C, 51D, 51E Severe: Severe: Severe: Deep to water Large stones, Large stones, Large stones, Manteo depth to rock, piping. no water. depth to rock, depth to rock, depth to rock, slope. slope. slope. slope. 52D, 52E Severe: Severe: Severe: Deep to water Large stones, Large stones, Large stones, Manteo depth to rock, piping, no water. depth to rock, depth to rock, depth to rock, slope. large stones. slope. slope. slope. 53B Moderate: Severe: Severe: Deep to water Slope Favorable Favorable. Masada seepage, hard to pack. no water. slope. 53C Severe: Severe: Severe: Deep to water Slope Slope Slope. Masada slope. hard to pack. no water. 54B Moderate: Severe: Severe: Deep to water Slope Favorable Favorable. Mayodan seepage, hard to pack. no water. slope. 54C Severe: Severe: Severe: Deep to water Slope Slope Slope. Mayodan slope. hard to pack. no water. 55B Moderate: Moderate: Severe: Deep to water Peres slowly, Erodes easily, Erodes easily, McQueen slope. piping. no water. slope, percs slowly. percs slowly. erodes easily. 56B Severe: Severe: Moderate: Deep to water Slope, Erodes easily Erodes easily. Meadowville seepage. piping. deep to water, erodes easily. slow refill, depth to rock. 56C Severe: Severe: Moderate: Deep to water Slope, Slope, Slope, Meadowville seepage, piping. deep to water, erodes easily. erodes easily. erodes easily. slope. slow refill, depth to rock. 57B Severe: Severe: Severe: Peres slowly, Wetness, Wetness, Wetness, Mount Lucas seepage. piping, no water. frost action, percs slowly, percs slowly. percs slowly. wetness. slope. slope. 58B4. Moderate: Moderate: Severe: Deep to water Slope, Erodes easily Erodes easily. Myersville seepage, thin layer, no water. erodes easily. slope. piping. 58C, 58D, 58E Severe: Moderate: Severe: Deep to water Slope, Slope, Slope, Myersville slope. thin layer, no water. erodes easily. erodes easily. erodes easily. piping. o 0) C See footnote at end of table. r f v Albemarle County, Virginia 25 2 tests, and controlled grazing are useful in pasture 20 inches in the Cataska soil and to more than 30 management. inches in the Hartleton soil. The surface layer and Potential productivity for trees is low for the Cataska subsoil are commonly very strongly acid or strongly acid, soil and moderately high for the Hartleton soil. The soils unless limed. are managed mostly for pine. The survival of seeds and Most areas of this complex are in woodland. seedlings is severely affected by droughtiness during the This complex is not suited to hay and cultivated crops. growing season. Logging roads and skid trails should be Large stones and steep slopes make the use of modern constructed on the contour to reduce the concentration tillage equipment impractical. The soils are droughty of runoff and help control erosion. The slope limits the during the growing season. The hazard of erosion is a safe operation of heavy equipment. major management concern. Depth to bedrock and slope are the main limitations This complex is poorly suited to pasture crops. for nonfarm uses of this complex. Maintaining a mixture of grasses and legumes and This complex is in capability subclass VIIs. overgrazing are major pasture management concerns. Proper stocking rates to maintain desirable grasses and 11E—Cataska-Hartleton very stony loarns, 25 to 60 legumes, addition of lime and fertilizer according to soil percent slopes. This complex consists of steep to very tests, and controlled grazing are useful in pasture steep, excessively drained and well drained, moderately management. deep and deep soils on side slopes. Stones, 3 to 10 feet Potential productivity for trees on this complex is low rs apart, cover 3 to 15 percent of the surface. Slopes are smooth and about 500 to 1,000 feet long. Areas of this for the Cataska soil and moderately high for the complex are along the mountain ranges and are long Hartleton soil. The soils are managed mostly for pine. and winding. They range from 20 to about 100 acres. The survival of seeds and seedlings is severely affected This complex is about 60 percent Cataska soils and 30 by droughtiness during the growing season. Logging percent Hartleton soils. Other soils make up the rest. roads and skid trails should be constructed on the The areas of individual soils are so small or so contour to reduce the concentration of runoff and help intermingled that to separate them in mapping was not control erosion. The slope limits the safe operation of practical. heavy equipment. Typically, the surface layer of the Cataska soil is very Depth to bedrock and slope are the main limitations dark grayish brown and brown channery loam about 5 for nonfarm uses of this complex. inches thick. The subsoil is yellowish brown, friable very This complex is in capability subclass Vlls. channery silt loam about 15 inches thick. The substratum 12C—Catoctin silt loam, 7 to 15 percent slopes. is about 18 inches thick. It is 90 percent phyllite and shale fragments coated with yellowish brown silt loam. This soil is moderately deep, strongly sloping, and well Hard phyllite and shale are at a depth of 38 inches. drained. It is on side slopes and narrow convex Typically, the surface layer of the Hartleton soil is ridgetops. Areas are irregularly elongated and range from yellowish brown channery loam about 7 inches thick. 5 to about 20 acres. The subsoil is yellowish brown and brownish yellow Typically, the surface layer is dark brown and dark channery and very channery loam about 25 inches thick. yellowish brown silt loam about 5 inches thick. The The substratum is about 12 inches thick. It is brownish subsoil is about 13 inches thick. It is strong brown very yellow extremely channery loam. Hard phyllite and shale channery silt loam containing pockets of reddish brown are at a depth of 44 inches. silty clay loam. The substratum below a depth of 18 Included with these soils in mapping are small areas, inches is yellowish brown extremely channery silty loam. generally less than 3 acres in size, of well drained Hard greenstone bedrock is at a depth of 28 inches. Tusquitee soils. The Tusquitee soils are along small Included with this soil in mapping are small areas of streams and in valleys. Also included are small areas of well drained Myersville, Rabun, and Starr soils. The soils that have an extremely stony surface layer, areas Myersville and Rabun soils are throughout the mapped that have outcrops of rock, and small areas that do not area. The Starr soils are on foot slopes and along small have stones on the surface. The included soils and drainageways. Also included are small areas that have outcrops make up about 10 percent of mapped areas. outcrops of rock and areas that have slopes of less than Permeability is moderately rapid or rapid in the 7 percent. The included soils and outcrops make up Cataska soil and moderate or moderately rapid in the about 20 percent of mapped areas. Hartleton soil. The available water capacity is very low Permeability is moderately rapid, and available water for the Cataska soil and moderate for the Hartleton soil. capacity is very low. Surface runoff is rapid. The hazard Surface runoff is very rapid. The hazard of erosion is of erosion is severe. This soil has good tilth. The subsoil very severe. The natural fertility and organic matter has low shrink-swell potential. The root zone is 20 to 30 content are low. The subsoil has low shrink-swell inches thick. The organic matter content is low to Potential. The root zone extends to a depth of less than moderate, and the natural fertility is medium. This soil 26 Soil Surve' commonly is strongly acid to slightly acid, unless limed. Permeability is moderately rapid, and available water Depth to bedrock is 20 to 40 inches. capacity is very low. Surface runoff is rapid. The hazard Most areas of this soil are in woodland. A few areas of erosion is severe. This soil has good tilth. The subsoil are in pasture. has low shrink-swell potential. The root zone is 20 to 30 This soil is moderately well suited to cultivated crops. inches thick. The organic matter content is low to Crop response to lime and fertilizer is limited by the very moderate, and natural fertility is medium. This soil is low available water capacity. Conservation tillage, using commonly strongly acid to slightly acid. Depth to bedrocl cover crops and grasses and legumes in the cropping is 20 to 40 inches. system, and returning crop residue to the soil help to Most areas of this soil are in woodland. A few areas maintain organic matter content and control erosion. are in pasture. They also improve tilth, infiltration, and fertility and This soil is poorly suited to cultivated crops. Crop increase the available water capacity. response to lime and fertilizer is limited by the very low This soil is moderately well suited to pasture and hay available water capacity. Conservation tillage, using crops. Establishing and maintaining a mixture of adapted cover crops, grasses and legumes in the cropping grasses and legumes, the use of proper stocking rates, system, and returning crop residue to the soil help to controlled grazing, and the use of lime and fertilizer maintain organic matter content and control erosion. according to soil tests help increase the carrying They also improve tilth, infiltration, and fertility and capacity of pasture. Overgrazing causes compaction of increase the available water capacity. the surface layer, reduces plant growth, and increases This soil is moderately well suited to pasture and hay runoff and erosion. crops. Establishing and maintaining a mixture of adapted The potential productivity for trees on this soil is grasses and legumes, the use of proper stocking rates, moderate for oaks and pines. Seeds and seedlings controlled grazing, and the use of lime and fertilizer survive and grow well if competing vegetation is according to soil tests help increase the carrying controlled. The conditions for survival and growth can be capacity of pasture. Overgrazing causes compaction of improved by good site preparation, including cutting, the surface layer, reduces plant growth, and increases spraying, mowing, and girdling. Slope and erosion are runoff and erosion. the major hazards or limitations to the growing and harvesting of trees. The potential productivity for trees on this soil is This soil is limited for most nonfarm uses. Slope, depth moderate for oaks and pines. Seeds and seedlings to bedrock, and seepage are limitations for sanitary survive and grow well if competing vegetation is facilities. Slope and depth to bedrock are limitations for controlled. The conditions for survival and growth can be most building sites. Because of slope and droughtiness improved by good site preparation, including cutting, this soil is poorly suited to lawns, landscaping, and golf spraying, mowing, and girdling. Slope and erosion are fairways. Depth to bedrock limits its use as a source of the major hazards or limitations to the growing and roadfill. This soil is limited for most recreational harvesting of trees. development. Slope limits its use for playgrounds. This This soil is limited for most nonfarm uses. Slope, depth soil is good for use as openland wildlife habitat and fair to bedrock, and seepage are limitations for sanitary for use as woodland wildlife habitat. facilities. Slope and depth to bedrock are limitations for This soil is in capability subclass Ille. most building sites. Because of the moderately steep slopes this soil is poorly suited to lawns, landscaping, 12D—Catoctin silt loam, 15 to 25 percent slopes. and golf fairways. Slope, excess fines, and depth to This soil is moderately deep, moderately steep, and well bedrock limit its use as a source of roadfill. This soil is drained. It is on side slopes. Areas are irregularly limited for most recreational development. Slope limits its elongated and range from 5 to about 50 acres. use for playgrounds. This soil is good for use as Typically, the surface layer is dark brown and dark openland wildlife habitat and fair for use as woodland yellowish brown silt loam about 5 inches thick. The wildlife habitat. subsoil is about 13 inches thick. It is strong brown very This soil is in capability subclass IVe. channery silt loam containing pockets of reddish brown silty clay loam. The substratum below a depth of 18 12E—Catoctin silt loam, 25 to 45 percent slopes. inches is yellowish brown extremely channery silt loam. This soil is moderately deep, steep, and well drained. It Hard greenstone bedrock is at a depth of 28 inches. is on side slopes. Areas are irregularly elongated and Included with this soil in mapping are small areas of range from 5 to 50 acres or more. well drained Myersville, Rabun, and Starr soils. The Typically, the surface layer is dark brown and dark Myersville and Rabun soils are throughout the mapped yellowish brown silt loam about 5 inches thick. The area. The Starr soils are on foot slopes and along small subsoil is about 13 inches thick. It is strong brown very drainageways. The included soils make up about 20 channery silt loam containing pockets of reddish brown percent of mapped areas. silty clay loam. The substratum below a depth of 18 88 Soil Survey i ili ,;. and wetness commonly interferes with early tillage. 40 inches. The organic matter content is low to Conservation tillage, use of cover crops, including moderate, and the natural fertility is medium. This soil ill grasses and legumes in the cropping system, and commonly is very strongly acid to medium acid I returning crop residue to the soil help to maintain organic throughout, but reaction in the surface layer and upper matter content and tilth, reduce crusting, and increase part of the B horizon is variable because of local liming. water infiltration. Bedrock is generally at a depth of more than 5 feet. This soil is well suited to most pasture and hay crops. Most areas of this soil are farmed or in pasture and I Alfalfa commonly is short lived because of seasonal hay crops. Some areas are in woodland. f wetness. Establishing and maintaining a mixture of This soil is well suited to cultivated crops. When lime r. grasses and legumes, the use of proper stocking rates, and fertilizer are applied according to soil tests, crops controlling grazing, and the use of lime and fertilizer respond well. Minimum tillage, use of cover crops, according to soil tests help increase the carrying including grasses and legumes in the cropping system, capacity of pasture. Overgrazing or grazing when the soil and returning crop residue to the soil help to maintain is wet causes compaction of the surface soil and organic matter content and tilth and help to control i damages stands of grasses and legumes. erosion, reduce crusting, and increase water infiltration. i ? Potential productivity for trees on this soil is high, I especially for loblolly pine, yellow-poplar, sweetgum, and This soil is well suited to pasture and hay crops. oaks. Seeds and seedlings survive and grow well. The Establishing and maintaining a mixture of grasses and soil is soft when wet, and the use of heavy equipment is legumes, use of proper stocking rates, controlled razin and use of lime and fertilizer accordingto soil limited during wet periods. g g, tests help increase the carrying capacity of pasture. i, Shallow depth to the seasonal high water table, moderate shrink swell potential, clayey subsoil, and slow Overgrazing causes compaction of the surface soil and I- permeability of the subsoil are the main limitations for increases runoff and erosion. nonfarm uses. The seasonal high water table and Potential productivity for trees on this soil is very high. moderate shrink-swell potential limit use of this soil as a The soil is managed mostly for hardwoods. Seeds and ; building site. The slowly permeable, clayey subsoil and seedlings survive and grow well if competing vegetation i are limitations for most sanitary is controlled. Black walnut, yellow poplar, and loblolly I the seasonal wetness pine grow well on this soil. facilities. The seasonal wetness is a limitation for ! , 1 recreational development. Wetness and excess fines The moderately permeable subsoil and depth to rock limit the use of the soil as a source of roadfill. are the main limitations for nonfarm uses. The moderate This soil is in capability subclass Ile. permeability and depth to rock limit use of this soil for sex some sanitary facilities. Slope and the easily erodible IIIMEMyersville silt loam, 2 to 7 percent slopes. surface layer are limitations for some recreational areas. 1 This deep, gently sloping, well drained soil is on narrow, The low strength and excess fines limit use of the soil as weakly convex ridgetops. Slopes are smooth and 100 to a source of roadfill. I 300 feet long. Areas of this soil range from 3 to about 25 This soil is in capability subclass Ile. f acres. Typically, the surface layer of this soil is dark brown 58C—Myersville silt loam, 7 to 15 percent slopes. and brown silt loam about 7 inches thick. The subsoil is This deep, strongly sloping, well drained soil is on mostly yellowish red silty clay loam and silt loam about narrow, convex ridgetops and side slopes. Slopes are 29 inches thick. The substratum to a depth of at least 65 smooth and 100 to 400 feet long. Areas of this soil inches is mostly weathered greenstone in shades of range from 3 to about 30 acres. brown, yellow, red, and black that crushes to silt loam. Typically, the surface layer of this soil is dark brown Included with this soil in mapping are small areas of and brown silt loam about 7 inches thick. The subsoil is well drained Catoctin, Fauquier, and Rabun soils. The mostly yellowish red silty clay loam and silt loam about Catoctin soils are near the breaks to steeper slopes and 29 inches thick. The substratum to a depth of at least 65 1 around outcrops of rock. The Fauquier and Rabun soils inches is mostly weathered greenstone in shades of are scattered throughout the mapped area. Also included brown, yellow, red, and black that crushes to silt loam. are small areas of soils that have stones on the surface Included with this soil in mapping are small areas of and severely eroded soils that have a yellowish red silty well drained Catoctin, Fauquier, and Rabun soils. The clay loam surface layer. The included soils and outcrops Catoctin soils are near the breaks to steeper slopes and make up about 20 percent of mapped areas. around outcrops of rock. The Fauquier and Rabun soils Permeability and available water capacity are are scattered throughout the mapped area. Also included moderate. Runoff is medium. The hazard of erosion is are small areas of soils that have stones on the surface A' moderate. This soil has good tilth. The surface layer is and severely eroded soils that have a yellowish red silty friable and easily tilled. The subsoil has low shrink-swell clay loam surface layer. The included soils and outcrops potential. The root zone extends to a depth of at least make up about 20 percent of mapped areas. I.