Embed Size (px)
Citation preview
ADOA01 269 RUMMEL KELEPPER AND KAHL dIALTIMORE MD F/G 13/13
NATIONAL DAM INSPEC TION PROGRAM. COLUMBIA LNG (NOI ID NUMBER MO -ETC (U)
JUlL AG E J ZEIGLER DACMD BI -0C 0050
N C L IF iEG NL
WILOUR CREEK. CALVERT COUNTY
MARYLAND LE'NDI ID NO MD- 116
COLUMBIA LNG CORPORATION
I < PHASE I INSPECTION REPORTNATIONAL DMINSPECCTIOhNPOGA
Prepared ForDEPARTMENT OF THE ARMY
Baltimore District, Corps of Engineersco Baltimore, Maryland 21203
ByRUMr'IELKLEPPER & KAHL
~ ~O ~Consulting Engineers
49q' Baltimore, Maryland 21202
PHESAPEAKE BA
WjLBUR_0EEK, -LVERTCUNTY)
pLMIAN
PHASE I INSPECTION REPORT
Prepared for: . ' .
DEPARTMENT OF THE ARMYBaltimore District Corps of Engineers
Baltimore, Maryland 21203
By:RUMMEL, KLEPPER & KAHLConsulting Engineers1035 N. Calvert Street
Baltimore, Maryland 21202
July 1980
S. s .
I,-
PREFACE
This report is prepared under guidance contained in the RecommendedGuidelines for Safety Inspection of Dams, for Phase I Investigations.Copies of these guidelines may be obtained from the Department of theArmy, Office of Chief of Engineers, Washington, D.C. 20314.
The purpose of a Phase I investigation is to identify expeditiouslythose dams which may pose hazards to human life or property. Theassessment of the general condition of the dam is based upon visualIobservations and review of available data. Detailed investigations andanalyses involving topographic mapping, subsurface investigations,material testing, and detailed computational evaluations are beyond thescope of a Phase I investigation; however, the inspection is intended toidentify any need for such studies which should be performed by theowner.
* In reviewing this report, it should be realized that the reported con-dition of the dam is based on observations of field conditions at thetime of inspection along with data available to the inspection team. Incases where the reservoir was lowered or drained prior to inspection,such action, while improving the stability of the dam, removes thenormal load on the structure and may obscure certain conditions whichmight otherwise be detectable if inspected under the normal operatingenvironment of the structure.
it is important to note that the condition of the dam depends on numer-ous and constantly changing internal and external factors which areevolutionary in nature. It would be incorrect to assume that thepresent condition of the dam will continue to represent the condition ofthe dam at some point in the future. Only through frequent inspectionscan unsafe conditions be detected and only through continued care andmaintenance can these conditions be prevented or corrected.
Phase I inspections are not intended to provide detailed hydrologic andhydraulic analyses. In accordance with the established Guidelines, thespillway design flood is based on the estimated "Probable MaximumFlood" for the region (greatest reasonably possible storm runoff), orfractions thereof. The spillway design flood provides a measure ofrelative spillway capacity and serves as an aid in determining the needfor more detailed hydrologic and hydraulic studies, considering thesize of the dam, its general condition and the downstream damage poten-tial.
The assessment of the conditions and recommendations was made by theconsulting engineer in accordance with generally and currently acceptedengineering principles and practices.
CHESAPEAKE BAY
WILBUR CREEK, CALVERT COUNTY
MARYLAND
COLUMBIA LNC
NDI ID NO. MD-116
COLUMBIA LNG CORPORATION
PHASE I INSPECTION REPORT
NATIONAL DAM INSPECTION PROGRAM
July 1980
CONTENTS
Description Page
SECTION I - Project Information. I
SECTION 2 - Design Data 6
SECTION 3 - Visual Inspection 8
SECTION 4 - Operational Procedures 10
SECTION 5 - Hydrology and Hydraulics 11
SECTION 6 - Structural Stability 15
SECTION 7 - Assessment, Recommendations, and 16
Proposed Remedial Measures
APPENDICES
Appendix Title .
A Visual Inspection ChecklistB Engineering Data Checklist -
C Photographs-D Hydrology and HydraulicsE Plates
AV -!:,
SGeology Dit
L W W
w PHASE I INSPECTION REPORTRATIONAL DAM INSPECTION PROGRAM
BRIEF ASSESSMENT OF GENERAL CONDITIONAND RECOMMENDED ACTION
Name of Dam: Columbia LNGNDI ID NO. mD-116
Size:Main Damn: Intermediate (830 acre-feet, 74 feet high)Secondary Dam: Small (27 acre feet, 34 feet high)
Hazard Classification:Main Dam: HighSecondary Dam: Significant
Owner: Columbia LNG Corporation20 Montchanin RoadWilmington, Delaware 19807
State Located: MarylandCounty Located: CalvertStream: Wilbur CreekDate of Inspections: July 2, 1980 and August 5, 1980
* Based on the visual inspection, avail-able records, past opera-tional performance, and in accordance with the guideline criteria estab-lished for these studies, Columbia LNG is judged to be in fair condition.
The facility inspected at Columbia LNG is a complex consisting of amain dam and a secondary dam. The dams were completed in 1974 to retainspoil generated during the dredging of a trench for a tunnel to beconstructed to an offshore docking facility in the Chesapeake Bay. Thetunnel provides access to the docking facility and contains twopipelines used to convey liquified natural gas from the docking facilityto storage tanks onlshore. Dredged spoil was directed into the mainimpoundment where it was retained while larger sediments settled out ofsuspension. Partially clarified water was directed through a drop inletspillway into the secondary impoundment right of the right abutment ofthe main dam. In the secondary impoundment, additional retention timewas provided for fine sediments to settle out of suspension.Sufficiently clarified water was directed from the secondary impoundmentback to the Chesapeake Bay through a drop inlet spillway and pipelinethrough the embankment.
Dredging for the tunnel was completed in 1974, and currently theonly inflow into thie main impoundment is surface runoff from the drainagearea and precipitation directly on the lake. Inflow into the secondaryimpoundment is overflow from the main impoundment, precipitationdirectly on the lake, and a minor amount of surface runoff.
'q, Columbia LNGNDI ID NO. MD-116
The water level behind the main dam varies, but during normal flowthe pool level is controlled by the principal spillway weir notch crestat elevation +76.2. The principal spillway is located just upstream ofthe right abutment of the dam. The water level in the secondaryimpoundment is normally maintained at +49.2, weir notch crest elevationof the drop inlet spillway which is located near the center of theupstream embankment.
A minor amount of erosion was noted along the waterline of theupstream slope of the main embankment. No slope protection is provided onthe upstream slope of either the main or secondary dams. An erosiongully was noted along the left abutment-of the main dam, approximatelyhalf way up the slope. Two seepage areas were noted near the toe of themain dam. One area is located left of the collection box and did nothave a measureable flow. The second area is approximately 120' right ofthe collection box and had an estimated flow of 2 gpm. Two seepage areaswere noted downstream of the toe of the secondary dam and left of thedownstream channel. The seepage nearest the toe flowed at an estimatedrate of 10 gpm and could represent leakage from the buried collection boxlocated in the general vicinity. The other seepage area starts approx-imately 100 feet downstream of the outlet conduit and extends approxi-mately 100 feet along the downstream channel. All seepages noted wererelatively clear and did not appear to be transporting fines.
'~According to the hydrologic and hydraulic analyses, both the mainand secondary dams will pass 100 percent of the Probable Maximum Floodwithout overtopping, and therefore the spillway of each damn isconsidered adequate.,
The following remedial measures are recommended to be accomplishedby the Owner:
1. Repair the erosion noted just above the water line along theupstream slope of the main dam.
2. Retain a Professional Engineer experienced in dam design andconstruction to investigate the sources of the seepage areasnoted near the downstream toe of the main embankment and theseepage areas located downstream of the toe of the secondarydam. The seepages should be monitored and, if necessary,should be controlled in accordance with the recommendationsof the Professional Engineer.
3. Develop a formal warning system to alert any personnel down-stream of the dam in the event of emergencies.
iv~
Columbia LNG0NDI ID NO. MD-116
Submitted by:
RUMEL, KLEPPER &KAHL
Of Af4#,Vl
~tf ~ Edward J. Zeig r, EIAssociate
AL 0 Date:
W1A,
Aprve
y
I _______
COLUMBIA LNG
W/ ' -'
Upstream Face of Main Embankment
Downstream Face of Main Embankment
vi
PHASE I INSPECTION REPORTNATIONAL DAM INSPECTION PROGRAM
COLUMBIA LNGNDI ID NO. MD-116
SECTION 1PROJECT INFORMATION
11 General.
a. Authority. The Dam Inspection Act, Public Law 92-367,authorized the Secretary of the Army, through the Corps ofEngineers, to initiate a program of inspection of damsthroughout the United States.
b. Purpose. The purpose of the dam inspection program is todetermine if the damn constitutes a hazard to human life orproperty.
1.2 Description of Project.
a. Dams and Appurtenances. The main and secondary dams of theColumbia LNG spoil embankments. are earth fill damsconstructed with compacted random fill. Each dam has achimney drain and a slurry trench cutoff wall. The main damis 744 feet high at its maximum section and is approximately670 feet long. The main dam was constructed across WilburCreek. The secondary dam is 34 feet high at its maximumsection and is approximately 230 feet long.
Inf low into the main impoundment is either from surfacerunoff from the drainage area or from precipitation fallingdirectly on the lake. -, A distinct channel for Wilbur Creekupstream of the main dam could not be identified. Inflow intothe secondary- impoundment is overflow from the mainimpoundment, precipitation falling directly on the lake, anda minor amount of surface runoff.
The flood discharge facility for the main dam consists of theprincipal spillway which is a drop inlet; The drop inletconveys overflow to the secondary impoundment through a 42inch asbestos bonded corrugated steel pipe. The principalspillway is located just upstream of the right abutment ofthe main dam.- 1The flood discharge facility for the secondarydam also consists of a drop inlet spillway. The drop inlet ofthe secondary dam conveys water through the dam embankment ina 48 inch asbestos bonded corrugated metal pipe. The'overflow is discharged into a channel containing riprap whichserves as energy dissapators. Water flows from this channelinto a fresh water marsh.
The normal pool elevations of both impoundments correspond tothe crest elevations of the respective drop inlets.
b. Location. The spoil embankment complex is located approxi-
mately 0.5 mile inland from the Chesapeake Bay and approxi-
mately 1.2 miles northwest of the Cove Point Lighthouse inCalvert County, Maryland. The Columbia LNG facility is shownon the U.S.G.S. Quadrangle, Cove Point Maryland, at latitudeN 380 23' 24", and longitude W 670 24' 6". A location map isincluded as Plate E-1.
C. Size Classification. Main dam - Intermediate (830 acre-feet,74 feet high); Secondary dam - Small (27 acre-feet, 34 feethigh).
d. Hazard Classification. High Hazard. There is a guardhouse,tunnel portal, and ventilation building for the 6400+ footlong tunnel, and liquified natural gas pipelines downstreamof the main dam which could sustain damage in a floodresulting from a dam failure. Failure of the secondary dam alsohas a potential to damage the LNG pipelines, but asignificant hazard classification is warrented.
e. Ownership. Columbia LNG Corporation, 20 Montchanin Road,Wilmington, Delaware 19807
f. Purpose of Dams. To contain spoil generated during dredgingof a trench for a liquified natural gas tunnel constructed to
an offshore docking facility.
g. Design and Construction History. Construction of the damswas completed in 1974. The dams and appurtenant structureswere designed by Woodward - Moorhouse & Associates, Inc. of
New York. The dams were constructed by C.J. Langenfelder &Son, Inc. of Baltimore, Maryland. According to the typicalsection of both embankments shown on the contract drawings,both dams are constructed of compacted random fill. Each dam
has a chimney drain and slurry trench cutoff wall.
In 1976, revisions were made to the drop inlet boxes of both
the main dam and secondary dam spillways. These revisionswere designed by Woodward-Moorhouse & Associates, Inc. of New
York, and constructed by C. J. Langenfelder & Son, Inc. ofBaltimore, Maryland.
h. Normal Operating Procedure. As they presently exist, thelakes retained by both dams are normally maintained at orjust below the crest elevation of the drop inlet spillway.
-2 _______
1.3 Pertinent Data.
a. Drainage Area.
Main Dam 0.19 square milesSecondary Dam 0.02 square miles
b. Discharge at Dam Site.
Main Dam 170 cfs outflow atelevation 87.5
Secondary Dam 178 cfs outflow atelevation 54.8
c. Elevation (Feet Above m.s.l.).
(1) Main Dam
Top of Dam 87.5 (design)87.5(1ow point on crest)
Normal Pool 76.2(Spillway notchcrest)
Upstream Invert Outlet Works 72.5
Downstream Invert Outlet Works 51.0Downstream Toe 14+Maximum Tailwater Will normally be below
the outlet invert
(2) Secondary Dam
Top of Dam 55.0 (design)54.8(low point on crest)
Normal Pool 49.2(Spillway notchcrest)
Upstream Invert Outlet Works 40.4
Downstream Invert Outlet Works 20
Downstream Toe 21+
Maximum Tailwater Wifl be below the outletinvert
d. Reservoir Length.
Normal Pool Level - Main Dam 680'
Normal Pool Level - Secondary Dam 250'
e. Storage (Acre-Feet).
(1) Main Dam
Normal Pool Level 514
Top of Dam 830
-3-
I
(2) Secondary Dam
Normal Pool Level 15Top of Dam 27
f. Reservoir Surface (Acres).
(1) Main Dam
Normal Pool 23.3Top of Pool 30.2
(2) Secondary Dam
Normal Pool 1.6Top of Dam 2.3
g. Dam.
(1) Main Dam
Type EarthfillLength 670+'Height 74+ maximumTop Width 36T
Volume of Fill 280,000+ cu. yds.Side Slopes Upstream IV:2.5H
Downstream IV:3HZoning NoneImpervious Core NoneCutoff Slurry trench cutoff wall
chimney drain inembankment
Grout Curtain None
(2) Secondary Dam
Type EarthfillLength 230+'Height 34+T maximumTop Width 307Volume of Fill 39,500+ cu. yds.Side Slopes Upstream 1V:2.5H
DownstreamTop of slope, IV:3HBottom of slope, 1V:7H
Zoning NoneImpervious Core NoneCutoff Slurry trench cutoff wall
chimney drain inembankment
Grout Curtain None
-4-
h. Outlet Works.
(1) Main Dam
Type Free flow conduitPipe Size and Material 42 inch asbestos bonded
corrugated steel pipeEntrance Invert 72.5Exit Invert 51.0Type of Energy Dissipator Stone riprap
(2) Secondary Dam
Type Free flow conduitPipe Size and Material 48 inch asbestos bonded
corrugated steel pipe
Entrance Invert 40.4Exit Invert 20.0Type of Energy Dissipator Stone Riprap
i. Principal Spillway.
(1) Main Dam
Type Drop Inlet
Crest of Elevation of 76.2Spillway Notch
Length of Spillway Notch 6 feetCrest Elevation of Spillway 76.7Length of Spillway 24 feet (including notch)
(2) Secondary Dam
Type Drop Inlet
Crest of Elevation of 49.2Spillway Notch
Length of Spillway Notch 10 feetCrest Elevation of Spillway 49.7Length of Spillway 25 feet (including notch)
-5-
SECTION 2
DESIGN DATA
2.1 Design
a. Data Available. The available information was provided bythe State of Maryland, Water Resources Administration. The
information includes contract drawings dated May 15, 1973,and the design report entitled, Erosion and Sediment ControlMeasures at LNG Receiving 'Terminal Site, Cove Point,Maryland, revised May 30, 1973. As-built drawings ofrevisions made to the main and secondary spillways dated 1976were available at the Columbia LNC plant.
(1) Hydrology and Hydraulics. Hydrologic and hydraulic cal-culations for the dams are included in the design report.
(2) Embankment. Design calculations and results of the sub-
surface investigations are summarized in the designreport.
(3) Appurtenant Structures. The structural details of theappurtenant structures are shown on the contract drawingsdated 1973. The revisions made to the drop inlet boxes ofboth the main and secondary dams are shown on the 1976 as-built drawings available at the Columbia LNG plant.
b. Design Features.
(1) Embankment. The main dam was constructed across WilburCreek and the secondary dam was constructed across asmall valley right of the main dam. An extensive sub-surface investigation was conducted under the supervisionof Woodward-Moorhouse & Associates, Inc., to evaluate thefoundation conditions of the dam and to locate borrowsources.
The typical sections for both dams shown on the contractdrawings indicate that the dams are constructed ofcompacted random fill. Constructed along the center ofeach dam is a chimney drain, and constructed along the.upstream side of each chimney drain is a slurry trenchcutoff wall. Drainage from the chimney drains iscollected in abutment filters in the embankment anddirected into a collection box located just beyond thetoe of the embankment of each dam. The collection box forthe main dam was accessible, but the collection box forthe secondary dam was buried. Drainage is directed fromthe toe collection boxes to a third collection boxthrough 8 inch diameter steel pipes. From thiscollection box, the drainage is discharged into the
fresh water marsh. A 3 foot deep main spillway filter wasconstructed adjacent to the right abutment of the maindam to intercept any water that may seep around the rightabutment of the dam. Typical sections of the dams areshown on copies of the contract drawings included inAppendix E.
Piezometers were installed on the crest and on the down-stream slope of both dams to monitor the water level inthe embankment both during and after the dredging opera-tion. Seventeen piezometers were installed in the maindam and three piezometers were installed in the secondarydam. Personnel at the Columbia LNG facility continuallycheck and record the water levels in the piezometers.
(2) Appurtenant Structures. The appurtenant structures ofeach dam consist of a principal spillway which includes adrop inlet and the outlet works. The drop inlet of themain dam conveys overflow into the secondary impoundmentthrough a 42 inch corrugated steel pipe. The drop inletof the secondary dam conveys overflow through the embank-ment in a 48 inch corrugated steel pipe. The contractdrawings indicate that the 48 inch pipe has three anti-seepage collars.
c. Design Data.
(1) Hydrology and Hydraulics. Design data are included inthe design report.
(2) Embankment. Design data are included in the designreport and on the contract drawings.
2.2 Construction. Construction of the dams was completed in 1974.Revisions were made to the drop inlet boxes of both dam spillwaysin 1976. As-built drawings are available at the Columbia LNGplant.
2.3 Operation. The only records maintained by the owner are waterlevels regularly recorded in the piezometers on both the main andsecondary dams.
2.4 Other Investigatons. An engineer from the Wilmington office ofthe Columbia LNG Corporation conducts an inspection of both damsand appurtenant structures annually.
2.5 Evaluation.
a. AvailabiLity. The design report and the contract drawingsare available, and the as-built drawings of revisions made tothe main and secondary dam spillways was available at theColumbia LNG Plant.
b. Adequacy. The available data is considered sufficient to
evaluate the design and construction of the dams.
-7-
SECTION 3
VISUAL INSPECTION
3.1 Findings.
a. General. The on site inspection of each Columbia LNG spoilembankent consisted of:
(1) Visual inspection of the embankment, abutments, andembankment toe.
(2) Visual examination of the appurtenant structures.
(3) Evaluation of the downstream area hazard potential.
The specific observations are shown on Plate A-I.
b. Embankment. The general inspection of each embankmentconsisted of searching for indications of structural dis-tress, such as cracks, subsidence, bulging, wet areas, seepsand boils, and observing general maintenance conditions,vegeiative cover, erosion, and other surficial features.
(1) Main Dam. Minor erosion was noted on the upstream slopealong the waterline. There is no slope protection on theupstream slope. An erosion gully was noted along theleft abutment approximately half way up the slope. Asmall seepage of immeasurable flow area was noted nearthe downstream toe left of the collection box. Thesource of the seepage is not evident. Another seepagearea was noted near the toe of the dam approximately 120
feet right of the collection box. The estimated flowrate of the seepage was 2 gptn.
The crest of the dam was surveyed and the variance inelevation was 18 inches between the high and low points.Also, the low point on the crest corresponds to thedesign crest elevation of the main dam, +87.5. Freeboardat the time of inspection was approximately 13.5 feet.The dam crest profile is included on Plate A-2.
(2) Secondary Dam. Two seepage areas were noted downstreamof the toe and left of the drainage channel. The seepagearea nearest the toe has an estimated flow rate of 10 gpm,is located near a buried collection box, and could beassociated with leakage from the box. The second seep islocated approximatley 100' downstream of toe and extendsalong the drainage channel for 100'. The water flowingfrom both seepage areas was clear.
-8- 4
The crest of the dam was surveyed and the variance inelevation was 12 inches between the high and low points.Also, the low point on the crest is 2.5 inches below thedesign crest elevation of the secondary dam which is +55.Freeboard at the time of inspection was approximately 8feet. The dam crest profile is included on Plate A-3.
c. Appurtenant Strucuture8. The appurtenant structures werefound to be in satisfactory condition. The collection boxlocated at the toe of the secondary dam should be uncoveredand checked for possible leakage.
d. Reservoir Area. In general, the reservoirs of both dams aresurrounded by heavily grassed or wooded areas.
e. Downstream Channel. The structures downstream from the maindam include a guar-dhouse, the tunnel portal and ventilationbuilding for the underwater tunnel to the docking facility,and two above ground liquified natural gas pipelines. If themain dam failed, the resulting flood could damage thesefacilities. The downstream channel of the secondary damempties into a fresh water marsh. If the secondary damfailed, the resulting flood could damage the facilities noteddirectly downstream of the main dam. However, based on ourvisual observations, damages sustained from a failure of thesecondary dam would be significantly less than damagessustained by a failure of the main dam. Consequently, a highhazard classification is warranted for the main dam and asignificant hazard classification is warranted for thesecondary dam.
3.2 Evaluation. The visual examination and observations of theColumbia LNG spoil embankments indicate that both dams are in faircondition and the appurtenant structures are in good condition.It is recommended that the minor erosion on the upstream slope ofthe main dam be repaired. A Professional Engineer experienced indam design and construction should be retained to investigate thesources of the seepage noted along or beyond the toes of the maindam and the secondary dam and to recommend measures forcontrolling the seepages if they are related to the dams.
SECTION 4OPERATIONAL FEATURES
4.1 Procedure. There are no formal operating procedures for eitherdam. The pool level of each reservoir is normally maintained at orjust below the weir crest elevation of the drop inlet spillways.
4.2 Maintenance of the Dams. Maintenance of the dams is considered tobe fair. The downstream slopes of both dams and the upstream slopeof the secondary dam are moved regularly. Each dam is subjected toa thorough in house inspection annually.
4.3 Maintenance of Operating Facilities. The maintenance of theoperating facilities is considered to be satisfactory.
4.4 Warning System No formal warning system exists for alertingpersonnel downstream of the dams in the case of any emergency.
4.5 Evaluation. The overall maintenance condition of the dams and theappurtenant structures is considered to be satisfactory.
-10-
SECTION 5HYDRAULICS AND HYDROLOGY
5.1 Evaluation of Features.
a. Design Data. The revised May 30, 1973 report, Erosion andSediment Control Measures at LNG Receiving Terminal Site,Cove Point Maryland, indicates that the design of the mainimpoundment spillway was based upon an inflow design flood of212 cubic feet per second (cfs) resulting from a 100-year, 6-hour storm of 6.5 inches over the impoundment drainage areaof 0.19 square miles. The report indicates that thesecondary impoundment, which receives most of its inflow fromthe spillway outletting from the main impoundment, has aspillway capacity sized for an inflow design flow of 230 cfs.The drainage area tributary directly to the secondaryimpoundment is 0.02 square miles and the combined secondaryimpoundment drainage area including that of the mainimpoundment totals 0.21 square miles.
b. Experience Data. No records of maximum pool levels areavailable.
c. Visual Observations. Several observations made during thevisual inspection of the Columbia LNG impoundments areparticularly relevant to the hydraulic and hydrologicalevaluations.
(1) Embankments. The survey 'of the existing dam crestprofiles performed during the visual inspection indicatesthat the main impoundment crest lies at or slightly aboveits design elevation with the low point equalling itsdesign crest elevation of 87.5 feet above mean sea level.While the crest level of the secondary impoundment isgenerally higher than its design elevation of 55 feetabove m.s.l., the field survey indicates the crest lowpoint to be 0.2 below the dam crest design elevation.Crest profiles established from these inspections wereemployed in subsequent hydraulic analyses.
(2) Appurtenant Structures. The drop inlet spillwaysobserved during the visual inspection for the main andsecondary impoundments have not been constructed in con-formance with the spillways shown on the May, 1973contract drawings for the dam itself. It was learnedduring the visual inspection that the overflow weirstructures were constructed in 1976, or two yearsfollowing completion of the dam embankments. Ratingcurves which reflect these as-built conditions have beenderived for the drop-inlet spillways and outlet works and
are employed in subsequent hydraulic analyses.
At the time of the visual inspection it was observed thatpool levels behind both the main and secondary embank-ments were several feet below the level of the impound-ment spillways. It was observed that spillway and outletworks for both of these impoundments were free of debrisand were dry.
(3) Downstream Conditions.. While there are no dwellingsdownstream from the Columbia LNG spoils impoundment com-plex, the portal structure for the tunnel which connectsthe liquified natural gas plant with the offshore dockingand unloading facilities lies directly in the path of themain dam at a distance of only 500 feet from itsdownstream toe, and therefore is susceptible to seriousdamage in the event of a failure of the main damembankment. The potential for loss of human lives existsat this location since security personnel regularlypatrol the tunnel entrance. In addition the liquifiednatural gas transmission mains which exit from the tunnelportal and travel overland to the LNG storage facilitieswould also be vulnerable to serious damage should a
failure of the main impoundment occur. Failure of thesecondary dam may result in some damage to the abovementioned facilities causing an interruption of their usebut, because these facilities are not in direct line withthe secondary embankment, the potential *for seriousdamage of these facilities is significantly less than thedamage potential resulting from failure of the primaryimpoundment. In keeping with the potential hazardclassification criteria established by the Office of theChief of Engineers (OCE), these downstream conditionssuggest that a "high" classification be assigned to themain dam of the Columbia LNG impoundment complex and a"'significant" classification be assigned to the secondarydam.
d. Overtopping potential. According to the criteria promulgatedby the Office of the Chief of Engineers, the recommendedSpillway Design Flood (SDF) for a dam classified as "inter-mediate" with a "high" hazard potential, such as the maindam, is 100 percent of the Probable Maximum Flood (PMF) andthe recommended SDF for a dam classified as "small" with a"ssignificant" hazard potential, such as the secondary dam,ranges between a 100-year flood and 50 percent of the PMF.The Probable Maximum Precipitation (PMi') index as adjustedfor the LNG impoundment complex drainage area is 20.0 inchesin 24 hours.
(1) Main Impoundment. Employing criteria established by theCorps of Engineers, Baltimore District, 100 percent and50 percent PMF inflow hydrographs developed using theHEC-1 computer program have peaks of 316 cfs and 158 cfs,
-12-
respectively for the main impoundment. It is importantto note that the peak flow for 50 percent of the PMFderived is significantly less than the 212 cfs designinflow previously determined in the design report for a100-year storm. This disparity is understandable sinceit is recognized that the Snyder method of synthetic unithydrograph determination employed in the HEC-1 model mayproduce hydrograph peaks somewhat less than those derivedusing other methods when applied to relatively smalldrainage areas where the time of concentration isrelatively short. However, in accordance with guidanceprovided by the Corps of Engineers, Baltimore District,no adjustment have been made to the PMF's determined forthe Columbia LNG impoundment complex to account for thisdisparity.
PHF inflow hydrographs were routed through the ColumbiaLNG main impoundment for percentages ranging from 20percent of the PMF to 100 percent PMF with each routingstarting at the normal pool elevation of 76.2 feet abovem.s.l. For the 50% PMF routing, the impoundment waterlevel reached an elevation of 78.0 feet above mean sealevel or 9.5 feet below the low point in the dam crest.For the 100% PMF routing, the reservoir water levelreached an elevation of 80.8 feet above mean sea levelremaining below the low point in the dam crest at anelevation of 87.5 feet above mean sea level. See AppendixD for a tabulation of the flood routing results.
(2) Secondary Impoundment. Outflow hydrographs from the mainimpoundment, developed from the above mentioned floodroutings, were combined with inflow hydrographs developedfor the drainage area tributary only to the secondaryimpoundment to derive combined inflow hydrographs for thesecondary impoundment. The resultant combined inflowhydrographs have peaks of 137 cfs for a 100 percent PMFand 68 cfs for a 50 percent PMF.
PM? inflow hydrographs were routed through the ColumbiaLNG secondary impoundment for percentages ranging from 20to 100 percent of the PMF with each routing starting atthe normal pool elevation of 49.2 feet above m.s.l. Forthe 50 percent PMF routing, the impoundment water levelreached an elevation of 50.3 feet above m.s.l. or 4.5feet below the low point in the dam crest. For the 100percent PMF routing the impoundment water level reachedan elevation of 51.8 feet above m.s.l. remaining 3 feetbelow the low point in the secondary dam crest at anelevation of 54.8 feet above mean sea level. Results forintermediate routings are found in Appendix D.
-13-
e. Spillway Adequacy.
(1) Main Impoundment. The main impoundment of the ColumbiaLNG impoundment complex will pass 100 percent of the PMFwithout overtopping, and therefore its spillway is ratedadequate.
(2) Secondary Impoundment. The secondary impoundment of theLNG impoundment complex will pass 100 percent of the PMFwithout overtopping. Since this flood is greater thanthe Spillway Design Flood required for the secondary dam,the spillway capacity for this impoundment is ratedadequate.
-14-
SECTION 6
STRUCTURAL STABILITY
6.1 Evaluation of Structural Stability.
a. Visual Observations.
(1) Embankment..
(a) Main Dam. Of the deficiences of the main dam notedin SECTION 3, the more severe are the two seepageareas noted near the toe on either side of thecollection box. At this time, these deficienciesare not considered serious relative to the stabilityof the dam.
(b) Secondary Dam. The only deficiencies were the twoseepage areas noted downstream of the toe. Theseepages are considered extensive enough to possiblyaffect the stability of the dam if they are relatedto the dam.
We reconunend that the sources of the seepages at themain and secondary dams be investigated by aprofessional engineer experienced in the design andconstruction of dams, and that measures be taken tocontrol the seepage if they are related to the dam.
(2) Appurtenant Structures. The structural conditions of theappurtenant structures of both dams are considered to besatisfactory.
b. Design and Construction Data.
(1) Embankment. Based on the available design calculationsand the con .tract drawings, there are no conditions whichadversely affect the stability of either dam.
(2) Appurtenant Structures. The contract drawings for thedams dated 1973 were obtained from the State of MarylandWater Resources Administration and the as-built drawingsof revisions made to the main and secondary dam spillways'dated 1976 are available at the Columbia LNG Plant.
C. Operating Records. The structural stability of the dams isnot considered to be affected adversely by the operationalfeatures of the dams.
d. Seismic Stability. The dams are located in Seismic Zone 1.Based on our visual observations, the static stability ofboth dams appears to be adequate. Consequently, neitherstructure should present hazards from earthquakes.
-15-
SECTION 7
ASSESSMENT AND RECOMMENDATIONS/REMEDIAL MEASURES
7.1 Dam Assessment.
a. Assessment. The Columbia LNG main reservoir is anintermediate, high hazard impoundment and the secondaryreservoir is a small, significant hazard impoundment.Failure of the main dam embankment could cause serious damageto the liquid natural gas tunnel, portal facilities andpipelines located immediately downstream. Failure of thesecondary dam embankment could also damage these facilities,but to a lesser degree. The visual observations indicatethat both the main dam and the secondary dam are in faircondition. However, the sources of the seepage areas notednear or downstream of both dams should be investigated by aProfessional Engineer experienced in the design and construc-tion of dams. The investigating engineer should recommendmeasures of controlling the seepages if they are related toeither dam, and the owner should implement the recommendedmeasures.
Hydrologic and hydraulic analyses indicate that both the mainand secondary impoundments will pass 100 percent of the PMFwithout overtopping, and therefore the spillway capacity foreach of these dams is rated adequate.
b. Adequacy of Information. Available information, in conjunc-tion with the visual observations, is considered to besufficient to make the recommendations that are given below.
rC. Urgency. Although there is no urgency in instituting theremedial measures recommended below, the measures should beaccomplished in a timely manner.
d. Necessity for Additional Data. We recommend that the Ownerretain a qualified Professional Engineer to conduct aninvestigation to determine the source of the seepage noted ator below the toes of the main and secondary dams and torecommnend a means of controlling the seeps if they are.related to the dams.
7.2 Recoimmendations/Remedial Measures.
It is recomended that the following remedial measures beimplemented by the Owner:
So ~ he erosion noted J,~ above the water line along theslope of tbo
b. Retain a Professional Engineer experienced in dam design andconstruction to investigate the sources of the seepage areasnoted near the downstream toe of the main embankment and theseepage areas located downstream of the toe of the secondarydam. The seepages should be monitored and, if necessary,should be controlled in accordance with the recommendationsof the Professional Engineer.
c. Develop a formal warning system to alert any personnel down-stream of the dam in the event of emergencies.
-17-
APPENDIX A
VISUAL INSPECTION CHECKLIST
PHASE I
0
I r.4
t~ $4 '44 1
. 4-) 4J (A0) mT I $4
43 0 $4 0 )
4J
4-) 04 C
I.H C)zH&43
U - .
CE-iI .4j
P4z P4 4 Ow 0 ~P4 cn 4.4 0
H 4J- 0'
$4 Qj 0 I , .04'U: 0It) U E-4 ~
En co
0
rg
9) 00M4 4J
0 0a
HH
o 41 00 0 0zz
0 +
Wo
*--4
0-
.2* 0
%. -cO N
0 0
F4
oo 90 0~o t- U
00
z, 0
1 014
1E-
U) II
H U 0
> ) HnM -4w t
iu
~~i.
ut F
EqL 4- is
I- If
ci _ i
C C;~~-4 zj-
Ch-
0c0 1IvW
0*II' d30
0
VV
-4 p r
((Lk
H Ha 64.
-'0 a
a ; _ _ _ _
H2
9482
0-
to~
0I !
z 04-'
4-In
0-1
~ 00
rfb~~. .4 9 ' ~ I.. *
2U)U2 ~ q.
p. H ~4- P4
gp-~C) ~ uca
.4 an * {~in
0N
II0
I __ __ __ __
0 ~4N .u~ U2
'.40
04rz11-e 14 0Cfl 04 '~
6
p4~ r2 a'
046
ci c0 0 9 0
z z Z Z
b2 .4* .1 1 10fli 04
Li
Z 04 Co0 NU
~1*
- ~ ~ I
4- t
0. p -
0 a
AA
64-
E47 OX64-
PC~he
om,04 0
0, P4 E
S.~
0- 0 L
C A,-LH
ii
:51
E-4 -C~Qp
- x t
o 8- d ~ -
4'~""""'~ Approxim .60
Eros~rosio Alen 4 RE
-ro OFAI6Ag%
COLUMB LiNe0 00 200' 300
PAYEDBI LNGUA COPRTO
VISUAL INSPECTIOE_____ _____ _____ _____ _____ _____ _____ _____ ___ _ JUL0,901P AT1A1
PIC .
C4
21 1.- Ca -
CM - A
CDJ IIJ.
LLI-I.9=c
- ca c
-C
r.J
10
-I 5?CDD
C2LUBI LN3
PHS I INPCTOnRPR
ELEVATION DMCETSRE
__________________________________ JULY 1980 PLATE A-2
C0cmIa.-
I--L1A C1
6- - 9 2
= I- Cc
CD CIO 1*C W
C2C - j -
5-nAJ I.Ca C,
5.4
C3
L)JCZ
mc.149
4-0C
c C- 3Cac
PHASE I INSPECTION REPORTIn Wai NATIONAL OAM INSPECTION PROGRAM
COLUMBIA LNGELEVATION SECONDARY DAM
COLUMBIA LNG CORPORATION
DAM CREST SURVEY
JULY 1980 PLATE A-3
APPENDIX B
ENGINEERING DATA CHECKLIST
PHASE I
-~4w
-4-.4-
c W)-C o
H- Z- E-1 6
H
z W
HZ OZ 4 rFV
H~ 8 0 j ~-
Ci))z 0
E-4 (n H-- 8~-
E4.
In~C H04'-
00
E---o0)-
-v 4-0
H E-
-E -0~ 0i- 4aH
Z E-4 z4
HZ0
m-4-
--
0
C)C
4-co ck- 3 ,
W'4 E-4.P
HH E-4
H~DI-4 En C'
ca
Hn z020
!Z
0
-I
72; V
z" (3 .<L-.--
0 .
•4 -
0o
H H
H
E-4 0 r
cniE. 1- ,
U1 0 -I
H(~HH4-
orL3 -
q) ~ cc)
Z) E-1
H~~ tn'0-0+R o 0 A-Uoo Z H9 -
H 0 9 % -4 F4 UE-1 0H u 0 zEn n 4 WH0
E-4 0 C Wad W o(1M
APPENDIX C
PHOTOGRAPHS
otuO~~ FILTERFE~UA
~~8~STOE OFt~
C42#0 WIDDT3H
S 100' 200' 30 COLUMBI LNG CORPORATIOPAUIEE TOOLOCATION
A ~ ~ ~ ~~ TE Phoogap IdntScaioEete1~~~~~~~~~~~~~~~~~D G__________________________ JULY 190PAT)-
COLUMBIA LNG
A. Crest of main embankment
1* B. Piezometers on crest of main
embankment
C-i
COLUMBIA LNG
C. Main Spillway (drop inlet)
A0-2
___________________________________________________________ a-t2
-
COLUMBIA LNG
E. Guardhouse downstream of mainembankment
F. Crest of secondary embankment
C-3
Fa
COLUMBIA LNG
G. Upstream slope of secondary embankmentand drop inlet
V
H. Outlet pipe from secondary embankment
C-4
-a
- ' 'e
APPENDIX D
HYDRLOGY AN) YDRAULICS
BASE DATA FOR DETERMINATION OF PROBABLE
MAXIMUM FLOOD, UNIT HYDROGRAPH ANDINFLOW HYDROGRAPHS
Name of Dam: Columbia LNG Main Dam, NDI-ID MD-l16
Unit Hydrograph Parameters
Watershed Drainage Area 0.194 sq. miles
Main Channel Length, L 0.66 miles
Main Channel to Centroid Legsh, Lca 0.30 miles
Lag Time tp - Ct (L x Lca) 2.5 hours
Basin Zone Location from Unit Hydrograph
Coefficient Map 37
Basiy CoefficientsCp 0.35
Ct 4.07
Inflow Hydrograph Parameters1
Base Flow at Start of Storm 1.5 c.f.s./sq. mile
Initial Rainfall Loss I inch
Uniform Rainfall Loss 0.05 inches/hour
Ratio of Peak Discharge Used to Compute
Base Flow which Deviates from Hydrograph
Falling Limb 0.05
Ratio of Recession Flow occuring 10
Tabulation Intervals Later 2.0
Rainfall Data2
Probable Maximum Precipitation Index
for 24 hours and 200 square miles 25 inches (Zone 6)
Percentage Adjustments of PMP for
Drainage Area6 hour storm 112%
12 hour storm 123%
24 hour storm 132%
lasin Coefficients and Hydrograph Data established by Corps of
2 Engineers Baltimore District.Rydrometeorological Report 33, Corps of Engineers, 1956
D-1
BASE DATA FOR DETERMINATION OF PROBABLEMAXIMUM FLOOD, UNIT HYDROGRAPH AND
INFLOW HYDROGRAPHS
Name of Dam: Columbia LNG Secondary Dam, NDI-ID MD-116
Unit Hydrograph Parameters
Watershed Drainage Area 0.0184 sq. miles
Main Channel Length, L 0.12 milesMain Channel to Centroid Le8 gth, Lca 0.07 milesLag Time tp = Ct (L x Lca) 0.946 hoursBasin Zone Location from Unit Hydrograph
Coefficient Map 37Basiy Coefficients
Cp1 0.35
Ct 4.07
Inflow Hydrograph Parameters'
Base Flow at Start of Storm 1.5 c.f.s./sq. mile
Initial Rainfall Loss 1 inchUniform Rainfall Loss 0.05 inches/hourRatio of Peak Discharge Used to Compute
Base Flow which Deviates from HydrographFalling Limb 0.05
Ratio of Recession Flow occuring 10Tabulation Intervals Later 2.0
Rainfall Data2
Probable Maximum Precipitation Indexfor 24 hours and 200 square miles 25 inches
Percentage Adjustments of PMP forDrainage Area
6 hour storm 112%12 hour storm 123%24 hour storm 132%
Blasin Coefficients and Hydrograph Data established by Corps of
2 Engineers Baltimore District.Hydrometeorological Report 33, Corps of Engineers, 1956
D-2
Tabulation of
Reservoir Area and Storage Vs. Elevation
Name of Dam: Columbia LNG Main Dam, NDI-ID MD-116
Pool Surface1 Reservoir2
Elevation Area Storage
feet above acres acre-feet
m.s.l.
25 (Reservoir Bottom) 0 0
30 1.4 3.5
50 9.5 112
70 18.5 392
87.5 (Top of Dam) 30.2 830
90 31.8 896
Name of Dam: Columbia LNG Secondary Dam, NDI-ID MD-116
1 .2Pool Surface Reservoir
Elevation Area Storag,.
feet above acres acre-fret
m.s.l.
28 (Reservoir Bottom) 0 0
30 0.07 0.07
40 0.7 4.0
50 1.7 16.1
54.8 (Top of Dam) 2.3 27.3
60 3.0 39.4
70 4.7 77.9
Area Plainimetered from 80-scale photogrammetric mapping shown
May 15, 1973 contract drawings by Woodward-Moorhouse & Associates, Inc.
2 Computed by Rummel, Klepper & Kahl. Refer to "Reservoir Storage
Computations" on Page D-4.
D-3
RESERVOIR STORAGE COMPUTATIONS
Name of Dam: Columbia LNG , NDI-ID MD-116
MAIN DAM
ELEV. PLAINMETERED AREA AVG. INCREMENTAL ACCUMULATEDAREA AREA VOLUME VOLUME
FEET SQUARE INCHES ACRES ACRES ACRE-FEET ACRE-FEET
25 0 0 00.69 3.45
30 9.3 1.37 3.55.43 108.6
50 64.6 9.49 11214.02 280.4
70 126.0 18.54 39225.19 503.8
90 216.6 31.84 896
SECONDARY DAM
ELEV. PLAINMETERED AREA AVG. INCREMENTAL ACCUMULATEDAREA AREA VOLUME VOLUME
FEET SQUARE INCHES ACRES ACRES ACRE-FEET ACRE-FEET
28 0 0 00.0335 0.067
30 0.45 0.067 0.070.389 3.89
40 4.80 0.71 4.01.21 12.1
50 11.55 1.70 16.12.33 23.3
60 20.15 2.96 39.43.85 38.5
70 .32.24 4.74 77.9
Area plainmetered from 80-scale photogrammetric mapping shown on May
15, 1973 contract drawings by Woodward-Moorehouse and Associates, Inc.
D-4
. . . . . . ... .'.-A .
SPILLWAY/OUTLET RATING CURVE TABULATION-
Name of Dam: Columbia LNG Main Dam,. NDI-ID mD-116
6-Foot 24-FootPool Weir Notch Weir OutletElevation Capacity Capacity capacityfeet above c.f.s. c.f.s. c.f.s.
76.2 076.7 13.8 077.0 17.7 16 76.878.0 125 89.779.0 290 10180.0 491 ill184.0 1600 14588.*0 3070 17290.0 3917 184
Calculation Basics
6-Foot Weir Notch Capacity (Modified sharp crested weir with verticalupstream face)
Q = CLH1.5
Q = 3.25 x 6 x H1.5
Q = 25.2 H 1 .5, whre H = Pool Elevation 76.2
24-Foot Weir Capacity (Modified sharp crested weir with vertical
upstream face)
Q -CLH1.5
Q -3.35 x24 xH1 .5
Q - 80.4 111.5 where H - Pool Elevation =76.7*
Outlet Capacity of 42-inch Pipe (Orifice Control)
Q aCa \1 2g14
Q0.6 x 9.62 '[64.4 H
Q - 46.3 H'5,where H ftPool Elevation a74.3
Computed by Rummel, Klepper & Kahl
D-5
--- DATE~ 4 su mUJET-C Ll!-------- SHEICT NO.-! --- FA---
CHKD. BY - --- DATE ---- ------------------------------ JOB 1
MA )l DPAYn.
40 t:cq
4
-C,
0
4) RUMMEL. KLEPPER&~ KAHL * ENGINEERS
SPILLWAY/OUTLET RATING CURVE TABULATION1
Name of Dam: Columbia LNG Secondary Dam, NDI-ID MD-116
10-Foot 25-FootPool Weir Notch Weir OutletElevation Capacity Capacity Capacityfeet above c.f.s. c.f.s. c.f.s.
49.2 040.7 12.9 050.0 26.1 50 120.851.0 104 135.152.0 139 150.053.0 165 160.054.0 189 171.055.0 210 181.256.0 229 191.0
Calculation Basics
10-Foot Weir Notch Capacity (Modified sharp crested weir with inclined
Q . CLH 1 .5
upstream face)
Q = 3.65 x 10 ft x H1 .5
Q - 36.5 H 1 .5 , where H = Pool Elevation minus 49.2
25-Foot Weir Capacity (Modified sharp crested weir with inclined
upstream face)
Q = CLH1 .5
Q - 3.65 x 25 ft x H1 .5
Q = 91.25 H1.5, where H - Pool Elevation minus 49.7
Outlet Capacity of 48-inch Pipe (Orifice Control)
Q n Ca -F2g
Q - 0.6 x 12.56ftX64.4 W5
Q = 60.4 H0 5 , where H " Pool Elevation minus 46.0
1 Computed by Rummel, Klepper & Kahl
D-7
DATK.?tiJI.AP SUKT-- SHEETNOq
CHKD. BY.- - DATE---- --------------------- - - O -- VMEJ~~eE~3d---'---- -----
10
40
rQ a
0
I4 4
RUMMEL.,KLEPPER &KAHL ENGINEERS D-B
W 0.z
24 0 004 0 i Dr0 0
00
0
xZ0f% P00a0 .0 9040 . I- (D *0.0o 0 M W
z IK-0 0
0;;. 00no- Io 4~(d - 0
.J 0.
oL M~ 0 M I-
000a 0 q gfzV0 OFiO0
Wt=0 .0
0
-01: 0Z4 J
-0 .0 in 0rd 1L F-0 0 50.4 P4 (0 --.c1 410
. a .0 'OW
:_M *.-., I 4
IL~~ .0j-I * 04 t4- - -0 05-. -. 00040000
*.( 0 51zW * P
*0 0
2>*
0 -*L* 0 9rl , , ti aPW0 dM n08 ,c
El '
i ri i d
cc2
-0000- Ji66c uga a -8
8 ~8 z-00 In, .. .-.
-. r - ci 40
I IL
0 e.d 00.
01- 4 00 '
4 ow 8*'0 1O
me - DA lI ~ 0 0C. W lz woo _j Ja.le z u- 0. 402K 2 w D- .4 0 0 -'8 0 5 0 1 0.0 00 w -
c ~ ~ U 20. 0I- 4o 0 ('4 - aCL x tow U3~0 0 8z t
LL U, w 041- 9 420 on 2 0 -Li . I - I 11. 00 -z . . . i
g- U W 50 a 00 m4 a- Z;- (vIu Ai 4S-Wi m o 0 .aw>~M w In 0 00- U'0 (on Gn 0U 1
12 0 0 D w O0W. W-0 0 o
0KW a- Z 2- >0 0- I. fl w04 -420g > rd Z8N
4c -w- -C 0 L0m (
:: 4. Z. 0 w
400 40 0
)10.0 dO A lX o z 0.0 0D-z0
0.1 "' -. % 0. ILocc 1. c
- 0 1. w 0 M-M>04r 0, 0 4i W 3 ~ 00
201- 20 5 ~ . o I-2*~I 04 1- 0C 00
w0 *7 1- 10 IO 49('
11 0 0 .. .- 0 .02M 1. 0 . -d 9 0 0. -4-0
*i@0*>~tP 2 > IS
- 0-0 0-
r 0O
28 :
0-10
co8
0 10 0
-A a
*4 a v -
0~- 0 110C 1-k
04 t. 00 x . I
0 CW
or r 8lc 0000
0 .1-0 0,
0 L 0 1 In ~-C 0 . 0 w w
000 0
0 0 000 0 x I r % i
10 10 0 rd 0N a :: 1 :1'in 0n 0..0
0 0000 0.00m M 0-0 0 0 0
0. N 0"4 r
0- . we
CA r,-O 0. a.
~~~-. 08 ~ - 40 n0
0 wo w. *l0 0 w fl
0~ ~ .aV ~ .c -1 Jo z -j - j I -
W W w i w i w tLi & l W I LLimc~ .. w -w. 4 - . 4 .
LL. 1-1 0- a-1 0- 0-
CV 1 In 1O 1 00 - 4- - - - *aM 40 M MMM
099
q ". -qc
V0 -
-Cc 11InIiI. wt-
IL -. t M0-
00 (A -C-it C
LL -
> U.j M I4 C OW -C
%0 0 0 -x In
CC 0
Nl m2 -0
W- M a.ic .t 1)
*L n- m
(tu w-
z -ItrI-,
,a ) I4
SLWtoM hO>0)4d d l0
Ca~m 0o ri cit co
LL WH000000000
1LJ
-Ir OOO0O0000
I.- =000000000
I-.W0 0000cca -Cw
> A 0 0qn WOVO-r~mmNr Kiwr-aOND-o-
2 U. L
W ou 4.4
Nl 0
.4 4000000000
z
I W0 ->W V-0000A wd-I
dt4:) 0.J-.440 VNWWwo- W, .3i o 6
0
*m cgoo oo-.
I-1
00
14
I OS
r4-I.oo rd 04 54a 0
0 On oo4
' oo
00t
d.00IL -0 0.
ZoU - U o o 0x 0 0000 C
I.-- i i a 0,N w44m a r -HIi . 44
-0- 0
01 0 rd a ~ rdS ' 0 0
> ) .04 4c0!'4.
I-0 bl 044
m- * "o 0
o ; 4 d-; 0 i 00t
0 u
in I -ni.4 4n
10 w0
4 2 06 a .
a (0 0
ILM 0 CV MZ
0 -0
*OW a WO 0c -i401
4c It 4I
co4 4(00 .0 0 u -fl
* a. 2 W. 0. -z IV
2- . (00 *o U.- 0. w = -CL
08 W
a. 4cl ZO w
.5 . 0 a. ILLI~~~~~ -x 4 *(A -n " ;,2. p" d
V , 00 U. Cd (A 0 "
S*~ U) W (0 a.&Z 1
CL M:0 ioI - 0
jo~~~U 4 xII.. - S o. I
U.~ C! F~ 0 0g
c z s o .0
1- U a r5 3
0 .0 -
a- to .0.0 -C I.- N a 0wo Cw 4
Ic
0 u
-- MO
I-La I
-Cwi
P-
ILUi
0 0 t;I rdWin in -n
.j
9L
FoA.
h-.j
LA I- t 0
uc~0P Z2
wC(0U
0 vv
> 0:- o .- w
x a -
* *4
w 't I
*~ -4X0.-*,*-
0 Mmq(D rMI W0N D .-a-M-1- 0 ld-f
g 44u -Wq 0 ONMIMMNlr00-41
a~ $4
>qC-O.C E4~ 0.
0 0 4 4 >
o~J
zu 4 .04HIL 0 r.- WO00 M-aVN MIflP4l01
VN*N - in4IV t
$4 a~ -
000 00iO rE0 Qi . 0i AlrZ--ow -- .. n r. 0 0
Z~n 0 0-..-- -.
in >1
00. 0cOE 4444
0: E0 I MON -.0Wtro. 0 inO 0f 01449390 . M-vwr)! a 0 i
0 r, * .ai
-j~
fla M- ~r-.A P% -Wo;A0 N d M 00 0 r-wr- 0~i0 04 0 O. rd 0444 'U
4-6~ "1 0 Wi. A nI0~
*o0 ZO -. 0O -0-20. .CdV r.41MnO10n rd -oi-oi o $U4 to
0 6 a-oO 0- ina
*0 0)w ON * O C) in N 0 ZZZ ZZZ ZZI (DUMO...e 41
*0 a*~4 w*m
* .51
a, aW-* 4 t
*Bill - - Alrd MNUN NU MMr lAl~C*0 5
LL a
889
00 80
-o 10 go1
8 800
* z
0 8 ~ru1-- 00 0 0 4 0i
K a 00r C 0 .0 0
0-. -oI- 0-0 * K 0 (.
00. U 0 LL 0, x 1- 0. - K-. 0PZC -- C N D _24 a: J4 00
a( . .Jc w2 d I.- Wj C- 0W K
0- go A ~ 0. -C In
$W E 021-0 * 0 Ic Ofl1 D
in' A 0 -0 . Z 1 0 -W 0(5 0 .a AW :9 0 MX W 0 M E OZ. 0 20 0
-C~~ Ul 1 M~ A -. w - a
wO -JJ I t 40J- 0 w i 0 A5) LC 00
IL4 0a. 0 0 - 2 K 0 00- ca,. 3t - ic Z ~ ZOO4.M - 00
liz~ z 0 w2 00 4 w0 . 0 -C -C zu .. a. -
40 0 -C -C1 v -C C L
0. >. * S-I In* LCCL 05 x 1t 0 0*0 de 00 * o60(* 0-0
02 Il E 9L 00 C-s .0 0 W
cc 0.JW I- to 08..
to InI- a0n
so *
w os- a *
0-1
~I0.0 lK c
c ox OR
gi -- -
w w *i w L w L
w w wIL I IL L 0 IL L *
40
co o
;!M I1 .=
tad~g 2% o
00 -0 vf
in 40 in In
0
IL W - -
~a-- 00
~- 4f0 -
w 0 on 01
w 00
ILo I
I-b.0
h. 0 0000 06000
ok
00000 0
i1-00 6 6 6 0
to
> >0 0 w- 0 ,-,(
S in
0~ 0I-444000
1 -1 G 0- 0 r>l
aOU,
ObWW.00J4 4~* £6
A~PPENDIX E
PLATES
j, Rocky Pt
COLUMBIA LNG
SCALE
LOCCIOLMA
__________________________________________PLATE E-1
MAN
t00
'a RANDOM FILL
z 40(OUTLET DRAIN-6 GIN. DIA is GAuGE.AsPNALT COATED 2F
6 NONPIERFORATED CORRUGATED STEEL PIPE 2FEXITIN GRUND(For Location and Invert See aeNa 3)
'a 20 -SURFACE
SLURRY TRENCHCUTOFF WALL
O Carrgated Steel (See rmNsSAnti-Seep Collarsfa 20 ft c/c(See Detail 3) SECT
100
j SE
I-
3 ILLc
1- 40 - 46 INDIA I1GpklEFULLY PIDMKRtMA1O STEEL PIPE
RANDOM FILL
-See 001@11220_ -- - - -
WAY TRENCH
(see * Now)/EXISTING GROUND(UTE RW60.CAI 6UE~.aSURFACE TE RI O I ASAPA
0 ~NONVERFORATED CORRUAE.f0ueePe steel STEELPIPE (Fer LecetiOm SECT
Lotli- Sameveiete. "et SmeeuDraw" No, s) is"
Isee De"eil1
*song Pee FO wo(t
40 944 %f.ew e wrmmgu
map"0 C-c (Use 11emeed) inC1sau D-0 fe.ew qe 444 ?S.Oqa &"$Nowe P1w, Left "itegaget FitersfeWhu
Ur medow, mom. tEVAG9 Ce00d mioewfwwg/e"o 111101 -
SETO - s eio
. f
3F RANDOM FILL I-
CIMNEY DRAIN (S.. Detail 1)
EXISTING GROUNDppran all25 SURFACE 1 .'n ~IFT(EUROPEAN METHOD) STRIPPED GROUND SURFACE -1'-j-YF-T(AMERICAN METHOD)
TION A-A DETAIL I
8'6~
PLAN SECTIO I L
PlANM~m I EXISTING~tJN S R RCE Ir1UJ~pACII aJL
TTAENIAN MEIO i-IsillI
ION B-B 13-
I
ILEVAT00Of avuuASKUus'g SECTION F-F
so: IfPw (oomTAIL I
5m T(0a'-.' N I A LNGS CORPORATION 7*
SFOL 9MIANKMCMT
Ca Pow. nU*YL
EMBANKMENT SECTIONS AND 0IETAR.'
I~~~ ~ ~ ~ goal* o,.... ai f. r of
Case is liam 0 a n -a o 9PLATE .
.AI
CONNECT TOMAIN SPIU.WW
(SEE MWG.NO II I
£ EAKING - OF 42 W.WALL60 FULLYPAE
I11D229 9 P JOINT NUMBER
12971279 PLANScalo lI..20ft
(F. Lecetlest See D"ft
LIMITS OF PERMANENT CUT(S. D NaL
100 COMPACTED/RANDOM FiLL
I-so EXISTING GROUNDINVEL725
2
d I42 INd WA 6 GAUE ASBESTOS BOOw AED CORRUGAT ED STEEL PIPE
40
+ + + I I I . II
PIPE JOINT NUMBERS
SECTION A-Ascale I imf act$
).8.4w
RIPRAPo (STILLING -
AREA)
I'N202 694LE971554
42IN.DIA
AGEASBESTOS BOWDEDCOPCERADMFLRUSATED STEEL PIPE OR NATURAL SUISRADE
SECTION B-BNOT TO SCALE
JOINTLT12
- I'-OFILT R MATERIALI PEA GRAVE ASEISB2TO ENCASE CULVERT 4LSERSz
C- II E FT THICK LAYEROF RIP RAP (AS PER T39)
EXISTING GROUND ANOM Flu.DSURFACECOMPACTED RANDOM FILL
OR NATURAL SUSOAM
SECTION C-CPlOT TO SCALE
T-'
13 14 L
COLUMBIA LNG CORPORATIrMSPOIL EM&UAMNID .
cmWS ? . :1~wMAIN SPILLWAY'- OUTLET PIPE.,- -
4
WOODWARD- AS NOS A ASOITS. Ml. ~Ci~~gy emNIAUISI mamuWe ~ mum
"kw~~- "f,-to
utI
TROGH t fIE CONAR EMANKTEP ECU.
Pipee JOINT
NUMBRS \ 'T.EEPAE COLAR
60 25GS
"CIMNEYIwa DRAIN
a40 SeDWI3FT 401h WIA 16GAUGE FULLY PAVEDSee .6.61 AI~FPMOE O ICORRUGATED STEEL PIPE
all _s u poXISTNGGROUND SURFACE-w2
0 I 2 3 4 5 6 1 aPIPE JOINT NUMBERS
* SECTION A-AScale 1 * 20'
/U50.6
47 t 6 147U44 lag.lib(pgra)-.46 -(Slope 6% ApprovwN* 4
FRONT ELEVATIONScale.o 2. 0
C-1 S;. detail A: ~ ~ Se yia
slepe l%(Appml- -Slope 1% (Appra)
C.j 0i
TROUGH STRUCTURECsma I% 2
II
LU *
S LICrON01
DETAIL I SWCPO M S~t
Vol.
4n
DETAIL A
33% Va" L ItM IStf
CONE DETAILLSae *-'0 -W I N I. - EA113'me
- iTAR
Iola" =16101 gtf. 0-0 low"" see "as.amo 4o o$ 7 .k 0 NllIm w " M L T
4 samsCl" t 1Ii "
TYPIAL ISECOD SPLIWA
APPENDIX F
.GEOLOGY
COLUMBIA LNG
APPENDIX F
REGIONAL GEOLOGY
The Columbia LNG Main and Secondary Dams are situtated on thesediments of the Pleistocene Columbia Group, specifically the WicomicoFormation, which include sand, clay, and gravel. The average thicknessof the Wicomico Formation is 20 feet, and the average total thickness ofthe Columbia Group is 70 feet. The sediments of the Columbia Group lieunconformably on the sediments of the Miocene Chespaeake Group. TheColumbia LNG Plant is located in the Coastal Plain PhysiographicProvince.
F-i
"COLUMBI *~ A LNG
ireCove P.~ Q~c%
SCAee
X i. 2M.CLMI N
uuain GEOLGY MA
if~~cv PtITNIIIf IIit AiL
S*SICM331(1
RUMLKEPEoIKH
w Y 1
PLEISTOCENE
r Pi] Loam. awmd. ,rate.
Beaches and Marshes
in o mchI ,d grarri.II bomidera, pDea*.. Pw
0 Talbot
1'"., p L,, m. elar. wn. mW.I~Iboai&Swg.
Wicomico-J
0o°Ps Lnas. Noy/. *Md. t.
boulder. eal.
Sunderland
MIOCENE
L M Csm U C P. -aNdy-ek. m, .
r St. Mary's
UI3 J ~dmgiaelg. iand. mars.
4• Choptrnk(I)
Cal vert
COLUMBIA LNG
REFERENCE: GEOLOGY MAP LEGENDGEOLOGIC MAP OF CALVERT COUNTY,PREPARED BY STATE OF MARYLAND,MARYLAND GEOLOGICAL SURVEY,SATED 1902. RUMMEL, KLEPPER & KAHL
' . .. . .. nm
