Item No 41 - Brief Summary of Possible Mine Workings-OCR

4E5P
ESP Associates PA October 19 2007
Beazer Homes
1300 South Boulevard
Suite
Charlotte North Carolina 28203
Attention Mr Jade Eastridge
Reference BRIEF SUMMARY OF POSSIBLE MINE WORKINGS
Morehead Commons
Charlotte North Carolina
ESP Project No E4-UD42.301
Dear Mr Eastridge
ESP Associates P.A ESP is providing geotechthcal engineering
and construction material
testing services for the referenced project The majority of our services
have been provided for
Beazer Homes however portion of our services were provided for Lane SE LLC ESP was
authorized by both Beazer Homes and Lane SE LLC to share information regarding the
referenced project
Historic maps of the area suggest that gold mining may have once taken place on or in the
vicinity of the southeast portion of the site Our literature search revealed Open File Report
2005-05 from the North Carolina Geological Survey NCGS titled Old Gold Mines in
Charlotte North Carolina Potential Geologic Hazard for Development This report indicated
that abandoned goldmines from the late 1800s to early 1900s were located southwest of the
Charlotte city center Using historic library holdings and rediscovered city engineering geology
reports the authors mapped the location of possible abandoned gold mines which based on the
mapping in the report are in the general vicinity of the southeast portion of site Included in the
mapping were the possible locations of horizontal tunnels which were used in the mining
P.O Box 7030 Charlotte NC 28241
1.800.960.7317 NC 704583.4949 fax [phone] SC 803.802.2440 fax [phone]
www.espassociates.com
Brief Summary of Possible Mine Workings ESP Project No E4-UD42.30
Morehead Commons October 19 2007
process Based on
the mapping it appears the project site is potentially underlain by several
abandoned horizontal and vertical shafts However the authors note the
locations shown in the
map are approximate The portion of the property shown to contain possible mining activity is
generally east of Cedar Street
During an exploration in late September 2007 wood fragments were encountered in boring
performed by ESP in the southeastern portion of the site adjacent to Interstate 1-277 between
depths of 63.5 and 66 feet within the residual soil profile ESP performed test pit in the general
area of this boring to determine if there was vertical shaft near this location The test pit was
excavated to an approximate depth of 10 feet and was extended laterally approximately 20 to 30
feet either side of the boring parallel to the existing fence line The test pit did not reveal the
presence of any abandoned shafts
To further assist in determining the possible presence of abandoned mine shafts at the site ESP
facilitated resistivity survey at the site resistivity survey allows for profile of the
subsurface materials to determine the presence of anomalies which may indicate possible
water soil or air filled voids beneath the ground surface or changes in soillrock mineralogy The
resistivity survey indicated the presence of several possible anomalies and recommended
additional subsurface exploration to aid in resolving the existence and nature of the anomalies
ESP then performed an additional five borings at the site at locations indicated by the resistivity
survey to determine the nature of the most prominent anomalies reported Sampling of the
soils was conducted at frequent intervals at and/or near depths of the anomaly as shown on the
resistivity survey These borings did not encounter any voids or subsurface materials which
might indicate the presence of abandoned mine shafts at the site One of the borings was drilled
at the same approximate location of the previous boring
that encountered the wood fragments
and encountered similarwood fragments from approximately 66 to 69 feet below ground surface
confirming our previous finding in that area
Brief Summaiy ofPossible Mine Workings ESP Project No E4-UD42.301
Morehead Commons October 19 2007
During grading operations on September 26 2007 while cutting the southeastern portion of the
site to proposed grades the site grading contractor uncovered void space east of the
intersection of Cedar Street and Dunbar Street More specifically the void space was located
approximately 90 feet east and 50 feet north of the referenced intersection The void space
appeared to be possible old mine tunnel that was approximately 3.5 to
feet in height to
feet wide neatly cut and extended into the undisturbed area approximately 10 to 15 feet before it
began to curve and the depth could no longer be determined The bottom of the tunnel was at or
near proposed excavation grades Representatives of ESP met with Mr Eastridge of Beazer
Homes and the grading contactors Gelder Thompsons superintendent Robert to discuss the
finding At that time ESP recommended that the exposed shaft be mapped if possible with
some type of robotic equipment since the shaft was likely unsafe for access Mr Eastridge
authorized ESP to begin investigating methods to map the shaft observed During our research
over the next couple of days ESP learned that the open access to the shaft had been destroyed
and the opening could no longer be observed At that time the contractor attempted to dig in the
previous location of the opening but the shaft location
has not been rediscovered as of the date
of this letter
Based on the results of our involvement with the project to date it is ESPs opinion that old mine
workings likely exist on the southeastern portion of the Morehead Commons project ESP
recommends that that the southeastern portion of the site be monitored closely during remaining
cutting operations If void space or possible mine opening is encountered work should stop in
that area and the area be protected so that additional exploration can be performed In addition
mine consultant specializing in locating/mapping of old mine workings should be contracted by
Bearer to fully investigate the potential for mine workings in the near
surface profile of that
portion of the site The effect of any mine shafts if present on the proposed structures will be
function of the location and depth of any potential shaft in relation to the proposed structures As
requested by Mr Eastridge ESP has researched potential consultants specializing in mapping of
abandoned mines Our research has revealed consultant Blackhawk Geophysical in Colorado
who has experience and expertise in locating and mapping abandoned mine workings As
Brief Summary of Possible Mine Workings ESP Project No E4-UD42301
Morehead Commons October 19 2007
requested ESP has discussed general/generic project information with
Blackhawk and we are
awaiting recommended scope and anticipated cost from them to further investigate the
potential presence of mine workings In addition to any mapping efforts recommended by
Blackhawk detailed soil boring program could be implemented once specific column and wall
foundation locations are known to evaluate specific loading areas More specifically soil
borings could be performed at each proposed column location The borings would need to be
extended to depths equal
to the anticipated depth of the stress increase for the foundation
loads
ESP appreciates the opportunity to be of service during the referenced project If you should
have any questions regarding this letter please contact us
Sincerely
ESP Associates PA
Construction Services Manager
Brian Welch PE
Division Manager
MJS/BFW/ms