Penetrometers

CPT/CPTU

STATIC CONE PENETROMETER 200kN/TR GEOMIL

The penetrometer 200 kN/TR manufactured by Dutch company GEOMIL  is designed for geotechnical static penetration tests. Cone penetration test consists in vertical pushing the rods with special cone tip into the ground at constant rate of 2,0 cm/s ± 5mm/s. Penetrometer together with accessories is mounted on uniaxial trailer. Penetrometer is powered by compression – ignition engine 1D 81 C. Equipment is anchored to the ground with the use of disk bits. Penetrometer is provided with measuring – recording device GME500 IP65 which records parameters measured during the test. It has to be mentioned that the described equipment is brand new as it was manufactured in 2009.

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Penetrometer 200 kN/TR GEOMIL

 

The most important technical specifications of CPTU are presented in the table below.

Technical specifications of CPTU penetrometer

 

cone of 60° apex angle
cone base area 1 000 mm2
length of cylindrical area 7,0 – 10,0 mm
cone length 24,0 – 31,2 mm
cone base Ø

34,8 – 36,0 mm

friction surface 150 cm2
length of friction sleeve 133,7 mm
friction sleeve Ø 35,7 mm

During test system of sensors placed in cone (load cells of friction sleeve and cone as well as sensors for pore pressure and inclination) connected with recording device GME500 IP65 records values of:

  • point resistance qc

  • local friction fs

  • dynamic pore pressure u

  • inclination I

New measurement device has producer certificate however, according to PN-B-04452:2002 standard it is sent for re-calibration after each 3 000 m of sounding but not less often than once each six months. Condition of the cone and its correct dimensions (see Table 1) are checked each time before test. Before test filter and empty spaces are de-aerated and filled with fluid (e.g. hydraulic oil). Before pushing cone into soil the recording device executes automatic calibration and determine „zero” of the measurement equipment. Identical procedure is repeated after test. These measurements allow to obtain measuring error, which should not exceed 5%. Inclination of rods is controlled during the test and it should not be bigger than 2%.

Data recording and graphic presentation of test results is made with the use of GEOMIL software: CPTest and CPTask. Interpretation of test result is executed according to binding standards with the use of new software for CPT test interpretation CPT Star produced by Sof-Projekt company. This software enable for efficient elaboration of test results, calculation of soil parameters as well as graphic edition of test’s card. CPTask and CPT Star also enable data export to excel files.

DYNAMIC PENETROMETER DPSH

Super heavy dynamic penetrometer DPSH made by Swedish company BORRO AB is designed for vertical geological sounding in order to obtain relative density ID of non-cohesive soils. Test consists in measuring soil resistance to penetration by penetrometer’s cone tip. Penetrometer is equipped with a „loosing” cone. It is powered by combustion engine HONDA.

According to PN-B-04452:2002 standard the relation between number of blows for each 20 cm of penetration (NK) and relative density (ID) of sands of coefficient of graining non-uniformity U>3 is described by the formula:

 

ID = 0,441 log N20 + 0,196.

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Photo: DPSH penetrometer BORRO

 

Technical specifications of DPSH penetrometer is presented in table below.

hammer weight 63,5±0,5 kg
drop height 750±20 mm
energy of hammer impact 238 kJ/m3
cone of 90° apex angle
cone base area 20 mm
cone base Ø 51±0,5 mm
length of cylindrical area 51±2 mm
height of cone tip 25,3±0,4 mm

 

Parameters like hammer weight or drop height correspond with parameters of  the oldest, standard penetrometer used in geotechnical investigation i.e. Standard Penetration Test. Drop height should be checked before testing, because equipment can be reset for so called Swedish standard (50 cm). The rods with cone tip are vertically driven into the soil in a constant way. Frequency of blows is kept within limits from 15 to 30 blows/min. (20 according to producer’s instruction). A 1,5x rotation of rods around their axis is made each 1 m of probing in order to decrease skin friction of the rods.

DYNAMIC PENETROMETER DPL/DPM

Dynamic penetrometer DPL/DPM manufactured by Nordmeyer company is designed for vertical geological sounding in order to obtain relative density ID of non-cohesive soils. Test consists in measuring soil resistance to penetration by penetrometer’s cone tip. DPM penetration test is executed with the same equipment as DPL after changing the rods and adding a bob of 20 kg weight.

According to PN-B-04452:2002 the relation between number of blows for each 10 cm of penetration (NK) and relative density (ID) of sands of coefficient of graining non-uniformity U>3 is described by the formula:

for DPL ID = 0,429 log N10 + 0,071

for DPM ID = 0,431 log N10 + 0,176

Technical specifications of DPL and DPM penetrometer is presented in table below.

 

Technical specifications of DPL and DPM penetrometer

Set DPL DPM
hammer weight [kg] 10±0,1 30±0,3
drop height [mm] 500±10 500±10
energy of hammer impact [kJ/m3] 50 150
cone of 90° apex angle
cone base area [cm2] 10 10
cone base [mm] 35,7±0,3 35,7±0,3
length of cylindrical area [mm] 35,7±1 35,7±1
height of cone tip [mm] 17,9±0,1 17,9±0,1

The rods with cone tip are vertically driven into the soil in a constant way. Frequency of blows is kept within limits from 15 to 30 blows/min. (20 according to producer’s instruction). A 1,5x rotation of rods around their axis is made each 1 m of probing in order to decrease skin friction of the rods.

DYNAMIC – VANE PROBE SLVT

Dynamic-vane probe SLVT (Fig 1) is designed for soil penetration, mostly for weak soil testing such as firm and soft cohesive soils or organic soils and establishing their mechanical properties. Test is combination of dynamic penetration DPL with the possibility of undrained shear strength τfu measurement through recording the torque of cross tip (Fig 2) using the torque wrench. Company has also an older type of such a probe: ITB-ZW.

 

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Fig 1. Dynamic-vane probe SLVT

 

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Fig 2. Scheme of the probe cross tip

 

Standard Penetration Test SPT

Test consists in measuring soil resistance to penetration by penetrometer’s tip into a bottom of the borehole and identification of soil on the basis of taken samples.

The SPT penetration test is executed with the use of 63,5 kg hammer. The drop height is 760 mm. The soil resistance  is measured as the number of blows (N) needed to penetrate the soil to the depth of 300 mm (after initial 150 mm penetration caused by dead weight of device and initial penetration).

The penetrometer may be ended by a cylinder with a cutting shoe to take samples during the test or by a cone which assures reliable results when coarse grained soils are tested.

The old type of SPT penetrometr were lowered into a borehole on rods with anvil on the top.
Recently (BDP version bought by „Geoprojekt Szczecin” in 2010) is lowered down the hole on a wire,  which reduces remarkably the total weight of the set, as drilling rods are not used. Watertight lining of hammer and releasing mechanism plus additional load against buoyancy when water column is high (>20m) assure a proper way of testing also below the ground water level.

The old type of SPT penetrometr were lowered into a borehole on rods with anvil on the top.

Recently (BDP version bought by „Geoprojekt Szczecin” in 2010) is lowered down the hole on a wire,  which reduces remarkably the total weight of the set, as drilling rods are not used. Watertight lining of hammer and releasing mechanism plus additional load against buoyancy when water column is high (>20m) assure a proper way of testing also below the ground water level.

The old type of SPT penetrometr were lowered into a borehole on rods with anvil on the top. Recently (BDP version bought by „Geoprojekt Szczecin” in 2010) is lowered down the hole on a wire,  which reduces remarkably the total weight of the set, as drilling rods are not used. Watertight lining of hammer and releasing mechanism plus additional load against buoyancy when water column is high (>20m) assure a proper way of testing also below the ground water level.

 

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photo: Nordmeyer

Pressuremeter

Ménard pressuremeter consists of the BX Ø 58 mm probe and the box supplying – monitoring unit of GC type. Both parts are connected by a concentric cable. Currently “Geoprojekt Szczecin” possesses two pressuremeters: one GC type (Fig 1a) and the new one with electronic recording device GEOSPAD (Fig. 1b).

 

 

 

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Fig. 1. a) the GC type pressuremeter connected to the probe (from Ménard instruction ‘1975),
b) the new device with the probe and GEOSPAD recorder

 

 

The cylindrical probe consists of three expandable cells. The probe exerts equal pressure on borehole walls through water supplying to measurement cell and gas to two protection cells.

 

Characteristic diameters of BX probe are given below in Table № 1.

 

Table № 1 Characteristic diameters of BX pressuremeter probe 

outer diameter of the probe [mm] length [mm] volume of measurement chamber [mm3] borehole diameter
total of measurement chamber of protection chamber measurement part altogether min. [mm] max. [mm]
58±2 550 210±5 120±15 450 535 60 66

 

 

The probe is placed in substratum at a required depth in pre-drilled borehole of the diameter greater of not more than 15% of the diameter of the probe, i.e. 60 – 66 mm for BX probe. Dry drilling is executed above groundwater table, and slurry drilling with the use of bentonite mud below. Its density is adjusted to the drilled soil.

The use of drilling mud protects borehole wall against cavern formation and keeps its  constant diameter. In gravels or rubble fill cased drilling is necessary sometimes to prevent bore-hole from filling up. „Geoprojekt Szczecin” drills boreholes with the use of H25S and BIRDIE mechanical drilling rigs.

 

The test is preceded by resetting manometers, filling in the system and measuring its stiffness i.e. determining corrections related to reaction of the device to given pressure to  correct test results.

Some elements reveal elasticity e.g. cable connecting the probe with monitoring unit. These deformations are measured during calibration for volume losses, which is executed in calibration pipe by increasing pressure by 0,1 MPa till a tight contact with pipe is obtained, and then pressure increments grow to 0,25 or 0,5 MPa. Value of correction a = ΔV/Δp  is obtained from the ratio of volume increment (V) measured with volume of liquid pumped into the probe to the increase of pressure ( Δp; Fig. 2).

 

 

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Fig. 2.  Calibration for volume losses  

(from AFNOR NF P 94-110-1-N)

 

 

 

Shields of the probe have their own stiffness which is determined by calibration for pressure losses. This calibration is executed by putting the probe at surface level and adjusting the pressure by 0,01, 0,02 or 0,025 MPa steps kept for 60 s, noting the volume of chamber after that time. Pressure is increased to boundary value of stiffness which is conventionally adopt as  pel = 700 cm3 (Fig. 3).

 

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Fig. 3.  Calibration for pressure losses  

(from AFNOR NF P 94-110-1-N)

 

 

 

 

After calibrations, the results of which are considered during interpretation, the probe is placed into the borehole at a required depth and media are supplied through pressure cable connecting supplying – monitoring unit with the probe. Pressure steps of 0,2; 0,5; 1,0 or 2,0 at are most commonly used depending on the type of the soil tested. The number of increments varies from 7 to 16. Changes in volume of the probe are measured then. Numerical data are read from manometers and view-finder tube and written down manually or, on request, with an equipment allowing their automatic recording (SPAD).

These data allow to create so-called pressuremeter curve. It shows three stages of the test:

 

  1. phase of the adjustment of the probe to borehole wall; it is characterized by a quick volume growth and it is not interpreted;
  2. quasi-elastic phase: the segment similar to a straight line;
  3. creep and plastic deformation  phase, again characterized by a quick volume growth.

 

Shape and range of particular sections of the curve depends on the kind of soil. Corrected (by calibrations) results are interpreted following the French Standard NF P 94-110-1-N with the use of PRESJOMETR 2.0. software (Fig. 4a, 4b). The interpreted parameters are: pressuremeter modulus  EM  , pressuremeter limit pressure  pl  and creep pressure  pf .

 

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Fig. 4. a) Card of pressuremeter borehole 

 

grafikaFig. 4. b) result of a single pressuremeter test (PRESJOMETR 2.0 software)

 

 

 

Pressuremeter is used for obtaining both basic soil parameters and parameters used directly for building design. Results of pressuremeter test gives the information about two most important soil parameters for designing purposes: soil strength (bearing capacity) and compressibility. Test allows to evaluate limit and permissible bearing capacity and also settlement.

 

 

Referred standard:

AFNOR 1999-10-07 NF P 94-110-1-N  Norme française. Sols: reconnaissance et essais.

Essai pressiométrique Ménard. Essai sans cycle

(French standard. Soil: reconnaissance and testing. Ménard pressuremeter tests.

Tests without cyccles.)

Laboratory

Geoprojekt Szczecin ground – chemical laboratory is in possession of the following devices:

 

  • triaxial shear test apparatus with pore pressure measurement
  • the box apparatus for determining cs and φs with direct shear test
  • oedometrs (12 items) with the maximum load of 400 kPa
  • mechanical Proctor apparatus for obtaining optimum moisture content and maximum dry unit weight
  • Cassagrande apparatus for determining liquid limit
  • two sieve shakers with full set of sieves of 200 and 300 mm diameter
  • Kamieński’s cell and K605-A apparatus for permeability tests
  • Corfield apparatus for determining corrosion risk of soil
  • pocket devices:
    • pocket vane torque TV do for determining shear strength of soil τf
    • pocket penetrometer PP for determining soil cohesion cu

 

And basic laboratory equipment such as laboratory dryer, heating panel, electronic balances and roasting furnace (800ºC).

Static Plate Load VSS

 

Plate load test with the use of VSS plate  is designed to determine density of fill, bearing capacity and density of substratum and some types of substructures (like road foundations).  This test allows to establish the values of primary E1 and secondary modulus of elasticity E2 and effective strain Io. The test characterizes the superficial substratum to the depth of 30-50 cm, this is way it is often used for linear constructions, especially for roads.
The test consists in measurement of soil settlement under  the plate while loading with the use of counterweight.

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Plate load VSS (photo: www.szkurlat.com.pl)

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Exemplary graph of test results with its interpretation

Drilling rig

H35S.M DRILLING RIG

H35S.M drilling rig is made for vertical boreholes with the use of a quick-rotary wet drilling (right circulation) or core drilling. Also rotary dry drillings can be conducted with bucket auger or screw auger with the use of casing pipes as well as percussion drilling in which drilling material is removed by bailer mounted on drill string. Drilling rig is mounted on MAN TGS 26.320 chassis (Fig.1, 2) and powered by an independent combustion engine Mobil 5-W40 of 105 kW. Maximum range of core drilling Ø146 mm with the use of “throw into” method is 150 m and cased drilling with the use of percussion – rotary method of diameter Ø298  mm  – 50 m.

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Fig 1. H35S.M drilling rig in a service position

 

 

Technical specification is presented in table below

DRILLING RIG

drilling rig weight

9000 kg

length/width/height (in transport)

10050/2550/3900 mm

drilling rig height

9700 mm

Guaranteed level of sound power LWA

105 Db

ROTARY HEAD

Torque

60 – 600 daNm

Rotational speed

700 – 60 rot./min

Swimming spindle

45 mm

H30G-14.00 casinghead

diameter DN45

drilling jump

5400 mm

pressure force

50 kN

pull out force

80 kN

SLIDEWAY SHIFT

jump

1300 mm

pressure force

250 kN

pull out force

380 kN

rod diameters

45 – 195 mm

max diameter of casing pipes

298 mmm (11 ¾ “)

HYDRAULIC PUMPS

gear

I

II

III

IV

efficiency (l/min)

0 – 130

45

0 – 130

45

Max pressure (MPa)

21

25

22

25

WINCH

max force

44 kN

cable diameter/length

14mm/250m

HYDRAULIC OIL L-HV46

tank capacity

610 dm3

Nominal accuracy of filtration

10 m

Purity grade acc. ISO4406

22/17/14

Max temperature

65 C

max pressure

max efficiency

fluid

SHELL – SCREW PUMP

„BELLIN” NG 1200L2/PC5

2,4 MPa

500 dm3/min

water, polimeric drilling fluid, concrete and bentonite suspensions

SHELL – PISTON PUMP

TRIPLEX TRX200

4,5 MPa

200 dm3/min

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Fig 2. Technical drawing: H35S.M drilling rig in service position

 

 

Core drillings are carried out with „throw into” method GBS-146 or SK6L-146 in casing pipes of diameter 140 mm with the use of drill bit of inside diameter 146 mm
(Fig. 3). Drilling bit of inside diameter of  102 mm and length 1500 or 3000 mm is placed at bottom of the borehole, during drilling it is filled up with soil (core uptake). Filled up core barrel is pulled out with the use of winch and after placing sample (core) into a box is throw into a borehole again. The drilling is carried out with bentonite drilling mud (slurry), the parameters of which is adjusted for drilled soil. Drilling fluid is pumped into borehole constantly through entire volume of casing pipe, from where removes drilling material through space between pipes and borehole walls at the same time stabilizes wall of the borehole. At the surface drilling fluid is collected in sedimentation tank where drilling material is separated (through sedimentation) from drilling fluid which is used again in drilling.

Drilling rig can also be equipped with other systems of core drilling.

 

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Fig 3. Drilling bit scheme (drawing by GEOD)

 

 

 

H30S.M DRILLING RIG

H-30S drilling rig is designed for vertical drilling of maximum diameter  Ø  300 mm. Drilling can be carried out with the use of:

 

  • a slow-rotary method with the use of bucket auger mounted on rod and pulled out when it is filled with cuttings,
  • a cable tool drilling with the use of bailer lowered into the borehole on drill string,
  • a slow-rotary method with continuous flight (screw) auger.

Drilling with method a and b is carried out in casing pipes screwed with threads. Maximum range of drilling is 50 m.

Drilling rig is mounted on STAR 266 track (Fig.1, 2) and powered by an independent compression – ignition engine URSUS-PERKINS 3250A of 34 kW.

 

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Fig 1. The H30S drilling rig during cased drilling.

 

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Fig. 2. A technical drawing of H30S drilling rig

 

Technical specification is presented in table below

 

BASIC PARAMETERS

drilling rig weight

5150 kg

length/width/height (in transport)

8800/3800/3500 mm

drilling rig height

9000mm

HYDRAULIC DRILLING MACHINE

gear

I

II

torque (daNm)

500

250

rotational speed (rot/min)

n1 10

n2 35

n3 45

n4 20

n5 70

n6 90

HYDRAULIC WINCH 2,5 T

max force

25 kN

reel speed

0,8 m/s

JERK-LINE

eccentric

300/225

jump

850/510

percussion frequency

40 1/min

PRESSURE MECHANISM

max pressure force

22kN

max pull out force

45 kN

mechanism stroke

4400 mm

 

Type of drilling tools is adjusted to the drilled soil. Dry sands and cohesive soils are drilled out with the bucket auger and saturated non-cohesive soils with the bailer.
A continuous flight auger drilling is used in simple soil conditions, drilling for mineral resources (aggregates) as well as in the cases when (short) time and (low) price are decisive factors.

DRILLING RIG ŁBU

Drilling rig ŁBU is designed for vertical drilling of maximum diameter  200 mm. Drilling is carried out with continuous flight augers without casing. This machine is used in simple ground conditions, in mineral deposits prospecting and also in cases where decisive factors are (short) time and (low) drilling costs.
Drilling rig is mounted on ZIŁ truck (what allows to access also in rough conditions) and powered by a compression – ignition engine. Maximum range of uncased drilling is 50 m.
This rig is rarely used nowadays because of its limited possibilities, but it can be successfully used e.g. to confirm lithological profile of substratum initially investigated with CPT or DPSH penetrometers, what can significantly reduce the necessary drilling costs and time.

Drilling rig ŁBU is designed for vertical drilling of maximum diameter  Ø  200 mm. Drilling is carried out with continuous flight augers without casing. This machine is used in simple ground conditions, in mineral deposits prospecting and also in cases where decisive factors are (short) time and (low) drilling costs.
Drilling rig is mounted on ZIŁ truck (what allows to access also in rough conditions) and powered by a compression – ignition engine. Maximum range of uncased drilling is 50 m.
This rig is rarely used nowadays because of its limited possibilities, but it can be successfully used e.g. to confirm lithological profile of substratum initially investigated with CPT or DPSH penetrometers, what can significantly reduce the necessary drilling costs and time.

 

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Drilling rig ŁBU during operation

 

BIRDIE 200

Hydraulic drilling rig mounted on tracks BIRDIE 200 is a self-propelled device designed for drilling in soil of different consistency, hard rock and concrete. Drilling device is mounted on tracked chassis of changeable track width, on which also motor set is mounted. Diesel engine (four-stroke, vertical, water-cooled) gives the power for hydraulic pumps of motor set. Drilling can be carried out with the use of augers or as wet drilling. The maximum range of uncased drilling of maximum diameter Ø76 mm is 30 m

 

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Drilling rig BIRDIE 200

 

Technical specifications of the drilling rig as well as its technical drawing are given below:

General dimensions (see figure below)

  • wheel space
  • track width
  • total track length
  • minimum wheel space (with closed tracks)
  • maximum speed
  • maximum load
  • total weight (without additional equipment)
  • 1080 mm
  • 230 mm
  • 1423 mm
  • 764 mm
  • 2 km/h
  • 0.62 kg/cm2
  • 1600 kg

 

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Drilling rig BIRDIE in service position

WINDOW SAMPLER

Window sampler RKS manufactured by Nordmeyer company is designed for soil sampling with the use of percussion method. Sampler is driven into the soil with the use of combustion or electric hammer. This method allows for drilling with continuous sampling of the diameter to Ø100 mm. Typical range of drilling is ca 10 m, or even more in favourable conditions.

 

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(photo: Nordmeyer)

 

DRILLING TRIPODS L-30 and GEO-15

Geprojekt Szczecin” has at its disposal two partially mechanized tripods designed for vertical drilling of maximum diameter Ø200 mm (Fig 1). Drilling can be carried out with the use of:

  1. a slow-rotary method with the use of bucket auger mounted on rod and pulled out when it is filled with cuttings,
  2. a cable tool drilling with the use of bailer lowered into borehole on drill string.

 

Tripods are used mostly in limited access areas where cased drillings are necessary, also for drilling on the water (Fig 2).

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Fig 1. Drilling with the use of tripod (A. Wyra, G. Poloczek Stosowanie maszyn i urządzeń wiertniczych. Poradnik dla ucznia)

Cased drilling starts with bucket auger (“Schappe”) with diameter Φ225 mm. Casing pipes Φ203 mm are lowered into borehole after drilling out at least 1 m of soil or after meeting ground water table, then the drilling is continued with auger of smaller diameter, and pipes are pushed manually during drilling.

Type of drilling tools is adjusted to the drilled soil. Dry sands and cohesive soils are drilled out with the bucket auger and saturated non-cohesive soils with the bailer.

 

SOIL SAMPLER BPE 130

BPE 130 device is a percussive soil sampler. The sampler is driven into the soil with the use of a 70 kg hammer dropped from the height of 400 mm. A-class undisturbed samples of very high quality and of the diameter of Ø 100 mm are obtained this way. The method allows to make continuous sampling in cased boreholes. As the cores are taken to PVC pipes, they can be transported and stored in a safe way.

 

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Photo: Nordmeyer

 

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Photo: Nordmeyer