Berlin Lake Dam EarthCache

Have you ever come across a dam and wondered how it was built or how it impacts the surrounding area? This earth cache is designed to teach you about the type, maintenance, and impact of the dam you see before you. This cache is located in a beautiful picnic area complete with tables, swings, and bathrooms. If your not in a hurry you should take a nice picnic lunch. No night caching and please do not attempt to go onto the concrete portion of the dam.

This cache created by an

In order to log this cache you must send me the answers to these questions. Logs made by those who fail to answer the questions will be deleted.

1. What geological feature made this the best location to place Berlin Dam?

2. What type of rock is exposed in the gorge? ie: granite, obsidian, sandstone, limestone, shale, slate. If you do not know what type of rock this is, please describe the color, texture, and grain size of the rocks you see.

3. What year is on the side of the dam?

4. What do you believe came first, the gorge or the dam? What evidence can you find to support your idea?

5. Identify the soil series type present at the site of the dam.

6. What characteristic of the soil type(s) found at the dam may benefit the dam?

Mahoning County is in the glaciated part of the Allegheny Plateau. The southern part is within the western foothills of the Appalachin Mountains. The northeastern part of the county contains some sloping to steep areas, mainly along the Mahoning River. The central and northern parts are mostly a nearly level plateau, where the average elevation is about 1150 feet. The highest elevation in the county 1,320 feet, is in Green Township in the southern par of the county. The lowest, 800 feet, is near Lowellville in the northeastern part of the county, where the Mahoning River flows into Pennsylvania.

Drainage throughout most of the county is eastward toward the Mahoning River. Drainage in small areas in the south-central and southeastern parts is southward towards the Middle and North Forks of Little Beaver Creek, which flows into the Ohio River. Because elevations are higher in the southern part than in the rest of the county, Meander Creek and Mill Creek which have their headwaters in the southern part of the county, flow toward the norh. They finally join the Mahoning River, which flows southeastward through Youngstown on its way to the Ohio River. Water drains southward only from a small area in the south-central part of the county near Salem.

Nearly all of the supplies of water for the county are obtained from reservoirs, but Sebring, Beloit, and Lowellville obtain their supplies from wells. Drilled wells are the main source of water for most farms. Manmade lakes in the county are Berlin Reservoir, Meander Creek Reservoir, Milton Reservoir, Pine Lake, Evans Lake, McKelvey Lake, and Lake Hamilton.

Several kinds of glacial drift cover Mahoning County, but only glacial drift of Wisconsin age is exposed at the surface. Glaciers apparently had crossed the county before the Wisconsin Glaciation, because deposits of Illinoian and of pre-Illinoian drifts are buried beneath the Wisconsin age were deposited during three substages of the Grand River Lobe of the Late Wisconsin glacial period.

The glacial drift in underlain by sedimentary rocks of the Pennsylvania, Allegheny, and Pottsville Formation. These rocks are composed of alternating thick and thin layers of shale, sandstone, limestone, and coal that dip slightly to the south and east. Some of the rocks are an important source of minerals, and all are mined for local use. Some natural gas is produced from the deeper formations.

The Geeburg series consist of deep, light-colored, moderately well drained soils that have a high content of clay. Thee are mostly gently sloping but are steep in some places. They are on uplands in the northwestern part of the county, where they have formed in clay glacial till of Wisconsin age. The till is low in content of lime.

In a typical profile of a Geeburg soil in a wooded area, the surface layer is very dark gray silt loam about 2 inches thick. The subsurface layer is dark brown and brown silt loam about 4 inches thick. The subsoil is mostly brownish clay to silty clay. It has contrasting grayish mottles throughout, and it has grayish coatings on the subsurfaces of many of the peds in the lower part. The substratum, at a depth of about 54 inches, is brownish silt loam over coarse silty clay loam.

These soils are very slowly permeable and have a moderately deep root zone. The available moisture capacity is generally medium. The water table is higher during winter and spring, especially in the less steep areas. The clayey Geeburg soils have a high shrink-swell potential. This is a severe hazard to the foundations of buildings.

The Steeper areas of these soils are mostly in pasture or trees, but the less steep areas are farmed to a limited extent. Corn, wheat, and hay are the crops commonly grown.

The Remsen series consist of light-colored, somewhat poorly drained soils that are nearly level or gently sloping. These soils are on uplands, where they have formed in clayey glacial till that has a low content of lime. The till is of Wisconsin age.

In a typical profile of a Remsen soil in pasture, the surface layer is very dark grayish-brown and dark grayish-brown silt loam about 10 inches thick. The subsoil is mostly brownish clay that contains contrasting grayish and brownish mottles and has grayish coatings on many of the subsurfaces of the peds. The substratum, at a depth of about 48 inches, is olive-brown clay.

These soils have a seasonal high water table, and they have mottling and grayish coatings in the subsoil indicating that the subsoils are naturally wet. In most places the root zone is moderately deep and the available moisture capacity is medium. Remsen soils have a high shrink-swell, which is a hazard to foundations.

About half of the acreage is in field crops. The rest is about equally divided between pastures and woodland. Commonly grown crops are corn wheat and hay.

Light-colored, poorly drained soils that are nearly level or gently sloping are in the Trumbull Series. These soils have formed in loamy glacial till that is low in content of calcareous material and is of Wisconsin age. They are mostly in the northwestern and western parts of the county.

In a typical profile of a Trumbull soil in a wooded area, the surface layer is very dark grayish-brown silt loam about 8 inches thick. This layer is mostly light brownish gray but is very dark grayish brown in the uppermost 2 inches. The subsoil is brownish and grayish silty clay loam that contains gray coatings on many of the peds. The substratum of olive-brown sily clay loams is at a depth of about 38 inches.

Permeability is very slow both in the subsoil and in the substratum. The mottling and coatings throughout most of the profile indicate that these soils are naturally wet. The water table is high during wet periods, and water drains slowly, even where artificial drainage is provided. In areas that are drained, the root zone for most annual crops is moderately deep. Within the root zone, the available moisture capacity is medium to high.

In Mahoning County areas of Trumbull soils, except those in nonfarm uses, are used as woodland, for pasture, or for growing field crops, mainly corn, hay, and wheat. More than one-third of the acreage is in trees, less than one-third is in field crops, and the rest is in pasture.

Authorized by the Flood Control Act of 1938, Berlin Lake is one of 16 flood control projects in the Pittsburgh District. The project provides flood protection for the Mahoning River Valley as well as for the Beaver and Upper Ohio Rivers. Since its completion in 1943, Berlin has prevented flood damages estimated to be in excess of $1 billion. The project has the capability to store the equivalent run-off of 6.9 inches of precipitation from its 249 square mile drainage area. Discharge is regulated by the control tower containing three 36” ball valves, two 36” ring jets and 18’ x 30’ tainter gates

The project also provides communities downstream with a clean and dependable water supply and has helped to alleviate pollution problems along the Mahoning River Valley. If you look across the gorge you will notice a large brick building, the pump house. During periods prolonged drought, the pumps inside this building can be used to move water through a large pipe to Meander Reservoir near Austintown to ensure a continuous supply of fresh drinking water. Additionally, Deer Creek Dam, which was built on project lands by the City of Alliance, Ohio, under agreement with the Department of the Army, provides a reservoir for domestic water supply to nearby communities.

Berlin Dam is actually made up of two distinct types of dams. The central part is a partially controlled concrete gravity dam which is flanked on each side by rolled earth filled abutments.

In a gravity dam, stability is secured by making it of such a size and shape that it will resist overturning, sliding and crushing at the toe. The dam will not overturn provided that the moment around the turning point, caused by the water pressure, is smaller than the moment caused by the weight of the dam. This is the case if the resultant force of water pressure and weight falls within the base of the dam. However, in order to prevent tensile stress at the upstream face and excessive compressive stress at the downstream face, the dam cross section is usually designed so that the resultant falls within the middle at all elevations of the cross section (the core). For this type of dam, impervious foundations with high bearing strength are essential.

When situated on a suitable site, gravity dams can prove to be a better alternative to other types of dams. When built on a carefully studied foundation, the gravity dam probably represents the best developed example of dam building. Since the fear of flood is a strong motivator in many regions, gravity dams are being built in some instances where an arch dam would have been more economical.

Gravity dams are classified as "solid" or "hollow" and are generally made of either concrete or masonry. This is called "zoning". The core of the dam is zoned depending on the availability of locally available materials, foundation conditions and the material attributes. The solid form is the more widely used of the two, though the hollow dam is frequently more economical to construct. Gravity dams can also be classified as "overflow" (spillway) and "non-overflow."

Earth-fill dams, also called earthen, rolled-earth or simply earth dams, are constructed as a simple embankment of well compacted earth. A homogeneous rolled-earth dam is entirely constructed of one type of material but may contain a drain layer to collect seep water. A zoned-earth dam has distinct parts or zones of dissimilar material, typically a locally plentiful shell with a watertight clay core. Modern zoned-earth embankments employ filter and drain zones to collect and remove seep water and preserve the integrity of the downstream shell zone. An outdated method of zoned earth dam construction utilized a hydraulic fill to produce a watertight core. Rolled-earth dams may also employ a watertight facing or core in the manner of a rock-fill dam. An interesting type of temporary earth dam occasionally used in high latitudes is the frozen-core dam, in which a coolant is circulated through pipes inside the dam to maintain a watertight region of permafrost within it. Because earthen dams can be constructed from materials found on-site or nearby, they can be very cost-effective in regions where the cost of producing or bringing in concrete would be prohibitive.

During extended periods of increased precipitation the US Army Corps. of Engineers maintenance workers must inspect the dam daily to ensure that their are no issues with the dam's structural integrity. This is accomplished by checking the the readings on five pressure gauges located inside the heart of the dam as well as checking the water levels in two dozen piezometers located on the earthen portions of the dam. It is a time consuming and hated duty, lol.

A piezometer is a small-diameter observation well used to measure the hydraulic head of groundwater in aquifers. Similarly, it may also be a standpipe, tube, vibrating wire piezometer or manometer used to measure the pressure of a fluid at a specific location in a column.

Piezometers should ideally have a very short screen and filter zone, so that they can represent the hydraulic head at a point in the aquifer. If the filter zone is located at a specific isolated depth, the piezometer is defined punctual, or, if the piezometer has a filter on all its length, is defined windowed. The windowed piezometer is cheaper than the punctual one, but cannot give information on vertical flows. The main problem with the piezometers is the time-lag between the variation of piezometric level in the aquifer and the respective variation in the piezometer. This time-lag is related to the piezometer (type, shape, etc.) and the soil. Modern piezometers with little time-lag are the piezometric cells, where the pressure on a membrane is measured by the pressure of gas (pneumatic piezometric cells), by vibrating thread extensimeters or by electrical extensimeters (strain gauges piezometers). The piezometers employed at Berlin lake look like three foot tall green pipes sticking out of the ground with metal caps and pad locks on them. Each of the pipes has been given a unique number designation which can be seen on the attached metal tag. Readings are taken by feeding a log moisture probe down the shaft to determine the current level of the water flowing through the dam. If at any time the water level begins to rise within one or more of the piezometers steps must be taken to repair the dam in that area.

Reservoirs held behind dams affect many ecological aspects of a river. Rivers topography and dynamics depend on a wide range of flows whilst rivers below dams often experience long periods of very stable flow conditions or saw tooth flow patterns caused by releases followed by no releases. Water releases from a reservoir including that exiting a turbine usually contains very little suspended sediment, and this in turn can lead to scouring of river beds and loss of riverbanks; for example, the daily cyclic flow variation caused by the Glen Canyon Dam was a contributor to sand bar erosion.

Older dams often lack a fish ladder, which keeps many fish from moving up stream to their natural breeding grounds, causing failure of breeding cycles or blocking of migration paths.[35] Even the presence of a fish ladder does not always prevent a reduction in fish reaching the spawning grounds upstream. In some areas, young fish ("smolt") are transported downstream by barge during parts of the year. Turbine and power-plant designs that have a lower impact upon aquatic life are an active area of research.

A large dam can cause the loss of entire ecospheres, including endangered and undiscovered species in the area, and the replacement of the original environment by a new inland lake.

Large reservoirs formed behind dams have been indicated in the contribution of seismic activity, due to changes in water load and/or the height of the water table.

I hope you have enjoyed taking part in my very first earth cache. If you are having trouble answering questions 1, 2 and 5 from your current location please visit the additional waypoint provided for a closer look at the geology of the area. Please follow all posted rules and venture near the water at your own risk. Also if you are visiting this cache during the Ohio spring rain season keep an eye out for the maintenance workers who will be checking the piezometers.

Additionally, if you feel like it please post a picture of yourself at ground zero, making sure to avoid giving away any of the answers.

The following references were utilized in the creation of this page:

The 1971 edition of the Soil Survey of Mahoning County, Ohio.

http://www.lrp.usace.army.mil/rec/lakes/berlin.htm

http://www.wikipedia.org/

FTF goes to: Bikinguy & Goalie003!