February 4th updates are highlighted in yellow.
February 5th updates are highlighted in blue.
Februrary 11th updates are highlighted in orange. 
February 18th updates are highlighted in this blue.

Lake Berkeley dam was constructed between 1948 and 1950 and was renovated during the 1980s. During a significant rain event in 2009, the dam and spillway areas sustained damage. Gwinnett County, along with several other Georgia counties were declared federal disaster areas. Since that time, the City of Berkeley Lake has been working to determine a corrective plan. 

Roles and Responsibilities 

What entities are responsible for Lake Berkeley and associated properties?

The City of Berkeley Lake is responsible for the earthen dam, gabion spillway and the parking lot adjacent to the dam.

The Berkeley Lake Homeowners' Association owns and is responsible for the lake, picnic area and beach.

The City of Berkeley Lake rents the parking lot adjacent to the dam to the Berkeley Lake Homeowners' Association for $100 per year.

The Berkeley Lake Homeowners' Association is responsible for removal of sediment from the lake.

Who are the community leaders with responsibilities related to Lake Berkeley, the dam and spillway?  What are their roles and responsibilities?

Financial 

How are repairs to Lake Berkeley dam and spillway to be funded?

Application has been made to FEMA and GEMA for support available in response to the national disaster declaration.  FEMA may reimburse the city for up to 75% of approved costs.  GEMA may reimburse up to 12 and half %.  The city and its engineers are maintaining close contact and collaboration with these groups in an effort to qualify for all available funding. However, FEMA's initial verbal response to our engineer indicated that they did not expect to provide as much funding as the City had previously been led to expect. Mayor and engineers are trying to set up a meeting with FEMA to discuss the matter further.

Will there be a financial impact to city residents?

Any city expenditure has financial impact to city residents.

What’s happening with FEMA?

Many citizens have contacted our 2 US Senators (Isakson and Chambliss) and our US Congressman (Linder).  As a result the Mayor has gotten helpful responses from Johnny Isakson’s staff and John Linder’s staff, as well as a director of FEMA in Washington.  A meeting scheduled between the Mayor, City Engineer, and our local FEMA contact had to be postponed due to a death in his family in Germany.  It is being rescheduled for when he returns from overseas.   John Linder’s aide has arranged with the Mayor to attend that meeting, and it is hoped that a Safe Dams representative will join them. 

Will there be a Town Hall meeting about the dam repair?

The Mayor has suggested to Council that one be scheduled on a Saturday in the Chapel.  Most council members are supportive of the idea, and prefer that one be scheduled after some resolution is reached with FEMA to discuss that information and specific plans for going forward.
 

Georgia Safe Dams Program, the Army Corps of Engineers, Piedmont Geotechnical Consultants and Clark Patterson Lee

What is the Georgia Safe Dams Program?

Georgia Safe Dams Program is part of the Environmental Protection Division under the Department of Natural Resources.

For what is Georgia Safe Dams Program responsible?

Georgia Safe Dams Program responsibilities include:

• Inventorying all existing and proposed dams over 25 feet tall or with a 100 acre-feet of storage at the top of the dam.
• Re-inventorying existing low hazard (Category II) dams at least every five years.
• Classifying dams based on development within the dam failure flood zone downstream.
• Approval of plans and specifications for construction and repair of all high hazard (Category I) dams.
• Continuously monitoring Category I dams for safety.

How often does the Georgia Safe Dams Program inspect the Lake Berkeley dam?

Annually.

What role does the US Army Corps of Engineers have in this situation?

The COE administers the Clean Water Act (the primary federal law in the US governing water pollution) and has jurisdiction over impacts to wetlands and waters of the US.

Can I speak directly to the city’s engineers?
 
If you come to the Town Hall meeting on Saturday, March 13th at 10AM at Lake Berkeley Chapel, you can.  Other individual conversations with various interested citizens will not be funded by the city.  A Professional Engineer’s time is quite expensive, and we are trying to spend your taxes wisely, while also meeting the need for citizen interaction at the Town Hall meeting, as we have previously at City Council meetings where the engineer took citizen questions. 

Lake Berkeley Dam

When was the Lake Berkeley dam built?

The dam was built between 1948 and 1950.

What are the responsibilities of the City of Berkeley Lake for maintaining the dam?

The city is responsible for mowing and maintenance activities and prevention of trespassing on the dam.

What happened during the September 2009 rain event?

From September 15 to September 21, the City received 12.5 inches of rain. Of the 12.5 inches, 6 inches fell on September 21, which put enough water into the lake to raise its elevation by 4 feet. On September 23, while mowing the dam, a City contractor discovered a slope failure about 2/3rd of the way up the dam face.

As diagramed, earthen slopes can develop a cut-spherical weakness area. Slips along the weakness area sometimes occur after a period of heavy rain, when the pore water pressure at the slip surface increases, reducing the effective normal stress and thus diminishing the restraining friction along the slip line. This is combined with increased soil weight due to the added groundwater.

Is Georgia Safe Dams Program requiring the City of Berkeley Lake to repair the earthen dam?

Yes.

If the City of Berkeley Lake does not repair the earthen dam, what could happen?

Georgia Safe Dams Program could file suit requiring the City to repair or breach the dam. 

Could the Georgia Safe Dams Program sue the City of Berkeley Lake for not repairing the dam?

The SDP has taken many legal actions against dam owners for failing to properly maintain their dams.  The state attorney general’s office provides them with litigation support.

Could Georgia Safe Dams Program require that the Lake Berkeley dam be removed?

Typically, the SDP gives owners the choice of repair or removal, and they require that owners provide them with progress updates.  For example, they would give a deadline for an owner to hire an engineering firm and then require them to show them that a contract had been executed.  They then set deadlines for certain milestones to be reached.  If progress stalls, new legal action is taken.

What are the qualifications of Piedmont Geotechnical Consultants?

Piedmont Geotechnical Consultants are geotechnical engineering experts, and have specialized in dam engineering for many years.  Karl Myers’s experience actually pre-dates the Safe Dams Program.  They have intimate knowledge of the typical problems and appropriate solutions for these kinds of dams.  They have worked on dozens of earthen embankment dams and Karl Myers sat on the committee that created the geotechnical engineering standards in the Rules for Dam Safety, which are the rules by which the Safe Dams Program regulates the state’s high hazard dams.

What are the qualifications of the City Engineer, Rich Edinger of Clark Patterson Lee?

Rich Edinger has served the City of Berkeley Lake very well in every way these last few years as our city engineer, but here are his qualifications specific to dams:  When Rich was the Public Works Director at the City of Suwanee, he supervised their project to renovate a high hazard dam that Suwanee purchased as part of its open space initiative.  This project involved all of the same issues that Berkeley Lake is now dealing with (stability issues, seepage, proper internal drainage, low level drain, etc.). Because of their expertise in dams  Peidmont Geotechnical Consultants was also hired to assist in Suwanee’s project.   References from Suwanee are excellent, for both Rich Edinger and PGC as engineers that apply critical thinking about the problem at hand, consider the constraints of the particular site and understand the regulatory landscape. 

Who from the city other than the City Engineer, Rich Edinger, is talking to the Georgia Safe Dams people?

Karl Myers, Craig Robinson (Piedmont Geotechnical Consultants) and Rich Edinger (City Engineer, Clark Patterson Lee) have been the point contacts with the Safe Dams Program because they can represent the City of Berkeley Lake best. Tom Rozier and Walter Anderson participated in a conference call with our engineers and a representative of the Safe Dams Program. 
 
Are we sure the City isn’t just giving in to Georgia Safe Dams Program's demands? 

We’re not giving in to Georgia Safe Dams Program, but we acknowledge that the dam must meet Georgia Safe Dam Program's standards, which exist to prevent tragedies like the 1977 failure of the Kelley Barnes dam near Toccoa that took 39 lives (http://en.wikipedia.org/wiki/Kelly_Barnes_Dam).  Catastrophic failures of engineered systems occur due to many small unrecognized or unresolved problems that, combined, cause the catastrophe.  What looks minor on the surface can be a symptom of a larger problem.  That’s why we initiated an investigation into the nature of the failure – to find the cause and formulate a repair strategy.  Georgia Safe Dams Program has already acknowledged that we don’t have to perform another Hydrology and Hydraulics Study because it’s not related to the problem we see.  The question has always been “how to find ways to meet the GSDP’s standards while still producing an economical design.”

What is the elevation of the dam's crest?

Currently, 979.5 feet above sea level.

What was learned from drilling on the dam and analysis of the cores?

• Fill material is “draped” over residual ridge running parallel with North Berkeley Lake Road.
• The blanket drain is not as extensive as originally thought.
• Embankment material is not compacted as well as it ought to be.
• There is a shallow phreatic surface.
• The dam is only marginally stable.  It does not have the factor of safety that a high hazard dam should have.

What are the safety standards associated with earthen dams?

The Georgia Safe Dams Program has standards for the construction of high hazard dams.

What does it mean that Lake Berkeley's dam is classified as a Category I dam?

There will be probable loss of life in the breach zone should the dam fail catastrophically.

What are the primary design specifications for a Category I dam?

The design principle for an earthfill dam embankment is to determine that cross section which, when constructed with available materials, will fulfill its required function with adequate safety at a minimum cost.  To accomplish this, the following criteria must be met:

• The embankment must be safe against overtopping of the inflow design flood by the provision of sufficient spillway and outlet works capacity.
• The slopes of the embankment must be stable during construction and under all conditions of reservoir operation, including rapid drawdown of the reservoir.
• The embankment must be designed so as not to impose excessive stresses upon the foundation.
• Seepage flow through the embankment, foundation, and abutments must be controlled so that no internal erosion takes place and so there is no sloughing in the area where the seepage emerges.  The amount of water lost through seepage must be controlled so that it does not interfere with planned project functions.
• The embankment must be safe from overtopping by wave action.
• The upstream slope must be protected against erosion by wave action, and the crest and downstream slope must be protected against erosion by rain and wind.

An embankment designed to meet the above criteria will prove safe provided proper construction methods and control are achieved. 

What design specifications are not being met for Lake Berkeley's dam?

The dam is marginally stable, does not have a low level outlet, and does not contain an adequate internal drainage system.  Some construction practices used in previous eras would not be allowed today, such as draping the earth embankment over a residual ridge, and only compacting the fill material to 92 percent of standard proctor.

What is a Hydrological and Hydrology (H&H) study?

An assessment of how much water will flow into the lake in an extreme rain event and how the lakes hydraulic structures will behave under said rainfall.

Will a Hydrological and Hydrology study be required?

Not unless we lower the elevation of the dam.

What is the expected cost for repairing the dam?

Our engineers have submitted a cost estimate to FEMA of approximately $4 million for the entire project including exploration and study performed so far and repairs previously discussed with Georgia Safe Dams Program and FEMA. 

How many cubic yards of sediment is expected to be impacted on the dam?

Present estimates are between 40,000 and 80,000 cubic yards.

Perspective on 40,000 cubic yards: If you took an area 850 feet long (about the length of the dam) by 100 feet wide and filled about 13 feet – that would equal about 40,000 cubic yards.

What is the composition of that material and could it be used elsewhere?

The material is not good structural fill and has high moisture content.

What is the expected cost for removing and transporting the material suggested to be replaced?

A conservative estimate is between $7.50 and $10.00 per cubic yard.

What is 'borrowed dirt' and how much is expected to be required for the project?

“Borrow” is an engineering term used to describe a remote source of soil.  We will need approximately 80,000  cubic yards of borrow.

Why can’t the dirt now on the dam be compacted and still be used rather than replaced?

Trying to dry out soil after removing it costs more than finding a borrow source and hauling it in because the weather doesn’t cooperate and causes delays.

Could the dirt needed to rebuild the dam be taken from the lake bed?

The City Engineer has already considered this.  He believes from historical research that much if not all of the dirt that’s on the dam now was removed from the lake bed; and that soil is not serving well.  However, if it were a good option financially relative to the other sites that he is exploring (including one fairly nearby), and if soil testing in another end of the lake (not near the dam) showed promise, it could be a possibility.

How long are repairs to Lake Berkeley's dam expected to take?

The construction phase is expected to take between 180 and 270 days.

What are the overall steps or phases for evaluating, bidding and construction activities relating to repairing the dam?

Broadly speaking, the phases include Problem identification, Design Development, Construction Documents, Right-of-Way/Easement Acquisition, Permitting, Contractor Pre-qualification, Bidding, Construction and Post-Construction.

Will the City of Berkeley Lake place sediment from the dam into the lake?

The City and the Berkeley Lake Homeowners' Association, owners of the lake bottom, are still discussing whether it would be mutually beneficial to do so.

Will Gwinnett County need to relocate the water main alongside North Berkeley Lake Road?

A portion of the water line will need to be relocated to the opposite side of North Berkeley Lake Road.

What is the current slope of Lake Berkeley's dam versus the optimal slope?

The dam stability calculations are still in process, but generally, a conservatively stable slope is 3:1. The dam is currently 2.5:1.

What will the impact be for North Berkeley Lake Road?

A portion of the road may need to be removed and replaced, depending on the final established dam slope.

Gate Valves, Spillway and Siphons

What types of devices are being considered to be incorporated into the dam for controlling the water level?

The Safe Dams Program requires 2/3 of the volume of the lake to be drained within ten days.  Possibilities include a siphon that discharges to either a chute spillway or a drop structure that leads to a discharge culvert.

What is a Gabion Spillway?

In their simplest form, gabions are essentially rock-filled wire baskets or cages. Gabions are useful for a number of applications. Similar to a retaining wall, they can be used for slope stabilization; can protect culverts, streambanks, and other channels against high-velocity moving water; and can even be formed into a variety of aesthetically pleasing structures. Gabion mattresses, with a small height relative to their lateral dimensions, may be used to line channel bottoms, for levee revetment, and for scour protection. Vertical diaphragms are often affixed to the base of gabion baskets to provide additional reinforcement and to limit internal movement of the rock filling.

Lake Berkeley

What is the size of Berkeley Lake?

Berkeley Lake is approximately 88 acres.

What is the plan for adjusting the level of the lake?

Until it becomes necessary to lower the lake additionally for dam repairs, the plans are to maintain the lake 10’ below normal full pool

Are we really sure that the lake has to be lowered further?

The lake must be significantly lowered, and perhaps drained, to perform the repair.  Soil cannot be compacted appropriately at a high moisture content, and the seepage through the dam will preclude getting the moisture content right. Also, we need to remove a portion of the embankment to install the internal drainage system, and the dam is already only marginally stable.  Performing this repair while the lake is up could lead to a catastrophic failure.
 
How long with the lake remain lowered?

Under these circumstances, the lake level is managed by the City of Berkeley Lake and until the concerns with the dam are resolved the lake will not be allowed to return to full pool. Present estimate – 14 to 18 months.

What is the impact to fish and lake’s ecosystem on lowering the lake?

BLHA is presently investigating this impact and studying remedies. It is not expected that FEMA will provide reimbursement for this.

What terms might be helpful to better understand related discussions?

CHIMNEY DRAIN - A vertical structure of free-draining material (usually coarse sand or gravel) within an embankment placed to intercept and control seep water. (See Filter)

COFFER DAM - Temporary structure enclosing all or part of a construction area, so construction can proceed in a dry area. A "diversion coffer dam" diverts a river into a pipe, channel, or tunnel.

CREST OF DAM - The elevation of the uppermost surface of a dam excluding any parapet wall, railings, etc. In international usage, it refers to the crown of an overflow section of a dam.

CREST WIDTH - The width or thickness of a dam at the level of the crest of the dam. In general, the term "thickness" is used for gravity and arch dams and "width" is used for other dams.

FILTER (Filter Zone) - A band or zone of granular material that is incorporated into a dam and is graded (either naturally or by selection) so as to allow seep water to flow through the filter to a drain layer without allowing the migration of fine material from the protected zone to the drain layer.

GROUT CURTAIN (Grout Cutoff) - A barrier produced by injecting grout into a vertical zone in the foundation parallel to the dam centerline to reduce seep rates under a dam.

INCLINOMETER - An instrument, usually consisting of a metal or plastic tube, inserted in a borehole and a sensitized monitor either lowered into the tube or fixed within the tube. This measures at different points the inclination of the tube from the vertical. The lateral position at different levels of the tube may be found by integration relative to an assumed fixed point, usually the top or bottom of the tube. The system may be used to measure settlement.

RIP RAP - A layer of stones, broken rock or precast blocks placed in random fashion on the upstream slope of an embankment dam, on a reservoir shore or on the sides of a channel as a protection against waves, ice action and flowing water. Very large rip rap is sometimes referred to as armoring.

SEEP - The interstitial movement of water that may take place through a dam, its foundation, or its abutments.

SLOPE - The side of a hill or mountain, the inclined face of a cutting, canal or embankment or other inclination from the horizontal. In the United States, it is measured as the ratio of the number of units of horizontal distance to the number of corresponding units of vertical distance. The term is expressed as a percent when the slope is gentle, in which case the term "gradient" is also used.

SPILLWAY - A structure over or through which flood flows are discharged. If the flow is controlled by gates, it is a controlled spillway; if the elevation of the spillway crest is the only control, it is an uncontrolled spillway.

TOE OF DAM - The junction of the downstream face with the ground surface.