# Transactions of the American Society of Civil Engineers, vol. LXXII, June, 1911 E. D. Hardy and American Society of Civil Engineers Trivia Quiz Questions and Answers

What was the average turbidity of the Potomac River water entering the Washington, D.C. filtration plant in 1911?

• 10 parts per million
• 106 parts per million
• 500 parts per million
• 1,000 parts per million

Correct Answer: 106 parts per million

Correct Answer Explanation: The report states that the average turbidity of the raw water entering the filters was 106 parts per million. This means that there were 106 milligrams of suspended particles in every liter of water.

What is the name of the device that uses a jet of water to move sand or other materials?

• Ejector
• Schmutzdecke
• Coagulator
• Under-drain

Correct Answer Explanation: An ejector is a device that uses a jet of water to move sand or other materials. This is a common method for removing sand from filters for cleaning and replacement.

What was the average typhoid fever death rate in Washington, D.C. for the five years after the installation of the filtration plant?

• 59 per 100,000 population
• 37 per 100,000 population
• 149 per 100,000 population
• 6,400 per 100,000 population

Correct Answer: 37 per 100,000 population

Correct Answer Explanation: The report indicates that the average typhoid fever death rate in Washington, D.C. for the five years after the installation of the filtration plant was 37 per 100,000 population. This represents a significant decrease from the average death rate of 59 per 100,000 population in the six years prior to filtration.

What was the average length of a filter run at the Washington, D.C. filtration plant in 1911?

• 10 days
• 30 days
• 113 days
• 365 days

Correct Answer: 113 days

Correct Answer Explanation: The report states that the average length of a filter run was about 113 days. This means that the sand filters would operate for an average of 113 days before needing to be cleaned and the sand replaced.

What was the primary reason for closing the gates at Great Falls during the summer months?

• To prevent flooding
• To control the flow of water
• To exclude excessively muddy water
• To reduce the amount of water treated

Correct Answer: To exclude excessively muddy water

Correct Answer Explanation: The report mentions that the gates at Great Falls were closed to exclude excessively muddy water, particularly during the summer months. This was done to ensure that the water entering the filtration plant was not too heavily contaminated with sediment.

Which of these preliminary treatment methods was found to be most effective in removing turbidity?

• Rapid filtration
• Maignen scrubber
• Coagulation
• Sand filtration

Correct Answer Explanation: The report highlights that experiments conducted with different preliminary treatment methods showed coagulation to be the most effective method for removing turbidity, which is the cloudiness caused by suspended particles in the water.

How many acres of filter surface area did the Washington, D.C. filtration plant have in 1911?

• 1 acre
• 29 acres
• 40 acres
• 141 acres

Correct Answer: 29 acres

Correct Answer Explanation: The Washington, D.C. filtration plant had 29 slow sand filters, each with an effective area of 1 acre. This means that the total filter surface area was 29 acres.

What was the average cost of labor for sand handling at the Washington, D.C. filtration plant in 1911?

• \$0.03 per cubic yard of sand handled
• \$0.26 per million gallons of water filtered
• \$0.34 per cubic yard of sand handled
• \$0.50 per million gallons of water filtered

Correct Answer: \$0.26 per million gallons of water filtered

Correct Answer Explanation: The report indicates that the average cost of labor for sand handling was about \$0.26 per million gallons of water filtered, reflecting the significant expense associated with maintaining the sand filters.

What is the layer of organic matter that forms on the surface of slow sand filters called?

• Schmutzdecke
• Ejector
• Coagulator
• Under-drain

Correct Answer Explanation: The Schmutzdecke is the layer of organic matter that forms on the surface of slow sand filters. This layer plays a crucial role in the filtration process, as it traps and removes impurities from the water.

What was the average bacteria count in the raw water entering the filters at the Washington, D.C. filtration plant?

• 149 per cubic centimeter
• 6,400 per cubic centimeter
• 106 per cubic centimeter
• 500 per cubic centimeter

Correct Answer: 6,400 per cubic centimeter

Correct Answer Explanation: The report states that the average bacteria count in the raw water entering the filters was 6,400 per cubic centimeter. This highlights the importance of filtration for removing harmful bacteria from the water supply.

What was the most expensive component of filter maintenance at the Washington, D.C. filtration plant in 1911?

• Raking
• Scraping
• Washing in place
• Sand handling

Correct Answer: Sand handling

Correct Answer Explanation: The report highlights that sand handling is the most expensive component of filter maintenance. This was due to the labor involved in removing, cleaning, and replacing the sand.

How did raking the sand surface of the filters affect the time between scrapings?

• It decreased the time between scrapings
• It did not affect the time between scrapings
• It increased the time between scrapings
• It varied the time between scrapings

Correct Answer: It increased the time between scrapings

Correct Answer Explanation: The report indicates that raking the sand surface of the filters effectively extended the time between scrapings. This was because raking removed accumulated debris and prevented clogging, allowing the filters to operate for longer periods before needing to be cleaned.

What was the average cost of filter operations at the Washington, D.C. filtration plant in 1911?

• \$0.03 per cubic yard of sand handled
• \$0.26 per million gallons of water filtered
• \$0.34 per cubic yard of sand handled
• \$0.50 per million gallons of water filtered

Correct Answer: \$0.50 per million gallons of water filtered

Correct Answer Explanation: The report states that the average cost of filter operations was about \$0.50 per million gallons of water filtered. This includes the costs of sand handling, labor, and other maintenance.

What was the name of the reservoir that had a capacity of 141,000,000 gallons?

• Dalecarlia Reservoir
• Georgetown Reservoir
• McMillan Park Reservoir
• Great Falls Reservoir

Correct Answer: Dalecarlia Reservoir

Correct Answer Explanation: The report mentions that the Dalecarlia Reservoir had a capacity of 141,000,000 gallons. This reservoir was part of the Washington Aqueduct system, which supplied water to the city.

What was the average cost of pumping water for sand handling?

• \$0.03 per cubic yard of sand handled
• \$0.06 per cubic yard of sand ejected and washed
• \$0.26 per million gallons of water filtered
• \$0.50 per million gallons of water filtered

Correct Answer: \$0.06 per cubic yard of sand ejected and washed

Correct Answer Explanation: The report indicates that the cost of pumping water for sand handling was \$0.06 per cubic yard of sand ejected and washed, highlighting the costs associated with removing and cleaning the sand.

What was the average bacteria count in the filtered water leaving the Washington, D.C. filtration plant?

• 149 per cubic centimeter
• 6,400 per cubic centimeter
• 106 per cubic centimeter
• 500 per cubic centimeter

Correct Answer: 149 per cubic centimeter

Correct Answer Explanation: The report states that the average bacteria count in the filtered water was 149 per cubic centimeter. This represents a significant reduction from the bacteria count in the raw water, demonstrating the effectiveness of the filtration process in removing harmful bacteria.

Which of these is NOT a method of cleaning filter beds described in the report?

• Raking
• Scraping
• Washing in place
• Hydraulic sand ejection

Correct Answer: Hydraulic sand ejection

Correct Answer Explanation: Hydraulic sand ejection is a method of removing sand from the filters, not a method of cleaning the filter beds. Raking, scraping, and washing in place are all methods used to clean the filter beds and remove accumulated debris.

What was the average depth of sand in the filters at the Washington, D.C. filtration plant?

• 10 inches
• 20 inches
• 40 inches
• 60 inches

Correct Answer: 40 inches

Correct Answer Explanation: The report states that the average depth of sand in the filters was 40 inches. This depth of sand was necessary to ensure effective filtration and removal of impurities from the water.

What was the average amount of sand removed from a filter during a scraping?

• 10 cubic yards per acre
• 50 cubic yards per acre
• 213 cubic yards per acre
• 1,000 cubic yards per acre

Correct Answer: 213 cubic yards per acre

Correct Answer Explanation: The report indicates that the average amount of sand removed from a filter during a scraping was about 213 cubic yards per acre. This was the typical amount of sand that needed to be replaced after a filter run.

What was the average consumption of water in Washington, D.C. in 1911?

• 6 million gallons per day
• 20 million gallons per day
• 60 million gallons per day
• 100 million gallons per day

Correct Answer: 60 million gallons per day

Correct Answer Explanation: The report states that the average consumption of water in Washington, D.C. was 60 million gallons per day. This represented the daily water demand of the city.

How did the introduction of the filtration plant affect the typhoid fever death rate in Washington, D.C.?

• The death rate increased significantly
• The death rate decreased significantly
• The death rate remained the same
• The death rate was not recorded

Correct Answer: The death rate decreased significantly

Correct Answer Explanation: The report highlights that the installation of the filtration plant led to a significant decrease in the typhoid fever death rate in Washington, D.C. This demonstrates the effectiveness of filtration in preventing waterborne diseases.

What was the average cost of sand handling per million gallons of water filtered?

• \$0.03
• \$0.26
• \$0.54
• \$1.06

Correct Answer Explanation: The report states that the average cost of sand handling was about \$0.54 per million gallons of water filtered. This shows that sand handling was a significant expense for the operation of the filtration plant.

Which reservoir had a capacity of 180,000,000 gallons?

• Dalecarlia Reservoir
• Georgetown Reservoir
• McMillan Park Reservoir
• Great Falls Reservoir

Correct Answer: McMillan Park Reservoir

Correct Answer Explanation: The McMillan Park Reservoir was part of the Washington Aqueduct system and had a capacity of 180,000,000 gallons. This reservoir played a crucial role in providing water to the city.

What was the average cost of filtering water at the Washington, D.C. filtration plant?

• \$0.26 per million gallons of water filtered
• \$0.50 per million gallons of water filtered
• \$0.54 per million gallons of water filtered
• \$1.06 per million gallons of water filtered

Correct Answer: \$1.06 per million gallons of water filtered

Correct Answer Explanation: The report states that the average cost of filtering water was about \$1.06 per million gallons of water filtered. This included the costs of sand handling, labor, and other maintenance.

What was the cost of replacing sand using a hydraulic ejector?

• \$0.03 per cubic yard of sand
• \$0.06 per cubic yard of sand
• \$0.26 per cubic yard of sand
• \$0.50 per cubic yard of sand

Correct Answer: \$0.03 per cubic yard of sand

Correct Answer Explanation: The report states that the cost of replacing sand using a hydraulic ejector was \$0.03 per cubic yard. This method was considered to be more economical than traditional methods of sand handling.

What was the size of the gates at Great Falls?

• 10 inches
• 20 inches
• 40 inches
• 60 inches

Correct Answer: 10 inches

Correct Answer Explanation: The report mentions that a 10-inch hydraulic dredge was used to remove mud from the Dalecarlia Reservoir. This suggests that the gates at Great Falls were also relatively small.

What was the average cost of filtering water at the Washington, D.C. filtration plant in 1911?

• \$0.26 per million gallons of water filtered
• \$0.50 per million gallons of water filtered
• \$0.54 per million gallons of water filtered
• \$1.06 per million gallons of water filtered

Correct Answer: \$1.06 per million gallons of water filtered

Correct Answer Explanation: The report states that the average cost of filtering water was about \$1.06 per million gallons of water filtered. This included the costs of sand handling, labor, and other maintenance.

How much mud was removed from Dalecarlia Reservoir by the hydraulic dredge in 1907 and 1908?

• 100 cubic yards
• 1,000 cubic yards
• 10,000 cubic yards
• 100,000 cubic yards

Correct Answer: 100,000 cubic yards

Correct Answer Explanation: The report states that a 10-inch hydraulic dredge removed more than 100,000 cubic yards of mud from Dalecarlia Reservoir in 1907 and 1908. This highlights the significant amount of sediment that could accumulate in the reservoirs.

What was the uniformity coefficient of the sand used in the filters at the Washington, D.C. filtration plant?

• 0.32
• 1.77
• 2.00
• 4.00

Correct Answer Explanation: The report states that the sand in the filters had an average effective size of 0.32 millimeters and a uniformity coefficient of 1.77. This means that the sand grains were relatively uniform in size.

What was the percentage of time that the gates at Great Falls were closed?

• 1.5%
• 10.5%
• 40%
• 50%

Correct Answer Explanation: The report indicates that the gates at Great Falls were closed for 10.50% of the time, excluding 40.06% of the suspended matter from the water supply. This highlights the importance of managing the water flow to minimize contamination.

Which of these is NOT a factor that contributes to the effectiveness of slow sand filtration?

• Straining
• Oxidation
• Bacterial action
• Coagulation

Correct Answer Explanation: Coagulation is a separate process used in water treatment, primarily for removing turbidity. The effectiveness of slow sand filtration relies on straining, oxidation, and bacterial action, which are all natural processes that occur within the sand bed.

What was the total capacity of the three settling reservoirs in the Washington Aqueduct system?

• 140 million gallons
• 141 million gallons
• 180 million gallons
• 461 million gallons

Correct Answer: 461 million gallons

Correct Answer Explanation: The total capacity of the three settling reservoirs was 461 million gallons (141 million gallons for Dalecarlia Reservoir, 140 million gallons for Georgetown Reservoir, and 180 million gallons for McMillan Park Reservoir).

How did the use of hydraulic sand ejection affect the cost of sand handling?

• It increased the cost
• It decreased the cost
• It had no effect on the cost
• The report does not provide information on this

Correct Answer: It decreased the cost

Correct Answer Explanation: The report highlights that the hydraulic sand ejection system significantly reduced the cost of sand handling compared to traditional cart-based methods. This innovation made the operation of the filtration plant more efficient and economical.

What year was the Washington, D.C. filtration plant completed?

• 1900
• 1905
• 1911
• 1915

Correct Answer Explanation: The report mentions that the Washington, D.C. filtration plant was completed in 1905. This was a significant milestone in improving the quality of the city’s water supply.

What was the average turbidity of the filtered water leaving the Washington, D.C. filtration plant?

• 10 parts per million
• 106 parts per million
• 500 parts per million
• 1,000 parts per million

Correct Answer: 10 parts per million

Correct Answer Explanation: The report states that the average turbidity of the filtered water was 10 parts per million. This represents a significant reduction in turbidity compared to the raw water, demonstrating the effectiveness of the filtration process in removing suspended particles.

What was the primary method used to remove mud from the Dalecarlia Reservoir?

• Raking
• Scraping
• Washing in place
• Hydraulic dredge

Correct Answer: Hydraulic dredge

Correct Answer Explanation: The report states that a 10-inch hydraulic dredge was used to remove mud from the Dalecarlia Reservoir. This method was effective in removing large quantities of sediment.

What was the average effective size of the sand used in the filters at the Washington, D.C. filtration plant?

• 0.10 millimeters
• 0.32 millimeters
• 1.00 millimeters
• 2.00 millimeters

Correct Answer: 0.32 millimeters

Correct Answer Explanation: The report states that the sand in the filters had an average effective size of 0.32 millimeters. This size of sand was suitable for effectively filtering the Potomac River water.

What was the name of the bacteria that was commonly found in the intestines of humans and animals?

• Bacillus coli
• Schmutzdecke
• Ejector
• Coagulator

Correct Answer: Bacillus coli

Correct Answer Explanation: Bacillus coli is a type of bacteria that is commonly found in the intestines of humans and animals. Its presence in water is an indicator of fecal contamination.

What was the primary purpose of the gates at Great Falls?

• To regulate the flow of water
• To prevent flooding
• To control the temperature of the water
• To provide a source of drinking water

Correct Answer: To regulate the flow of water

Correct Answer Explanation: The gates at Great Falls were primarily used to regulate the flow of water entering the Washington Aqueduct system. This was necessary to ensure that the filtration plant could handle the water flow and maintain water quality.

What was the name of the chemical used to disinfect water by killing bacteria?

• Hypochlorite of lime
• Aluminum sulfate
• Sand
• Schmutzdecke

Correct Answer: Hypochlorite of lime

Correct Answer Explanation: Hypochlorite of lime is a chemical that is used to disinfect water by killing bacteria. This is a common practice in water treatment to ensure that the water is safe for drinking.

What was the primary source of water for the Washington, D.C. filtration plant?

• The Potomac River
• The Chesapeake Bay
• The Ohio River
• The Mississippi River

Correct Answer: The Potomac River

Correct Answer Explanation: The report states that the Washington, D.C. filtration plant was designed to treat water from the Potomac River. This river is a major source of water for the Washington, D.C. area.

What was the cost of operation of the Washington, D.C. filtration plant in 1911?

• \$20,000 per year
• \$50,000 per year
• \$82,000 per year
• \$100,000 per year

Correct Answer: \$82,000 per year

Correct Answer Explanation: The report states that the cost of operation of the filtration plant was about \$82,000 per year. This includes the costs of sand handling, labor, and other maintenance.

Which reservoir was known for its capacity of 140 million gallons?

• Dalecarlia Reservoir
• Georgetown Reservoir
• McMillan Park Reservoir
• Great Falls Reservoir

Correct Answer: Georgetown Reservoir

Correct Answer Explanation: The Georgetown Reservoir had a capacity of 140 million gallons, making it one of the largest reservoirs in the Washington Aqueduct system.

What was the purpose of the under-drain system beneath the sand bed of the filters?

• To collect the filtered water
• To distribute the water evenly
• To remove the Schmutzdecke
• To prevent clogging

Correct Answer: To collect the filtered water

Correct Answer Explanation: The under-drain system was a network of pipes beneath the sand bed that collected the filtered water and transported it to the distribution system.

What was the difference in pressure between the water entering a filter and the water leaving the filter called?

• Loss of head
• Turbidity
• Coagulation
• Schmutzdecke

Correct Answer Explanation: The difference in pressure between the water entering a filter and the water leaving the filter was called the loss of head. This pressure difference is an indicator of the efficiency of the filter.

What was the average filtration rate at the Washington, D.C. filtration plant in 1911?

• 1 million gallons per acre per day
• 2 million gallons per acre per day
• 3 million gallons per acre per day
• 4 million gallons per acre per day

Correct Answer: 2 million gallons per acre per day

Correct Answer Explanation: The report states that the average filtration rate was about 2 million gallons per acre per day. This was a typical rate for slow sand filters during that time period.

How many slow sand filters were there at the Washington, D.C. filtration plant in 1911?

• 10
• 20
• 29
• 40

Correct Answer Explanation: The Washington, D.C. filtration plant had 29 slow sand filters, each with an effective area of 1 acre. This was a large-scale filtration plant for its time.

What was the main reason for the implementation of the hydraulic sand ejection system at the Washington, D.C. filtration plant?

• To reduce labor costs
• To improve the quality of the filtered water
• To increase the capacity of the filters
• To make the operation more environmentally friendly

Correct Answer: To reduce labor costs

Correct Answer Explanation: The hydraulic sand ejection system was implemented to significantly reduce the cost of labor associated with sand handling. This was a major factor in making the operation of the filtration plant more efficient and economical.

What was the average typhoid fever death rate in Washington, D.C. for the six years prior to the installation of the filtration plant?

• 37 per 100,000 population
• 59 per 100,000 population
• 149 per 100,000 population
• 6,400 per 100,000 population

Correct Answer: 59 per 100,000 population

Correct Answer Explanation: The report indicates that the average typhoid fever death rate in Washington, D.C. for the six years prior to the installation of the filtration plant was 59 per 100,000 population. This highlights the significant public health challenge posed by waterborne diseases before the implementation of filtration.

What was the most significant finding of the experiments conducted with different filtration rates?

• Increasing the filtration rate significantly affected the quality of the effluent
• Increasing the filtration rate did not significantly affect the quality of the effluent
• Increasing the filtration rate had no impact on the cost of operation
• Increasing the filtration rate resulted in a decrease in the cost of operation

Correct Answer: Increasing the filtration rate did not significantly affect the quality of the effluent

Correct Answer Explanation: The experiments conducted with different filtration rates showed that increasing the rate did not significantly affect the quality of the effluent, but it did increase the cost of operation. This finding challenged the traditional emphasis on low filtration rates.

Which of these is NOT a component of the Washington, D.C. filtration plant described in the report?

• Pumping station
• Slow sand filters
• Filtered-water reservoir
• Rapid sand filters

Correct Answer: Rapid sand filters

Correct Answer Explanation: The Washington, D.C. filtration plant described in the report utilized slow sand filters, not rapid sand filters. Rapid sand filters are a different type of filter that operate at higher filtration rates.

What was the purpose of the preliminary treatment experiments conducted at the Washington, D.C. filtration plant?

• To determine the most effective method for removing turbidity
• To improve the efficiency of the slow sand filters
• To reduce the cost of filtering water
• To increase the capacity of the filtration plant

Correct Answer: To determine the most effective method for removing turbidity

Correct Answer Explanation: The preliminary treatment experiments were conducted to evaluate different methods for removing turbidity, which is the cloudiness of water caused by suspended particles. Coagulation was found to be the most effective method.

What was the main purpose of the 1911 report on the Washington, D.C. filtration plant?

• To provide a historical account of the plant’s construction
• To evaluate the effectiveness and efficiency of the plant’s operation
• To recommend improvements to the plant’s design
• To promote the use of slow sand filters in other cities

Correct Answer: To evaluate the effectiveness and efficiency of the plant’s operation

Correct Answer Explanation: The main purpose of the 1911 report was to evaluate the effectiveness and efficiency of the Washington, D.C. filtration plant’s operation over a period of five years. The report highlighted the success of innovative practices and examined the impact of new technologies on water quality and public health.