Environmental Health Exam 4 (Final)

Recreational Water

• should contain limited bacteria

• even if a pool has chlorine, bacterial buildup is a concern

Percolation “Perc” tests

• Examine how rapidly water is absorbed into ground

• important for drain runoff and septic systems

• very important if building in rural areas

Permeability

• water permeable substances increase absorption rate

• less permeable decreases absorption rate

How perc tests work

dig a hole, fill with water, use measure stick to time how long it takes the water level to lower

Septic systems

treats waste water onsite (owner)

septic advantages

• More environmentally friendly (less water and energy)

• No monthly sewer bill from city/county

septic disadvantages

• expensive maintenance, owners oversee maintenance

• requires dedicated space on property for tank and drain field

sewer systems

transports the waste to central location for treatment (city/county)

What are the types of treatments?

• Primary, Secondary, Tertiary treatment

• typically flow of filtering larger to smaller

• after each type of treatment, collected sludge is sent to digesters

what treatment type: oxidation ditch

secondary treatment

what treatment type: Primary Settling Tank (Scrapers)

primary treatment

what treatment type: Sand Filtration

Tertiary Treatment

what treatment type: Disinfectant

Tertiary treatment

what treatment type: Clarifiers

Secondary Treatment

what treatment type: Carbon Bed Filtration

Tertiary treatment

what treatment type: Trickling Filter

Secondary Treatment

what treatment type: Pre-Filters

Primary treatment

A percolation or "perc" test is used to determine ________.

how rapidly water is absorbed into the ground—to that field drain runoff is absorbed

facts about septic systems

• tank, drainage field, and soil surrounding entire system

• sealed off container

• anaerobic bacteria digest solid particles

• strong drain cleaners can damage ecosystem w/in tank

Septic system drain fields

Liquid waste from septic tank is distributed through drain fields

Types of drain fields

Gravity system, sand lined trench, mound

Gravity system

• uses septic tank

• requires distribution box spread flow evenly, and that the water can run DOWNHILL

Sand Lined Trench

• uses a septic tank, pump tank, and sand filter tank before it gets to the field

• sand treats waste prior to reaching drain field

Mound

• great for environments with high clay content, and a high water table

• Possesses mound that contains network of pipes to disperse waste