PROBLEMS WITH A LEACH FIELD

Problems with a leach field are uncommon among new installations. Unless the field was poorly designed or installed improperly, there is very little rea­son why it should fail. However, extremely wet ground conditions, due to heavy or constant rains, could force a field to become saturated. If the field saturates with ground water, it cannot accept the effluent from a septic tank. This, in turn, causes backups in houses. When this is the case, the person who created the septic design should be looked to in terms of fault.

Older Fields

Older fields sometimes clog up and fail. Some drain fields become clogged with solids. Financially, this is a devastating discovery. A clogged field has to be dug up and replaced. Much of the crushed stone might be salvageable, but the pipe, the excavation, and whatever new stone is needed can cost thou­sands of dollars. The reasons for a problem of this nature are either a poor de­sign, bad workmanship, or abuse.

If the septic tank installed for a system is too small, solids are likely to en­ter the drain field. An undersized tank could be the result of a poor septic de­sign, or it could come about as a family grows and adds onto their home.

A tank that is adequate for two people may not be able to keep up with the us­age seen when four people are involved. Unfortunately, finding out that a tank is too small often doesn’t happen until the damage has already been done.

Why would a small septic tank create problems with a drain field? Septic tanks accept solids and liquids. Ideally, only liquids should leave the septic tank and enter the leach field. Bacterial action occurs in a septic tank to break down solids. if a tank is too small, there is not adequate time for the breakdown of solids to occur. increased loads on a small tank can force solids down into the drain field. After this happens for a while, the solids plug up the drainage areas in the field. This is when digging and replace­ment is needed.

in terms of a septic tank, a pipe with a fast grade can cause solids to be stirred up and sent down the outlet pipe. When a four-inch wall of water dumps into a sep­tic tank at a rapid rate, it can create quite a ripple effect. The force of the water might generate enough stir to float solids that should be sinking. If these solids find their way into a leach field, clogging is likely.

We talked a little bit about garbage disposers earlier. When a disposer is used in conjunction with a septic system, there are more solids involved that what would exist without a disposer. This, where code allows, calls for a larger septic tank. Due to the increase in solids, a larger tank is needed for satisfac­tory operation and a reduction in the risk of a clogged field. I remind you again, some plumbing codes prohibit the use of garbage disposers where a septic system is present.

other causes for field failures can be related to collapsed piping. This is not common with today’s modern materials, but it is a fact of life with some old drain fields. Heavy vehicular traffic over a field can compress it and cause the field to fail. This is true even of modern fields. Saturation of a drain field will cause it to fail. This could be the result of seasonal water tables or pro­longed use of a field that is giving up the ghost.

Septic tanks should have the solids pumped out of them on a regular ba­sis. For a normal residential system, pumping once every two years should be adequate. Septic professionals can measure sludge levels and determine if pumping is needed. Failure to pump a system routinely can result in a build­up of solids that may invade and clog a leach field.

Normally, septic systems are not considered to be a plumber’s problem. Once you establish that a customer’s grief is coming from a failed septic sys­tem, you should be off the hook. Advise your customers to call septic profes­sionals and go onto your next service call; you’ve earned your money.

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ational rainfall statistics are needed for computing the requirements of storm water systems. The expected rainfall rates are needed to fig­ure out systems for roof drains, storm sewers, and similar methods of controlling storm water drainage. Fortunately, the rainfall rates for major cities are listed in this chapter. Similar information can often be found in plumbing codebooks. You will also find rain maps in this chapter and some codebooks. You can’t accomplish much with only the rainfall rates. Consider the following information as reference material that you can use at anytime to compute the needs for controlling storm water. (Figs. A1.1 to A1.5)

309

Virginia Bristol 2.7 Charlottesville 2.8 Lynchburg 3.2 Norfolk 3.4 Richmond Washington 3.3 Omak 1.1 Port Angeles 1.1 Seattle 1.4 Spokane 1.0 Yakima West Virginia 1.1 Charleston 2.8 Morgantown Wisconsin 2.7 Ashland 2.5 Eau Claire 2.9 Green Bay 2.6 La Crosse 3.1 Madison 3.0 Milwaukee Wyoming 3.0 Cheyenne 2.2 Fort Bridger 1.3 Lander 1.5 New Castle 2.5 Sheridan 1.7 Yellowstone Park 1.4

FIGURE A1.1 ■ (Continued) Rainfall rates.

OJ GO

[Birmingham, Alabama
[Anniston, Alabama	[Montgomery, Alabama
J^oents, AruonT
[Bentonville, Arkansas
‘Fort Smith, Arkansas
Mt. Tamalpais. California
Eureka, alifornia	.Fresno, California,
•Los Angeies, California
ft Reyes, California	■Red Sluft, Calilorni
.Sacramento, California,
.Sen Lois Obispo, California
‘San7rancfsco, California	San Jose, California
[Denver,
Minutes Duration

FIGURE A1.5 ■ Rainfall intensity-duration-frequency charts. (Courtesy of McGraw-Hill)

Grand Junction, Colorado1
-^Pueblo, Colorado	•Wagon Wheel Gap, Colorado	^Hartford, Connecticut
Jacksonville, Florida
1W ashing ton r D. C.	; Apalachicola, Florida
New Haven, Connecticut’
;Sand Key, Florida;
:Key West Florida
Pensacola, Florida
Macon, Georgia-
Augusta, Georgia
■Savannah, Georgia-	.Lewiston, Idaho,
■Thomasulfa, Georgia*
:Chicago, minors
.Pocatello, Idaho	Peoria, Illinois
■Evansville, Indiana
‘indlanapolis. Tndiana
;Fort Wayne, Indiana
ICharles City, Iowa’
;Des Moines, Iowa
davenport Iowa
; Keokuk, Iowa;	.Concordia, Kansas
Minutes Duration

Wichita. Kansas
«Podge City, Kansas’	■Topefcs. Kansas
Shreveport, Louisiana
^Lexington, Kentucky;	і Louisville, Kentucky	New Orleans, Louisiana
•Portland, Maine	.Baltimore, Maryland	■Boston, Massachusetts
‘Eastport, Maine
	■Detroit Michigan	-East Lansing, Michigan
;Alpena, Michigan;
•Escanaba, Michigan
■Grand Haven, Michigan	•Grand Rapids, Michigan	‘Houghton,
|Sault Ste. Marie, Michigan	Duluth, Minnesota.
[Marquette, Michigan
•Moorhead, Minnesota
[Minneapolis, Minnesota	]St. Paul,.Minnesota1	[Meridian, Mississippi
[Colombia, Missouri	Hannibal, Missouri	•Kansas City, Missouri
Vicksburg, Mississippi;
Missouri	‘яїоак.’Missouri
Minutes Duration

Miss dull, Montana
Каи spell, Montana
;Omaha, Nehraska!
;Lincoln, Nebraska	■North Platt», Nebraska
Atlantic City, New Jersey
.Winnenuicci, Nevada	■Concord, New Hampshire]
T re ntonNewTersoy
■SmghamtQ. n, New York
Fe, New Mexico
Oswego, ftewYoTk
.Rochester, New’York	-Asheville, North Caroline-	^Charlotte, North
■Raleigh, North Carolina
filming ton, North
Greensboro, North Carolina^
;&evils Lake, NorthDskota"
Bismarck, Norl

‘Cleveland, QbfO	■ Sandusky. Ohio
‘Columbus, Ohio
.Portland, Oregon
■Roseburg, Oregon	Erie, Pennsylvania	IHamsburs	Philadelphia, Pennsylvania
Шоск island Rhode Stand
Pennsylvania	Reading, Pennsylvania	[Scranton, Pennsylvania^
Greenville,’South СаюІівГ
■Columbia, South Carolina
‘Providenot, Rhode stand
Charleston South Carolina-
10
[Pierre, South D kota	■Yankton, Sou h Dakota’
Rapid City, South Dakota
[Chattanooga, Tennessee	■ Nashville, Tennessee1
•Knoxville Tennessee	; Mem phis, Tennessee;
■Amarillo, Texas-	[Brownsville, Texes
■ Corpus CbristJ, Texas —
Mmutes Duration

Fort Worth, Texas	.Galveston, Texas	Houston, Texas,
Palestine, Texas
San Antonio, Texas
Port Arthur, Texas
■Burlington, Vermont1	Northtield, Vermont —
Lynchburg. Virginia	Richmond. Virginia	-Wytheville, Virginia-
Seattle, Washington
.North Head, Washington.	/ort Angeles, Washington.	.Spokane, Washington.
Tacoma, Washington1	Walla Walla, Washington.	Yakima, Washington
;Green Bay, Wisconsin-	■la Crosse, Wisconsin’	•Madison, Wisconsin
Parkersburg, West Virginia
[f-M. ii wau’k ее, Wi7;	■ Sheridan. Wyoming’
-Cheyenne, Wyoming-
■Lander, Wyoming-
;San Juan, Puerto Rico;
-Honolulu, Hawaii
■Fairbanks. Alaska	Juneau, Alaska
Minutes Duration