Agenda - 05-22-1989 - Laserfiche WebLink

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, EFFLUENT PUMPING For maximum corrosion resistance. EQUIPMENT FOR . the discharge piping, junction box PRESSURE SEWERS and shutoff valve are made of plastic materials.Mercury ball level controls In grinder pump pressure sewer are standard.Some engineers speci- systems there has been only one size fy a redundant check valve to be 10- centrifugal grinder pump (2 hp) avail- cated in service line for added able for installation at the individual protection. An anti-siphoning valve home. However, in a STEP pressure is added to the internal piping if low sewer, the engineer can choose from heads or negative heads (downhill a variety of horsepowers and sizes. runs) are expected to prevent any STEP pumps can be 1/3, .4, 1/2, 1, siphoning action. In most cases, the . 1-1/2 and 2 hp, depending on the cover is made of steel so that it can head and flow requirements.The per- - . withstand the weight of a riding lawn formance, weight, and cost of the mower. Pump basin covers are nor- STEP pumps increase as . horse- many installed flush with the ground power increases. The STEP pumps level. An anti-flotation flange held that are available are basically sump by concrete is provided to prevent pumps, small hp sewage ejectors or the basin from moving upward in modifications thereof. highwater table areas. One of the drawbacks of currently . available STEP pumps is that they • generate much higher flows than PERFORMANCE needed. As an example, a 1/2 hp Since STEP pumps are pumping a STEP'pump can generate up to 80 gpm with shut off heads to 78 feet. clarified liquid from a septic tank. Since the peak wastewater flow there is usually very little problem generated from an average individual with the pump plugging.The risk of home is no more than 8-15 gpm, plugging is greater if an old septic you can see that the flow rates are much tank is used which is generating higher than needed. The high flow ohveearvysoflioidwssdaunedtopoinssfiiibtrlyatsioonm.e carry rates make it more difficult to hydrau- over solids due to infiltration. lically design a pressure sewer and t At one time, it was assumed that will increase pipe sizes. In addition, the high flow rates of the standard a high percentage of old septic tanks effluent pumps can create problems could be utilized as part of a STEP when discharging into a variable pressure sewer.Now,the consensus gravity sewer system. of opinion is that the majority of old septic tanks should be replaced with new ones.One of the problems Septic tanks can be made of fiber- in using old septic tanks is the ques- glass,polyethylene or concrete.Con- tion of how do you determine if the Crete is the most readily available, tank is leaking. By the time you The most common size used is 1000 . pump out the septic tanks, find the gallons,although 500 and 750 gallon leak and repair it (assuming this can size tanks have been used in some be accomplished), it may be less pressure systems. In commercial expensive to put in a new septic tank. applications, larger size septic tanks will be required. Two potential problems associated with STEP systems are corrosion Variations of an audio and visual and odors.'AS previously indicated, alarms are used, although the most . . corrosion can be overcome by popular and cost-effective is a red _ choice of materials.Since the septic flashing alarm light mounted on con- tank is vented through the house trol panel. Most all control panels plumbing system,no outside venting with a disconnect switch are located is required. Care must be taken to outside so they will be easily acces- . insure the cover to the wet well is sible to the serviceman. The prefer- sealed properly. Odors can be a able location of the panel and alarm problem at intermediate pump sta- is on the side of the home or garage tions if vented to atmosphere. This to minimize aesthetic concerns of can be solved by installing an under- the home owner. If desired, the ground venting system. panel can be located at the septic • tank/pump basin and mounted on a . pedestal. ....._...._.__;. 3 CRAIG S.MORGAN AND ASSOCIATES,R:A....----," 1:1232=5=11.11,