48 • JUNE 2011 • FLORIDA WATER RESOURCES JOURNAL

Slick Solutions: Fairforest Grease& Septage Receiving Station

M. Steve Cavanaugh Jr. and Janet Hurley Cann

SpartanburgWater, a water andwastewaterutility in Spartanburg, South Carolina,began upgrading its FairforestWastewater

Treatment Facility in 1999.By 2007, PhaseVI ofthese upgrades was completed, including state-of-the-art screening, biosolids storage and han-dling, odor control, and instrumentation. Theentire facility was advanced with the exceptionof the grease and septage receiving system. The

existing system consisted basically of a “hole inthe ground” where haulers could discharge di-rectly to the plant headworks (Figure 1).

There were several issues with the simplesystem:1. The station received a high volume; on av-

erage the wastewater treatment facility re-ceived 40 loads of grease and 180 loads ofseptage per month.

2. The single “hole in the ground” was cum-bersome for haulers to use and resulted in atraffic jam of trucks at the treatment plantentrance, an inconvenience for the haulersand a nuisance for plant operations.

3. There was no treatment of the grease andseptage before they entered the processtrain, creating challenges to the balance ofthe facility and putting downstream treat-ment components at risk of damage.

4. A cumbersome record-keeping system pro-vided a large margin of error in treatmentfacility influent records. Spartanburg Waterhas a rebate program in place that appliesto residences inside the Spartanburg Sani-tary Sewer District service area where pub-lic sewer service is not available. Althoughthis is a great service for residents with nopublic sewer availability, the record-keep-ing system placed an added strain on thewastewater treatment facility staff.

Spartanburg Water officials felt stronglythat these shortcomings must be addressed inorder to protect their investment in the Fair-forest Wastewater Treatment Plant.

The Solution

Spartanburg Water retained the servicesof Cavanaugh & Associates, P.A., to investigateoptions for a more efficient grease and septagereceiving station. Working together, the Spar-tanburg/Cavanaugh team brainstormed con-cepts for the perfect station, which wouldinclude:1. Separating grease and septage.2. Providing pretreatment before integration

into the plant process train.3. Providing better metering, control, and

record keeping.4. Allowing for multiple integration locations

of grease and septage.

Steve Cavanaugh Jr., P.E., is the founderand president of Cavanaugh & Associates,a engineering, surveying, and utility serv-ices firm headquartered in Winston-Salem,North Carolina. Janet Hurley Cann, P.E., isa project manager with SpartanburgWater, a utility which operates the Spartan-burg (South Carolina) Water System andthe Spartanburg Sanitary Sewer District.

Figure 1: OriginalGrease and SeptageReceiving Station

FLORIDA WATER RESOURCES JOURNAL • JUNE 2011 • 49

5. Moving traffic away from the wastewatertreatment plant entrance.

6. Providing multiple discharge points to al-leviate traffic jams.

The final design exceeded these basic needs.Using an existing side entrance to the plant andvacant real estate within the fenced area of thefacility, a three-bay receiving station was sited(Figure 2). The main components of the designare highlighted in the following sections.

SSttaattiioonn AAcccceessssiibbiilliittyy && CCoonnvveenniieenncceeThe concept for the layout of the drive and

roadway system was to create a separate ingressand egress into the plant, along with sufficientmobility so that haulers can drive in, circle theseptage and grease storage tank, and select anavailable discharge bay. Where possible, the exist-ing paved area was used; where necessary, heavy-duty paving was installed except in the baysthemselves, where concrete pads were poured.

UUnnllooaaddiinngg BBaayyThe three unloading bays provide truck

drivers with a secure connection of the truck dis-charge pipe to a four-inch Kamlok Quik Dis-connect. The disconnect is located in the sumpadjacent to the drain gate, which is depressed toallow for a full tanker drain. Both the bay draingrate and the pipe connection sump are drainedto the structure drain sump-and-pump stationthat returns the flow to the plant headworks area.

The unloading bays are covered by alighted canopy. It is equipped so that the Spar-tanburg Sanitary Sewer District may allow for24-hour load delivery if necessary in the future.Currently haulers unload from 6 a.m. to 6 p.m.

AAuuttoommaatteedd FFllooww CCoonnttrrooll aanndd RReeccoorrdd KKeeeeppiinnggThe driver swipes a Dallas key and enters

the load type (septage or grease) and locationinformation. Upon receiving input on the loadtype, a three-way selection plug valve, drivenby an electric actuator, selects the correspon-ding pipe position to either septage or grease.Load flow is delivered once the hauler manu-ally opens the truck valve. The flow is thenlocked out until the appropriate sequence andidentification are obtained.

Flow is measured by a bullet-nosed magmeter upstream of the three-way plug valve,which is elevated above the Quik Disconnectvault to ensure a full pipe for appropriatemeasurement. Also, the controls software hasthe ability to print load information for thehauler and track actual gallons delivered forfurther analysis by Spartanburg Water. Thehauler also receives a printed receipt.

CCoonnttrroollss//RReebbaattee IInntteeggrraattiioonnThe former system for implementing the

rebate system was antiquated and cumbersomefor treatment plant staff. When a hauler deliv-

ered a load, he provided the location address tothe Spartanburg Water. The address was veri-fied by hand against a map at the plant to makesure the residence was eligible for the rebate. Aletter was then generated manually and for-warded to the resident, with hard-copy reportsprovided to the accounts payable departmentto generate the rebate.

The new system, developed by Avid Solu-tions, is fully automated with touch screensand easy-to-use features. County tax informa-tion is integrated into the programming, elim-inating the need to verify the address against ahard-copy map on the wall. Letters are gener-ated automatically to residents who are quali-fied for the rebate, and the systemcommunicates directly with the finance de-partment. The new control system generatesreports for review and management purposes.

DDiisscchhaarrggee RRoouuttiinnggThe hauler indicates the type of discharge

he is delivering at the bay. The automated three-way plug valve directs the flow to either greaseor septage piping, where it flows by gravity tothe appropriate screening area. The septage isscreened before continuing to the septage wetwell, which is sized to handle approximately3,000 gallons (just over one truck load).

Flow is pumped into the septage holdingarea of the storage tank. At the completion ofthe septage dump cycle, a solenoid valve opensand delivers hot water to flush the open linefollowing load delivery. The parallel system forgrease operates in the same manner.

SSccrreeeenniinnggThe screening station handles septage and

Figure 3: Unloading Bay

Figure 2:Grease &Septage Receiving Station Layout

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grease independently (Figure 4). A HydrodyneScreen (Model # HF26-18-117-6L) was se-lected for this application. The flow passes intothe screen and is diverted through a grid oneach side of the unit. The unit has stainlesssteel elements that separate solids and conveyscreenings out of the channel.

At the top of the unit, a hot-water spraywashes the solids into the screenings washerand compactor. Organics and wash water arereturned to the channel, while solids are con-veyed to the dumpster area. Although both theseptage and grease screens are equipped withtheir own wash system and compactor, thereis a common conveyer to the dumpster. Allscreenings are bagged before dropping into afull-length, roll-off dumpster.

SSeeppttaaggee && GGrreeaassee HHoollddiinngg TTaannkkThe holding tank is a Crom prestressed

concrete tank with a dome cover to preventodors from developing in the storage of thegrease and septage (Figure 5). The tank size of600,000 gallons (344,000 gallons for septageand 66,000 gallons for grease) was appropri-ate, based on historic load data (1,981 loads ofseptage and 441 loads of grease).

SSeeppttaaggee TTaannkk MMiixxiinnggThe prestressed concrete tank is equipped

with appropriate inlet and outlet connectionpoints constructed for the septage and greasestorage tanks. A plug valve controls flow fromthe septage holding area back to the wet wellfor recycle into the tank. This recycle is aug-mented by submersible mixers. All piping isrouted beneath the tank floor.

GGrreeaassee TTaannkk MMiixxiinnggSimilar to the septage tank mixing, grease is

also mixed through recycle using the pumping

system with augmented mixing. Grease flowsback to the grease wet well and is controlled bya plug or pinch valve. Flow and piping isarranged from the wet well to provide completewet well drainage and recirculation for cleaning.GGrreeaassee TTrreeaattmmeenntt && DDiissppoossaall

There is a separate hot-water recircula-tion system located at the exit end of the greasescreening chamber that is engaged after theload delivery is started. Hot water liquefies anysolidified grease and flushes the lines. The ul-timate fate of grease options are:1. Delivery to the plant digester.2. Delivery to the load station for loading and

delivery for beneficial reuse.3. Delivery to the head works of the plant.

Construction Schedule

OOrriiggiinnaall sscchheedduullee::� Notice to Proceed—July 6, 2009

Figure 4: Screening Area

Figure 5: Holding Tank

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FLORIDA WATER RESOURCES JOURNAL • JUNE 2011 • 51

� Substantial Completion—January 4, 2010� Readiness of Final Payment—March 6, 2010

CCuurrrreenntt sscchheedduullee::� Notice to Proceed—July 6, 2009� Substantial Completion—March 11, 2010� Readiness of Final Payment—May 12, 2010

Several circumstances impacted the con-struction schedule for the project. First, aftera 10-year drought, the flood gates opened andthe drought ended, resulting in multiple raindelays. Second, as with most existing treatmentplant sites, there were unforeseen under-ground obstacles. On the chosen receiving sta-tion site, the team dealt with typicalbrownfield conditions, bad subsurface condi-tions, and debris, including the remnants ofan abandoned digester.

The Budget

The original project estimate, developedin 2007, was $1.8 million. The project is nowcomplete (see Figures 6, 7, and 8). Consider-ing a few unknowns as stated above and costeffective modifications to the automation ofthe station, the current construction cost issummarized in Table 1.

Project Benefits

� SStteewwaarrddsshhiipp ooff RReessoouurrcceess – After investingmillions in the Fairforest Wastewater Treat-ment Plant upgrade, the development ofthis grease and septage receiving stationprotects that expenditure.

� SSeeppaarraattiioonn ooff GGrreeaassee && SSeeppttaaggee – By sep-arating grease and septage, operators havemore control. Grease can be eliminatedfrom the process train altogether by eithersending it to the digester or hauling it to thelandfill.

� HHaauulleerr AAccccoouunnttaabbiilliittyy – The automationof the new receiving station provides moreaccurate record keeping.

� HHaauulleerr AAcccceeppttaabbiilliittyy – The three-bay sys-tem eases traffic jams by allowing multipledischarges at one time, thus making it eas-ier for haulers to access.

� FFiinnaall FFaattee OOppttiioonnss – Operators have morecontrol over when, where, and at what rategrease and septage are introduced into theplant.

� MMaakkee IItt EEaassyy ttoo PPrreevveenntt EExxtteerrnnaall DDuummppss– Eventual 24-hour access to a state-of-the-art receiving station makes it easy to “do theright thing.”

� EEaassyy aanndd SSeeppaarraattee AAcccceessss – Moving the re-ceiving station away from the wastewatertreatment plant entrance and designing itfor smooth traffic flow to ease congestionand confusion.

Lessons Learned

CCaannooppyy FFoooottiinnggThe extent of the footing for the canopies

was underestimated. At the shop drawingstage, it was learned that canopy footings were

four feet by four feet by four feet to accom-modate wind load, etc. There was conflict rel-ative to the actual placement of these footings;however, an adjustment was made during thecourse of the submittal and shop drawing

Figures 6 & 7: The Completed Unloading Area

Figure 8: Completed Grease & Septage Storage Tank

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process to modify to a cantilevered canopythat would be accommodated more easily inthe bay area.

LLiigghhttiinnggDuring the course of construction, the re-

strike sequence was evaluated closely. It wasdetermined that the amount of time betweenhaulers entering the facility and lights movingto full luminosity should be minimized.

H i g h e r - e f f i -ciency lightingwith lower re-strike times wasselected duringthe shop draw-ing and submit-tal process.

MMoovviinngg tthhee TTaannkkDur-

ing the pre-bidmeeting, it wasdetermined that10 to 14 workingfeet were neededcircumferentiallyaround the pre-stressed concrete

tank. The tank was moved for the appropriateadjustment and ease of construction while theproject was still out for bids.

ppHH PPrroobbeeInitially pH probes were designed for the

facility; after the start of construction, it wasdetermined that the maintenance and theharsh environment for these pH probes werenot the right application. These were deletedfrom the overall process.

TTiimmiinngg MMaatttteerrssAt the outset of construction, the schedule

was very aggressive. It is important to note thatweather delays and ongoing construction anddelivery schedules must be managed proac-tively; flexibility for unforeseen conditions at abrownfield site (buried concrete, unsuitablematerial, etc.) should have been expected.

TTeeaamm//IInnssppeeccttoorr CCoommppeetteennccyyThe strongest asset for moving this proj-

ect forward was the manner in which the part-nership was established among the contractor,the engineer, the owner, and the owner’s rep-resentatives. This partnership was a model ofhow to do a project and work through in-clement weather conditions, changes in thefield, and cost-effective end results.

Conclusion

The Spartanburg Water septage and greasereceiving station has proven to be an innova-tive, unique system employing three dischargebays and a unique separation system. The $1.6-million facility provides a valuable service toSpartanburg Water customers and promotesenvironmental protection and consciousness byproviding a safe, convenient, easy method forseptage and grease disposal. ����

Table 1: Construction Costs

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