PREDL Systems and BOSSales worked with Ghilotti Con-struction, GHD Engineering, Jensen Precast, and the City of Rohnert Park to submit a Value Engineering proposal that exceeded the specified requirements of the original bid. Jensen Precast, Sacramento, CA manufactured the lined MH structures.

Background

A few years ago Rohnert Park started a plan to rebuild ex-isting MHs that required rehabilitation. I&I was a costly is-sue because another jurisdiction was paid a per gallon fee to process sewage at a regional wastewater treatment plant. Flow meter results indicated spikes associated with storm events and possibly other non-event ground water infiltration issues. Concrete corrosion in MHs due to H2S gas was a chronic issue that needed to be addressed.

PREDL Systems’ Solution

The submitted solution addressed overall cost, I&I control, and protection against concrete corrosion. Installation com-plexity was substantially reduced providing lower costs and shorter timeline for the total project. The final submittal pro-posed an entire concrete MH structure fully lined with FRP (Base) and PP (Barrel, Cover and Collar) components.

PREDL’s proposal supports the 24” DR25 C900 PVC pipe within a 48” instead of 60” MH structure. This reduced con-struction costs without compromising access and structural integrity. PREDL’s FRP Bells are fully integrated with the one-piece molded custom built MH Base Liner. Compres-sion gaskets provide a watertight seal between the Base Liner and pipe system. This design has been proven to control I&I for over 25 years in the sanitary sewers of com-parable utilities. The MH barrels will be lined with PP to pro-

tect the concrete structure from the known corrosive effects of H2S (Hydrogen Sulfide) gas and MIC (Microbial Induced Corrosion). Joints between sections will be sealed with bu-tyl, cap strips and plastic extrusion welds.

All PREDL Liner System products are mechanically bonded to the concrete during the precasting process. The MH Base Liner flow channels are manufactured with exact fac-tory precision to align with the required pipe size, inlet an-gles and elevations. The smooth non-porous flow channels help eliminate H2S gas produced by turbulence.

Accepted Value Engineering Proposal for Rohnert Park, CA.

T H E M A N H O L E L I N E R E X P E R T S

predlsystems.com 1.855.773.3562

Original Proposal PREDL Systems

Value Engineering Proposal

1. SHOP WELD HDPE BOOT FLANGE TO HDPE LINER ON MANHOLE ID. (TYP).

2. MIN. OF ONE 3” HDPE GRADE AND ADJUSTMENT RING. MAX. OF ONE 1/4” HDPE GRADE RING.

3. SEAL BARREL SECTIONS IN PLASTIC BASKET, RAM-NEK APPROVED ALTERNATIVE. TYPICAL JOINT USE (2) 1/4” X 2 1/2” RAM-NEK SEALS.

4. SHOP APPLY 1/4” THICK POLYMER CONCRETE OVER TOP OF CONCRETE BENCH. TROWEL SMOOTH AND SLOPE TOWARDS U-SHAPED CHANNEL.

5. AFTER LOWER RING SECTION IS SET, CUT OUT TOP HALF OF PIPE FLUSH WITH INSIDE FACE OF M.H. WALL AND CONSTRUCT SHELF AND U-SHAPED CHANNEL. MAKE ELEVATION CHANGES GRADUALLY AND DI-RECTIONAL CHANGES WITH SMOOTH CURVES. SLOP AND SIZAE OF CHANNELS SHALL MATCH UPSTREAM AND DOWNSTREAM PIPES. MAN-HOLE CHANNELS SHALL MATCH THE SLOPE OF THE PIPE.

6. PROVIDE COUPLING (TYP) PER SPECIFICATIONS. WRAP COUPLING WITH 50 ML CORROSION TAPE.

7. CAST PVC INLET/OUTLET STUB-OUTS INTO PRE-CAST MANHOLE BASE, OR BARREL SECTIONS (TYP.) FILL AND ANNULAR VOIDS WITH NON-SHRINK GROUT.

8. OVERLAP HDPE LINER 6” MIN. (TYP.) FIELD WELD OVERLAPPED SEC-TIONS.

9. PRE-CAST MANHOLE BASE AND BARREL SECTIONS WITH INTEGRAL HDPE LINER.

10. GLUE HDPE B OOT TO PVC STUB-OUT (TYP).

11. VERIFY INLET/OUTLET ELEVATIONS AND ORIENTATION BEFORE ORDER-

ING PRECAST PRODUCTS.

12. INSTALL EXTERNAL JOINT SEAL AT ALL BARREL CONNECTION SEC-TIONS.

13. PROVIDE DUAL SST STRAPS OVER HDPE BOOT TO SECURE BOOT (TYP).

14. CUT AND REMOVE ANY EXCESS PVC INSIDE MANHOLE WITHOUT DIS-TURBING HDPE BOOT FLANGE.

15. WELD HDPE LINER TO HDPE GRADE RING (TYP).

16. TRIM BOTTOM OF FIRST HDPE GRADE RING TO SIT FLUSH ON MH SLAB.

17. SPARK TEST PER SPEC. (TYP).

18. VACUUM TEST RING JOINTS PER SPEC. (TYP).

19. TAPE WRAP HDPE GRADE RING JOINTS WITH 50 ML CORROSION TAPE (TYP).

20. APPLY SEALANT BETWEEN FRAME AND GRADE RING (TYP).

48” PREDL Lined Precast MH Base 60” or 72” Diameter Precast Concrete

Sanitary Sewer Manhole

ALL TASKS WITH STRIKE THROUGH INDICATES WAYS IN WHICH TIME AND COSTS WERE REDUCED WITH PREDL’S VALUE ENGI-NEERING PROPOSAL. THESE STEPS TYPICALLY DONE AT THE JOB SITE ARE COMPLETED IN ADVANCE WITH FACTORY PRECI-SION DURING THE FRP BASE LINER MANUFACTURING PRO-CESS. ADDITIONAL COST SAVINGS WERE REALIZED WHEN THE REQUIRED SIZE OF THE MH WAS REDUCED FROM A 60” TO A 48” STRUCTURE AS RESULT OF USING PREDL’S PROTECTIVE POLY-

MER LINER PRODUCTS..