The long-term performance of geocomposite sheet drains were monitored at three sites by measuring the effect of the drains on site groundwater hydrology during peak groundwater events. The study is on-going with a maximum record of 14 years at one site in the southern Sierra Nevada Range, CA.‍?Over a 3-year period, the drain at one site produced as much as 100 liters per minute with no rise in the water table just down gradient from the drain. The peak hydraulic gradient toward this drain consistently reaches 0.66 to 0.73 during major rainstorms and returns to a S2base levelS3 of 0.45 to 0.50 within 10 days after a storm peak.‍?At a second site, the drain flowed up to 15 liters per minute with no water table rise in a retaining wall fill down gradient from the drain. Performance of this drain was consistently favorable over a 14-year period with no deterioration. Limited data suggest that the drain discharge (liters per minute) is proportional to about 13 times the hydraulic gradient toward the drain.‍?At a third site, drain performance is limited by construction problems. A collapsed trench wall during drain placement caused an uneven drain slope toward the outlet. This is a common problem of trench drains at sites with a high water table. The problem could be greatly mitigated by returning to one of the pioneering geocomposite drain designs, the Eljen Drain, in which vertical sections of the drain are completely independent units that can be immediately dropped into a trench behind the excavator. Despite the construction problems, the drain is partially dewatering the road prism just down gradient, as seen by approximately 1.2 meters of groundwater drawdown beneath the road.

This research study focused on positive drainage of pavement structures. The open-graded base course concepts included non-stabilized, asphalt cement concrete (AC) stabilized and portland cement concrete (PCC) stabilized. Drainage systems included pipe in trenches, fin-type, pipe beneath transverse joints and retrofitted pipe. Non-drainage elements included 3.05 m (14 ft) wide driving lanes, and a 30.48 cm (12 in.) layer of "select embankment". Twelve projects were monitored, both portland cement concrete surface and asphaltic concrete surface. Measurement surveys included Pavement Distress Index (PDI), transverse joint faulting, International Roughness Index (IRI) ride quality, and coring at the transverse joints.

An investigation was conducted to evaluate prefabricated edge drain (PED) construction procedures and to assess the condition of PEDs installed in Ohio between 1988 and 1993. The research included a survey of department of transportation engineers in other states and Ohio Department of Transportation (ODOT) design and construction engineers. The condition of PEDs installed in Ohio was evaluated at six sites throughout Ohio by excavating short sections of PEDs for visual inspections and permittivity testing. A video borescope with a 25-ft (7.6-m) long fiber optic cable was used to investigate the in situ condition of the PED. Permittivity testing of the PED fabric was conducted in the field on PED samples removed from the excavations. Specifications for installing PED vary considerably among the states using PED. ODOT current specifications require placing the PED on the outside of the trench and using a granular backfill. Problems that have been reported include deformation of the PED core, compression of the filter fabric into the core, blinding and clogging of the filter, sedimentation of the core and blockage of drainage outlets. In most cases, the problems were considered minor. The problems cited above were observed at all six sites during the video borescope inspections. In spite of problems with the filter fabric, the permittivity of the filter fabric was not significantly reduced. The problems with PED result in reduced drainage capacity. However, the PEDs are effective in providing drainage provided the drainage outlets are not blocked. Construction specifications should be observed to minimize problems. Maintenance personnel should inspect drainage outlets on a regular basis to ensure that the outlets are not blocked.

Contains nine papers that were presented in the eponymously named, ASTM sponsored, conference held in Seattle, Washington, on June 29th, 1999. The papers are divided into treatments of field performance studies, pavement design and drainage, and testing, corresponding to the sessions of the symposium. Topics include cold-climate pavement drainage; performance-based specifications for highway edge drains; and tests of toe drain performance, transmissivity of geosynthetic drains, and clogging behavior. Annotation copyrighted by Book News, Inc., Portland, OR.