After the landscape timbers are tied together and staked in as one sturdy unit, we shift to the grade they enclose. We want to allow any water to easily escape the 3 foot wide walkway. The entire walkway is pretty level as it sets, so we set up the laser level and carefully cut a shallow trench right in the center of the walkway. The trench is the the width of a shovel and gently slopes to either side from the center of the back wall, then continues to slope to the front at both sides. Landscape fabric is laid in and 4" perforated drain pipe is laid into the trench. River rock completes the system.