4 - Initial Risk Assessment / Forest Road Drainage Installation Practices in the Pacific Northwest

Forest Road Drainage Installation Practices
in the Pacific Northwest

4 - Initial Risk Assessment	Step-By-Step Assessment, Hazard, Consequence

Risk assessment in general means to assess the Hazard of an event to take place, then to look at the Consequence of the event if it took place. Combining hazard and consequence will result in a Risk Rating. This assessment looks at risks to water quality for fisheries and domestic water uses. Follow the step-by-step risk assessment below.

1) Hazard Rating: from the table below, determine the potential sediment hazard from overburden.

Hazard Table: Potential Sediment Sources connected to the crossing
Hazard:	Low	Moderate	High
Description:	Rock; thin rubbly or	Intermediate	Deep, fine-textured or noncohesive overburden cohesive overburden (OB)

2) Consequence Rating: from the table below, determine the consequence if sediment is introduced to the watercourse. A high consequence is where sediment generated at the site quickly reaches a fish-bearing channel or water license diversion; low consequence is a site that is not hydraulically connected to a fish-bearing stream or a water license intake.

Consequence Rating for Water Supply & Fish Habitat
Low	Moderate	High
Areas not hydraulically connected to fishbearing waters or to waters being lawfully diverted or utilized under the Water Act.	Areas hydraulically connected to downstream fish-bearing waters or to waters being lawfully diverted or utilized under the Water Act but sufficiently buffered or diluted to maintain suspended sediment levels at or below CDWS* at the point of diversion or use.	Areas hydraulically connected to waters being lawfully diverted or utilized under the Water Act but not sufficiently buffered or diluted to maintain suspended sediment levels at or below CDWS* at the point of diversion or use, or where there are fish on site or a short distance downstream.

* Canadian Drinking Water Standards

3) Risk Rating: from the table below, determine the risk by combining hazard and consequence determined above. A high hazard and a high consequence will result in a very high risk rating.

Risk Table	Hazard
Consequence	Low	Moderate	High
Low	L	L	M
Moderate	L	M	H
High	M	H	VH
	Risk

Layout engineers should "risk rate" proposed crossings during site selection. If the initial risk rating is moderate, high or very high, a revised risk assessment should be done to determine possible measures to reduce the initial risk. If additional measures can not reduce the risk to a level appropriate for the environmental risks, a different stream crossing site may have to be selected. If in-stream work is required and fish are on-site, drainage structures should be built inside fisheries windows. Remember that fisheries windows refer to the time frame with the "lowest risk" to fish populations; therefore, sediment generation must still be controlled. In-stream work outside the fisheries window requires the approval of the appropriate agencies. Fish removal and stream diversions etc., may be required.

Before installation work begins, the layout engineer and the construction supervisor should review the risk rating with machine operators.

4 - Initial Risk Assessment