protected function _purgeDeletedConditions($model, $expiration = '-90 days') {
		$purgeDate = date('Y-m-d H:i:s', strtotime($expiration));
		$conditions = array();
		foreach ($this->settings[$model->alias] as $flag => $date) {
			$conditions[$model->alias . '.' . $flag] = true;
			if ($date) {
				$conditions[$model->alias . '.' . $date . ' <'] = $purgeDate;
			}
		}
		return $conditions;
	}