add_filter('wpali_distance_shipping_rate', 'wpali_add_base_price_to_rate', 10, 2);
function wpali_add_base_price_to_rate($rate, $obj)
{
    if (!empty($rate['meta_data']['value'])) {
        $meters = $rate['meta_data']['value'];
        $distance_in_km = $meters * 0.001;
        $distance_in_km = round($distance_in_km, 2);

        if ($obj->debugging == 'yes') {
            wc_add_notice('Distance in KM: <br />' . '
<pre>' . print_r($distance_in_km, true) . '</pre>', 'notice');
        }

        if ($distance_in_km > 10) {
            $price_per_km = $rate['cost'] / $distance_in_km;
            $cost_per_first_10km = 29;
            $cost_per_remaining_kms = ($distance_in_km - 10) * $price_per_km;
            $rate['cost'] = $cost_per_first_10km + $cost_per_remaining_kms;


            if ($obj->debugging == 'yes') {
                wc_add_notice('Price per KM: <br />' . '
<pre>' . print_r($price_per_km, true) . '</pre>', 'notice');
                wc_add_notice('Cost per remaining KMs: <br />' . '
<pre>' . print_r($cost_per_remaining_kms, true) . '</pre>', 'notice');
            }
        } else {
            $rate['label'] = 'Fixed distance rate';
            $rate['cost'] = 29;
        }
    }
    return $rate;
}