Postgres on Engineyard space at 100%, pg_xlog filled up with files

Question

I have a database that is growing rapidly. VERY rapidly. My /db directory is at 100% now, and there are a bunch of new files in pg_xlog.

My background is in Oracle and MySQL. I do not know what is going on with this database. I know that I need to hire a Postgres DBA quickly.

Is there anything in the immediate term that I can do to fix my issue? I notice that deleting data does nothing to mitigate my space issue.

Output from pg_settings is:

archive_command             /bin/true                       configuration file
archive_mode                on                              configuration file
archive_timeout             1min                            configuration file
checkpoint_segments         100                             configuration file
checkpoint_timeout          5min                            configuration file
client_encoding             UTF8                            session
DateStyle                   ISO, MDY                        configuration file
default_statistics_target   100                             configuration file
default_text_search_config  pg_catalog.english              configuration file
effective_cache_size        1358MB                          configuration file
hot_standby                 on                              configuration file
hot_standby_feedback        on                              configuration file
lc_messages                 C                               configuration file
lc_monetary                 C                               configuration file
lc_numeric                  C                               configuration file
lc_time                     C                               configuration file
listen_addresses            *                               configuration file
log_destination             csvlog                          configuration file
log_line_prefix             %m:                             proc=%p,user=%u,db=%d,host=%r   configuration file
log_min_duration_statement  2s                              configuration file
log_rotation_age            1d                              configuration file
log_rotation_size           100MB                           configuration file
logging_collector           on                              configuration file
maintenance_work_mem        128MB                           configuration file
max_connections             512                             configuration file
max_files_per_process       65535                           configuration file
max_stack_depth             6MB                             configuration file
max_standby_streaming_delay -1                              configuration file
max_wal_senders             5                               configuration file
port                        5432                            configuration file
search_path                 public, "$user", public         session
shared_buffers              424MB                           configuration file
temp_tablespaces                                            configuration file
wal_buffers                 8MB                             configuration file
wal_keep_segments           128                             configuration file
wal_level                   hot_standby                     configuration file
wal_writer_delay            200ms                           configuration file
work_mem                    32MB                            configuration file